Taro: A Review of Colocasia esculenta and Its Potentials 9780824887612

Citation preview

TARO

TARO

A REVIEW OF COLOCASIA ESCULENTA AND ITS POTENTIALS

Edited by

Jaw-Kai Wang with the assistance of

Sally Higa

UNIVERSITY OF HAWAII PRESS Honolulu

© 1983 University of Hawaii Press All rights reserved Manufactured in the United States of America

Library of Congress Cataloging in Publication Data Main entry under title: Taro, a review of Colocasia esculenta and its potentials. Bibliography, p. Includes index. 1. Taro. I. Wang, Jaw-Kai, 1 9 3 2 . II. Higa, Sally. SB211.T2T37 1983 635'.2 82-21903 ISBN 0 - 8 2 4 8 - 0 8 4 1 - X

Contents

Figures Tables Foreword Acknowledgements I.

GENERAL BACKGROUND 1. Introduction Jaw-Kai Wang 2. Taxonomy of the Genus Colocasia Donald L. Plucknett 3. Anatomy and Morphology of Taro Colocasia esculenta (L.) Schott Michael S. Strauss 4. Physiology and Phytochemistry Leslie A. Sunell and Joseph Arditti

vii xi xvii xix 1 3 14

20 34

5. Nutritive Value Bluebell R. Standal

141

6. Acridity of Taro and Related Plants in Araceae Chung-shih Tang and William W. Sakai

148

II. PRODUCTION TECHNOLOGY 7. Agronomy Ramon S. de la Pena

165 167

8. Pests of Taro Wallace C. Mitchell and Peter A. Maddison

180

9. Taro Diseases Jeri f. Ooka

236

vi

Contents

III. UTILIZATION 10. Processed Food fames H. Moy and Wai Kit Nip

259 261

11. Animal Feed James R. Carpenter and William E. Steinke

269

12. Industrial Uses Gerald J. L. Griffin and faw-Kai

301 Wang

IV. PLANNING AND DEVELOPMENT 13. Production Systems Planning faw-Kai Wang and William E. Steinke

313 315

14. Socio-Economic Aspects of Taro as Food Gary R. Vieth and Fen-Fen Chang

346

15. Production Management Considerations faw-Kai Wang

355

Afterword Contributors Literature Cited Index

359 361 367 395

Figures

2.1 A general view of the taro plant. 3.1 Scanning electron microscope view of a transverse section of a taro leaf. FIGURE 3 . 2 Underside of a taro leaf showing prominent leaf enations. FIGURE 3 . 3 Meristem of a taro showing encircling petiole bases. F I G U R E 3.4 Periderm layers of Colocasia esculenta x 400. F I G U R E 3.5 Pollen grain of taro, Colocasia esculenta. F I G U R E 3.6 Seed of taro showing prominent ridges as well as the funiculus and hilum. FIGURE 3.7 Development of taro seedlings. F I G U R E 3.8 Development of leaves of taro seedlings. F I G U R E 4.1 Phosphorus concentration in the corms of two taro varieties as influenced by the concentration of phosphorus in the culture solution. FIGURE 4.2 Dry weight of taro plant parts as a function of fertilizer levels. FIGURE 4 . 3 Total and reducing sugars in taro plant parts as a function of nitrogen and potassium levels. FIGURE 4 . 4 Starch levels in taro corms as a function of nitrogen and potassium levels. F I G U R E 4.5 Photosynthesis in taro. F I G U R E 4.6 The amino acid sequence of taro ferredoxin compared with those of spinach, alfalfa, L. glauca, and Scenedesmus. F I G U R E 4.7 Evolutionary scheme of alfalfa, L. glauca, Scenedesmus, spinach, and taro. FIGURE 4 . 8 Inflorescence fruit, seed, and seedlings of taro and their parts. FIGURE FIGURE

19 22 24 25 26 28 30 31 32 38 40 42 43 44 46 47 48

viii

List of Figures

Stepwise diagram of purifying calcium oxalate crystal (needle form) from taro tissue. F I G U R E 6.2 Mass spectra of 5-hydroxymethyl fufural (HMF) isolated according to Suzuki (1969). FIGURE 6 . 3 Gas chromatograms of the typical co-distilled volatiles of taro corm CH2C12 extract. FIGURE 7.1 Lowland taro planted in raised beds. FIGURE 7.2 In most South Pacific islands, upland taro is planted in a hole made with a wooden stick. FIGURE 7.3 A single-row planter being adapted for mechanical planting in upland taro. FIGURE 7 . 4 Taro planting sett, called " h u l i " in Hawaiian, is prepared from the main plant or sucker. FIGURE 7 . 5 Harvesting is accomplished by loosening the corms with a metal pipe inserted between the main corm and cormels or suckers. F I G U R E 7.6 Planting setts being prepared at the time of harvest. F I G U R E 7.7 Harvested corms and cormels in buckets on an improvised raft or boat pulled to the side of the field where the corms are placed in bags. FIGURE 7-8 Taro leaves and petioles at maturity; the main corms and some cormels become visible as they push out of the soil surface. F I G U R E 9.1 Phytophthora leaf blights. FIGURE 9.2 Phyllosticta spot. F I G U R E 9.3 Cladosporium leaf spot. FIGURE 9.4 Taro soft rot. FIGURE 9.5 Southern blight. FIGURE 9.6 Black rot. FIGURE 9.7 Rhizopus soft rot. FIGURE 9.8 Dasheen mosaic. FIGURE 9.9 Hard rot of taro. FIGURE 9.10 Glyphosate (Roundup) injury. FIGURE 9.11 Lime-induced chlorosis in coral soils. FIGURE 11.1 Typical cross-sectional view of trench silo. FIGURE 11.2 Lactic acid levels and pH's of Lehua leaves during 30-day fermentation period. F I G U R E 12.1 Plot of melt flow index ( M F I ) against starch mean particle size for blends of 30 phr starch in low density polyethylene. F I G U R E 6.1

154 160 162 169 170 171 172

176 177

178

179 241 243 244 246 248 249 250 252 255 256 257 277 280

308

List of Figures Effect of added filler on the viscosity of a paper cooling plasticol. FIGURE 13.1 Yield function for wetland taro kg/ha harvested during bi-weekly period shown. FIGURE 13.2 Schedule of activities within each planting of paddy taro. F I G U R E 13.3 Type I schedule of crops (each crop consists of four successive growth cycles). F I G U R E 13.4 Type II schedule of crops (each crop is one growth cycle). FIGURE 1 3 . 5 Paddy taro harvest, kg/period, type I resource availability. F I G U R E 13.6 Paddy taro harvest, kg/period, type II resource availability. FIGURE 13.7 Labor demand per period, type I resource availability. F I G U R E 13.8 Labor demand per period, type II resource availability. F I G U R E 13.9 Machine demand per period, type I resource availability. F I G U R E 1 3 . 1 0 Machine demand per period, type II resource availability. F I G U R E 13.11 Land use pattern. F I G U R E 13.12 Integrated taro food, fuel, and feed production system.

ix

FIGURE 12.2

309 318 322 324 325 327 327 329 330 330 331 331 336

Tables

Number of Countries, Area, and Production of Roots and Tubers in Asia, Africa, and Oceania during 1974 T A B L E 1.2 Recent Trends in World Production of Taro T A B L E 1.3 Root Crop Distribution on a Climatic Basis T A B L E 1.4 Mean Annual Production Figures for Taro for the 1 9 6 5 - 1 9 7 4 Period TABLE 1.5 Proximate and Mineral Analysis of Leaves and Petioles of Taro T A B L E 2.1 Relationship Between the Characteristics of Taro Varieties and Their Chromosome Composition T A B L E 3.1 Comparison of Distribution of Stomata on Adaxial Surfaces of Colocasia esculenta with other Genera T A B L E 4.1 Water Relations of Taro T A B L E 4.2 Effects of Calcium on Dry Weight and Cormel Number in Taro TABLE 4.3 Concentrations of Minerals in the Dry Matter of the Third Leaf of Taro Plants Provided with Different Amounts of Potassium T A B L E 4.4 Concentration of Macroelements in the Dry Matter of Taro Roots at Harvest Time TABLE 4.5 Concentrations of Macroelements in the Dry Matter of Taro Corms at Harvest Time T A B L E 4.6 Effects of Potassium Fertilization on Composition of Upland Taro Leaves T A B L E 4.7 Effects of Potassium Fertilization on Composition of Lowland Taro Leaves TABLE 1.1

6 7 8 9

12 18 23 56 57

58 60 61 62 63

xii

List of Tables

4.8 Effects of Nitrogen Fertilization on Composition of Upland Taro Leaves T A B L E 4.9 Effects of Nitrogen Fertilization on Composition of Lowland Taro Leaves TABLE 4.10 Effects of Phosphorus Fertilization on Composition of Upland Taro Leaves TABLE 4 . 1 1 Effects of Phosphorus Fertilization on Composition of Lowland Taro Leaves TABLE 4 . 1 2 Phosphorus Concentrations in Leaf Blades of Three Cultivars of C. esculenta as Affected by Phosphorus Levels in the Soil TABLE 4 . 1 3 Nutrient Levels in Leaf Blades and in the Corms at Harvest Time of Three Varieties of C. esculenta Maintained in 0 . 0 1 2 ppm Phosphate Solution TABLE 4.14 Composition of Petioles and Blades of Individual Leaves of Six-Month Old Taro Plants Grown in Pots TABLE 4.15 Nitrogen, Phosphorus, and Potassium Content of the Roots and Corms of Six-Month Old Taro Plants Grown in Pots TABLE 4 . 1 6 Contents of Nitrogen in Taro Plants T A B L E 4.17 Amino Acid Composition of Taro Ferredoxin TABLE 4 . 1 8 Molar Extinction Coefficients of Plant Ferredoxins TABLE 4 . 1 9 Effects of Morfactin, Coumarin, and Gibberellic Acid on Sprouting of Setts of Colocasia esculenta TABLE 4 . 2 0 Effects of Radiation on Mutation in Colocasia esculenta T A B L E 4.21 Seed Weight and Germination in T a r o T A B L E 4.22 Germination of Taro Pollen TABLE 4.23 Effects of Gibberellic Acid (GA) on Flowering of Taro TABLE 4.24 Germination of T a r o (Colocasia esculenta var. antiquorum) Seed After Various Periods Under Different Storage Conditions TABLE 4.25 Germination of Taro Seeds TABLE 4.26 Treatments Used to Induce Multiple Plantlet Formation in Seedlings of Colocasia esculenta var. esculenta T A B L E 4.27 Effects of Storage Conditions on Taro Corms TABLE 4.28 General Composition of Taro TABLE 4.29 Protein and Amino Acid Content of Taro TABLE 4.30 Vitamin Content of Taro T A B L E 4.31 Mineral Content of Taro TABLE

64 65 66 67

68

69 70

71 72 74 75 76 78 79 80 81

82 83 85 88 89 107 130 132

List of Tables TABLE 4 . 3 2

xiii Pigments, Alkaloids, and Oxalic Acid Content of

Taro 4.33 Fatty Acid Content of Taro T A B L E 4.34 Sterol Content of Taro T A B L E 5.1 Nutrient Composition of Corms, Petioles, and Tender Leaves of Taro T A B L E 5.2 Amino Acids and Protein Quality of Taro Corms T A B L E 5.3 Nutrients in Raw and Cooked Tahitian Taro 'Belembe' T A B L E 5.4 Oxalic Acid Content of Parts of the Taro Plant T A B L E 6.1 Weight Gains and Food Intake of Weanling Male Rats Fed Diets Containing 50 Percent Taro or Specific Fractions of Taro T A B L E 6.2 Results of Preference Test of Taro Leaf Diet, Silaged Taro Leaf Diet, and Standard Diet on Swiss Webster Mice T A B L E 6.3 Results of Preference Test of Taro Leaf Diet at 2.5 Percent and 1 Percent Levels and Ethanol Extracted Taro Leaf Diet Against Standard Diet T A B L E 6.4 Results of Preference Test of Taro Corm Diet and Methylene Chloride Extracted Taro Corm Diet Against Standard Diet T A B L E 8.1 Invertebrate and Vertebrate Pests that Damage the Leaves of Taro, Colocasia esculenta (L.) Schott TABLE 8.2 Invertebrate and Vertebrate Pests that Damage the Petioles of Taro, Colocasia esculenta (L.) Schott TABLE 8.3 Invertebrate and Vertebrate Pests that Damage the Corms and Roots of Taro, Colocasia esculenta (L.) Schott T A B L E 8.4 Parasites and Predators of Invertebrate Pests of Taro, Colocasia esculenta (L.) Schott T A B L E 8.5 Invertebrates and Vertebrates Associated with the Culture of Araceae T A B L E 8.6 Summary of Pesticides Registered for Use on Taro in Hawaii TABLE 11.1 Composition and Nutritive Value of Taro Leaves TABLE 1 1 . 2 Time to Death for Rats Fed Tannia and Dasheen TABLE 1 1 . 3 Total Dry Weight of Upland Taro Leaves and Petioles in Relation to Age at Cutting and Nitrogen Application Rates TABLE 1 1 . 4 Types of Feeds Satisfactorily Ensiled with Taro Tops TABLE

136 139 140 143 144 146 147

151

152

152

153 193 211 214 220 230 235 272 273

275 279

xiv

List of Tables

TABLE 11.5 Silage Characteristics as Ranked by Preferences by Cattle TABLE 11.6 PH and Lactic Acid Content of 3 Varieties of Taro Silage TABLE 11.7 PH and Lactic Acid Content of Various Taro Silage Combinations When Concentrates of Roughages Were Added at Ensiling TABLE 11.8 Proximate and Mineral Analysis of Fresh Taro Tops and Ensiled Taro Tops and Whole Plants of Lehua Maoli Variety TABLE 11.9 Amino Acid Composition of Silage Made from Lehua Tops TABLE 11.10 Chemical Composition of 3 Varieties of Taro Silage TABLE 11.11 Mineral Content of 3 Varieties of Taro Silage (DM Basis) TABLE 11.12 Amino Acid Composition of 3 Varieties of Taro Silage TABLE 11.13 Chemical Composition and In Vitro True Digestibility of Silages Made from Combinations of Taro Leaves and Other Feedstuffs TABLE 11.14 Mineral Content of Silages Made from Combinations of Taro Leaves and Other Feedstuffs (DM Basis) TABLE 11.15 Dry Matter Intake, Rumen pH and In Vitro DM Digestibility of Taro Silage Combinations Fed Sheep TABLE 11.16 Performance of Lambs Fed Alfalfa Cubes or Taro Silage During 55-Day Growth Trial TABLE 11.17 Summary of 42-Day Swine Growth Trial TABLE 11.18 Potential Feed Costs When Including Taro Silage in Growing Swine Rations TABLE 11.19 Performance of Gilts When Fed Taro Silage TABLE 11.20 Chemical Composition of Various Tropical Feedstuffs TABLE 11.21 Mineral Composition of Various Tropical Feedstuffs TABLE 12.1 Gelation Temperatures of Starches TABLE 12.2 Iodine Affinities of Starches TABLE 12.3 Estimated Alcohol Yield Per Metric Ton (Wet Weight) of Selected Crop TABLE 12.4 Energy Balance of Ethanol Produced from Corn TABLE 12.5 Advantages of Using Taro Starch in Plastic Production

280 282

283

285 286 288 288 289

290 292 294 296 296 297 298 299 299 303 304 305 305 307

List of Tables 13.1 Production Activities and Resource Demands 13.2 Summary of Results T A B L E 13.3 Estimated Operational Parameters for Integrated Taro Food, Feed, and Fuel Systems T A B L E 14.1 Recent Trends in World Production of Taro T A B L E 14.2 Taro Production in the Philippines T A B L E 14.3 Main Regions of Taro Production T A B L E 14.4 Production Rank Score of Selected Staple Crops in Two Locations TABLE 1 4 . 5 Taro Production in the State of Hawaii and on the Island of Kauai T A B L E 14.6 Comparative Costs of Selected Crops in Hawaii T A B L E 14.7 Relative Ranking of Production Costs for Staple CropsTABLE 14.8 Prices of Starchy Staples in Papua New Guinea as Percent of the Cost of Taro T A B L E 14.9 Prices as a Percent of Starch Staples in the Philippines of the Cost of Taro T A B L E 14.10 Average Prices of Staple Crops in 1961-1965 TABLE TABLE

xv 321 326 337 347 347 348 349 350 351 352 353 354 354

Foreword

TO agricultural research workers of my generation (and I started work in Nigeria in 1951), it was axiomatic that all the tropical root crops were neglected, and a great deal of application and persistence was needed by anyone who wished to work on them. One also needed to be pretty thickskinned to stand up to the comments of one's colleagues who were working on "respectable" cash crops—cacao, say, or oil palm or coffee—or even on food crops, so long as they were grains, perhaps rice or sorghum, about the time they considered as being wasted on root crops. It is hardly too much to say that in addition to persistence, devotion, and a thick skin, one also needed a private income, for research on root crops, however good its quality, was not likely to facilitate rapid promotion. After many years of this background, it is difficult to realize that times are changing, and in reading the draft of this book I was brought to a sudden stop by the comment at the end of the editor's Introduction: "Unlike cassava, yams, and sweet potato, taro is still a neglected crop. The importance of the other three has already been recognized. . . . " This comment was a cause for reflection, and it is, of course, very true. So, some root crops are less equal than others. Since 1967, that crucial year for tropical root crops when the first International Symposium on Tropical Root Crops was held, and when the classical paper of de Vreis, Ferwerda, and Flach (1967) on the largely unrealized yield potential of root crops in comparison with other food crops was published, there have been very great advances in knowledge, especially of cassava, the most important of the tropical root crops, and substantial ones on yams. Taro and the other edible aroids have truly continued to be very largely neglected, although some very good work has been done, very largely by scattered, individual workers, and I feel this more than anything else is a good reason why this book should appear now.

xviii

Foreword

A text such as this, by bringing together compactly what is known of the crop, its products, and their utilization, is not only of value for teaching purposes or as a handy guide for those already involved with the crop. It is also—or should be—seminal to further investigations, by providing a readily searchable data base and also simply by drawing attention to the crop. I know that my own book on yams had that effect: since it was published, also in 1967, nearly as many new publications again have appeared on that crop as were available at the time I wrote it, derived from the whole past history of agricultural science. It is my sincere hope that this work by Professor Wang and his collaborators will have a similar effect with taro. It deserves to, as a very distinguished group of authors has been brought together to produce it, representing a large proportion of the world's expertise on taro. Taro is certainly not the most important of root crops if it is viewed simply in terms of officially recorded global production, which is around five or six million tons per annum, compared with over one hundred million for cassava and around twenty million for yam. Nevertheless, it is one of the most widespread of the root crops, being grown to some extent almost everywhere throughout the humid tropics. It is, of course, in parts of the South Pacific that taro is at its greatest importance, where it provides the major nutritional base for the populations of many of the islands, and at the same time its cultivation and utilization are deeply integrated with the cultural life of the people of most of these islands. It is also one of the most ancient of man's food crops; indeed many believe it to be the oldest of all, though I tend to favor a higher antiquity for the yams. Many, too, believe, with much justification, that rice first appeared as a weed in flooded taro fields and was eventually selected out as a crop in its own right, to develop finally into one of the world's most important food grains. If so, taro has indirectly made an even bigger contribution to world nutrition than it has made directly. I hope this book will become enough of a success that within a few years we may see another edition, extended to include the other aroid root crops, which, if possible, are even more neglected than taro has been. D . G . COURSEY

Past President International Society for Tropical Root Crops

Acknowledgements

IT is not an exaggeration to say that this book owes its existence primarily to the research support given to the University of Hawaii at Manoa by the U. S. Department of Agriculture under Section 406 of the 1966 Food for Peace Act and to a lesser extent to the research support given to the University of California at Irvine. Dr. Peter H. van Schaik, Associate Area Director, Western Region, USDA, and our project monitor, has contributed significantly to this project by his insistence on clearly written and well-organized reports and his encouragement that the UCI and UHM projects maintain a close working relationship. As a matter of fact, the editor first came to realize the feasibility of producing the first English book on taro by pooling the talents of so many authors after his research group had successfully satisfied Dr. van Schaik's stringent requirements for a well-integrated annual report. The decision to proceed with the book was made during one of the annual exchange visits between members of the UCI and UHM taro projects. As expected, the College of Tropical Agriculture and Human Resources at the University of Hawaii at Manoa has contributed heavily toward the realization of this book. This book is dedicated to the intended beneficiaries of the Food for Peace Act and to the early supporters of the Act, among them the former Hawaii congressman and now U.S. senator, the Honorable Sparky Matsunaga.

I

GENERAL BACKGROUND

Introduction Jaw-Kai Wang

BREAKTHROUGH improvements in the major grain crops have increased world food production dramatically during the last twenty years. The advancements in grain production, however, have not brought significant benefits to areas where root crops are the major staples. Therefore, more emphasis should be directed toward such root crops as taro, which is a staple food in many developing nations of Asia, Africa, and the Pacific. Taro (Colocasia esculenta), a member of the Araceae family, is an ancient crop grown throughout the humid tropics for its edible corms and leaves, as well as for its traditional ceremonial uses. The plant is said to have spread from India, its likely center of origin, eastward into Burma and China, and southward to Indonesia (Chang 1958; de la Pena 1970; Plucknett, de la Pena, and Obrero 1970). Subsequently it was taken to Melanesia and Polynesia (Trujillo 1967; Yen and Wheeler 1968). 1 In the Pacific, the crop attained supreme importance in the diets of the inhabitants (de la Pena 1970). Quantitatively it became, and still is, the most important crop. Today the plant is widely used throughout the world, in Africa, Asia, the West Indies, and South America. Taro is of great importance in many places such as the Carribbean, Hawaii, the Solomons, American Samoa, Western Samoa, the Philippines, Fiji, Sri Lanka, India, Nigeria, Indonesia, New Hebrides, Tonga, Niue, Papua New Guinea, Egypt, and others (de la Pena 1970; Plucknett 1970, 1976; Plucknett, de la Pena, and Obrero 1970). In these areas many people depend heavily upon taro as a staple food. More recently, taro was introduced by the U. S. Department of Agriculture to the southern United States as a supplement to potatoes (Young 1913,1917,1924a, 1936). Taro constituted the staff of life for the Hawaiians when Captain Cook arrived in the islands in 1778 (Miller 1927; Potgieter 1940). At

4

G E N E R A L BACKGROUND

that time an estimated three hundred thousand people in the islands lived chiefly on poi (a fermented or unfermented taro paste), sweet potato, fish, seaweeds, and a few green vegetables and fruits (Potgieter 1940). They used no grains or animal milk in their diet, and animal proteins were a rarity (Miller 1927). Yet the good physique and excellent teeth of the Polynesian people (Chappel 1927) testified to an adequate diet. 2 The early Hawaiians considered taro to be a very healthful, easily digested food, "most soothing to the stomach, and highly beneficial to an invalid" (Young 1936). T a r o has played a similar role in the diets of the Melanesians and Micronesians, who ate boiled or baked corms and the leaves of taro (Malcolm 1952, 1953, 1954, 1955; Oomen and Malcolm 1958). Young taro leaves are used as a main vegetable throughout Melanesia and Polynesia (de la Pena 1970). They are either boiled or covered with coconut cream, wrapped in banana or breadfruit leaves, and cooked on hot stones (Miller, Bauer, and Denning 1952; Kubo 1970). Thus, taro is one of the few major staple foods where both the leaf and underground parts are equally important in the human diet. Within the last fifty years, several investigators have confirmed the superiority of taro over other starchy staples. The digestibility of taro starch has been estimated to be 9 8 . 8 percent (Langworthy and Deuel 1922; Potgieter 1940). The size of the taro starch grain is one-tenth that of potato (Payne, Ley, and Akau 1941). Because of its ease of assimilation, taro can be used by persons with digestive problems (Derstine and Rada 1952; Potgieter 1940). T a r o flour and other products have been used extensively for infant formulae in the United States and have formed an important constituent of proprietary canned baby foods. T a r o is especially useful to persons allergic to cereals and can be consumed by children who are sensitive to milk (Rada 1952; Roth, Worth, and Lichton 1967). Poi can be used as a carbohydrate base to formulate milk substitutes (Standal 1970; Standal and Kian 1968). Sensitivity to taro occurs far less frequently than it does to other starches (Feingold 1942). In an intensive survey of tooth decay among the Melanesian inhabitants of the Manus Islands (northwestern Papua New Guinea), a comparison was made between people who ate only taro and those subsisting on sago (Metroxylon sp.) (Kirkpatrick 1935; Potgieter 1940). Those eating taro had better dental arches and showed a lower incidence of acute or subacute infection of the gums. This was ascribed to the higher vitamin content of taro. Additionally, in an investigation of teeth among infants of Oriental stock in Hawaii, those who received rice as their main carbohydrate showed a higher incidence of dental decay compared to those of the same ancestry fed a diet where taro replaced rice (Larsen, Jones, and

Introduction

5

Pritchard 1934; Potgieter 1940). Similarly, a marked improvement in dental conditions and a reduced incidence of pneumonia, diarrhea, enteritis, and beriberi resulted among babies born on Hawaiian plantations who were fed poi and sweet potato in place of bread and rice (Jones, Larsen, and Pritchard 1934; Potgieter 1940). With the introduction of cash crops there is a tendency for the farmers to neglect subsistence gardens and to use the money earned to purchase store food. This trend can introduce serious nutritional problems among people whose primary diet is taro-based (Barrau 1958). For instance, in the Rabaul district of Papua New Guinea observers consider dietary standards to have declined as per capita incomes have increased. Conditions in Tahiti and areas of French Oceania give a clear indication of the consequences of hasty abandonment of traditional diets, where taro and breadfruit were very important. As the islands have increased the import of flour, sugar, rice, canned meat, fish, and milk products, tooth decay has gradually become a major problem (Kirkpatrick 1935; Larsen, Jones, and Pritchard 1934). In many ways taro is a unique crop. Its starch granules vary in size from 1 to 3 microns (Coursey 1968). More recently Griffin (see chap. 12) has determined taro starch to be between 1 and 6.5 micrometers in size and showed that it can be useful as an additive to render plastics biodegradable (Griffin 1978). The policies of governments in developing nations are usually centered around reducing imports, increasing exports, and raising the standard of living and nutritional levels of the population. In most countries these policies have led to crop improvement programs centered on local staple crops. For the most part these have been grains such as wheat, corn, and rice. Root crops in general and taro in particular have been neglected because only 10 percent of the world population— approximately 400 million out of 4 billion people (Coursey and Haynes 1970)—is using root crops as a major staple. The time has come, however, to increase the world production and utilization of root crops. The present status of world taro production is unclear. Production and consumption patterns are thought to be mainly of the subsistence type with very little commercial marketing activities. Production is generally in small plots and the taro may be intercropped between other plants. Production from these plots is almost always ignored when production data is compiled, with the result that statistics nearly always show production figures much lower than they actually are. Even with that, the 1974 FAO Production Yearbook lists taro as being grown on 762,000 hectares in fifteen countries in Asia, Africa, and Oceania, with a total production of 4.353 million metric tons (FAO 1975).

6

GENERAL BACKGROUND

Taro production is widely varied. Yields vary tremendously because of quantitative and qualitative differences in inputs and management practices. In Hawaii, where the major variety is Lehua Maoli, the average state yield of paddy taro is 23 MT/ha/yr of marketable corms, but on the island of Kauai, where better agronomic practices have been observed, the average yield is 31 MT/ha/yr of marketable corms (Plucknett and de la Pena 1971). The lack of trained root crop specialists in many areas of the world not only prevents the expansion of knowledge concerning proper agricultural practices but may also limit the dissemination of existing information. In view of the fact that taro is a familiar crop throughout the humid tropics, its potential food value either in the fresh or processed form is considerable. Taro flour is a specific example of untapped potential in a processed product. The technology exists to convert taro tubers into

TABLE 1.1

NUMBER O F COUNTRIES, AREA, AND PRODUCTION O F ROOTS A N D TUBERS IN A S I A , A F R I C A , A N D OCEANIA DURING 1974

Roots and Tubers

Number of Producing Countries

Area (1000 ha)

Production (MT 1000)

15 19 26 4

2,553 13,153 5,135 61

25,235 122,095 50,223 699

33 35 24 9

6,556 5,478 409 669

47,541 6,192 3,299 3,397

5 5 2 4

19 106 44 32

217 568 907 257

As ia Cassava Sweet Potato Potato Taro Af ri ca Cassava Sweet Potato Potato Ta ro Oceania Cassava Sweet Potato Potato Ta ro

SOURCE: A d a p t e d from Food and Agriculture O r g a n i z a t i o n of the United Nations Production Yearbook, 197*» (Rome, 1975).

7

Introduction

flour (Moy et al. 1979), which could then be mixed with wheat flour to make bread. Considering the geometric increase in bread consumption throughout the developing world over the last twenty years, the possibility of using at least one locally available crop in its production would appear to warrant serious investigation. Figures on wheat flour imports into Nigeria emphasize the importance of bread in Africa. During the 1940s, imports never exceeded 5,000 tons per annum, but by 1966 they had reached 120,000 tons annually (Gusten 1968). Existing data on production systems and costs need to be drawn together for particular countries or regions similar to the way it was done for Hawaii by Vieth, Begley, and Huang (1980). Patterns of production and prices should be recorded in taro growing areas. Feasibility studies need to be carried out on the cost of processing taro into flour in specific root crop areas. These should be followed by transport and storage analysis and an assessment of the government support needed to improve production and marketing facilities. Finally, the major problems and potentials for making taro available in the form of bread, or

TABLE 1.2

RECENT TRENDS

IN WORLD PRODUCTION OF TARO

Year

Production (1000 MT)

Area (1000 hectares)

Yield (kg hectare" 1 )

1962 1963 1964 1965

3317 3426 3455 3465

636 603 637 643

5213 5684 5421 5386

1966 1967 1968 1969

3495 3656 3503 4033

618 669 630 731

5656 5460 5557 5518

1970 1971 1972 1973 1974 1975

3641 3961 4088 4252 4356 4502

626 720 742 786 810 816

5815 5504 5508 5408 5377 5520

SOURCES: Data from Food and Agriculture Organization of the United Nations Production Yearbook, 1973 (Rome, 1974); and Food and Agriculture Organization of the United Nations Production Yearbook, 1975 (Rome, 1976).

TABLE 1.3

ROOT CROP DISTRIBUTION ON A CLIMATIC BASIS 1

A f r i c a n Yam Bean Anu Arracacha Arrowhead Arrowroot Cassava Chavar Chinese Water Chestnut Chufa E. I n d i a n Arrowroot Elephant Yam F a l s e Yam Giant T a r o Hausa Potato Jeruselem Artichoke Lotus Root Maca Oca Potato Queensland Arrowroot Radish Shoti Swamp Taro Sweet P o t a t o Tannia Taro Topee Tambo 111 i ueu Yacon Yam Yam Bean

2

3

x

X

h

(x) H X X X X

5

6

xH

xH

7

X X

X

(x) x

X

xA

xA

X

X

X

X

X

X

X

X

X

X

(x)

X X

X

(x) xA

X X

X

X

X

xA

X

X

X

X

X

X

X

X

X

X

X

(x)l

X

xH xH

(x)

X

X

X

X

X

X

X

X

Xl

(x)

xA

X X

X

X

(x) X

X

(x)l

(x) 1 (x)

(x) 1 xH

X

X

X

X

(x) 1

X

X

(x) (x) xH xH' x

xH xH (x)l

NOTE: R e p r i n t e d by p e r m i s s i o n of the p u b l i s h e r from Crop and Product P i g e s t No. 2: Root C r o p s , by D. E . Kay (London: Tropical Products I n s t i t u t e , 1973). () - L i m i t e d c u l t i v a t i o n A - Aquatic conditions required

I H

1. 2. 3.

5. 6. 7. 8.

Tropical rainforest T r o p i c a l monsoon T r o p i c a l savanna Dry t r o p i c a l , i . e . , steppe and d e s e r t

- I r r i g a t i o n required - High a l t i t u d e Humid s u b t r o p i c a l S u b t r o p i c a l (Mediterranean) Humid i n t e r m e d i a t e Dry i n t e r m e d i a t e

ai 0 •— O) > - -C en

en 00 -3-LA — 0 LA LA rA VÛ 0 LA — rA CA

—)

>•

© •

C_> rA CM L. CM v -O 3 CL 1•—

.—,

OO ra 0

• (U ai -C — in e ~ e 3 Q. 0 —3

O t/ì t/i c 3 0 co (/I in ai •— E E_ al 1 3 a) 2 Q. c 0 >-D • 0 "O - (D — — (D (D (D 3 < < O z îd —3 — a.

ro >-

LlJ 0 t- 0 O 0 Z CJ

10

G E N E R A L BACKGROUND

some other form, should be defined and evaluated. The marketing channels through which this product would pass, the problems at each step, and the likely acceptability of the new product in rural and urban areas need to be investigated. One of the problems that has impeded taro utilization is that taro leaves, petioles, and corms contain an irritating or acrid agent. Raw taro can cause a burning, itching sensation in the mouth and throat when eaten. It can cause similar sensations on the skin. The basic cause of the acridity is not well known. Some have believed it to be caused by calcium oxalate crystals that have bundles of needle-shaped crystals called raphides. Others suspected that a chemical toxin is the cause of acridity. Still others blamed it on a mechanical irritation caused by the rubbing of sandlike particles or druses (Sakai 1979). Recent work, however, has put all this in doubt because of the inability to duplicate earlier results and the failure to extract the acrid agent by conventional means (see chap. 6). The existence of this acridity has made some form of cooking a prerequisite for the consumption of taro, for it has been shown that high temperatures will eliminate the acridity problem and make taro edible. The high cost of cooking, however, both in terms of its high fuel cost and its handling process, has very much limited the potential of utilizing taro as an animal feed in the humid tropics where sun drying in the field is difficult. The development of animal industries in the humid tropics has long been hampered by the inabilty to produce locally grown feeds. Imported feeds are expensive and locally grown feeds are not readily available in sufficient quantities, mainly because of the climate. Areas of high rainfall do not lend themselves to the production of hay, as solar drying is unreliable. The tropics also have a comparatively short day-length and low solar irradiation due to heavy cloud cover. This, coupled with marginal soil fertility, means that most feed grain crops do not do well in such areas. A healthy animal industry is necessary to the continued growth of the economies of developing nations located in the tropics. Improved protein sources are needed desperately. In these areas, increased production of meat, milk, and milk products is essential for balanced and improved diets. Against this background, the importance of a successful search for alternate feeds becomes obvious. The suggestion has been made that root crops in general, and taro in particular, could be excellent sources of animal feed (Coursey and Halliday 1975). Coursey and Halliday specifically suggested that silage could be made from the entire Colocasia plant. However, they left the question of acridity unanswered. In feeding trials using flour from taro corms or meal made from the

Introduction

11

ground corms, in all cases it was found that supplements of protein and some essential vitamins and minerals were necessary, because the protein level in the meal was too low for animals to perform well (Mondonedo and Alonte 1931; Fetuga and Oluyemi 1976; Szylitetal. 1977; and Soldevila and Vincent-Chandler 1978). When the digestibility of the taro plant was estimated (Westgate 1918), the values given for taro tops (leaves and petioles) were 0.54 of digestible protein in 45 kg of fresh material. When converted to a dryweight basis, the digestible protein content is 8 percent of the total dry matter and 64 percent of the crude protein in the material. Oyenuga (1959) gave values for taro leaves of 17.22 percent of dry matter as digestible crude protein and 15.5 percent of dry matter as digestible true protein. The varieties of taro used in these analyses were not identified. Other measures used in proximate analysis and given by Oyenuga agree fairly well with recent values, but his values for protein are consistently higher by about 5 percent on a dry-matter basis. Proximate and mineral analysis of taro tops (leaves and petioles), variety Lehua Maoli, reveals the values shown in table 1.5. The analysis showed high levels of protein, fat, and minerals present in taro leaves and petioles. The College of Tropical Agriculture and Human Resources at the University of Hawaii at Manoa, supported by grants from the Department of Agriculture (Section 406 of the 1966 Food for Peace Act), has established a taro research group (Wang and Otagaki 1979), which began in 1980 to explore the possibilities of low energy processing of taro into an animal feed. Following a systematic analysis, the silage process was determined to be the most promising candidate for energy requirement and easy adaptability by both large and small farmers. The project has also developed a method of ensiling taro that reduces or eliminates acridity. Ensuing research has firmly established the potential of taro silage as an animal feed in the humid tropics. The ability to utilize taro as an animal feed has several important implications: 1. It has been repeatedly demonstrated that the demand level for animal protein increases with the rise in living standards. Therefore, the demand for animal meat and milk will increase as the developing countries in the humid tropics improve their living standards, while the demand for taro as a staple may falter. The ability to process taro into a low-cost animal feed will allow taro producers to follow the change in the market demand pattern for taro and move from subsistence-type farming into cash cropping. 2. The "pocket market" phenomenon is common to almost all island-

12

GENERAL BACKGROUND TABLE 1.5

PROXIMATE AND MINERAL ANALYSIS OF LEAVES AND P E T I O L E S OF TARO ( V a r i e t y Lehua M a o l i )

Dry m a t t e r , % a s

sampled

7.85

Dry m a t t e r b a s i s , % Crude p r o t e i n Crude f a t Crude f i b e r Ash Phosphorus P o t a s s i urn C a l c i um Magnes i um S o d i um Dry m a t t e r b a s i s , Manganese 1 ron Copper Zi ne

19-9 8.5 16.1 11.2 .24 3.47 1.16 .28 .04 ppm 289 943 5 122

SOURCE: W. E. S t e i n k e , J . K. Wang, J . R. C a r p e n t e r , and R. S . de l a Pena, " T a r o Silage: An A l t e r n a t i v e f o r the Wet T r o p i c s , " paper p r e s e n t e d a t the W i n t e r M e e t i n g o f the American S o c i e t y o f A g r i c u l t u r a l E n g i n e e r s , C h i c a g o , Dec. 2 - 5 , 1980.

type economies where natural variation in yield can be very damaging to the maintenance of a stable pricing pattern, which is so important to the well-being of the farming sector. To be able to absorb periodic excessive production at reasonable prices will contribute immeasurably to the development and maintenance of a stable taro industry in these places. There is strong hope that taro will regain its former prominence in the humid tropical zone of the world. However, unlike cassava, yams, and sweet potatoes, taro is still a neglected crop. The importance of the other three has already been recognized and a number of international and national research institutions have placed special emphasis on these crops. In Colombia, the International Centre for Tropical Agricultural

13

Introduction

(CIAT) focuses on cassava; the Asia Vegetable and Research Development Center (AVRDC) in Taiwan works on sweet potatoes; and the International Institute for Tropical Agriculture (IITA) in Nigeria carries out research on cassava and sweet potatoes. In addition, the white potato is being investigated at the International Potato Centre (CIP) in Peru. But to date, no comparable concentrated research effort has been focused on taro, which is probably the most underreported and understudied root crop despite its worldwide importance (National Academy of Science 1975; Coursey and Haynes 1970).

NOTES 1. T h e literature survey pertaining to this chapter was completed in June 1979. 2. This and the following seven p a r a g r a p h s are adapted f r o m an unpublished review by G. V. H. Jackson, D e p a r t m e n t of Agriculture, Solomon Islands, a n d J. Arditti, d e p a r t m e n t of developmental and cell biology, University of California, Irvine.

2 Taxonomy of the Genus Colocasia Donald L.

Plucknett

THE Araceae is a large family, comprising some hundred genera and more than fifteen-hundred species. Mostly tropical or subtropical plants, the aroids grow mainly in moist or shady habitats. Some are terrestrial plants while others are vines, creepers, or climbers. Many species of the Araceae are also epiphytes. The major edible aroids are classified in two tribes and five genera; Lasioideae (Cyrtosperma and Amorphophallus) and Colocasiodeae (Alocasia, Colocasia, and Xanthosoma). Colocasia and Xanthosoma are the most important of the edible genera. Colocasia is thought to have originated in the Indo-Malayan region, perhaps in eastern India and Bangladesh, and spread eastward into Southeast Asia, eastern Asia, and the Pacific islands; westward to Egypt and the eastern Mediterranean; and then southward and westward from there into East Africa and West Africa, from whence it spread to the Caribbean and the Americas. Xanthosoma is a native of South and Central America. As is typical of ancient food crops, and particularly vegetatively propagated food crops, the taxonomy of Colocasia is confused. Linnaeus first described taro in 1753 as belonging to two species, Arum colocasia and Arum esculentum (Hill, 1939). Schott in 1832 established the genus Colocasia (which is thought to take its name from the Egyptian word for taro, coicas or kulkas) and renamed Linnaeus' species C. antiquorum and C. esculenta. Later, in 1856, Schott apparently reconsidered his position and used only one name, C. antiquorum, to apply to a single polymorphic species. In the meantime, a number of other species of Colocasia had been

15

Taxonomy of the Genus Colocasia

described, including C. nymphaeifolia, C. acris, C. fontanesii, and C. euchlora. Schott in 1856 reduced these species and C. esculenta to botanical varieties of C. antiquorum. In 1879 Engler agreed with Schott on the species C. antiquorum and added two varieties, C. typica and C. illustris, to the five already named. Later, in 1920, Engler and Krause added two more varieties, C. aquatilis and C. globulifera. Hill (1939) pointed out that according to the International Rules of Botanical Nomenclature the species C. esculenta took precedence over C. antiquorum, that if one polymorphic species was to be recognized it should be C. esculenta, and that C. antiquorum would then become a variety. Some authors also recognize two distinct varieties of C. esculenta, var. esculenta ( = var. typica A. F. Hill) and C. esculenta var. antiquorum (Schott) Hubbard and Rehder. With all of the above considered, there are still those who consider that there should be two species of Colocasia—C. antiquorum and C. esculenta—and that they can be differentiated on the basis of their floral morphology as follows (Purseglove 1972): —sterile appendage of spadix exserted, much shorter than the male portion —sterile appendage of spadix retained within the spathe, longer than male portion

C.

C.

esculenta

antiquorum.

This key may not be very helpful in many cases, however, because floral characters are often not useful in differentiating species, as many Colocasia cultivars rarely flower. To summarize, there are different botanists who consider the Colocasia situation to be one of the following: 1. there are two species, C. esculenta and C. antiquorum-, 2. there is one polymorphic species, C. esculenta, with several botanical varieties; or 3. there is one polymorphic species, C. antiquorum, with several botanical varieties (Haudricourt 1941). What is really needed in the long term is a careful reexamination of the genus and its types. In the meantime, however, it is probably best to agree with A. F. Hill (1939) and Purseglove (1972) and consider C. esculenta (L.) Schott as a single polymorphic species.

16

GENERAL BACKGROUND

BOTANICAL

VARIETIES

At least ten botanical varieties of Colocasia have been suggested: C. typica, C. nymphaeifolia, C. globulifera, C. aquatilis, C. acris, C. antiquorum, C. euchlora, C. fontanesii, C. illustris, and C. esculenta (Hill 1939; Purseglove 1972). It appears that C. esculenta var. typica is a synonym of C. esculenta var. esculenta, so that leaves nine. Purseglove (1972) suggests that there are two major groups of cultivated C. esculenta, var. esculenta and var. antiquorum, and that the dasheen of the West Indies (which is generally referred to as taro in the Pacific) should be considered as C. esculenta var. esculenta, and that the eddoe of the West Indies (generally referred to as dasheen in the Pacific and in Asia) is considered as C. esculenta var. antiquorum. This approach doesn't settle the matter of what to do with C. esculenta var. globulifera, which is the varietal name given to the eddoe of the West Indies (dasheen of Asia and the Pacific). Perhaps at this point it suffices to point out that those people who refer to C. esculenta var. globulifera or C. esculenta var. antiquorum are probably talking about the same group of plants. That brings us to the matter of plant types.

PLANT T Y P E S AND BOTANICAL

VARIETIES

There are two general types of crop plants in the cultivated Colocasia. general, they can be delineated as follows:

In

1. Plants that produce a large edible main corm with few cormels (sometimes called sucker corms), e.g., four or eight or so. Generally this group has twenty-eight chromosomes and can be grown under a wide range of water conditions, from flooded (as in Hawaii and other parts of the Pacific islands) to rain-fed upland conditions. This plant is C. esculenta var. esculenta. 2. Plants that produce a small or medium-sized main corm that often may be inedible because of acridity and a large number (fifteen or twenty or so, to as many as forty or more) of small edible cormels. Some cormels may possess some degree of dormancy. Generally this group has forty-two chromosomes and is grown as an irrigated crop like many other vegetables or as a rain-fed upland crop. This group of plants probably developed in Japan or China. This plant is C. esculenta var. antiquorum (sometimes called C. esculenta var. globulifera).

Taxonomy

of the Genus Colocasia

17

THE COMMON NAME DILEMMA In addition to the problems of the scientific names of Colocasia, the common name difficulties complicate the picture also. A major difficulty begins with the use of the name taro. T a r o is derived from the Polynesian words kalo or talo, which are probably derived from the Malay words,

talles or tallus. T a r o is used as a collective word for the edible aroids in general

(Alocasia,

Colocasia,

Cyrtosperma,

and Xanthosoma),

but it is also

applied to each of the aroids separately. The second common name that is applied widely, and confusingly, is dasheen. Thought to be a corruption of the French, de Chine (of or from China), the word dasheen is used to describe both major plant types of Colocasia. As was mentioned previously, the dasheen of the West Indies is not the same as the dasheens of Asia and the Pacific, which are called eddoe in the West Indies. Another name that is used widely is cocoyam; this name is used in parts of Africa to apply to both Colocasia (old cocoyam) and Xanthosoma (new cocoyam).

THE CHROMOSOME NUMBERS What help can chromosome numbers provide? As we pointed out, C. esculenta var. esculenta cultivars generally have twenty-eight chromosomes, whereas C. esculenta var. antiquorum cultivars generally have forty-two chromosomes. There is evidence that the place where greatest variation in chromosome number occurs is India (Yen and Wheeler 1968). The "Polynesian taros" primarily all have twenty-eight chromosomes, while generally there is a greater concentration of 42-chromosome types in East Asia. Yen and Wheeler (1968) speculate that the 28-chromosome cultivars preceded the 42-chromosome types into the Pacific islands. Fukushima et al. (1962) carried out some very interesting studies on the chromosome numbers of Colocasia cultivars in Japan in comparison with the uses made of their corms and cormels. They examined a total of 103 varieties, and found two types, 2n = 28 and 3n = 4 2 . The uses of the plant types are given in table 2.1. The authors point out that Japan has many cultivars with small cormels and that in southern China the large corm types (C. esculenta var. esculenta) prevail in sharp contrast to the north where the small cormel types (C. esculenta var. antiquorum) predominate.

18

GENERAL BACKGROUND

TABLE 2.1

RELATIONSHIP BETWEEN THE CHARACTERISTICS OF TARO V A R I E T I E S AND THEIR CHROMOSOME COMPOSITION

Characteristics of Corms and Cormels A c c o r d i n g to Use

Number o f V a r i e t i es Diploid

20

—

72

72

—

6

6

19

For many small

For both corms and cormels For

petioles

TOTALS

Totals

1

For l a r g e main corms cormels

Tri ploi d

5

2k

—

79

5 103

SOURCE: Data from E. Fukushima, S. Iwasa, S . Tokumasu, and M. Iwamasa, "Chromosome Numbers o f the Taro V a r i e t i e s C u l t i vated in J a p a n , " Chromosome I n f o r m a t i o n S e r v i c e No. 3, P- 38-39 (Fukuoka, Japan: F a c u l t y o f A g r i c u l t u r e , Kyushu U n i v . , (1962).

DIFFERENTIATING BETWEEN

CULTIVARS

There are probably thousands of cultivars of Colocasia in the world. More than three hundred named varieties have been listed in Hawaii; some of these are undoubtedly synonyms, but there can be little doubt that perhaps a hundred and fifty to two hundred and fifty cultivars were known in prehistoric days. Colocasia cultivars are differentiated on the basis of size; leaf shape and size; color of petiole, leaf, and corm flesh; flower shape and size; and their various uses. The most comprehensive attempt to classify and describe Colocasia cultivars was carried out by Whitney, Bowers, and Takahashi (1939) in Hawaii. They divided the cultivars into groups based on morphological characters such as leaf shape and point of attachment of the petiole (e.g., the piko group), shape and type of corm (e.g., the mana group), presence of certain undulation patterns on the leaf margin (groups kai, lauloa), and petiole color and color pattern (e.g., striping of petiole = manini group). Figure 2.1 shows a general view of the taro plant. Such a drawing can be labelled and used as a reference to describe Colocasia cultivars. A proposed descriptor guide for Colocasia has been published by the International Board for Plant Genetic Resources (1980); this can be used as the basis for describing and characterizing cultivars in research or germ plasm preservation work.

sinus

"piko," or point of attachment of leaf and petiole

petiole

>• "sucker" plant

cormel corm

FIGURE 2 . 1 . A

general view of the taro plant.

3 Anatomy and Morphology of Taro, Colocasia esculenta (L.) Schott Michael S. Strauss

PLANTS of the genus Colocasia are herbaceous, often with large leaves and bearing one or more underground stems or corms (Plucknett 1970). Knowledge of their anatomy is restricted to only a few studies. In general, taro, the principal edible species, has been described as a succulent, glabrous, perennial herb (Coursey 1968; Plucknett 1970; Plucknett, de la Pena, and Obrero 1970; Purseglove 1972) and is distinguished from similar Xanthosoma species by the presence of peltate rather than hastate leaves. While there is some disagreement on the correct taxonomic division of the various types of taro (Hill 1939; Purseglove 1972), Colocasia esculenta is generally considered the principal edible species. It has further been shown that individual populations of taro seedlings display considerable variability in chemical and physical characters (Arditti, Stephens, and Strauss 1979; Strauss et al. 1980). Thus it is not surprising to find some of the few morphological studies in disagreement. Discussion of the frequency of meiotic failure in gametogenesis has been such an area. This chapter summarizes most of the available literature on the anatomy and morphology of taro. Where possible, citations are restricted to the principal information sources as opposed to those making only casual mention of previously published material. Earlier reviews are

Anatomy

and Morphology of Taro

21

also cited where possible. The scanning electron micrographs were obtained from a U.S. Department of Agriculture funded taro project at the University of California, Irvine, and have not been published elsewhere. LEAVES The aboveground portion of a taro plant is composed of large leaf laminae on long erect petioles (Onwueme 1978; Purseglove 1972). The laminae are 25 to 85 cm long and 20 to 60 cm wide (Plucknett, de la Pena, and Obrero 1970; Purseglove 1972). Their shape is entire and ovate to sagittate with an accuminate apex and rounded basal lobes (Onwueme 1978; Plucknett, de la Pena, and Obrero 1970; Purseglove 1972). A major diagnostic feature of Colocasia is the presence of peltate leaves as opposed to the hastate condition of Xanthosoma (Ahmed and Rashid 1975; Coursey 1968; Norman 1972; Onwueme 1978; Plucknett 1970; Plucknett, de la Pena, and Obrero 1970; Purseglove 1972). One exception are leaves of cultivars in the "piko" group of Hawaii which are hastate (Onwueme 1978; Plucknett, de la Pena, and Obrero 1970). The surface of the lamina is glabrous and marked by a pinnate venation pattern with three major veins extending through the length of the lamina and through the two basal lobes. Laminae are 275 to 300 nm in thickness with approximately equal proportions of palisade and spongy mesophyll. The palisade layer is bilayered and spongy mesophyll forms large rectangular air spaces (fig. 3.1; Yarbrough 1934). Stomata occur on both adaxial and abaxial surfaces with the latter possessing approximately twice as many (Yarbrough 1934). Numbers of stomata are relatively low when compared with other plant species (table 3.1; Yarbrough 1934). Adaxial stomata are associated with prominent substomatal cavities which pass through the palisade layers into rectangular air spaces of the spongy mesophyll (Yarbrough 1934). Abaxial stomata open directly into these spaces (Yarbrough 1934). Exudation of water through hydathodes at the apex of the lamina has been reported (Dixon and Dixon 1931; Plucknett, de la Pena, and Obrero 1970). It should be noted that the stomatal counts are from a single leaf of a plant which was labelled "Colocasia esculenta" in the report. A photograph in the article illustrates an aroid which appears considerably different from most cultivated taros. Furthermore, caution should be exercised when interpreting data from a single, albeit large, leaf. Thus, data on stomata of taro are still needed to supplement the presently available information. Enations or outgrowths of the abaxial lamina surface have been noted in some cultivars (fig. 3.2; Gueguen 1908). These possess two distinct

22

G E N E R A L BACKGROUND

FIGURE 3.1. Scanning electron microscope view of a transverse section of a taro leaf. Note prominent palisade layer and rectangular spongy mesophyll spaces (bar = 50 j^m). palisade layers, one beneath each epidermal surface (Gueguen 1908). This condition has been observed at the University of Hawaii Agricultural Experiment Station in at least one cultivar, but always on the same half of the lower side of the leaf. It would suggest a rather early determination of the condition in the course of leaf development which results in a genetically (?) controlled overgrowth of meristematic tissue. Petioles are 1 to 2 m long, stout, and surround the apex of the corm from which they arise in whorls (fig. 3.3; Onwueme 1978; Purseglove 1972). Internally the petioles are solid but replete with air spaces which have been suggested as adaptations for growth in flooded conditions (Onwueme 1978).

Anatomy and Morphology TABLE 3 - 1

Plant

23

of Taro

COMPARISON OF D I S T R I B U T I O N OF STOMATA ON A D A X I A L SURFACES OF COLOCASIA ESCULENTA WITH OTHER GENERA

Number o f Stornata

Celt is

616

Fraxinus

600

Morus

i»80

C o l o c a s ia

116

p e r mm

2

SOURCE: Data from J . A. Y a r b r o u g h , " S t o m a t a l Count o f a S i n g l e L e a f o f C o l o c a s i a , " P r o c e e d i n g s o f t h e Iowa Academy o f S c i e n c e 4 l : 7 1 ~ 7 3 (1934).

In general, leaves and petioles of Colocasia display a wide variability in color, pattern, shape, and size, as well as in chemistry (Ahmed and Rashid 1975; Plucknett 1970; Arditti, Stephens, and Strauss 1979; Strauss et al. 1980). A relatively high linear correlation has been shown to exist between size or area of the second youngest leaf and corm weight (Reddy, Meredith, and Brown 1968).

CORMS Taro possesses enlarged, starchy, underground stems which are properly designated corms (Brouk 1975; Coursey 1968; Onwueme 1978; Plucknett 1970, 1976; Plucknett, de la Pena, and Obrero 1970). These have been found to be highly variable with respect to hydration, size, color, and chemistry (Plucknett 1970; Arditti, Stephens, and Strauss 1979; Strauss et al. 1980). The corm is composed, outwardly, of concentric rings of leaf scars and scales (Plucknett, de la Pena, and Obrero 1970; Winton and Winton 1935). It bears one or more smaller secondary cormels which arise from lateral buds present under each scale or leaf base (Onwueme 1978; Winton and Winton 1935). Shape varies from elongated to spherical with an average diameter of 15 to 18 cm (Brouk 1975; Onwueme 1978; Winton and Winton 1935). Anatomically, the tuber is composed of a thick, brown outer covering

24

G E N E R A L BACKGROUND

FIGURE 3.2. Underside of a taro leaf showing prominent leaf enations. This particular cultivar, maintained at the University of Hawaii Agricultural Experiment Station, Kauai, always produces the anomaly on the same side of the midvein of the leaf.

and starchy ground parenchyma (Onwueme 1978). Scattered through the ground tissue are numerous fibrovascular bundles, a few laticifers and raphide idioblasts (Onwueme 1978; Sunell and Healey 1979; Winton and Winton 1935). T h e outer barklike layer found between leaf scars has been designated periderm by one report (Paliwal and Kavathekar 1972). It is composed of twenty to thirty or more flattened cells which

Anatomy

and Morphology

of Taro

25

FIGURE 3.3. Meristem of a taro showing encircling petiole bases. The meristem measures approximately 100 nanometers across (bar = 50 /im). appear polygonal or elongated in surface view (fig. 3.4; Paliwal and Kavathekar 1972; Winton and Winton 1935). One to two clearly distinguishable layers of cork cambium cells are found below the periderm. These are thin-walled, nucleated, and rectangular. Interior to these is a ring of isolated mucilage ducts of varying size. These produce the mucilage that makes cut surfaces of the corm slippery (Paliwal and Kavathekar 1972). The remainder of the tissue, which composes the central cylinder, is composed of small, starch-filled ground parenchyma. Throughout this tissue are numerous isolated, individual laticifers which may branch extensively (Paliwal and Kavathekar 1972; Winton and

26

G E N E R A L BACKGROUND

FIGURE 3.4. Periderm layers of Colocasia esculenta (phe = phellem; pg = phellogen; pd = phelloderm) x 400. Reprinted by permission of the publisher from "Anatomy of Vegetative Food Storage Organs," by G. S. Paliwal and A. K. Kavathekar, Acta Agronomica 21(3-4): 313-318 (Budapest: Akademiai Kiado, 1972). pd

P9

phe

Winton 1935). One report distinguishes a layer of cortex cells between the periderm and central cylinder containing both laticifers and raphide idioblasts (Winton and Winton 1935). Only casual mention is made of the druses reported to be abundant in corms of taro (Paliwal and Kavathekar 1972; Sunell and Healey 1979). Cells of the central cylinder differed from the cortex by being somewhat larger and thinner walled, with an indistinct division between the two (Winton and Winton 1935). Vessels of the vascular bundles are up to 80 nm in diameter with spiral or spiral reticulate thickenings (Winton and Winton 1935). Laticifers are found adjacent to bundles or branching into the starchy ground tissue (Winton and Winton 1935). The association of large numbers of druse idioblasts with the vascular tissues of the developing corm has led to the suggestion that these represent a calcium storage mechanism (Sunell and Healey 1979). A few cultivars produce above or below ground stolons which may attain lengths of a meter or more. These have reportedly been used for propagation of taro in Malaysia (Ghani 1979). It is presumed that they arise from the lateral buds found on the corm, though no reports of their development were found. ROOTS The root system of taro is adventitious and fibrous. It is generally restricted to the upper levels of the soil, though arising from the lower portions of the corm (Onwueme 1978; Purseglove 1972). No studies were found with regard to morphology or development of the root system of taro.

Anatomy and Morphology of Taro

27

FLOWERS, FRUITS, AND SEEDS Inflorescences of Colocasia are comprised of a spathe 2 0 to 4 0 cm in length surrounding a spadix measuring 6 to 14 cm (Onwueme 1978; Purseglove 1972; Shaw 1975) that contains unisexual flowers. It is borne on a stout pedicel which, at 15 to 3 0 cm, is somewhat shorter than the petioles (Onwueme 1978; Plucknett 1970; Purseglove 1972; Shaw 1975). Generally, two to five inflorescences arise successively in the leaf axil (Plucknett 1970). T h e spathe is divided laterally into two unequal portions, the lower 3 to 5 cm being green and surrounding the pistillate flowers of the spadix. Above this is a longer, 15 to 35 cm, section that is yellow, oblonglanceolate, and rolled at its distal end (Purseglove 1972; Shaw 1935; Whitney, Bowers, and Takahashi 1939). The degree of opening of this upper portion has been used as a taxonomic character by some authors (Massal and Barrau 1956; Purseglove 1972). Sections of the spathe reveal raphide idioblasts and a few druses between vascular elements as well as a row of druses towards the edge (Shaw 1975). Green pistillate flowers are located at the base of the spadix and white sterile flowers near its tip (Shaw 1975). These unilocular ovaries possess a single sessile stigma (Onwueme 1978; Shaw 1975). The ovary contains thirty-six to sixty-seven ovules arranged on two to four parietal placentas (Shaw 1975). Sterile flowers are scattered among normal pistillate flowers. They lack a stigma and style complex and are slightly taller than fertile pistils (Shaw 1975). These flowers disappear as the fruits enlarge following pollination (Shaw 1975). Raphides are equally distributed in the ovary wall (Shaw 1975). E a c h ovary is 1 to 1.5 mm in diameter and the entire pistillate portion occupies 2 to 5 cm of the spadix (Plucknett 1970; Whitney, Bowers, and Takahashi 1939). Above the pistillate flowers is a narrow constriction of sterile flowers 2 to 5 cm in length and distally followed by the staminate flowers (Onwueme 1978; Plucknett, de la Pena, and Obrero 1970; Shaw 1975). T h e staminate flowers consist of two to six linear anthers fused to form a synandrium (Plucknett, de la Pena, and Obrero 1970; Shaw 1975; Whitney, Bowers, and Takahashi 1939). T h e four to twelve thecae along each are dehiscent by a terminal pore (Shaw 1975). Anthers produce pollen which, in one case, has been described as " s m o o t h " (Wilder 1923). This has been shown to be otherwise by use of the scanning electron microscope (fig. 3.5). Pollen grains are globular in shape, trinucleate, and possess up to four germ pores. Their average diameter is 35 mm (Jos, Vasudevan, and Magoon 1967). Finally, there is a sterile appendage

28

G E N E R A L BACKGROUND

FIGURE 3 . 5 .

microns).

Pollen grain of taro, Colocasia esculenta (scale is

50

which may be acute or obtuse (Shaw 1975). The length of this appendage has been used as a diagnostic character (Purseglove 1972). Flowers are not found in all cultivars of taro. This led one author to state: " T h e taros have been cultivated so long that many of them never flower and it is probable that no civilized man ever saw a viable taro seed." (Barrett 1928). This led to the assumption that taro seeds were indeed quite rare (Kikuta, Whitney, and Parris 1938; MacCaughey and Emerson 1913; Strauss, Michaud, and Arditti 1979; Whitney 1937; Willimot 1936). A recent study of taro fruits revealed an average of two to five seeds in each ripe berry of the inflorescence (Shaw 1975). This is still

Anatomy and Morphology

of Taro

29

considerably below the thousand to three thousand seeds the author has found in some ripe inflorescences (Strauss et al. 1980). Larger numbers of seed are found in ovaries at the upper and lower ends of the pistillate portion of the spadix, the number diminishing considerably at the midsection (Shaw 1975). The apparent sterility of taro with respect to seed production has been the subject of several studies. Early reports supported the belief that sterility of taro resulted from aberrant meiotic events during formation of the micro- and mega-spores (Banerji 1934, 1937; Mayeda 1932). That such events as desynapsis or multiple sporocyte formation occurred was confirmed by later work (Jos and Nair 1976; Krishnan, Magoon, and Vijaya Bai 1970a, 1970b; Vijaya Bai, Magoon, and Krishnan 1971). Other work demonstrated, however, that such events are probably insignificant and comprise a relatively small portion of the meiotic events in most cultivars (Abraham and Ramachandran 1960; Ramachandran 1978). These later studies still left open the question of apparent poor germination in taro. The seed of taro (fig. 3.6) is 1.0 to 1.5 mm in length and 0.7 to 1.0 mm in diameter. It is hard, straw-yellow or pale yellow in color, ovate, and longitudinally ridged. There is a conspicuous hilum at one end and a delicate, translucent funiculus (Barrau 1959; Kikuta, Whitney, and Parris 1938; Shaw 1975). Only two reports exist on the development of taro seedlings (Barrau 1959; Kikuta, Whitney, and Parris 1938). It is described by one author as follows: Distilled water was added to keep the paper and seeds moist. A day later the seeds were swollen and the longitudinal furrows began to fill out. In ten days the seed coat ruptured, and the radicle appeared from the anterior end. . . . The radicle grew rapidly. . . . The typically bilobed and almost circular cotyledon next emerged. . . . Chlorophyll developed almost immediately. The testa persisted on the cotyledon for a considerable length of time after germination. . . . In the first true leaf the petiole is attached to the blade at its margin. With each successive leaf, however, the petiole tends to progress toward the center of the blade and, consequently, the leaf of a mature plant is more or less peltate or umbrella-shaped. (Figs. 3.7 and 3 . 8 ; Kikuta, Whitney, and Parris 1938)

CYTOLOGY Somatic chromosome numbers reported for taro range from fourteen to forty-two (Plucknett, de la Pena, and Obrero 1970). The basic chromosome number is thought to be fourteen but has been suggested as seven (Larsen 1969; Ramachandran 1978; Vijaya Bai, Magoon, and Krishnan

30

G E N E R A L BACKGROUND

Seed of taro showing prominent ridges as well as the funiculus and hilum (scale is 500 microns). FIGURE 3 . 6 .

1971). In the Pacific, the diploid number appears to be primarily twenty-eight. Triploids with 2n = 4 2 have been reported to occur in the Solomon Islands (Jackson, Ball, and Arditti 1977b; Yen and Wheeler 1968), Japan (Plucknett, de la Pena, and Obrero 1970; Yen and Wheeler 1968), the Philippines, New Caledonia, and New Zealand (Purseglove 1972; Yen and Wheeler 1968). In the Solomon Islands, a marked difference in size is seen between the two somatic numbers. Plants with 2n = 4 2 are referred to as alowane (male) and those of 2n = 28 are called alokine (female) by the indigenous farmers (Jackson, Ball, and Arditti 1977b). In other areas " . . . no obvious morphological correlates were

V 3.7. Development of taro seedlings: A , seed; B, 10 days; C , 11 days; D, 1 2 days; £ , 1 3 days; F, 16 days; G, 18 days; H, 23 days. Reprinted by permission of the publisher from "Seeds and Seedlings of the Taro, Colocasia esculenta," by K. Kikuta, L. D. Whitney, andG. H. Parris, Amer.j. Bot. 24(3): 187. FIGURE

D

E

Development of leaves of taro seedlings: A, 1st leaf, 27 days; B, 3rd leaf, 55 days; C, 5th leaf, 80 days; D, 7th leaf, 93 days; E, 9th leaf, 103 days. Reprinted by permission of the publisher from "Seeds and Seedlings of the Taro, Colocasia esculenta," by K. Kikuta, L. D. Whitney, and G. H. Parris, Amer. }. Bot. 24(3): 188. FIGURE 3 . 8 .

Anatomy and Morphology of Taro

33

noted in the field during periods of collection or during the experimental growing in New Zealand of varieties of known chromosome number" (Yen and Wheeler 1968).

CONCLUSIONS Further investigation of the anatomy and morphology of taro should be of great significance, not only to development of the crop, but also to the study of botany. T h e existence of cultivars with leaf enations provides materials for the study of basic plant development. A more complete knowledge of embryo genesis and seedling development is necessary to the successful establishment of taro breeding programs. In virtually all areas covered by this review much additional study is needed.

NOTE I wish to thank R. E. Schultes and his associates at the Economic Botany Library, Harvard University, as well as the staff of the Northeastern University Interlibrary Loan Office for assisting in the location of printed materials. Additional thanks to Daniel Scheirer for reading and commenting on the manuscript and to Sally Higa, University of Hawaii, for her work on final preparation of the manuscript. Scanning electron micrographs are courtesy of J. Arditti.

4

Physiology and Phytochemistry Leslie A. Sunell Joseph Arditti

TARO is an ancient crop known from China and Egypt (Bowers 1967; de la Pena 1970; Fournier 1952; Greenwell 1947; Whitney, Bowers, and Takahashi 1939; Willimott 1936). It was particularly important to the people of the Pacific (Emma 1836-1885) and was observed by Captain Cook (Beaglehole et al. 1955, 1961) and Charles Darwin (Stone 1962). As a crop taro is still extremely important in the South Pacific, Southeast Asia, and Africa (Chandra 1979b; Ghani 1979; Sastrapradja and Hambali 1979; Wang and Steinke 1979; Wang and Otagaki 1979). On a world scale, taro is an underexploited crop (National Academy of Sciences 1975) that has been neglected scientifically. As a consequence, very little information is available on the physiology and phytochemistry of taro. The aim of this chapter is to summarize this information and by doing so call attention to the paucity of data and the need for additional research. While examining the available literature, 1 we noted a large number of papers of peripheral importance; they contain information which pertains to, but is not directly relevant to, taro physiology and phytochemistry.

WATER RELATIONS Very little is known about the water relations of taro. This is surprising because the same cultivars can be grown under dryland or flooded conditions, and this renders taro an ideal plant for comparative studies. The available information, however, seems to be based primarily on work with upland taro (table 4.1 ; Kato and Kamota 1969; K a t o e t a l . 1969). Generally, transpiration by taro is directly related to leaf area (Kato et al. 1969). Most of the water loss (60 percent) under field conditions

Physiology

and

Phytochemistry

35

occurs during the summer. Studies of drought resistance in taro have shown that cultivars differ in osmotic value, solute content and wilting point (Gomi 1957). There are several reports that taro leaves secrete water at their tips though guttation (for short reviews see Dixon and Dixon 1931; Flood 1919). Amounts exuded under field conditions can average 10 ml per night but volumes as high as 22.6 ml have also been collected (Flood 1919). Plants maintained in full-strength Knop's solution and those in dilutions of 1/2 to 1/8 exuded equal volumes (0.12-0.13 ml/hr). Where plants were placed in more concentrated or more diluted solutions, exudate levels decreased (Tazaki 1939). One of the earliest studies of taro exudates showed that the exudate had a freezing point not seriously different from that of distilled water, and its conductivity was lower than that of tap water (Dixon and Dixon 1931). However, other investigations found small amounts of solutes in the exudate (for a short review see Tazaki 1939). Concentrations of calcium and potassium in the exudate varied with the level of these ions in the culture solution (Tazaki 1939). A diurnal periodicity in nitrogenous constituents in bleeding sap of taro plants has been reported (Okamoto 1966; Okamoto and Izawa 1963). Maximal levels were recorded during the day and minimal ones at night. When plants are supplied with ammonium nitrogen, amino -N levels are higher than when nitrate is provided (Okamoto 1966).

MINERAL NUTRITION Limited information is available on the mineral nutrition of taro, although there are several studies on content (table 4.2). Some of the information is not very detailed because it deals with root crops in general (Jacoby 1972). Other papers are more specific. Taro contains relatively high amounts of calcium (Plucknett and de la Pena 1971) and this may well be due to the presence of numerous crystals of calcium oxalate (Black 1918). One hypothesis regarding the function of calcium oxalate crystals is that they are the result of inactivation of excess oxalic acid (Schimper 1888). Alternatively, the crystals may serve to rid the plant of excess calcium ions (Amar 1903; Olsen 1939; Stahl 1920; for reviews see Arnott 1973, 1976; Arnott and Pautard 1970). In either case, a commonly accepted idea has been that calcium oxalate crystals, once deposited, become metabolically inactive. Recent findings indicate that this may not be the case since crystal numbers and density change during plant development (Sunell and Healey 1979). This may have a bearing on the calcium balance within the plant. It is generally assumed that taro has high calcium requirements per-

36

G E N E R A L BACKGROUND

haps because the addition of lime to soils low in this element is beneficial (Kay 1973; Miyasaka and Bartholomew 1979; Onwueme 1978; Plucknett and de la Pena 1971; Yong 1971). In nutrition trials, calcium concentrations in plant tissues increased in direct proportion to the presence of this element in the solution (Miyasaka and Bartholomew 1979). In addition, higher calcium concentrations brought about increases in dry weight and the number of cormels (table 4.2). Calcium levels in petioles increased in age (Miyasaka and Bartholomew 1979). Although levels of several minerals are reported to have decreased with decreasing calcium concentration, the only statistically significant decrease occurred with magnesium (Miyasaka and Bartholomew 1979). Calcium deficiency symptoms include (Miyakasa and Bartholomew 1979) 1. failure of the leaf blades to unfurl 2. interveinal chlorosis 3. interveinal necrosis 4. petiole collapse 5. root dieback 6. death of the shoot tip Potassium requirements of taro, like those for calcium, are high (Kay 1973; Onwueme 1978). A study of potassium utilization from solutions containing 0.02, 0.06, 0.2, and 3.0 mg/1 has shown that half-maximal uptake occurred at 0.02 mg/1 (Cable 1973). Most growth measurements have a I n - I n correlation with time (Cable 1973). The number of suckers varied with potassium concentration as did the mineral content in leaves (table 4.3), roots (table 4.4), and corms (table 4.5). Uptake of minerals (K, NO a , and P) increased in the presence of sufficient potassium (Cable 1973). Potassium deficiency symptoms in taro are (Cable 1973; Onwueme 1978) 1. marginal chlorosis of the leaves 2. increased respiration in leaves 3. higher respiration in roots 4. decrease in leaf-water content 5. lowered respiratory stimulation by dinitrophenol, suggesting that potassium deficiency may tend to uncouple phosphorylation 6. death of roots 7. increased bleeding sap exudation (Okamoto and Izawa 1963) 8. higher levels of amino, ammonia, free-amino, and asparagine nitrogen in bleeding sap (Okamoto and Izawa 1963)

Physiology and Phyto chemistry

37

9. reduced total-, nitrate-, glutamine-, and residual nitrogen in bleeding sap (Okamoto and Izawa 1963) 10. high glycolic oxidase activity 11. reduced concentration of amino acids, nitrate, glutamine, and residual peptides nitrogen 12. increased respiration in leaves and roots (Okamoto 1967b) Roots are reported to be more sensitive than leaves to moderate potassium deficiency (Okamoto 1969b; for a review see Onwueme 1978). Applications of potassium enhanced translocation and transformation of sugars and nitrogen compounds in all parts of the taro plant. Taro yields were increased by potassium fertilization (de la Pena and Plucknett 1969). The addition of potassium to upland taro increased nitrogen, potassium, and phosphorus levels in petioles and blades, but reduced the concentrations of calcium and magnesium (table 4.6). In lowland taro, potassium fertilization increased levels of this element, decreased those of calcium and magnesium and had no effect on phosphorous and nitrogen (table 4.7). Uptake of potassium from nutrient solutions is greater than that of calcium (Tazaki 1939). Slight variations in potassium levels of culture solutions affect respiration of roots and this is reflected in exudation rates of bleeding sap (Okamoto 1969a). Glycolic acid oxidase has been detected in blades and petioles of taro, but not in roots (Okamoto 1967a). Activation of this enzyme by FMN and inhibition by acetaldehyde bisulfite were more pronounced in potassium deficient plants (Okamoto 1967a). Younger leaves had a higher level of activity and more tolerance to inhibitors than did older ones. As might be expected increased nitrogen fertilization raised yields (de la Pena and Plucknett 1969). In upland taro nitrogen fertilization increased the levels of phosphorus, potassium, and calcium (table 4.8). The effects on lowland taro were similar except that magnesium levels also increased (table 4.9). Bimonthly foliar applications of 5 percent urea gave good results (Reynolds, Isako, and Michael 1977). Taro responds well to fertilization with phosphorus (Onwueme 1978; de la Pena and Plucknett 1969; de la Pena, van der Zaag, and Fox 1979). Phosphorus content in leaves of upland taro was directly proportional to phosphate fertilization levels, whereas the opposite was true for other elements (table 4.10). The same was true for lowland taro (table 4.11). Phosphorus requirements for three cultivars grown under flooded and nonflooded conditions are 0.02 ppm (de la Pena, van der Zaag, and Fox 1979). Internal levels of phosphorus in taro corms increased in direct proportion to the concentration in the solution (fig. 4.1; table 4.12). Under nonflooded conditions, increased phosphorus concentrations had

38

G E N E R A L BACKGROUND Taro (Non-flooded)

.30

o

• Lehua O Bun Long

Q.

o Hh

.003

.012

.05

.1

.2

.4

1.6

Phosphorus in Solution (ppm)

FIGURE 4.1. Phosphorus concentration in the corms of two taro varieties as influenced by the concentration of phosphorus in the culture solution. Reprinted by permission of the publisher from " T h e Comparative Phosphorus Requirements of Flooded and Non-flooded T a r o , " by R. S. de la Pena, P. van der Z a a g , and R. I. Fox, International Foundation for Science Provisional Report no. 5 (Stockholm, 1979), p. 232.

no effect on the levels of other nutrients (de la Pena, van der Zaag, and Fox 1979; table 4.13). The application of nitrogen or potassium to taro plants had a marked effect on yield and the levels of organic constituents, including sugars, starch, and nitrogenous compounds (Izawa and Okamoto 1961). The greatest increase in yield was obtained for blades, petioles, roots, main corms, and cormels by fertilizing plots containing 20 mg of sand with 7.5 g (NH 4 ) 2 S0 4 , 5 g superphosphate, and 2.5 g KC1. The biosynthesis of sugars, starch, and nitrogenous constituents (total alcohol-insoluble, alcohol-soluble, residual, amide, ammonium, nitrate and nitrite nitrogen) during growth was affected by mineral nutrition. Response to fertilization over time differed with the plant part (figs. 4.2, 4.3, 4.4; tables 4.14,4.15,4.16). Only the addition of nitrogen resulted in significant increases in yield in experiments with potted plants in Hawaii (de la Pena and Plucknett 1969). Additions of phosphorus and potassium did not increase growth significantly. These fertilizers did have an effect, however, on the composition of plants (table 4.15). In studies of air pollution, taro was shown to be very sensitive to atmospheric fluoride (Suketa and Yamamoto 1975).

Physiology and

Phytochemistry

39

PHOTOSYNTHESIS As with other areas of taro physiology, little is known about the structural and physiological aspects of photosynthesis. Surprisingly, much of the available information on the structure of stomata of taro leaves comes from "an unusually vigorous specimen of Colocasia antiquorum var. esculenta (known commonly as elephant's ear or caladium) growing in a yard in Falmouth, Kentucky . . . " (Yarbrough 1934). A photograph accompanying the article (Yarbrough 1934) shows a human female 47 mm tall with the taro plant, which reaches a height of 57 mm. Assuming that the 47 mm represent 1.60 m, the taro plant must have been 2 m tall. Its largest leaf was 1 . 3 5 m long and 1 m wide with a total area of 18,146 cm 2 . The leaves were 2.75-3.00 mm thick and had a noticeable palisade layer consisting of two layers of columnar cells. Spongy mesophyll was also present, arranged in vertical sheets which by intersecting at right angles formed large air spaces. Each of these layers occupied approximately half the thickness of the leaf. The number of stomata on the upper surface averaged 50/mm 2 for a total of 45 million. On the underside the stomata numbered 116/mm 2 or 95 million for the entire surface. The total for the leaf was 140 million stomata, allowing for veins. Those on the upper epidermis had cylindrical substomatal chambers which ramified through the palisade region. Stomata on the lower epidermis were connected to air spaces which extended into the spongy mesophyll (Yarbrough 1934). One investigation of photosynthesis with the Japanese variety Ishikawawase (Sato, Kawai, and Fukuyama 1978) has shown that 1. plants produce 10-18 leaves that last 4 0 - 4 5 days (lower leaves) to 5 5 - 8 0 days (upper leaves) (fig. 4.5A); 2. upper leaves have larger areas (fig. 4.5A); 3. the rate of photosynthesis increases with growth, reaches a maximum 14-15 days after expansion, remains at this level for 10 days, and then is affected by senescence (fig. 4.5B, £); 4. the maximum rate of photosynthesis by a single leaf under light saturation is 3 0 - 3 5 mg C0 2 /dm 2 /hr for lower leaves and approximately 20 mg for upper and middle leaves (fig. 4.5C, F); 5. light saturation for younger leaves is 70 Klx and 2 0 - 3 0 Klx for those that are older (fig. 4.5C, F); 6. the suitable temperature range for photosynthesis is 2 5 - 3 5 ° C with 30°C being the optimum (fig. 4.5D); and 7. maximal rates of photosynthesis increased starting at the end of June and did not decline even in late September (fig. 4.5F).

o

LA

LA

O

CM

T3

4> «

C CS

U

CS

S cd N

•C o a. 0) a.

01 > o w®

Thr-

8 a i =a = & C3 cRJ> (3 >,JjO (0>(0> 0 H>-T - in — o CL — o o c L. >— < O 0 • ». 0 c > -C 4-> 1 tu E C 5 0) 0 u CL •— •s o E >3 (/I cr 0 co

cu ¡a .H a E I- — _c 4-1 3 .— • w C if) *— c — Ol o 0 — — Ifl 4-» 4-1 l -

E o O 14-

V. u0 O 3 « jz 4-» > - t J a> 3 -û c d) 3 — E 4-4 4-4 (U .— O in • 2 - c .— o > 4-1 sO T3 Uì Q O Q..Q E

ra

ra ra

raL.tu c

i co o tu z t*- ' — ' U— (0 >. u ' C Z XI O o

60 TABLE 4.4

CONCENTRATION OF MACROELEMENTS TARO ROOTS A T HARVEST TIME

IN THE DRY MATTER OF

Concentration, percent of dry matter Treatment 3 Low Med ium High Complete DMRT

N 3 .07 3 .18 3 .10 3 .32 ns

N03"b 0.45 0.50 0.45 0.47 ns

P 0 .41 0 .40 0 .38 0 .38 ns

K 1.97 2.20 2.57 3.08 ns

Ca 0.80 0.82 1 .02 0.94 ns

Mg 0 . 52e 0 ,• 5 5 e 0 ,45 e 0 , • 30 + .14

NOTE: Reprinted with the permission of the author from "The Potassium Requirement of Taro [Colocasia esculenta (L.) Schott] in Solution Culture," by W. J. Cable, M. Sei. Thesis, Univ. of Hawaii, Honolulu (1973). a

Low = 0.02 mi 11¡moles potassium; medium = 0.06 mi 11¡moles potassium; high = 0.20 mi 11¡moles potassium; complete = 3 mi 11¡moles. b Nitrate is expressed as nitrogen. c Means significantly different beyond the level by Duncan's Multiple Range Test (DMRT); values with the same letter in the superscript are not significantly different (ns).

61 TABLE 4.5

CONCENTRATION OF MACROELEMENTS TARO CORMS AT HARVEST T I M E

IN THE DRY MATTER OF

C o n c e n t r a t i o n , p e r c e n t of dry m a t t e r Treatment3 Low Medium High Complete DMRT

N 1.7'4 1.68 1.80 1.70 ±.42ns

NO3-b 0.34 0.32 0.35 0.41 ±.40ns

P

K

Ca

0.33 0.30 0.32 0.30 ±.24ns

1.84 1.94 2.20 2.30 ±.05ns

0.128 0.055 0.070 0.053 ±.l6ns

Mg 0.100c 0.080cd 0.074d 0.064d ±.025e

NOTE: Reprinted w i t h the p e r m i s s i o n of the a u t h o r from " T h e P o t a s s i u m R e q u i r e m e n t of T a r o [Colocasia e s c u l e n t a (L.) S c h o t t ] in S o l u t i o n C u l t u r e , " by W. J. Cable, M. Sei. T h e s i s , U n i v . of H a w a i i , H o n o l u l u (1973); table revised in " P o t a s s i u m R e q u i r e m e n t of T a r o in R e l a t i o n s h i p to G r o w t h , Foliar A n a l y s i s , Y i e l d , and Q u a l i t y as G r o w n in S o l u t i o n C u l t u r e , " by W. J. C a b l e , Int'l. Symp. Trop. R o o t Crops 1973 Proc. 3rd, p. 135. a

Low = 0.02 m i l l i m o l e s p o t a s s i u m ; m e d i u m = 0.06 m i l l i m o l e s p o t a s s i u m ; high = 0 . 2 0 m i l l i m o l e s p o t a s s i u m ; c o m p l e t e = 3 millimoles potassium, b N i t r a t e is e x p r e s s e d as n i t r o g e n . c > d V a l u e s w i t h the same letter in the s u p e r s c r i p t a r e not sign i f i c a n t l y d i f f e r e n t (ns) by Duncan's M u l t i p l e R a n g e Test (DMRT). e S i g n i f i c a n t l y d i f f e r e n t b e y o n d the 5% level by D M R T .

62 TABLE 4.6

EFFECTS O F POTASSIUM FERTILIZATION ON COMPOSITION OF UPLAND TARO LEAVES 9 Petioles, age (months)

Treatment kg/ha K

3

6

(Control) b 0 280 560 1120

1.25 1.62 1.63 1.69 1.92

(Control) 0 280 560 1120

.112 0 . ,147 0 . ,165 0 . ,201 0 . ,168 0.

0 (Control) 0 280 560 1120

8.40 3.10 10.13 10.27 11.15

0 (Control) 0 280 560 1120

1.19 1.17 O.87

0 (Control) 0 280 560 1120

0.10 0.19 0.11 0.11 0.10

0.84 0.87

9

1.12 1.19 1.20 1 .83 2.27

0..80 0. 73 0.• 73 0..92 0..88

164 143 158 145 153

0.164 0.253

12

Blades, age (months) 3

Percent N 1.29 3.• 75 4..20 1.33 4..09 1.11 1 .21 4..18 4..12 I.30

6

9

12

3.27 3.86 3.80 3.87 3.95

3..09 3..16 3..33 3..50 3..59

3.^3 3.47 3.20 3-23 3.68

0.265

O.25I

0 . 2 7 0

0 . 2 9 6

O . 3 0 6

0.321

0.281

0.298

0.266

0.288 0.299 0.297

O . 3 2 5

0 . 2 3 4

Percent P 0.203 0 . .231 0,.293 0.3II 0.281 0 . .340 0.350 0..339 0.364 0..331

11.27

3.32 3.13 5.77 5.70 5.90

Percent K 4.76 4.73 3.20 3-53 5.70 5-33 5.86 6.10 7.11 6.17

5. 27 3. 30 5. 79 6. 28 6. 35

3.91 3.31 4.77 4.67 4.69

4.03 3.24 4.05 4.20 4.53

O.87

0.72

O.63

1..24 1. 78 1. 92 0. 88 0.,92

1.16 1.30

0.57 0.60 0.55

Percent Ca 1.08 1.39 1.87 0.95 0.76 1.17 0.84 1.16 1.22 0.67

0.77 0.65

1.63 1.44 1.25 1.27 0.97

0.15 0.26 0.13 0.13 0.12

0.13 0.18 0.12 0.13 0.10

Percent Mg 0.14 0.18 0.22 0.31 0.18 0.14 0.16 0.12 0.09 0.15

0.,13 0.,27 0..15 0.,14 0..11

0.22 0.24

0.24 0.33

0. 0. 0. 0. 0.

7.30 2.71 7.85 9.61

1.04 0.66 0.68

0 . 2 7 5 O . 2 7 0

O.63

0 . 3 6 2

0 . 9 2

0.19

0.22 0.19

0 . 3 0 5

O.23

0.21 0.20

SOURCE: R. S. de la Pena and 0. L. Plucknett, "The Response of Taro [Colocasia esculenta (L.) Schott] to N, P, and K Fertilization Under Upland and Lowland Conditions in Hawaii," Int'l. Symp. Trop. Root Crops 1967 Proc. 1st (v. 1) sect. 2, p. 80. a

Average of three replications. Results of analysis expressed in percent oven dry weight. b Control plots were not fertilized; all other treatments received basic applications of 280 kg/ha each of N and P.

63 TABLE 4 . 7

Treatment kg/ha K

E F F E C T S OF POTASSIUM F E R T I L I Z A T I O N ON COMPOSITION OF LOWLAND TARO L E A V E S 3 Petioles, 3

age (months)

6

9

1

2

Blades, 3

Percent: N 4.02 0.65 O.74 4.62 0.64 4.32 0.66 4.51 4.30 0.71

(Control) 0 280 560 1120

1 ,00 . 1.,21 1 ,06 . 1 .11 . 1 .12 .

0.97 1.18 1.05 1.17 1.22

(Control ) 0 280 560 1120

0.,268 0.,327 0.,381 0.,363 0..361

O.57O 0.628 0.61(5 0.684 0.678

0.516 0.,463 0.,472 0,,405

0.307 0.337 0.316 0.316

(Control) 0 280 560 1 120

2.,05 1 .85 . 4..03 5.• 50 7..23

3.60 2.87 5-69 6.93 8.51

1..93 1..36 3..49 3..24 4..15

Percent: K 1.02 2.83 O.92 2.51 1.64 4.06 1.49 4.83 2.24 5.42

(Control) 0 280 560 1120

0. 77 0..81

0.7*» 0.84

0.• 56 0,.50

0.62

0..88 0..77 0,.71 0..60 0..45

O.58 O.52

(Control) 0 280 560 1120

0.• 58 0.• 57 0..52 0..42 0,.40

0.58

0..48 0..46

P e r c e n t Mg 0.71 O.33 0.68 0.33

0.38

0,.33 0..25

0.33 0.27

0.67

0.71 0.71

0.44 0.41 0.40

0..81

0.78 0..71

0..69 0..71

0.476

0.34

Percent: P 0.312 0.400

0.437 0.461 0.455 0.439

P e r c e n t : Ca 0.69 1.59 0.58 1.47 1.11 0.51

O.32

0.91

0.86

0.51 0.52

0.56

age

(months)

6

9

1

2

4. 09 4.,42 4. 23 4.,29 4.,22

3.13 3.31 3.23 3.24 3.25

2.78 3.11

0.,477 0.,542 0,.522 0.,547 0.,530

0.377 0.377 0.380

0.319 0.333

0.342

O.306

4..30 3..56 4..97 5..27 5.87

0.362

2.90

2.81 2.85

O..32I

0.316

4.30

2.60 2.28 3.37 3.32 3.62

1,.55 1..65 1,.29 1,.19 1,.13

1.55 1.44 1.28 1.14 1 .02

1.76 1.33 1.43 1.39 1.09

0,.35 0 .43 9,.35 0 .36 0 .40

0.35 O.45 0.24 0.25 0.26

0.33 0.37

2.85

2.30

4.14 3.90

O.32

0.27 0.28

SOURCE: R. S . de l a Pena and D. L . P l u c k n e t t , " T h e Response o f T a r o [ C o l o c a s i a e s c u l e n t a ( L . ) S c h o t t ] t o N, P , and K F e r t i l i z a t i o n Under Upland and Lowland C o n d i t i o n s i n H a w a i i , " I n t ' l . Symp. T r o p . Root Crops 1967 P r o c . 1 s t ( v . 1) s e c t . 2, p. 82. Average of three r e p l i c a t i o n s . R e s u l t s of a n a l y s i s expressed in e r c e n t oven d r y w e i g h t . C o n t r o l p l o t s were not f e r t i l i z e d ; a l l o t h e r t r e a t m e n t s r e c e i v e d b a s i c a p p l i c a t i o n o f 280 kg/ha e a c h o f N and P .

a

C

64 TABLE 4 . 3

EFFECTS OF NITROGEN F E R T I L I Z A T I O N ON COMPOSITION OF UPLAND TARO LEAVES 9 Petioles,

Treatment kg/ha N

3

age (months)

6

9

1

2

B l a d e s , age 3

(months)

6

9

1

2

(Control) 0 280 560 1120

1.25 1.00 1.63 2.28 2.70

1. 12 1. Oil 1. 20 1. 72 1. 82

0.80 0 . 77 0 . 73 0 . 82 0 . 87

Percent: N 1 .29 3.75 3.64 1.11 1.11 4.09 1.18 4.45 1.32 4.88

3 . 27 3. 30 3- 80 4 . 14 4 . 33

3.09 3.02 3-33 3.69 3.64

3.43 3.32 3.20 3.46 3.51

(Control) 0 280 560 1120

0.112 0.312 0.165 0.164 0.162

0. 0. 0. 0. 0.

164 411 158 144 144

0 ..164 0.431 0 . 275 0 . 178 0 . 185

Percent : P 0.231 0.203 0.356 0.385 0.340 0.281 0.285 0.317 0.232 0.316

0 . 265 0 . 338 0 .,281 0 .,281 0.,288

0.251 0.313 0.288 0.288 0.298

0.270 0.337 0.298 0.314 0.293

7. 7. 7. 7. 6.

30 99 85 10 27

3. 32 6.• 53 5.• 77 4..19 3..65

Percent 4.76 6.85 5.33 4.50 4.80

5.52 5.70 5.07 4.63

5..27 5..30 5..79 5..46 5..00

3.91 4.90 4.77 3-92 4.12

4.03 4.40 4.05 3.72 3.98

K

b.73

(Control) 0 280 560 1120

8.AO 10.70 10.13 9.15 7-90

(Control) 0 280 560 1120

1.19 1.06 0.87 0.95 0.97

0.87 0 . 71 0 . 66 0 . 83 0. 75

0.• 72 0..57 0.• 57 0.• 57 0.54

Percent 1.08 0.88 0.76 0.81 0.74

Ca 1.39 1.29 1.17 1.20 1.19

1,.24 1..03 0,.92 0.• 95 0,• 75

1.16 1.21 0.92 0.89 0.75

1.63 1.44 1.25 1.32 1.10

(Control) 0 280 560 1120

0.10 0.10 0.11 0.12 0.13

0 ..15 0 ..12 0..13 0..18 0..14

0,.13 0..10 0 .12 0..12 0 .11

Percent 0.14 0 . 12 0 . 14 0.15 0.12

Mg 0.18 0.15 0.18 0.19 0.20

0 .13 0 .11 0 .15 0 .17 0 .15

0.22 0.19 0.19 0.20 0.17

0.24 0.21 0.23 0.23 0.22

SOURCE: R. S. de l a Pena and D. L . P l u c k n e t t , " T h e Response o f T a r o [ C o l o c a s i a e s c u l e n t a ( L . ) S c h o t t ] t o N, P, and K F e r t i l i z a t i o n Under Upland and Lowland C o n d i t i o n s i n H a w a i i , " I n t ' l . Symp. T r o p . Root Crops 1 9 6 7 P r o c . 1 s t ( v . 1) s e c t . 2 , p . 73. a

Average of t h r e e r e p l i c a t i o n s . Results o f a n a l y s i s expressed in p e r c e n t oven d r y b a s i s . b C o n t r o l p l o t s were n o t f e r t i l i z e d ; a l l o t h e r t r e a t m e n t s r e c e i v e d b a s i c a p p l i c a t i o n s o f 280 k g / h a each o f P and K.

65 TABLE 4.9

EFFECTS OF NITROGEN FERTILIZATION ON COMPOSITION OF LOWLAND TARO LEAVES3 Petioles, age (months)

Treatment kg/ha N

Blades, age (months) 12

12

1.00 0.99 1.06 1.22 1.38

0.97 0.98 1.05 1.39 1.81

0.81 0.73 0.71 0.76 O.87

Percent: N 4.02 0.65 4.11 0.63 0.64 4.32 0.68 4.37 0.61 4.77

4. 09 4. 10 4. 23 4. 61 4.96

3.13 3.18 3.23 3.47 3-69

2.78 2.77 2.99 3.09 2.98

(Control) 0 280 560 1120

0.268 0.353 0.381 0.364 0.247

0.570 0.654 0.645 0.629 0.581

0.516 0.517 0.476 0.438 0.339

Percent: P 0.312 0.400 0.355 0.437 0.337 0.461 0.251 0.457 0.237 0.435

0. 477 0. 499 0. 522 0. 568 0.565

0.377 0.359 0.380 0.376 0.343

0.319 0.320 0.321 0.322 0.307

(Control) 0 280 560 1120

2.05 4.61 4.03 3.05 2.30

3.60 6.40 5.69 4.77 3.90

1.93 3-94 3.49 2.33 1.44

Percent: K 1 .02 2.83 4.44 1.76 1.64 4.06 0.97 3.37 0.85 2.99

4..30 5.23 4..97 4..80 4..53

2.85 4.27 4.14 3.34 2.70

2.60 3.45 3-37 2.71 2.46

(Control) 0 280 560 1120

0.77 0.64 0.67 0.74 0.85

0.74 0.62 0.71 0.80 0.74

0.88 0.72 0.71 0.77 0.64

Percent Ca 0.69 1.59 1.22 0.70 1.11 0.51 0.45 1.31 0.42 1.43

1,.55 1,.22 1..29 1.29 1..22

1.55 1.25 1.28 1.32 1.27

1.76 1.66 1.43 1.01 1 .02

(Control) 0 280 560 1120

0.58 0.46 0.52 0.61 0.56

0.44 0.33 0.41 0.49 0.49

0.48 0.31 0.34 0.45 0.45

Percent Mg 0.71 0.33 0.62 0.32 0.32 0.51 0.64 0.29 0.62 0.32

0 • 35 0 • 32 0 .35 0 .35 0 • 33

0.35 0.24 0.24 0.33 0.38

0.33 0.27 0.27 0.27 0.29

(Control) 0 280 560 1120

L

SOURCE: R. S. de la Pena and D. L. Plucknett, "The Response of Taro [Colocasia esculenta ( L . ) Schott] to N, P, and K F e r t i l i z a t i o n Under Upland and Lowland Conditions in Hawaii," I n t ' l . Symp. Trop. Root Crops 1967 Proc. 1st (v. 1) sect. 2, p. 74. Average of three replications. Results of analysis expressed in percent oven dry basis. b Control plots were not f e r t i l i z e d ; a l l other treatments received basic applications of 280 kg/ha each of P and K.

a

66 TABLE 4.10

EFFECTS O F PHOSPHORUS FERTILIZATION ON COMPOSITION OF UPLAND TARO LEAVES 3 Petioles, age (months)

Treatment kg/ha P

9

1

2

Blades, age (months)

3

6

3

6

9

1

2

(Control ) 0 280 560 1120

1.25 2.48 1.63 2.12 2.00

1.12 1.70 1.20 1.48 1.21

0.80 0.84 0.73 0.83 0.77

Percent N 1.29 3.75 1.25 4.38 I.11 4.09 1.32 4.23 1.22 4.28

3.27 3.99 3.80 3.99 3.72

3.09 3.53 3-33 3.68 3.16

3.43 3.53 3.20 3-74 3.66

(Control) 0 280 560 1120

0. 112 0.118 0.165 0.239 0.311

0.164 0.128 0.158 0.143 0.154

0.164 0.120 0.275 0.228 0.244

Percent P 0.203 0.231 0.159 0.232 0.281 0.340 0.313 0.340 0.461 0.407

0.265 0.254 0.281 0.287 0.283

0.251 0.245 0.288 0.310 0.319

0.270 0.266 0.298 0.320 0.379

(Control) 0 280 560 1120

8.40 10.90 10.13 9.67 8.77

7.30 8.68 7.85 7.26 7.08

3-32 5.67 5.77 5.12 4.60

Percent K 4.76 4.73 6.20 5.39 5-33 5.70 5.51 5.70 5.27 5.50

5.27 5.38 5.79 5.23 5.13

3.91 4.65 4.77 4.59 4.50

4.03 4.15 4.05 3.93 4.11

(Control) 0 280 560 1120

1.19 0.99 0.87 0.87 0.94

0.87 0.77 0.66 0.71 0.82

0.72 0.68 0.57 0.56 0.53

Percent Ca 1.08 1.39 0.81 1.13 0.76 1.17 0.78 1.16 0.90 1.27

1.24 0.89 0.92 0.95 0.96

1.16 1.04 0.92 0.95 1.11

1.63 1.27 1.25 1.23 1.35

(Control) 0 280 560 1120

0.10 0.09 0.11 0.13 0.13

0.15 0.13 0.13 0.12 0.12

0.13 0.10 0.12 0.13 0.10

Percent Mg 0.14 0.18 0.16 0.16 0.14 0.18 0.15 0.18 0.12 0.19

0.13 0.14 0.15 0.14 0.14

0.22 0.20 0.19 0.20 0.17

0.24 0.26 0.23 0.25 0.20

SOURCE: R. S. de la Pena and D. L. Plucknett, "The Response of Taro [Colocasia esculenta (L.) Schott] to N, P, and K Fertilization Under Upland and Lowland Conditions in Hawaii," Int'l. Symp. Trop. Root Crops 1967 Proc. 1st (v. 1) sect. 2, p. 77. a

Average of three replications. Results of analysis expressed in percent oven dry weight. b Control plots were not fertilized; all other treatments received basic applications of 280 kg/ha each of N and K.

67 TABLE 4 . 1 1

Treatment kg/ha P

EFFECTS OF PHOSPHORUS F E R T I L I Z A T I O N ON COMPOSITION OF LOWLAND TARO LEAVES 3

Petioles, age (months) 3

6

9

12

Blades, age (months) 3

6

9

12

(Control) 0 280 560 1120

1.00 1.31 1.06 1.16 1.10

0.97 1.17 1.05 1.19 1.27

0.81 0.74 0.71 0.73 0.74

Percent: N 4.02 0.65 0.62 4.74 0.64 4.32 0.66 4.61 4.28 0.70

4.09 4.44 4.23 4.46 4.42

3- 13 3. 30 3-23 3. 50 3.43

2.78 3.07 2.90 2.99 3.06

(Control) 0 280 560 1120

0.268 0.326 0.381 0.374 0.372

0.570 0.670 0.645 0.670 0.639

0.516 0.419 0.476 0.468 0.431

Percent: P 0.322 0.400 0.291 0.492 0.337 0.461 0.299 0.483 0.288 0.465

0.477 0.532 0.522 0.560 0.568

0. 377 0. 359 0. 380 0. 394 0. 374

0.319 0.344 0.321 0.334 0.335

(Control) 0 280 560 1120

2.05 5.02 4.03 3.85 3-75

3.60 6.00 5.69 5-63 5.00

1.93 2.33 3-49 2.52 1.93

Percent: K 1.02 2.83 4.45 1.33 1.64 4.06 1.26 4.10 1.00 3-94

4.30 4.70 4.97 4.83 4.83

2..85 3..32 4.,14 3.45 3..12

2.60 3.08 3.37 2.76 2.56

(Control) 0 280 560 1120

0.77 0.61 0.67 0.66 0.66

0.74 O.69 0.71 0.79 0.67

0.88 0.74 0.71 0.71 0.71

Percent Ca 1.59 0.69 1.09 0.56 1.11 0.51 0.49 1.10 0.53 1.13

1.55 1.24 1.29 1.37 1.27

1..55 1..21 1..28 1..23 1. 32

1.76 1.42 1.43 1.37 1.28

(Control) 0 280 560 1120

0.58 0.60 0.52 0.45 0.53

0.44 0.44 0.41 0.45 0.46

0.48 0.37 0.34 0.39 0.39

Percent Mg 0.33 0.71 0.64 0.31 0.32 0.51 0.52 0.31 0.55 0.31

0.35 0.37 0.35 0.35 0.35

0,.35 0 • 30 0,.24 0 .28 0 • 31

0.33 0.29 0.32 0.35 0.30

SOURCE: R. S. de la Pena and D. L. Plucknett, "The Response of Taro [Colocasia esculenta (L.) Schott] to N, P, and K F e r t i l i z a t i o n Under Upland and Lowland Conditions in Hawaii," I n t ' l . Symp. Trop. Root Crops 1967 Proc. 1st (v. 1) sect. 2, p. 78. Average of three replications. Results of analysis expressed in percent oven dry weight. b Control plots were not f e r t i l i z e d ; a l l other treatments received basic applications of 280 kg/ha each of N and K.

a

68 TABLE ¿t. 12

PHOSPHORUS CONCENTRATIONS IN LEAF BLADES OF THREE CULT IVARS OF C. esculenta (Non-flooded Experiment) AS AFFECTED BY PHOSPHORUS LEVELS IN THE SOIL

Phosphorus level in the soi1, ppm

Lehua

Bun-Long

0.002 0.003 0.006 0.012 0.025 0.05 0.1 0.2 0.4 1.6

0.29 0.37 0.39 0.38 0.41 0.45 0.47 0.56 0.59 0.66

0.25 0.31 0.32 0.32 0.35 0.35 0.39 0.45 0.50 0.58

Content, percent Dasheen 0.24 0.33 0.36 0.34 0.34 0.36 0.37 0.39 0.45 0.42

NOTE: Reprinted by permission of the publisher from "The Comparative Phosphorus Requirements of Flooded and Non-flooded Taro," by R. S. de la Pena, P. van der Zaag, and R. I. Fox, International Foundation for Science Provisional Report no. 5 (Stockholm, 1979) , p. 234.

69 TABLE 4 . 1 3

N U T R I E N T L E V E L S I N LEAF BLADES ( 3 m o n t h s a f t e r p l a n t i n g ) AND IN THE CORMS AT HARVEST T I M E OF THREE V A R I E T I E S OF C. e s c u l e n t a M A I N T A I N E D IN 0 . 0 1 2 ppm P H O S PHATE S O L U T I O N UNDER NON-FLOODED C O N D I T I O N S I N KAUAI Concentrât ion Percent

ppm

Cultivar

N

K

Ca

Mg

S

Leaves Lehua Bun-Long Dasheen

3..8 3..8 3..8

5..6 5.. 1 5 .5

2. 3 3..0 2..7

0..20 0..39 0..29

0.• 32 0.• 39 0..35

Corms Lehua Bun-Long

0.M 0..69

1..2 1..k

0.,20 0..13

0,.03 0..07

0..02 0.,0h

Mn

Fe

Cu

Zn

170 200 130

125 87 92

23 21 21

k2 ill 1(2

-

-

-

-

-

-

—

—

NOTE: R e p r i n t e d by p e r m i s s i o n o f the p u b l i s h e r from " T h e Compara t i v e P h o s p h o r u s R e q u i r e m e n t s o f F l o o d e d and N o n - f l o o d e d T a r o , " by R. S . de la Pena, P. van d e r Z a a g , and R. I . F o x , I n t e r n a t i o n a l F o u n d a t i o n f o r S c i e n c e P r o v i s i o n a l R e p o r t no. 5 ( S t o c k h o l m , 1 9 7 9 ) , p. 2 3 6 .

70 TABLE 4.14

COMPOSITION OF PETIOLES AND BLADES OF INDIVIDUAL LEAVES OF 6-MONTH-OLD TARO PLANTS GROWN IN PLOTS 3 Leaf number Petioles

Treatments

1

2

3

Blades 4

1

2

3

4

Control K P K NP NK PK NPK

0.88 1 .02 0.95 1.16 1.41 1.10 0.94 1.41

0.84 0.86 0.93 0.93 1.06 0.95 0.82 1.12

0.84 0.81 0.89 0.89 0.83 0.87 0.77 1.06

Percent N 3.16 0.79 0.77 3.67 0.85 3.51 3.84 0.82 4.06 0.79 0.85 3-77 3.68 0.75 0.97 4.79

3.29 3.60 3.63 3.52 3.49 3.65 3.47 4.16

3.00 3.27 3.19 3.49 3-33 3.36 3.03 3.41

2.53 2.83 2.85 3.01 2.86 2.69 2.53 2.60

Control N P K NP NK PK NPK

0.562 0.232 0.628 0.646 0.618 0.274 0.728 0.642

0.714 0.168 0.828 0.624 0.484 0.200 0.736 0.586

0.822 0.154 0.932 0.702 0.436 0.163 0.874 0.558

Percent P 1 .126 0.424 0.140 0.326 1 .210 0.478 0.836 0.512 0.452 0.484 0.154 0.352 1 .214 0.522 0.544 0.558

0.372 0.260 0.526 0.386 O.326 0.260 0.520 0.386

0.344 0.214 0.498 0.376 0.302 0.228 0.494 0.330

0.382 0.204 0.508 0.366 0.274 0.200 0.550 0.246

Control N P K NP NK PK NPK

4.20 2.52 4.20 5.68 3.34 5.96 5.60 6.50

4.55 1.84 4.05 4.90 1.90 5.10 4.45 5.48

4.40 1.46 3.80 4.90 1.60 4.55 4.45 5.86

Percent K 4.95 4.05 3.24 1.16 3.80 3.90 4.80 4.74 1.16 3.34 4.00 4.55 4.54 4.95 5.30 4.45

3.64 2.60 3.64 4.45 2.06 4.20 4.20 3.84

3.00 2.15 3.08 3.56 1.90 3.65 3.65 3.40

3.00 1.68 2.75 3.56 1.45 3.90 3.20 3.26

SOURCE: R. S. de la Pena and D. L. Plucknett, "The Response of Taro [Colocasia esculenta (L.) Schott] to N, P, and K Fertilization Under Upland and Lowland Conditions in Hawaii," Int'l. Symp. Trop. Root Crops 1967 Proc. 1st (v. 1) sect. 2, p. 84. a b

Composite samples from three plants per treatment. Rates for N, P, K and 0 (control) are 15 g/pot.

71 TABLE 4.15

NITROGEN, PHOSPHORUS, AND POTASSIUM CONTENT OF THE ROOTS AND CORMS OF 6-MONTH-OLD TARO PLANTS GROWN IN POTSa Contents, percent Roots

Corms

Treatments3

N

P

K

N

p

Cont rol N P K NP NK PK NPK

0.79 0.93 0.89 0.78 1.07 1.20 0.89 1.20

0.248 0.095 0.394 0.214 0.290 0.116 0.396 0.276

5.05 0.75 4.90 5-52 0.48 4.00 5.88 3.40

0.23 0.81 0.33 0.25 0.71 0.60 0.38 0.60

0. , 1 9 8 0. . 1 5 2 0. 2 3 9 0. 1 9 7 0. , 2 3 2 0. .121 0,.239 0. 212

K 1.00 0.56 0.94 1 .04 0.52 1 .20 1.02 1.17

SOURCE: R. S. de la Pena and D. L. Plucknett, "The Response of Taro [Colocasia esculenta (L.) Schott] to N, P, and K Fertilization Under Upland and Lowland Conditions in Hawaii," Int'l. Symp. Trop. Root Crops 1967 Proc. 1st (v. 1) sect. 2, p. 85. a

Rates for N, P, K and 0 (control) are 15 g/pot.

72

cs| z

-a- o — co

cm oo

CM

es

v û c o O 0"% CA CA

o o CM CM -3" LA

L A v O OO •— CA -q-

—

O CM O O M A N

en l a o CA — CM

n o L A CA L A

v O CM L A -3* C A - 3 -

z Osi

ca-3N L A O OO

( S N S -a- N \û

CM O CA CM

(Pi CM

IX —

Z

—

\ 0 vO

L A CA CO C n —

¿roo o\ \£> \ 0 OO

i 3" CM CA CM

en n cm — CM CM

CM CSJ z

CS Z CM

O CM PO cm e n e n CM CM CM

CM O CA OO CA O — CM CM

OO CM O CA \£> e n

— N CM

— CA-3(TiO -

O CA O f A LA vO

L A N —

f s | v û (71 oo oo

- 3 " CA OO \£> L A \ 0

- c o ça

r s n

vO O

LA

o oo N-a-

en la

oo

CA — CA CA

M i — CM - 3 " L A

ir\ N N — CM CM

\Û L A \ 0 CM CM CA

CA O CM CM CM « A

z

CM < Oo oc
a) l_ • a 4-J 0 ai 2 tn U> o 2 OI "O "O c 0) 2

> >

\

ra c

m < I-

ra

—} o.

tO a) en

LTV CM

o E O O — ra tu

3


u 0) 1— c y» o — l/> ^ E O 3 . e ns 4-« co II O 0) s_ O (/) CO E T3 _Í a> — ÍD 0) "O O - o T3 0) 4-J 1 nj O 0 -cr * 2T 3 a> c O" L. 3 O O X - < nj Z 0) Ü1 CM o — -0 en 4-» w c

-C 1/1

CM -3" • MD vû

—

o

LU O

CM EN

al O


— CM 0) t— O-l DC^—„ co co L. ro o ^— * •a C O CM CO1•— 0) CM — . * 4-> 01 c r— o> jD ro • — ' i- en c.ro >— >- CM -Q — > ». H c 3 LvO •• 0) Ol ro 1- "O ro X — .c 73 OI 13 < en tn C c ^ — ^ . — , — en •o Ol c ra E "O O) — >—' -—* 0) Ol 4-1 O 4-t c >ra • - .n 3 z ro-^ C vO CM OO•— i 3 — — o — co c —' ai ai 0) 0 o • » — .— -o -O vû CM c < CM •» CO M-3Oí ra — o ^ — ' !_ - en — en TD ro • «sLL. OI o — co CL. t/5 4-> c»-\ c tn -—' *> ro^ c"\ — c (U •ro — o C T I L T V 1-C >— • — ' 0) O en .c co —• r^ tn OJ —' ro O -5 c • -o en 0) TJ • —•o c o> — >—- — -Q •— r^i ^ tA ra M •— CT\ O —c ra vû vo 4-t >— * — - — X C < M 01 C/) • r. ra — , V X) Ifl tn — Ol LTV c E •*vO in LU un 3 ro-ora r^ C co N i n x ^ -3" 0 c < n — T3 Cs| en(< u — •o 3 C —— c i- ro ro "O r^ • — Ol c a i 0) i_u < ro— i— >*"D — ro L. VO c ro >— 3 en — oo c IS E •— < .c — E ro eu us — 3 .C S3 "O M- '—* -3* S N U) S3 4-J a i — O — — C 3 (/> ra-—' —' -C "O 3 a) 1_ LÜ ^ o ro CD (_> o o _—— . -, s ce (TWO CM CO CO "O LO cn-3O -3- Ol 0~l — c CM CMCO to —' — •—— ro —' •—'' '

— ,^

..

o> (U — co v£> .3-

.— ,

— .— ,y

— ,,

— ,,

I I I I tn 0) >

w V) in E E E u i_ O O O o o o

tn E 0 CJ

(/)

E L. O o

,

tn yi E E O O O o

ra a) •o

>

o ra a> 3 0 ra o cu o

1 L. T3 LO ra tn ra E "O 3 tn 3 0) 1) tn 0) ID 1_ c c O) •— E n •— •M ra ra OI 3 c C ra ra c c ro c c c ra O •— •— >— • C M 3 3 3 — O) — — — i/i c al DC — 4-1 ra +J •o -o . tfl c CT 4-1 - o (U c ra i/i irt • 3

ra

4-> 14-» C IO

o 3 cr\ — J-

V) OT l— (U o-l co in in .—• 3 o ra -3- ioi

-a

vo c —

,— L-




ra

0

a> -M

0 U

—

tfi w

E i_ O o

> (D

"O o

—

3 O

c a)

10 -O fD "O "O C O

c

E E £ -Q lü a) o O CM -i o o

-o

z

T>

si —

+-» c O Ë 1 CM

+J c 0) -o

K o X

,

.

I I

I I

tn E u O o

tn E u O o

tn E O o

ra4tu-1

TJ tu Mc

1

o la o r-« o criu\r«"iLj\o—

tn ra o o o o

*

o L.

ra

l-

ra

•—

•— >—

J3

ra ra

o

o i i J e d s v

I I

I i

I I

I I

I I

I I

I

I

I

I

I

I 1

I

I

I

I

I

I l l I I I

a u i sA"i

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I

I

I I I

a u i u i ß j v

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

au ; ßejeds\/ g

pio\/

aujajsÄQ

3uip|3S¡H

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

au J u o i q î a w

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

CM CTlOO -3" OO LT> o í -a- — %

'ÎUSIUOD

u i a i o j d

o

O

o

o

o o TD (U ID CÛ

CM

CD
- C E o O O 0 O c 0 a. ra* — • — L. o c c u 1- 3 u — ce 2 Z H-u- M- M--C o L. rara n mm o - *> r0 T3 o 0 o O o 1- oO O i_ U u L. < 1-u -D C t/i t/i ra _l O O rarararara rarara t3 l- l- ( - l- h- 1-l- l-

— .

— .

c (D 3 (D a. •C (/I c ra mo < u -C

•—

rara

ift

o in ra u O O raoc l-

— .

ra c 3 DI

v) rao _i c ra c C Q

raara

( -

o — ro r rj Z> c

u >o O) > > o > T3 O O ra id > o U > o O — ra > E E 1_ ra (0 (1) o O _J o o

"O 73 •u • O O tn o 1 1 — E E l_iD4-ll-ID4->l-(04Jl-l-l-l-t-l-l-l-l-.— E — ID O Q ) < U O Q ) a ) O m < U O < U < U O O O O O O O O O > n id O _ 1 Q . O — J O . O — I O . O — J O . O C J O O O O O O O O LU _ l (D

ID 3

a.

c

0 C -Q ID 10

-C ID 1/1 s : ID O

V4- 3 — .4-» .CO

c ID (L> "D 4-» C (D => —>

— .

r— C i- .c c — — U — c c ro o ro c c roroO s:3 CL l - -i 2: => ZJ Z> a o o

•—

I I

I I

l i l i

E l. O O "U S! E E ra u cu O 4-> o ir>

I

l i l i

l i l i 1 1 I I I

1 I

LA

I I

— .

3 jr o

ro m

•—

c

ro 0.

E i_ O o

I I I I

I

I I

I I I I

I

> u

C Ol CTI 3 C • . — . . — . 10 — ID — 1- 10 ZD a ) N r^ c o . » c — — > » o a> — CM-*» L- 10 Q . O l ^ ^ 4-» W — -o -no oi c a i x 3 m c«— "O c — i*\ ü i i — — ' (U C — X ' — L— C04J U1IO-QO C 4J *—' L_ • L— E 3 M l/l E • « z -a- o JQ c i en io r ^ -aO cm —' — x oi • o — 4J e n cm "o i/i— — — U1 — c l ••« N C 10 o X e n no i n 3 io oc t/i — 4J O l — n o u \ i m h - ^—. •— c e n e n 3 4->i— ^ 3 N — — io — ' o . o Q) " o oj i.c t/> > - > "O io c —J — ' 4-< o •« — io en io t/i e n . — . * io E 3 • ^ C M — LPlC-C c c o r ^ - o cm e n — — > - < a> o c c ^ — — — — > - e n ro TD T3 O O 10 — CL Q. . 1. . . . . c C O O) CM IO ID a) > . in ic ci — r^ t^ co o a) «CM c o o — en • • cn o i O « « j: i/i E — _ z: ~ 3 ~ O — - _C Q. _ c m J: OI 41 0) a) ^—. ro 4-» ID a) O / - « en 4J to — NO to o o : Q1 M * 1 N en c i l a " o — — X o « . — — en c » < a) m •» a O — ro — •O L/l c tu in 4J c - a -3- id MOl "O 4) 4-» 4J o

ro

Oj *o3 ID ID z a 10 - Q

O "O

10

C —

1o

eri

o c o — — tu ^ 4-1 en o iia o tu C T3

• c •— tu 4-» o 1-

c •— tu 4-4 • 0 c 10x OI O "O - O H ) c E O 1- •M Q) o l - ra en O 4J u OI • c -o ra en i_ •— c E 0) t/i 3 c 0 > ra CD u ra -Q > M•— c

4-1 4-1 E Ol +-> Cvl O ra c — x o co c 3 o o 3

ra -a o -o 0) 14~ o i x : •-

ra

E 3 O cr 4-4 c 4-» O) o c TD 3 a O -C */> O >• 4->

> 3 o c_>

3

ra

ra ra ra ra ra ra ra ra

O L. 4-»

ra

O T3 3 -C O

ra *

—

c

ra

a.

*—

-C 3 E -C o c o_

ra ra

"O 3 -C O

ra O 1-

ra

o

"O

73 c =>

ra

ra

ra re

ra

¿ ra

132 TABLE ^ - 3 1

MINERAL CONTENT OF TARO

&9

Cultivar 3

Unidentified Dasheen, unidenti fied Unidentified 3 3

Unidentified Unidentified 3 Nihopuu Papakolea-koae Lauloa palakea Martin Unidentified 3 Unidentified 3 Unidentified 3 Dasheen, unidentified Upland taro Upland taro Lowland taro Lowland taro Jat kachu Rampuri kachu Daulatpuri kachu Kalo kachu Panchamukhi Garothamma Garo kachu Hati rpara Jummukhi Guavi r Latamulchi Garo kachu Unidentified taro Kachu Unidentified taro Taro, unidentified Colocasia (Gabi)

Colocasia esculenta Taro, raw Hawaiian taro Taro, Hawaiian Taro, Chinese Taro, Japanese Taro, wetland Piiaii P i ko uIi u1i

Parts Corms Corms Corms Leaves and stems Corms, steamed Corms Corms Corms Corms Corms Leaves, cooked Leaves, cooked Corms, steamed Corms 12-month-old blades 12-month-old petioles 12-month-old blades 12-month-old petioles Leaf Petiole Corm Leaf Petiole Corm Leaf Petiole Corm Leaf Petiole Corm Corms Corms Corm Co rme1s Cormels Cormels Cormels Cormels Corm, dried meal Edible portion Leaf Petiole Corm S i mu1ated Milk Mixture Leaf blades Petioles Main corm Entire plant Cooked corms Corms & tubers Leaves & stems Leaves Shoot Stalk Corm Corm Steamed corms Air-dried cooked corms Air-dried cooked corms

§ 0.32 b 0.46 b 0.32^ 0.43 0.19 0.12 0.72 b 0.28b 0.35 b 1.88b 0.66 b 0.66 b 0.19 b 0.49 b 3.45 1.2 2.8 0.6S --

— —

-—

4.95 0.59 0.87 1.80

--

--

—

—

--

—

—

—

--

—

--

—

—

--

—

0.026

0.061

—

--

--

—

—

—

--

--

—

—

0.4 0.3

—

--

—

—

—

—

—

2.6

—

0.079

—

—

—

—

--

0.0263

0.0612

--

—

--

—

--

--

—

4.0 e 4.7 e 3.0 e 1.5 e

1.3 C 0.9 C 1.5 C 0.5 C 1.45 0.61 0.38 1.39 0.93 0.16 1.66 0.96 0.30 1.51 0.64 0.40 0.16 0.18 0.12 0.10 0.12 0.04 0.06 0.10 2.48 29.6 268.0 d 57.0 d 32.0 d 12 d 96 d 600 d -—

---

—

—

--

—

—

—

--

--

--

78.0 d 23.0 d 64.0 d

— — — —

--

—

—

—

—

--

--

—

--

--

—

-—

— —

—

—

—

--

—

—

—

--

—

—

—

-—

1237 d 367 514

—

—

—

--

—

--

—

--

—

0.145 0.045 0.057 0.061 44f 6l d 59 d

----

—

0.013 0.066 0.023 0.013 0.0263 0.059 0.089

0.03 0.032 0.069 0.032 0.0612 0.119 0.150

--

--

—

--

—

— —

--

--

—

--

-

—

--

--

--

—

—

--

--

—

0.3 C 0.28 e 0.32 e 0.32 e 0.79 O.72 0.24 O.31 0.56 0.36 0.66 0.81 0.24 0.48 0.49 0.25 0.27 0.31 O.38 0.30 0.35 O.50 0.33 0.4! 0.13

—

--

--

0.107

l8 d 28 d 76 d

—

-

— —

--

0.35 0.22 0.12 0.12 —

514 d —

684 d — —

--

--

--

--

—

—

0.0196 0.0147

0.5 0.408

A 1 l e n and A l l e n

1933

Chatfield and A d a m s

1931

F e i n g o l d 19^2 M a c C a u g h e y 1917 Martin and Spitttstoesser

Mi I ler

1929

Miller 0.23c 0.1 4 C 0.3C 0.3C 0.31 0.57 0.23 0.28 0.42 0.18 0.31 0.59 0.26 0.22 0.40 0.28 0.14 0.14 0.11 0.13 0. 10

0.16 0.10 0.10

1927

de la Pena and 1967, 1972 29.00d 42. 50 15.00 29.00 25.00 10.00 42.40 32.80 14.00 22.00 17.20 21 .40 8.00 7.60 6.00 7.60 8.70 7.60 7.80 8.00

1975

Plucknett

> C h o w d h u r y and Hussain

1979

F e t u g a and Oluyemi 1976 M a l e k , Begum, a n d A h m a d 1966 4.3 1.4 0.8

Tisbe and Cadiz

Standal

,.0f 1.0d 1.0 d

0.054 0.082

-

0.0017 0.0101 0.0017 0.0015

-— — —

0.005 0.0043

0.081 0.069

} 0.0001 0.0003

0.0012 0.001

1962

a n d Kian

Quisumbing

1914

d e la Pena

1970

1968

W a t t and Merrill

1963

W e n k a m and T h o n g

1969

Chung

1929

Derstine and Rada

1952

0.0001 | P a y n e , Ley, and A k a u 0.0001

1941

TABLE

4.31

(cont.)

Lowland Lehua palaii Mana opelu Taro, unidentified Mukhi kachu

Pani kachu^

Panchamukhi

kachu d

Garo kachu1* Lehua Bun-Long Dasheen Taro, unidentified Coiocasia esculenta var. esculenta cv Yandina cv Yandina sdlgs Coiocasia esculenta var. antiquorum cv UCt Runner cv UCI Runner sdlgs Unidentified taro

a

Air-dried cooked corms Air-dried cooked corms Not given Leaf blade Petiole Cormel Leaf blade Petiole Corm Stolon Leaf blade Petiole Corm Leaf blade Petiole Corm Leaves Corms Leaves Corms Leaves Petiole Blade Root

3.8 0.45 3.8 0.69 3.8

Corm Corm

0.65 h 0.73 h

Corm Corm Raw leaves Cooked leaves

0.78 h 0.75 h

0.106 0.169 I62d 230 45 35 312 48 26 32 219 42 39 285 29 16 2.3 0.2 3.0 0.13 2.7 0.2-0.37

I62 d 110 d

Name not given in original paper, b Calculated from data in the literature. Approximate average of several fertilizer treatments. d mg/100 g. e Limits not given f mg per ? 9 ppm. h % of DW. c

0.113 0.274

0.0296 0.0316

0.632 0.879

96 25

68 92 26 15 55 74 23 71 81 30 23

0.32 0.02 0.39 0.04 0.35

69 d 67 d

0.56 1.2 5.1 1.4 5.5 0.34-0.43 0.41-0.51 0.29-0.74

963 d

References

0.086 o.iu

0.2 0.03 0.39 0.07 0.29

0.0042 0.005 ld 3.48 0.89 1.13 2.79 0.53 0.92 0.72 2.78 0.5 1.01 3.1)6 0.46 0.51 125 9

0.084 0.109

0.0004 0.0001

0.0001 0.0001

0.0005 I 0.0007 I

239

1709

429

9

219

2009

419

929

219

1309

429

87

Payne, Ley, and Akau 1941 Grubben 1977

R a s h i d and D a u n i c h t

1979

R a s h i d and D a u n i c h t

1979

de la Pena, van der Zaag, and Fox 1979

A r d i t t i , Stephens, and S t r a u s s 1979

} }

S t r a u s s et a l .

1980

U . S . Dept. HEW 1972

O en

en

CM • OO co

o»-» LTV

CM CM

CM

vO • f—

CM

-=r • C^l

oo

00 —

ra o o

ra

co

co


1_ ra o — O O.

* ce

c o .— • 4-J CQ

c — 4J QJ

•— .— •—

C 3 O . CO E O O -c I c oí — < u CLM01 o 5

ce.

ra

•• c Ul 1I3 O O

5 Nutritive Value Bluebell R. Standal

WHEN a crop is being considered for food, nutritional value and consumer acceptance must be taken into consideration. The nutritional value of a food depends upon its nutritional contents and their digestibility and the presence or absence of antinutrients and toxic factors. As far as consumer acceptance is concerned, Colocasia esculenta, commonly known as taro or cocoyam, is an important food staple of developing countries in Africa, the West Indies, the Pacific region, and Asia. The corms are generally used as the main starch in meals, however, snacks are prepared from taro in numerous countries and are either sweet or salty, moist or crisp. Hawaiians traditionally use taro to make poi. After the corms are washed, they are steamed, peeled, and mashed with water to a sticky, pasty consistency which is called poi. The taste of poi is bland when fresh, but after staying at room temperature for one to two days, part of the starch is converted to dextrin, sugars, and acids, giving the poi a sweet-sour taste. Comparing the carbohydrate content of taro (Onwueme 1978) and of poi (Standal 1970), it was observed that dextrin constituted 0.5 percent of taro carbohydrates and poi dextrin 14.1 percent of poi carbohydrates. Young leaves and stems are used as vegetables and are cooked with water either by themselves or mixed with meat, fish, fish sauce, or coconut milk. As far as the author knows, the petioles are eaten raw only in the Khasi and Jaintia Hills of India. After the outer thin covering is peeled off, the young stems are cut into 1 cm pieces and mixed with pieces of lemons or limes, salt, and chili peppers. Usually the mixture is used as a snack. Only the nutritional value of taro (Colocasia esculenta) will be discussed in this chapter even though taro is a general name for other edible aroids such as Alocasia macrorrhiza, Cyrtosperma chamissonis, and Xanthosoma sagittifolium.

142

G E N E R A L BACKGROUND

C O R M S

Like the roots of other crops, taro corms are high in carbohydrates and low in fat and protein (Gopalan, Rama Sastri, and Balasubramanian 1977; Tisbe and Cadiz 1967; table 5.1). Human digestibility of the raw taro starch was reported to be 97 percent (Langworthy and Deuel 1922) and is the same as raw potato starch. The excellent digestibility suggests efficient release of nutrients during digestion and absorption of this food. Taro corms contain 0.78 percent of oxalic acid (table 5.4), however, which can bind calcium in the plant as well as in the intestinal tract and render it unavailable for nutritional utilization. Some corms contain raphides, which are needles of calcium oxalate (Sakai and Hanson 1974), suggesting a high concentration of oxalate. Boiling, baking, washing, and mashing of corms would reduce the oxalate content to some extent when the corms are served as prepared food. In table 5.1, nutrients data reported from India and the Philippines are listed. The values are similar, particularly when adjusted for moisture content. The exception to this is the vitamins, especially the provitamin A, carotene, and vitamin C. For supplying nutrients, the corms may be considered as a good source of carbohydrates and potassium. An average Westerner's serving of taro weighs around 75 g and can supply about 400 mg of potassium. The usual daily food intake of adults provides 1,950 to 5,900 mg of potassium a day. In Hawaii, servings of taro corms vary in size from 100 g among infrequent users to 500 g among frequent consumers of taro. Five hundred g of the corms would supply 2,000 mg of K, 200 g of carbohydrate, and 15 g of protein. This amount of protein is almost 33 percent of the recommended dietary allowance (RDA) of protein for women (Food and Nutrition Board 1980). Large servings of taro corms become a significant source of dietary protein, especially if taken more than once a day. The amino acids composition of the corms and the estimation of protein quality by chemical scoring of the essential amino acids were reported by FAO (1970) and are reproduced in table 5.2. The chemical scores (A/T) are 55 for lysine as well as methionine and 56 for isoleucine. These values indicate that taro protein is of medium quality which can be used to maintain adults but which cannot support pregnancy and growth of infants and children. Taro corms can thus serve as a dietary source of carbohydrates and potassium for all ages and as a major protein source for adults who depend on taro as their staple food. Although taro corms are a relatively poor source of ascorbic acid and carotene (Peters 1958; table 5.1), the carotene content is equivalent to that of cabbage and twice that of potato (Kirkpatrick 1935). Comparing

TABLE 5.1

NUTRIENT COMPOSITION OF CORMS, PETIOLES, AND TENDER LEAVES OF TARO (In 100 g Edible Portions) Corms India 3

Edible portion, % Moisture, g Protein, g Fat, g Total carbohydrates, g Fiber, g Food energy, kcal

Leaves

Philippi nes*3

India 3

81.0

Petioles

Philippines'3

Phi 1ippines D

55.0

84.0

73-1 3-0 0.1

77-5 2.5 0.2

82.7 3.9 1.5

79.6 4.4 1.8

93.8 0.2 0.2

21.1 1.0

19.0 0.4

6.8 2.9

12.2 3.4

4.6 0.6

97

85

56

69

19

2.0 268 78 4.3 11 1237

1.2 57 23 1.4 5 367

Ash, g Ca, mg P, mg Fe, mg Na, mg K, mg

40 1A0 1.7 9 550

0.8 32 64 0.8 7 514

Carotene, IU Thiamine, mg Riboflavin, mg Niacin, mg Ascorbic acid, mg

67 0.09 0.03 0.4 0

traces 0.18 0.04 0.9 10

227 82 10

28550 20385 •0.22 0.10 0.26 0.33 2.0 1 .1 12 142

335 0.01 0.02 0.1 8

SOURCES: (a) C. Gopalan, B. V. Rama Sastri, and S. C. Balasubramanian, "Nutritive Value of Indian Foods" (Hyderabad, India: National Institute of Nutrition, Indian Council of Medical Research, 1977); (b) V. 0. Tisbe and T. G. Cadiz, "Taro or Gabi," in Vegetable Production in South East Asia, ed. by J. E. Knott and J. R. Deanon, Jr. (Los Banos, Laguna: Univ. of the Philippines, 1967).

TABLE 5.2

AMINO ACIDS AND PROTEIN QUALITY OF TARO CORMS

Amino Acids

mg Amino Acids g Total N

Isoleucine Leucine Lysine Methionine Cystine

219 460 241 84 163

TOTAL S-containing amino acids

247

Phenylalanine Tyrosine

316 226

TOTAL aromatic amino acids

542

Threonine Tryptophan Valine Arginine Histidine Alanine Aspatic acid Glutamic acid Glycine Proline Serine

257 88 382 557 110 3A4 788 732 331 276 413

TOTAL essential amino acids TOTAL amino acids

2436 5987

A/Ea

70

A/Tb

55

NOTE: Limiting amino acids are lysine, methionine (chemical scores of 55 each), and isoleucene (chemical score of 56). a

A/E: The content of each essential amino acid in a food protein

145

Nutritive Value

equal weights of taro and whole milk, Miller (1927) reported that taro contains greater amounts of vitamin B-complex. Animal feeding tests with cooked taro showed excellent retention of riboflavin and niacin (Miller, Bauer, and Denning 1952).

LEAVES AND STEMS The leaves of certain cultivars of taro that are low in oxalic acid are used for green leafy vegetables in Hawaii, the Pacific countries, Southeast Asia, India, the West Indies, and Africa. Cultivars chosen for leafy greens vary among different countries and population groups. The old favorite in Hawaii is the cultivar Apuwai, which is still being cultivated in home gardens by older residents. Ninety-nine percent of the market variety is the cultivar Bun-Long, and since it is low in acridity, both younger and older leaves may be consumed without irritation to the mucous membrane of the mouth. The vegetable variety in India appears to be similar to Bun-Long. The amounts of nutrients in the leaves, evaluated in India and the Philippines, are listed in table 5.1. These are similar except for the vitamins. The nutrient content of cooked and raw leaves of "Tahitian taro" was reported by Miller and Branthoover (1957) and is reproduced in table 5.3. The loss of calcium, phosphorus, thiamine, riboflavin, niacin, and ascorbic acid due to cooking is shown. The amounts of vitamins in raw leaves from Hawaii, India, and the Phil-

(Ax) is expressed first as a ratio of total essential amino acids (Ex) in the food. These ratios are then expressed as percentages of the ratios between each amino acid in the egg (Ae) and the total essential amino acids of egg (E e ). The lowest of all these percentages is the chemical score, b A/T: The content of each essential amino acid in a food protein (Ax) is expressed as a percentage of the content of the same amino acid in the same quantity of egg protein (A e ). The amino acid showing the lowest percentage is called the limiting amino acid and this percentage is the chemical score (A x /A e )100.

146

GENERAL BACKGROUND

ippines (tables 5.1, 5.3) are different and may reflect storage and cultivar differences as well as the analytical methods used. Reported values for the amounts of antinutrient oxalic acid are compiled in table 5.4. The values for the leaves obtained by the author and by previous investigators are widely different. The Hawaii cultivars BunLong and Lehua Keokeo contain the lowest amounts of oxalic acid. The highest value, over 1 percent, was reported from the Philippines. Age and cultivar are important factors in evaluating oxalic acid content, and an estimation of all taro leaves on the basis of present available analytical data is unwise and could lead to either over- or underestimation and erroneous conclusions. Due to the oxalic acid and oxalates in taro, the bioavailability of calcium from the leaves remains uncertain even though chemical analysis suggests abundant calcium and the leaves have been evaluated as a generous source of calcium. At present, the leaves may be considered as an excellent source of carotene and potassium. The stem contains fewer nutrients than the corms or the leaves, but the amount of potassium remains generous (table 5.1). The amount of calcium is ten times less than the amount of oxalic acid (tables 5.1, 5.4) according to the Philippine data, suggesting a possibility that all calcium is bound.

T A B L E 5-3

NUTRIENTS IN RAW AND COOKED T A H I T I A N TARO PER 100 G

'BELEMBE'

Raw

Cooked

10-15 leaves

1/2 cup

36

29

2.6 0.9 6.2

2.1 0.7 5-0

Calcium, mg Phosphorus, mg Iron, mg

120 42 1.2

97 34 1.0

V i t a m i n A , IU T h i a m i n e , mg Riboflavin, mg Niacin, mg A s c o r b i c a c i d , mg

2045 0.06 0.24 1.0 96

A p p r o x i m a t e Measure: Kilocalories Protein, g Fat, g Carbohydrate, g

4884 0.04 0.20 0.5 38

Nutritive TABLE 5-4

147

Value OXALIC ACID CONTENT OF PARTS OF TARO PLANT

mg Oxalic Acid in 100 g

Source of Data Standal (unpublished data) Chinese variety Bun-Long (leaves) Standal (unpublished data) Hawaiian variety Lehua keokeo (leaves) Gopalan et , 1977 (leaves) Food Composition Table, Philippines (leaves) Food Composition Table, Philippines (stems) Food Composition Table, Philippines (corms)

99 234 430 1280 650 780

OTHER POTENTIAL NUTRITIONAL USES OF TARO Poi, which has always been used as a baby food in Hawaii, is drawing attention from the medical profession because of its low allergenicity, and it is being used elsewhere in the United States for this purpose (Glaser et al. 1967; Roth, Worth, and Lichton 1967). Taro flour was utilized by Standal and Pedrana in formulating formulas for weaning foods for children of the Pacific region. The food was produced in Western Samoa and field tested among Western Samoan children. The trials suggested its usefulness, and after minor revision the food is being used more extensively for field feeding trials. 1 A suggested means for increasing protein in taro is based on an observation by Gray (1966) in which fungus mycelia could be grown in carbohydrates and increase the protein content of the carbohydrate source, thus increasing protein supply using low energy input. In Sierra Leone, crude cassava flour was used as a carbohydrate source for production of a high-protein material that is odorless, tasteless, and differs little in appearance from the original flour. The protein content was raised to 38 percent (Gray and Abou-El-Seoud 1966b). Sweet potato protein was increased three to four times within a week using the same technique (Gray and Abou-el-Seoud 1966a). A similar process could be used to increase the amount of protein and possibly the amount of vitamins in taro by growing fungus mycelia in taro carbohydrates.

NOTE 1. B. R. Standal 1978; report submitted to the South Pacific Commission on weaning food research, pp. 1 - 4 .

6 Acridity of Taro and Related Plants Chung-shih Tang William S. Sakai

THE irritant property of plants in the Araceae has attracted attention since the early nineteenth century. In 1818, Bigelow reported that acridity in Arum triphyllum appeared to depend upon a distinct volatile component which disappeared almost entirely upon heating, drying, or simple exposure. After Bigelow's report of a "volatile acrid principle," various other chemical compounds in aroids were implicated as causes of acridity. They include alkaloids, glucosides, sapotoxins, and enzymes (see review by Walter and Khanna 1971). None of these chemicals has ever been firmly established as the cause of acridity. A physical cause for acridity was introduced by Madaus (1938) as a rationale for the sharp, piercing sensation experienced during ingestion. Since calcium oxalate crystals found in acrid plants are often needle-shaped, it was proposed that these sharp crystals inflicted wounds and caused a painful sensation. While the identity of acrid principle(s) of aroids is still uncertain, the information compiled over the years on this subject represents a substantial effort by researchers who were intrigued with the acridity phenomenon. For taro, this undesirable property imposes limitations on the use of fresh taro corms and tops (leaf and stem) as an animal feed. Presently, nearly half of the total fresh weight of the taro plant is not utilized. A solution to the acridity problem is important if taro is to become a competitive crop in the humid tropics. An understanding of the nature of the acrid principle would provide us with the needed information to efficiently remedy the problem through physical or chemical treatment, by microbial destruction such as fermentation (Steinke et al. 1980), or by breeding programs for the selection of nonacrid varieties.

Acridity of Taro and Related Plants

149

T O X I C EFFECTS O F ACRID PLANTS ACUTE TOXICITY

There have been numerous studies concerning the toxicity of plants in the Araceae. In particular, much work has been done on Dieffenbachia, perhaps the most toxic genus. Human consumption of this ornamental has almost caused death in children. A wide range of effects has been observed depending on where and how the toxic substance entered the victim's system. If the ground stem is placed on the skin, itching and swelling occur (Cherian, Smith, and Stoltz 1976). The petiole and leaf produce a similar but weaker reaction. Contact in the mouth produces a burning sensation, salivation, and swelling (Fochtman et al. 1969; Ladeira, Andrade, and Sawaya 1975; Walter and Khanna 1971). A case concerning a woman who had bitten into the stalk of D. sequine was reported by Drach and Maloney (1963). The victim suffered severe edema of the side of the face, tongue, buccal mucosa, and palate. Her speech was thick and almost unintelligible. Salivation was profuse, and she could not swallow, but the vocal cords and other body functions appeared to be normal. In the Caribbean, it is commonly known that Dieffenbachia chewed or swallowed causes a loss of speech for one to two days and is believed to also bring about male sterility that lasts 24 to 48 hours (Walter and Khanna 1971). These reactions vary within the genus. For example, the expressed juice from D. exotica applied to the oral cavity of a rat increased salivation and caused the tongue to redden slightly. Under the same circumstances, the juice from D. picta caused severe edema of the tongue, buccal mucosa, and palate. Unfortunately, in much of the literature this species distinction was not made. Guinea pigs remained healthy upon gastric intubation of Dieffenbachia stem juice, but intraperitoneal injection of this juice was fatal (Fochtman et al. 1969). Rats fed expressed juice lost weight. Later, they showed signs of acute poisoning, occasionally ending in death due to respiratory failure (Walter and Khanna 1971). Reports on the acute toxic effects of other genera in Araceae have been summarized by Ladeira, Andrade, and Sawaya (1975). These include Alocasia macrorrhiza, Arisaema stewardsonui, A. triphyllum, Arum maculatum, Philodendron, Zantedeschia aethiopica, and Xanthosoma atrovirens. In general, the cut surface or juice of the plants induces irritation or pain on the skin. Ingestion of the plants causes a burning sensation and in some cases a swelling in the mouth and gastric disfunction. Arisaema has been demonstrated to be lethal to experimental animals, while the deaths of children and domestic animals have been recorded

150

GENERAL BACKGROUND

due to accidental ingestion of Arum maculatum, Zantedeschia aethiopica.

Philodendrum,

and

E F F E C T S OF A C R I D I T Y IN T A R O

Taro (Colocasia esculenta [L.] Schott) has been cultivated for food in the tropics since ancient times. All parts of the plant contain acrid principles which are irritating to the mouth and esophagus. Farmers can feel the "sting" when they harvest the taro, but may gradually lose sensitivity to the irritant.1 The acridity can be destroyed by cooking or fermentation. Once the acridity is removed, both taro and the fermented taro (poi in Hawaiian) are excellent carbohydrate foods and sources of minerals and vitamins (Murai, Pen, and Miller 1958; Neal 1965). The dietary effect of a raw taro corm diet (Lehua Maoli variety) was examined by Stoewsand et al. (1979). Male weanling Sprague-Dawley rats were fed a semipurified complete diet containing 50 percent of either raw dried taro; taro starch; water-washed, dried precipitate of taro after starch removal; or a water-washed, ethanol extracted, dried precipitate. A 50 percent corn starch dietary group was used as a comparative control. The diet composition consisted of vitamin-free casein (22.0%), corn oil (5.0%), P and H minerals (4.0%), NBC vitamins (2.0%), sucrose (12.0%), nonnutritive fiber (500%), and taro or taro fractions (50%). All diets were mixed using a Hobart mixer for ten minutes. Eight animals per dietary treatment were fed the various diets ad libitum for 21 days. Their mean weight gain and average food consumption were recorded at the end of the feeding period. As seen in table 6.1, a positive correlation existed between weight gain, food intake of the testing animals, and acridity. Rats fed taro starch had mean weight gains similar to those of the corn starch fed control group. Feeding raw taro or taro cooked in a microwave oven for 1.5 minutes similarly depressed both weight gains and food intake. A further significant depression was observed in the rats fed the water-washed precipitate fraction of taro. This depression was reversed when the taro precipitate was extracted with ethanol. There is a distinct aversion, but not grossly observable toxic response, to consuming raw taro and especially to the taro precipitate fraction. This dietary repugnance is reversed when ethanol is used to extract or neutralize the causative factors. Upon gross autopsy, no abnormalities were observed. There was no inflammatory edema of tongue and mouth. A more sensitive method of detecting acridity was established by a feed preference bioassay using Swiss Webster mice.2 Taro acridity appears to be a feeding deterrent based on trial results with freeze-dried

151

Acridity of Taro and Related Plants TABLE 6.1

WEIGHT GAINS AND FOOD INTAKE OF WEANLING, MALE RATS FED DIETS CONTAINING 50 PERCENT TARO OR S P E C I F I C FRACTIONS OF TARO FOR 21 DAYS

Diets Corn s t a r c h Taro s t a r c h Blended raw t a r o wi th s t a r c h T a r o , microwave cooked 1.5 min Taro wi th s t a r c h e x t r a c t e d but untreated Taro w i t h s t a r c h e x t r a c t e d and ethanol t r e a t e d

No. of Animals

Weight Gain3

Food Intake

Degree of Acridity'3

18 26

__

+

27

2

334

+

13

NA

303

+

19

3

343

+

19

0

8 8

1 kk 138

+

8C 12 C

372 341

+

+

8

121

+

10 d

331

8

122

+

12d

8

103

+

20 e

8

135

+

17cd

+

0

a

Mean ± S - D . ; common s u p e r s c r i p t l e t t e r i n d i c a t e s n o n - s i g n i f i cance ( P ± 0 . 0 5 ) . b A s s e s s e d by t h r e e i n d i v i d u a l s , 0 = no a c r i d i t y ; 1 = some a c r i d i t y ; 2 = d e f i n i t e l y a c r i d ; 3 = extremely a c r i d ; NA = not a v a i l able.

Lehua Maoli taro leaves and corms. The results are statistically analyzed and summarized in tables 6.2, 6.3, and 6.4. The following points may be made from these results. 1. The ensilage process (Steinke et al. 1980) increased the acceptability of taro leaves as a mouse diet (table 6.2). 2. Feed preference tests demonstrated that mice rejected a diet containing 1 percent of freeze-dried taro leaves when a normal diet was available. Ethanol extraction improved the acceptability only slightly (table 6.3). 3. Taro corm at 20 percent level was not acceptable. Methylene chloride extraction improved the acceptability only slightly (table 6.4). CALCIUM OXALATE: A PHYSICAL EXPLANATION O F ACRIDITY Calcium oxalate crystals are found in a majority of the flowering plant families (Esau 1965; Franceschi and Horner 1980). These crystals are of

152

GENERAL BACKGROUND

TABLE 6.2

RESULTS OF PREFERENCE TEST OF TARO LEAF DIET, SILAGED TARO LEAF DIET, AND STANDARD DIET ON SWISS WEBSTER MICE 3 Average Daily Diet

Intake of Mouse

Experiment

Standard

Taro Leaf

1 2 3

5-8 6.1

(-O.l)b (-o.i) b

(g/day/mouse)

Silaged Taro Leaf

Total

0.3 5.2

5.8** 6.4** 5.2**

a

Average of 36 measurements. Standard diet was prepared by grinding rat chow pellets (Ralston Purina) into semi-powder form. Taro leaf diet contained 5% powdered, freeze-dried taro leaf in a standard diet base. Silage taro leaf was also a 5% mixture, b Negative diet intake due to contaminations from urine and feces. ** Significant at p x:

JZ

4->

a) E

ra

o

•—

M-

•—

4J c —

u C/Ì

< H-

».

ra

TI C

tf)

if) tf)

ra

ra

< If)

4-1

If) O a.

ta

ra

4-1

E 3 i— >jr

—

ra

ra ra L-

ai 4J a. o

JC.

4J

O

!_

XI (U 4-1 L11)

4J O

—

if)

—

4-1 c CD ID i— "O O •— c "O >— *— 3 C •—. o < ui if)

«

"O o

•—

raCD Li- o n

i_

ra

l_ a) a. Q. o

JO m if)

ra

L O)

— . If) E

(U (/)

•a

73 0) C

V

O) O a) O) CL T3 t/) C

• fu c _c 4-» -C "O JZ c XI c X4-1 ra XL ra ra >x >- 4-1 E OI >- -w ru 4-> c 4-> L- 4-1 OI 0 OI •— jr O D u0 ra O ra • —c LV- «— O ra •— oc •— 0 CÛ U O r •co — X Q. • — X.ra B •M 4-» O 4-J • — — L- E ra m «/» l/l ra o s: fü ra ü_ < - in o 4-» — tu — > 0 — 3 ra tn D.M- 4) e — < o o a) c — o • c o in ra > - tU o O "O •— m O a) a) —> Q. U- L- 4-» tu CU i E CL .c 11

0 c

Ifi

o co 4-1 ' — 0) L>- in o •— c c O 4- 0 o in •— ifì •— "O •— 4-» E in •—

V4o

ra— . ra

o o 0 4-»

•—

E

"O c

C

•—

o 4-1 tu CL

CL W

L. O

ra ra

ra

iI

„

3

(J

ra ra

*—

y-

•—

a_

-

u

ra O.

ra

— o — E

—

.—

ra ra 2 1/5 ra

—l •—

in CTI 3 .Q

0 L-

0) 3 1-

en u 3 L. •a o o .c in c ra 3 3 O CT" L. co co in 3 4->

•— •—

c

ra

•—

in a

—

L-C 4J O T3 c 0 0 CTIX

ra

O

IU

a>

ra ra

ra > i - —. CD 3 in O 0) ra 4-1 u 0 rar— "CT —

Q. IU O •— 4-1 E a. 0) O > n L. ai 4-> E 0) •

•—

•—

ra

> ra 3tn ra > - ra raT— H— > ora

CT)

CT> 3

ra ra CTI CTI

tn

o

3

CTI 3 -Q

ra ra ra O- cu c ra - •— — 3 i/i —ICS ra

ra

"O ra o tu — L. 14Q. — in o a) ra "O O-

in CT) CTI 3 3 -O a> tu

in in 3 3 in — i tn O 0 •— 3 •— L = o racoura

•—

• — •—

ra 3

ra

tu c

CJ

•—

ra CTI

si u

in

—.

"CT

tfi —

L.c 4J

ra h-

— i/> m ra

3 ia) 4-> z m 43 — ra < O 3 a. - a.

C




ra ü

in

•—

z:

0

>•

-Q >- O •— -o 3 E tu tn Li- a_

ra

tu tn 3 "O O

ra

•— "CT "4•— • —

a. O tn CL 4-J tn in

ra ra >. ra4-> a. ra i— in tn CL ra 3 > - >• tn SI — ra u ra u E rao ra i_ U- co —

— >—

>-

L. (D > s: 0) 3 "O ¿-j 0) x 0 c c 0J c (ft -C OJ 3 "O 0 >

(J) c >- oj 3 W- T3 C O

ra

-C o

— .U

(ft —

(4—

ra ra (ft

- c •w o (ft ra O ra (ft o u ~ — o >• 1- — ¡ - »4- 3 O < O >

o.

ro

CL m

(ft (ft

(U

•— —

O.H-

CT) CT)

3 3 •O _Q

u o

>

ra

3

—1T3 — ) — c •— u_ — Lli a)

Ú 4-1 ro .a —

ra (U

O 4-1 3

E

rora

(ft

O

ra o

(ft

r—

Q. OJ •• o 4-1 ift -C • — l_ (4- -C 01 3 CL a. (ft r. dl 4-1 (ft — (4C ui T3 OI — • — CL •C 3 3
-

.—

M0) 4-1

>1— (40) 4-1

-C 3

-C 3

>—

>—

(4(U 4J —

c O 4-1 4-1 O (J

Sz

M— (4- 3 — >—

n

3

SI

ro

3 a

a)

ra ra

—

Cl

>

4-» (ft

Q. 01 4-1

-C • — 4-* c >> .c u CL O E 0J X 4-1 u_ LO

.— ra

CT)

3 -O

ro

0) L. 4— a .

ra

(/i

"O

o

rora< cL_ •— in oí OJ OJ c ra4-1 c — 3 tn • 0 D ra OJ (/> T> O u 3 — r>

ra ra .— ra

o 4-1 (V (ft o oj -Q 3 > 3 T3 (ft 0 Ol L. oj Q. *-> T3 >

o 3 01 z

"O C

IA

ra .— ra

ra

ra OJ

oí >—

ra u

11) 4J a. o e

o X "O ID io tn E •—

ai a.

o

c m

3

i/i —

4O

w

c > m > 10 CT 0 ) C 01 — 01 r—

01 >

01

>

ra

C O

in 01

T3

ra oí

c o

in IU IU IU O 3 3 o - C m •— "O 4-J tn 3 o 3 •— •—i La. O 4-1 4-t E 4-» c tn L- c c •— 0 a. IU 4-1 -n a. 4-J CTI 10 c o 3 CTI - u C c a. •— •— o o 4-» 3 a. 1/1 1/1 .c m 4-1 w "O OI c ID C •— •— Q . ID

c — ID . c a. Q .
0) ID 4-1 t/l — 0) ID CTI 4) na 01 3 C E L- l/l ID O •M O • — 0 _c CO > E

ra

ID t/i >• — c 01

ra ra

C O

e - o a. o

4-» - — >-i/> OI

-C a. 10

sz >-

>•

>-

401 4->

401 4->

401 4-1

in "O "CT

-C

-C 3

-C 3


-

ra

•—

c c tn OI JQ O o r— n i u 01 n i ID Lt/l 01 i_ o "O 01 a c o 0 u t/l L. 3 01 3 •— 01 01 f — L. p— Q- ID

ra

a

a

¡j

JZ a.

I O c 3 u5 a E 01 01 O C u 01 ID -a 4-1 C

"O O O 3 4-1 tn 0) 3

ra ra

•—

•—

-C O o

O a. o L. 0) 3 01 •— i — X ID

ra

O

u ID 41 CL

E

3 Ö

'—"

,—,

ra 0) ra !»

4-»

ID 4-» m

E 3 O

c 0 4-1 - C 4-» a. O < O

c o u 3 to

•—

ra

10 c

(0 E u 4) 4-1 Q. O 1/) -C 0 o 4-J LO

ra ra t— . *—Lrara ra ra ra— 1_ ra raratu

. «

t/i

o

—

tu Q. l/> t/i O t/1 tu 4-1 tu > L. > >tu O tu - O 3 t / i 0 — -0 — 4-1 *— •— •— tu 0 E 4-J 4-1 CL E 43 E LU ULl- CD

-0 — a. O 0 u tu 0

U 4-1 4c 3 O

ra 0 tn

tn

rara ro rara tu tu tu tu

tu tu

tn

t-

Ltu CL Q. O _C ti-

tu

—

tu

CL OL tn

E 3

ra• o ra lU -0 u ra 0u at u 4J

tn -— 0 m tu t_> a) 4-1 t u -C

tn

3 .— 3 CTI tn C 3 0 tu i—

rarara ra — . >ra — . u rai c 3 ra ra ra . — Lra ra rara

0 t/i 0

tn 3 O U 0

ra Era Li- 0

CL E X UJ I -

3 •—

c

_J

tn

0 0 0

0

4-

• CL Q. CL /I 0 ral/> o

—

o

•—

< c 0

" O CO ai - 01 O CTI 4-1 C C L_ JZ ». — ra o> 4-/ o (/i 3 — . c 4-1 l/l CTI o 0) O CL t/i E C 01 o — •— — 01 >- 0) 0 > 4-1 r— 3 CU SZ > • 4-1 -— l/l

ra0 CTI 4-1 4-» O c a) 0) 3 •— > 4-4 u l/l 0 0 ™l OI IU c E i/i 3 4-1 01 l/l - C o • — 4-1 3 - C 4-1 l/l •— o •— " O - C c 4-1 5

1

IU

•— . c

l/l 3 C

V) 3 O

•—

IU

l/l

i— 1— •— > C u i/i . IU c 1—IU . _C •— — ra0)i/i ra — L. 4-1 l/l 3 o ra O •— O O o •— 4-1 O) 0 >«1 ra,—.4-1 CQ 01 i/i U 4 - l_ -Q

.—

— "CT

—

CQ _1

>• 4 -

4-> 4 - 01 ra ra ra c o — "O > •— IU 4-1 4-J CTI ra E E L- en O o T= l/l 0 Ol c 01 > O 01 01 o 01 •

ra

—

c 0

o

-

ra ra u

•— -

a.

ra E

L_

c • O tn dl

ra

L.

ti > ra 0 tn TD tn — . 01 ra ra 3 ra 1/1 0 a ai L01 >T3 . —0 !_ raa. E 01 a. ratn atn ratn ai 1tn tn 4-1 a tn 0 O E E c O tn 1/1 E ra 01 O ra 0 O tn O 0 >- u 0 — -Q 0 tn ai ra0O TJ ut tn "O c c 01 ra0 ra > 0 sz 4-1 01 ra >• 0 — O •—' a t/1 L. Q. c 1— — " c L- tn 0 P _Q LE E tn x: .c tn 01 ra0 ai ra 1. Lis

ra •a tt ra "O 0) .— 1/1

3

u

01

CL ra ra 0 ra 1/1 0)

.ai — L. tn O J: >- ai 0 — t/t •M t/t — O c 0 £ a VI CL to o.

l_ 4-> E c 3 m "O C u O O CL 0 O ü. O tn

tn

ra

0 en

•—

cu

CU E

r—

01 r—

•—




3 01 Z

•—

1

•— •—

*

0

(U

ra

O

ra .craO t+ra0 - tn i_ • — t/t ra raO tn X. ra < tn a. - ra — ra ai 0 rac — m

*—

»

a. * — CL a. 0 I— L-

1 tn 1 3 0




0

ra ai

tn

•M

ra rarara rara ra ra

ra

o • — 1- tn >» ra cu i« — -a o c c 0 O

4-1 4-J

O

O O 00 «. 1 _ —' tn o •a c t/1 01 •— > E c w o ai 3 in tn I- ra O 01 C

tn 01

01

o

o "o

c o

rat/1

C

01

ra ra -0 0 0 ra u ra4-» en tn raOI ai ra X. ra raO) > 0

"a •—

CL

>•

M E

3

0) 0

ra

Li-

0

4-»

—

i/> 3

1 o 4-1

IA ai I— o

IA e m 4-1 l/l

O i-

ro M-

ro (1)

w (U Q.

t 01 OI

ia

l/l o

i/i

>

ra 0)

c o

c o


0 0 E u ID 4-1 - C - 0 0 IA IA O •— C O

ro

ro IU

IA 3

ro

o 4-1 o IU

>

ro

CL CL IA

i/i IU 1/1 ID

•—

—

— Q. O C 01 ai X

10 u co

CL O L. 4-> c 10 a-

a. i/i

c tu 0 Ìo X l/l 4-1 •— 10 u >• L. — ID O •— — l/l E X ID — ü- z

ro IU

o

—'

— .

IU O - O "O c o

ro

IA o l/l — •— a. 0) O 4-4 o t4-1 a) 1— c 10 •— UJ a .

—

•—

1 - "O 01 C -Q — 3 • ro o i— l/l CL ro — T3 > » c 3 UJ L u t— ' c O — i. ai > — o u o m — l/l L— "7, — O LU

ro

3 ro

•,—-

i/i

—

•—

CL a) — C 1— — 3 — 10 0 LU

ro

ro

•—

oí m c o u o

•—

o

3 -O >Ol 3 -Q

ra

Ol 3 -O

>-

r— 10 iu E

>-

o ID +J u tu Lo ID " O X I •—s CTI t— 3 > - IU 1/1 ai L— O - O LL. IU O • o IA o o 4-1 i— •— o 0 U o 1 tu •— E o l/l •—" U — —i E 10 > IU LL. U- o

.—.

ro

•—

u 4-1 •—

yi/i 3 O O o o 0 c 10 r— Û-

ro

•—

CL

O

OI i c o •— •— c O l/l •— 3 CTI O o ID 4-1 0 I - 4-1 u • — ai N 0 T 3 l/l N 3 3 O tu C I l/l a.

Q. l/l

ro 1—

•—

IA 3 O O o O IA O l/l o c rf

—

•—

IA 3 O

u

1

l/l 3 C

•—

.—V 4-1 IU l0 c CTI •—

l/l •—

— .

r— •—-

IA •— 3 IU O O tu O u o 0 0 c o

ro

•—

— CL.

1 L-

•—

U 0 u o 01 10 — IA E -o IA 3 ID O tu O CO 0 l/l o 3 0 "O .

ra

o

1/1 a)

u

tfí — — ..

>

ra cu

CÛ

ra (ü

c O E E O o

2

tu z

4-1 o E

•M en 3 -C - Q 4-4 - C O 4-1 TD E o C E "O — OJ

"O

•—

.c 4-1 o O z


•—

E

o

ra

•—

i_ CL VI tu 73

> - to

ra ai ra ai

ra

— o ra

ra tu

.c 4-4 3 O -

tu 4->

c o

ra

—

CL VI — O < L. -C a. 1-

CL ra o.

ra o

«—

ra

ra 3

ra

•—

+->

>—

tu

• 3 o CL z vi tu

VI 1_ •— o >tu o a . tu i— •

m V

IO tu —

IO a) r—

tu

c 0

4-J

4->

•

tn tu

>

>

ra

ra ra tu tu tu

tu ra ra > > IO ra _)

„

in lU

>

ra tu

•—

-a tu tu 4-

4-1 IO tu

a>

a) ra ra > > ra ra

4-J tu a. c o T> c tn IO "O o in tu tu l+-

>

IO tu c 0

tn x> tu a) Li_ 1

ra c ura o O

i

*-i w CL tu a. Q. o in tn tn i— 3 *— 0 in • X to i in O

ra tu

¿j to tu

»

i i-

10

i

10

•—

»

i

i/)

>- c

o

+->

— .oa . ctu

MU z 1 E c E •— ii- MU Ol 3 0 O

ra ra

IU

1/1

-—

X

«—

O

3


-

10 o

—

—

»

E lO 3 u

E LO 3

ra tu

c io o

>•

E


tn 3

•—

tu tu "O o JO in 3 >• O u o x: o

.—

sz 4-1 O

•—

tu T.

I- 3

3
-

ra

E L.

»

•— •—

3 ÍS

3 V z

ra

CL tu CL L. a. tn

ra 0 ra o ra o

o 3 O JC in c Q. -M X LO •w O O . c tu - 2 g 3 J O 3 ra 2 L. tn _ c ra to X t-

ra ra OI ra

tu to -a — cn c — JZ. .—. a Q. i - 00 tu

4->

3 *— •—* —

tn tu •— tu — c JZ 3 4-» L. 4-> a -O 3 O 0 T. •— IU - a Li. U- 0 a. tu •jz 00

••

10 tn tu tu c c "O

E

0 3

O •— i— L. — 0 CL

ra— in3 ra•—. ra— ra ra tn L- tn u U "O >-

E 3

i 1 tu "O -C •— a. 3 •—

1 Ltu 4-1

c 0 o L- • V a> u cn IU — zz E 1— u 3 1

—>

yo

tn tn a) in u u « Q) 0] CL tu

»

»

to

ra

4-< O CL

-

—

—

—

+J CU tu 3 in

c O

Q) nj > U tu

< ra

ra1

tn tu 4-» > c 10 Q) — — a.

ra

•—

rara

1 O

o 4->

ra

i/1 tu

•a o "O C =) c ra ra.— ra u JZ1 >. ra 10 o IU 0 ra - in •— tn L. C - a ra ra ra o tu T3 c co z •u in tu ra 10 a) •— ra O c 0 c E 10 — i tu E tu tn 4-> a c 3 ra a . O3 •—c Û- < O u . c>- ra X. •— 3 o tn raO in JZ oEra•—i— TD CT < i— in C3 "a O tn - o tn co IU 3 ra tu K ico L. ra 10 4-> ra •» *—IO 13 ra •—rara CL. c ra o 3 c •— -M •— tn -J tn 3 IU •— a> (U 0 tn O tn tn 3 tn m E in 4-» CL c 1 - u O in 10 ra tu z L •— in in u ratu ra < Ztu i—ra .— rai/ira _Co O 4-J rac cra.— z raCL m a) 4^ CL — r— in M- •— JZ < M •— ra . r. 3 i— •— — 4-4 w m 0) •— to 4-» rao !ra tU c -Q ra — -O "O ra U !_ o in ra _ c c (U . CL L- raraa . c i/i 3 "D U ì_ 3 . raJZ O ai L- ra4-4 0 •— 4-t ra •— 1_ •— c rara4-> •— ra3 rara. i/ic — •— a . l/l 4— tu CL m 14- 1/1 o - — Ll. m CL a . Q. in (/> i

m 3 IU o -o l_ T3 0) C 1/1 0

0 tu L. .a

ra

ra o r— o ra ra3 i-

1-

E to li.

— — 3 > — O > C O O

Oí
ra >ra ra ra SZ ID sz cu a.

.— a) •— cu .— r— 3

O C in ra "O — c (0 ra D. • •> O. CO in in 3 01 > ro ra — ai in o — CL "a ra < in 0 • OJ E s ID MMra tn 3 :ra o i— SZ 3 o ra c 4-J i/i ra a.

_ ra o — i 1ra X.

in

-M

SZ

i_ CL 1_ o CL O •—i in —1 ra XIB z

a. Q. m E • 3 in •— < D "O > rara ID ra•— o r-

ra

4-1

o

—i

ra

ra

s

in lU > ra ID

Ift r0 • — ja c ra 0 -O m m c • — i 01 0 E .— 1— ra J3 "O .c • — .— CT 01 o 4-1 1_ — u ra 01 ai E z Ol — L. .— 01 .—, ai c o CL 4-1 o in 4-1 ai O 0 Ol OI 4-1 -C ra L. o E ra > >• OI ra •— a ra i

in ai > ra ai

•—

•—

4-1 ra ai ID

4-1 ra ai ai ra > L.

ra > ra ra i-

4-1 ra *— l/l ra i in » ra-a ID c ID ra in o • — .c ra ra c ra ra 4-1 O m — 3 • — in "O O 2 sz raOr* — O ra< c c a) I rara cra OI — .c t/1 SZ 0 •— 4 — 1 -a Q-o 1l/l c r— i/i m 0 — c "O m 3 ra ra ai h* m - c c — < •— — — c ra ID ra ra ra •— ra ra— >- c • — i— CL » ra O u • ra•— ra C L 2 O c 0 2 sz

sz

JZ

o

o

sz

1-

H-

J

ra

in 3 ID 4-1 O

ra ra -O ra •— o

ID E o ra c L_ > O •C

si o

aZ

ra

ra (D ra

»—

-a c 0 -C 4-1 0 o

ra

c ai - — "O in .— 3 o O ra >- L-ra• — 4-1 4-> jQ ID 3 Q. .— in o -o ra"O —C 0)c ID H- — c E E L •• L. O E >-

1)

,—v ai Ol

ro

in

>

ra (U

>

>

ra a)

ra

ra tu

o -C

in 4J

ra

a.

— , — ,

Ci-

3 0 co

GO

4-1 c o o

l/>

in tu a.

3 "O


0 >o — O — • — • — DO E •• e 3 ira

- 4-1

L>

3 C3

3 tu z

3 tu z

t-

ZD

—

ro

"O •— c o

tu IU 3

i— —

"O tu tn O i TJ

*—

o L. CO

tu tu 3

ro

tn 3 4-» 3 C 1O o

X)

in 3 i— 3 0

tu

"O tu in 0 c i 4-1 L. 0

tu tu 3

tz

>

>

ro N tu

in 3 4-1

>-

Lo

—-

in 3

tu o

tn

0

•— a

t_>

—

c tu

o

>-

ro

—

u 3 U O

tn 3 —

-Q O

JZ

in •— 4-»

•—

CL tn

e E •—

tu 4-» tn o in 3 o in 3 •— J3 Li- • — Q -

ro

O

LIU

U1 1 -

Ol

in — •

ro tu

c

LQ. tn tu -o

3 (J5

3

ra tu

ro tu

•a

-a ro ro ro Ol •. i. tn tn 3 a — • — — ra ro ro ro ro .—> c ro > ro JZa i—— c "O c E c o > — o o ro •.>-—ro — • — • — • in SZ > tn i — JZ ro — . L— • — h>• ro • ra — • — ' L- co L. — Q- 3 > s: tu ro ro ro ra < ro < <



4-» L. i/l O Q. 4-1 Q> t/1 La)

c 2 0 O u c ra -¡c 4-1 c 3 c O t/1 3 T3 4-t a> ro4-> •m Lt/i O Q. 4-1 0) t/1

l/l

>—

ID 3 vi 3

I 10 4-1 a) Ol tu > CTI C •— m 4-* -a 4-> .— O O U E

1

O 1ID 4-1

.o - 0 4-1 E 4-1 o 4-1 _C

en

i/i U CTI

tn

CL i/i IU

t/1 U

V

4-> tu t i -

t/i a) CT)

tn tu OI

> ra ra ra 1 1 — — ra

>

— 4-1 E t/i E a. 3 t/i o 0 -C c LL. L ) u tu E u. E >- >- O •—- 4-J t n l •— C 3 o E e | "O CD u . o "O

ra

ra

O oo

ra

O

a.

O-

SI

ra ra — •— ra E E CT) t/l ra tu l i - X.

S3

ra

ra "O

a) tu .a

o




ra ra 3

— . :

4 - •— — tu a •— IU

.—

ra(_>

OI tu s:

E

ra

u 0

tn tn

ra

•— CJ

T3 •—

tn —

3

O O o

Ë 3 —

>-

sz

O-

i0) >

tu ra

-C CL O

ra>-

o


.

ra

XI

ra


E 1) io — O "O — C 0) ID O

4-1 3 • — —* 4-1 — 1/1 0 3 0 ID — U u z IU •— 4-4 a -Q i O 10 •— -0 Li. E O •— a U- to •—

t/1 o — i_ a) E

O ID E -M

-c 4-1 o E TJ — ID

—

•—

ID

>-

Q- 0 . t/1

ra

01 c — -C CL Irt ••

Li- z :

>— — E 10 ll.

0

-0

•— •—

1—

E T3

ra

-e 4J o E 3 ID -C

V ra 0 -0 —

IU ID T3

>-

2 ID E -C L. o - 3 t/1 c E lO o -c 3 C O 1- 1O ID

«i — a) •—» 0 (/i 3 C t) O ID •— C 4J c O CL —1 a. — ni

—'

214

-a c 14- 3 c in • — — tu 0 3 ai ra cra 3 ra •— >• E c —> - • — -C t/i 0 •— in •—' . — u 3 E •— E > ra 0 Ll-ra c u. U0

r— 0 ai u E • c— m u ra 0) Li- to -0 _Q O ra

0

in 01 0 a) CL m •0 u c 'ui al 4-1 01 •a c 3

in E 0 O -C 01 3 O U -C 4-1 1— 01 c c 3 iin i ai — c •M O C "O O C O — J3 3 0 tn 4J c 4-4 ra c 01 "O c c

tn

—

O O 0

c ra UJ c

X 01 .— 4-» u 01 E ra C — C ID 2 ra *-> o ra"O 4-1 r— •— 3) F— 4tn JD •o o ID 4-* ta •— 1/) m O jz +-i m u) +j •M O E 0 U tn a. o 4-1 c 0 E 0 tn O a4c O cu o

O. O

ra

0 0 cC

1 L. ID

•C O 4-> C T3 ID C X ra C E 0 — • tn 1— Q. O a. 0 4- in •— 4-4 ra ID 4-1 e tn •— LOl U ID 0 E r— -0 JD .—* • — 3 •—.3 — tn ID tn • 3 tn 3 O) ra u • Li- a H-

3 XI

>-

—

ra

ID E -0 a) a •— L. 4-1 Ut

jO > ID

H

tn 3 C O

ID ra 4J ID ,— .—, O) •— L•— r — tn _ 1— > tu 3 ID Ì- O ID (D O ID •— J¿ O tn U O O O O O O C O i_ ra 01 LL. a.

O 3

X.

(D ID ni — ra -o ra i- — 3 m 3 a. u o o -o z ID >- ID -i — — IDe ••E i- IO ID Li. < "ö L. O ID

in E U O O c OJ C C

3

c o

4J in •— a

0) ja 4-J 3 i— O — C > l/l 0) OJ - 3 w i/i 0) —.— •— 01 W > C TI 0J U

o ID 01 —1 o.

A W 1 * -a Li. O ra •— < u * 4— .— . —a. — O in ra raOJ 3 o. TJ ra s 3

3 -Q

O 3 O o z Z Z
a. l/l o i/i 0 O) E c < 0 m i/l 3 O O o o JC O 4-» c 3 4-> 0) 4-J o 2 o X


- 0) 0 0 4-1 L. -Q +-» _c ai 3 k- o O > 4-J > - C •»—1' i/i O) O) O — i_ 4-» en o o re O) c 4-1 O 4-1 t/> U1 O —— 4-> (/> r— •— — -C O ra 3 3 O E U — i U i/i D 0) M- 4-> i— JZ > O l/l < o 22 tu LT>

ra

i/i 3 O

i/i a>

— .re ra ra rac ra ra ra •o -a c V ra"4-o ra i/i 4-1 ra i/i — ,4-1 "O c ra(CUL 3 ra re -o

c •—


o

i/i E L0 o

l/l l/l E l/l 4-» L —4 — * 0 •— j o 3 " O "O

l/l — i 3 c Cl O E O

1/1 tu c 0 - "o < -0 c O c •— C L/l — 3 r. C3 O 4-1 l_ O OI 3 • — •— U1 LL.

a. a. 1/1

ra c ra 3 a. re 0-

re

ra rarera ra

ra

1 i— •— (J

ra

ra

ra ra "O m ra tu C -Q >.

"O O O 3

re

ra ra

O l/l 4) to — C 4-> re 0) 3 Q) Q. -Q ra

.— N 3 O

1 4-» 1 >1 a) tu -Q "O i_ c "O 0) tu O u 1/1 t >> •— c L. L- — — 4-» 0 de

t/1 0) m OI c tu "O to E o i/i O E •— •— "O O i/t c i - •— JZ •— •I o l/l D E tU i E c O 4-» i c O t/1 tU .—, a. +J 3 M 4-> a i/i • c/1 0 0 in E ui 4-» -C 4-1 L- 3 L O O 0 > - l/l r: o •— O ' — T3 c —

— VI


O 3:

4) Ol c — o

tu re 1/1 -0 c — ra JZ 1a. 3 ra 1- ai 1- >. — •—» (U LO M- L4-» - 3 i— a — 1— m • • E E •— L. ra 3 0) Li_ UJ

ra

O

•4o

i—i

,—,

u.

4-»

E in

ra

O u c o

u

M-

.— O

ra CL o in 0) in 3 — Z

ra - 11) 4-> O TD •— 3 TD 0 CO •— 4-> U >-

ra

—s in 3 m

ro

ro — < .— • —I ro U) L l . TD l— O

0 i_ 0 m

in 3 t/î

ro

ro

ra a)

ro

E

•—'

in 4-1

-C m 3 -Q

c c

ro

TD

•— 4-1 3 C X. • i n E

3 4-f W

Lu

o£

i—

ra ra ra

ro ro

0) -0 •— >— u H) 0 L . +•> CL 0

o

0 •— u

(D

C O

en c 3 U 4 4-t C -O

Q. O O « 0 c m - C O a n E — ra .o 2 co

in — —

w E L. O O

0 0 c

ra 3 ra X

(U

4-1

ra rora

in E

W OI

*

O 0 ) • V c U1 — 0 — 0 —I •• E u •—• 1ro OI a) L U 0 TD u • 0 ra

I/) 0)

a) 1 - M— ra 0

"O

3

0

E

ro . -

TD

c • —.

>-

— ro L.

ra

l/ì 4-> c

- 0 •— a> o. a> M— CT) C TD 3 C 0

•

"O CL) CTI

C 0) 4-> 4-1 O

"O C

ra

-O

O O

•M

C 0

>»

e L.

0 0

"O c

"O O 0) 4 -

>

ro ra

ra

«1 - Q

a .

ra ira ra

L.

0)

4J

ra ra

L.

"O ti L. CL

tA

L.

L.

o .

a .

Ë 3

-

•3-

01

c o

c

.C Q.

—'

c/t 4-» O

OI

o L. — E a

.—

>—

•

T-I

VI 3 C E

0 JÛ >•— >--Q O) 0 C "O "O m •— 0 3 U L. 0. A.

3

VI O>

ra ra — . rarara• 1 ) T J

ra

ra

"O «

m

ra

o 4-F

VI C

— . JX

C L. 0 O) TN A . •0 0 . — •— m c 01 01 LlJ

T3

• —

TO tn W

4-» 4-» - C — .4-» 4-1JQ.: •— 1— CL

a. 1/1

TO 2

0

•—

4-4

in 3 E tn 3 E in T3 > - a >• c c l_

ra ra ra a.

TO ra ra Q. u

Ol O) LU

TO TO a.

TO —

•—

CL Ü1 S 3

a. VI m 3 0

TOra ra ra

1—1

ai

ig i l g i l n U TO i - TO L(U "O 0) "O 0> O. c o . c Q. o — o — O. c > - c > - -c g] L t) L I I E> -o > E. o> •E X 3: X

1

o

c

a. IA V) 3 a. 0 4-*

ra c

0 19

u t/1 ai 10 3 a . ai CL 3 c O tn CL 4-> 0 -C en 4-» a c c 0 0 ai c T3 0 3 C7> CTI ai 0 •— ai in . o. a > — 0 X X

• — ra ra ra

-0 ai 4-» . c CL CL O 0 C » X

• LiO —

TO

•—

0 0 0

• —

4-1 1 C 0 T} tn 3 • "O -a -a T3 ai dl i_ u a. a.

M-

•—

4-)

O

0 0

ra ra 2 3 TO ra X X

ra ra 3 u ra m X N

ai — 4-1 tn a 3 a> 0 -Q

0 0

T3 U

TO t/i ra 0 TO 3 — m — . —• T! tn TO ra ra • .— —4J O- 4-13 ra C TO ra tn c ra TO . m 3 — • — C 0 ra

*—~

'—'

3

E c >- 3 O V)

ra ra co

ra o

0 E

E ni

44-» C < D

O to

-aco

I —

—

ID

3 CT

t/> 3 E IU

IU ID _rz en o 3 c roO o o ' i p— c X u 10 IU . z 3 3: — 4-» m CO I-

>

a. co (/)

3 E O c IU i— IU 1-

1 3 10 in E 4J E 10 IU S IA uS 3

(0 O Ë ID

i/i

ID roroQ T3 L. "O >— C 10 — a. O Lo o (U o c ro 4-4 ro O) u CL 1— E CQ >a X

V. ID CL in •— •a — •— 4-1 ID L. o , •— ro ro E 3 a. en E ID IU CT in JZ O 0 .C O 3 4-> ID IU a) '—c £ i— E •— IU 0) M l3

-o ra V

-o ra 4) u Q. Ut 4) "D

11 — ÍÜ "O (0 njo

3

•> •—

o -*-» _c •—> O —s 9) •C > tn ^ — o a. c 3 E in .c t/i o tu L. c 3 e e e ,—V o ra O 0 m o O "O L. *• c 2 ra 3 tn c c 4-4 c J .—- 3 •— i_ o C 2 L. 1- —— .— >— O a — ra o O o o. E U — ' •C a. ,_i .e s: s: -c ra CTI — u. < X

•—

SZ


ra O 4-* ra—* ,—.—s E ra L. i_ Si O ra 4) E 2 o ra c i_ i_ o c o o >. — ' _£Z x: a:

s til z

ra tu

— c — •— ra 3 2 o ra X

o —« O to tn 4) 4) 4) 4) 3 E c ra EL. —4> — 4-> 4-< c >— 4-1 0 — 3 -C o •— 4) 4) ra ra 4) L. CO O —" XI E O '—' i_ ra"O ra a. 4) u.
—

ra o

-

tfí IU 4-1

ro

._ >. SZ CL O - • 1_ •— LU

• 1 1 1 ) — 0 4-. — — O) E >- " O u ra l u


- ro L- ra i0 ^ - C tfí - C tn o. >• 1- >H -C JZ o 1ho

-C Q. >

ra c o u ra ro

Ol

ra u

-C

1-

3 E O !_ -a O

ro

O u

tfí a.

tfí 3 0

O (0 E

c -C o

E L. • 3: co

•— •—

z

4-1 ra .a .—

4-1 ra in a. 3 < »

w

-a ra a> L. CL in (U

in — i 4-j rara - c ra ra I 1 o i s ì -o in i J3 ~o m in o ra o IB orava) u ra -o in 4-1 "O OI 1- "D m i- — i n to -Q i- — i n c 4-1 — m o> c i n ra - Q c a) < 1 > ra I U — T3 - — x i - cl ra c O. 4-1 - C 4-1 .> >- c > a . E Ol t n a. ra +oj oo. i n — — aj ra — — 4 - 0 - ( U c ( D i n in m m — c < u ra — ra o > 4-1 La>raE-co>+-i i- u >-4-i cn — — c cn —— O C K 0 0 mra— Q.— C O ill 4-1 Q. O ra *•> a u o c c ra C 4-1 •— .O tn > c c C c O c "O O) 0)O D IU 1—

10 10 .— 4-1 l/l O 10 tn 4-»«— 4-»•— 4-»•— w O) t/i to in to ó 0 "o Ô ô o o o o o o Z

X 10 410

o —' (0 _1

< LL. o

IO -o c 10 O) 10 c 10

•—

N C

10 1-

y-

3 o ui I
-

-C CL O l/l 0 1a

m 4-1

ra

^

' ra

.i—ra ra ra — ra ra ra . JZ


ra ra ra ra ra ra ra ra — ZZ ra :: ra ra o. ra ra o ra Zí l/l ra

o

JZ

ra ra ra ra (/> raJZ ra

o

ra

N

0

o

l/l u ai 3 O

N

JZ

LL. O l_ o

o

ra

ra ra ra


-

D. O

ra

.

CL O

o u Q

ra ra

1 >— i— 7 3 •— 4-1 1/1 o a

uí

c o l/l a> •— •— o JZ CL 0 c 0 o 1_ a

1

c 73 a> E o 4-1 i/i

•—

4-J 00

c 0 u 1 l/l o 3 O — •— "O t/i 0) ÜJ < ra -o ' 4J JC Q. >• l/l c •— CL O a> a> ra •— • racw c — Q- i/l raJZO ra - "O -C ra o E 4-t VI 0 LO i/l c c l/l L. t/l J2 •— CL o 0 O O CL 3 -M OI ra •a l/l t/i OI "O "O c ra • (U L. IU O "O c t/1 c c •Q 4- E OI c rara3 IU ra H s:

c 0 ó L. (/I ra •M > -C 4— o Q. -u t/1 o ra U o L. z O) *— 4-J ta OI 1— raIU •M i-1 •— >- 1— rajara•— o rao E ¿j -O l/l razs u ra "O « rarac O < 4—




CL E u -C t/1 -C t/1 r. . . 1 — 4tu >w ra tñ u J3 O o -J

T) tu 1/1 ra c •— 4ra •— > i/i ra SI

3 o O —I

m "O o o. o a) ra -X T3 L-

JZ

a. IU o ,—« ra OI i/i 4-1 73 -O t/1 3 C 4) 4-» O -C O 4-1 M LO cu ra o > e ra -

ra

e t/1 1) >

ra cu

73 ro (D

O) >

E 3 r— >jr O-

—

t/i •o u co

.c CL

ro ai > - ro 4-1 73 o ro >

—

•—

—'

73 o O DO 4-> L_ > < i—

t/1 •— ra E

E ra cu Li•o i. o ra

*—

t/i t/i 3 3 tu (U ra ro c c c CU c .— ro.— _J "O »— t/1 3 ra 3 00 uL. o L. 3 >. ro O 4-1 i t/1 .— t/1 E t/1 o ro 3 co ü- tfl

.— ro 4-1 ro •o Lo -C o Ë 3 r— >.c o.

~—

JZ

tu ro -o t/1 — tu c • E — L. L_ CL O Q. a. 4— > - t/i •— O t/i 3 a >. > - C o —L. E CL l_ ro >• cu ü- O 73 l_ • O ro

235 TABLE 8.6

SUMMARY OF PESTICIDES REGISTERED FOR USE ON TARO IN HAWAI I

Pesticide Herbicides CDEC ni trofen 3 da lapon 3 paraquat Insecticides Methomy 1 carbary 1 di azi non ma lath i on Bac i 1 lus thurinqiensi s d¡methoate Fungicides maneb captan 3 zineb mancozeb Nematicides methyl bromide plus chloropicrin^ D-D

Formulation(s)

Dryland Taro

EC, G EC, WP SP SC

X X

L WP, F EC, WP EC WP

X X X X X

Xe

Wetland Taro

Taro Leaf

X Xe

X X X

EC

X

WP WP WP WP

X X

X

X

X

G

X

L

X

X X

SOURCE: Data from B. Brennan, Agricultural Biochemistry Dept., Univ. of Hawaii, 1981 : personal communication. a

Tolerances and/or residue data available, b SLN petition in preparation. c Pre-plant or pre-emergence use only. d Also includes beetle larvae, weeds, and some pathogenic G - Granules e EC - Emulsifiable Concentrate F - Flowable WP - Wettable Powder L - Liquid SP - Soluble Powder D - Dust SC - Soluble Concentrate

9 Taro Diseases Jeri J. Ooka

ALTHOUGH taro is an important staple in much of the tropical world few comprehensive studies of the maladies affecting the crop have been undertaken in recent times, which would bring up to date observations and experimentation from twenty-five to fifty years ago. Yield loss of taro due to disease is not well known. Diffuse production and the subsistence nature of taro make statistics difficult to collect (FAO 1975). Even in Hawaii, where there is a small but vigorous commercial taro industry, yield loss statistics are difficult to collect. From informal and partial surveys of the taro industry, it is possible to estimate the loss in yield as being normally between 10 and 20 percent. Individual fields may suffer from little yield loss to as much as 30 percent loss due to Phytophthora colocasiae leaf blight (Trujillo and Aragaki 1964) and up to 100 percent from Pythium root and corm rot (Plucknett, de la Pena, and Obrero 1970). Most yield losses in the wetland taro crop may be traced to diseases. On the other hand, in dryland taro cultivation, water and insects may be more important primary factors in limiting potential yield.

DISEASE DEVELOPMENT For a plant disease to develop, a pathogen or disease-causing agent must contact a susceptible host plant in a suitable environment. Diseasecausing agents are divided into biotic and abiotic agents. Infectious diseases are caused by biotic agents. These include the fungi, bacteria, viruses, and nematodes. The most serious and widespread taro diseases are caused by Phytophthora colocasiae and Pythium spp. (Trujillo 1967). Noninfectious disease may be due to deficiencies or excesses. Abiotic

Taro

237

Diseases

disease agents include chemical excesses, herbicides, air pollutants, nutrient deficiencies, and imbalances. These diseases, while they may not be dramatic, probably contribute significantly to yield loss. T a r o has a large number of varieties (Whitney, Bowers, and Takahashi 1939; Handy 1940). Cultural preferences and geographical isolation in large part determine the variety of taro grown and desired. In Hawaii, for example, many taro varieties are locally developed and propagated. Such varieties have, in geographically isolated areas, the advantage of being selected for resistance to local diseases. Unfortunately, since taro is a vegetatively propagated crop and modern transportation has rapidly moved pathogens throughout the world, locally selected varieties without resistance quickly succumb to introduced diseases and are not always replaced by resistant varieties of taro because of preference for the old varieties (Jackson and Gollifer 1975a). However, the germ plasm of taro is probably sufficiently diverse so that host resistance to most diseases is available within the genus. The environment is also an important factor in disease development. With a virulent pathogen in the presence of a susceptible host, the environment, both biotic and abiotic, needs to be favorable for disease to develop. Such things as free moisture, humidity, pH, and temperature are important abiotic factors in disease development.

DISEASE CONTROL The aim of disease control or management is to minimize the effect of plant diseases on yield by manipulating the host and pathogen populations and their environments to reduce the chances of severe disease outbreaks. Although a single procedure may be successful in controlling a disease, it is far better to support this primary control with a number of secondary procedures. Control methods may be placed into four categories: biological control, chemical control, sanitation and cultural practices, and exclusion. Host resistance, a form of biological control, is a cost-effective disease management scheme. It is the control method of choice for many crops and a goal constantly sought by plant breeders the world over. The resistant host prevents the pathogen from entering or, if it enters, prevents it from developing sufficiently to cause diseases. Host resistance also avoids having to place potentially polluting and dangerous chemicals into the environment. Other forms of biological control, such as parasites of plant pathogens, have not been extensively exploited for disease management. Chemicals that protect the host from infection, provide therapeutic

238

PRODUCTION TECHNOLOGY

effects, or reduce pathogen population are useful for reducing the impact of many diseases. Protectant chemicals are generally applied as sprays to the host, so that a layer of the compound covers the plant and prevents pathogen propagules that land on the host from germinating and infecting the host. Folier diseases such as Phytophthora leaf blight may be controlled by this method. Protectant sprays are generally applied at regular intervals throughout the life of the crop, with the application interval shortened during periods when the environment is particularly wellsuited to disease development. Therapeutic chemicals for disease control are a fairly new addition to the arsenal of fungicides available. They are costly and many have a very narrow range of effectiveness. Several compounds show high biological activity at very low concentrations on the taro soft rot pathogen (Ooka and Matsuura 1981). Fungicides in this category are generally applied to fairly high value crops intensively grown such as hops (Hunger and Horner 1981), tomatoes (Cohan, Renveni, and Eyal 1979), and citrus (Farih et al. 1981). While therapeutic chemicals are attractive, more work to demonstrate their potential in disease management needs to be done. Eradicants reduce the pathogen population in the environment. These chemicals are generally applied prior to planting or after harvest of the crop. They lower the innoculum potential of the pathogen by killing the resting structures of the pathogen. These compounds may be very useful in controlling diseases caused by soil-borne pathogens such as Pythium spp. While the arsenal of chemicals for control of diseases is potentially large, many have recently been recognized as having detrimental effects on the environment and are no longer available for use. New chemicals in the United States require approval by the Environmental Protection Agency (EPA) before they may legally be used on the crop. The registration process, though costly, long, and tedious, has merit. Where taro is grown in wetland culture, it is especially important to carefully evaluate potential hazards of introducing chemicals into the aquatic environment; the potential for widespread damage is enormous. Sanitation and cultural procedures are time-honored methods of disease control. Sanitation removes diseased plants and debris from the crop area and thereby reduces the pathogen population, thus augmenting any host resistance and chemical control methods by lowering the innoculum potential of the pathogen. Cultural practices that produce a healthy plant substantially free of nutrient and water stress will produce a plant better able to withstand attacks by pathogens. Rotation with a nonhost is a good cultural method of reducing pathogen populations.

Taro Diseases

239

Many taro growing areas are located on islands or are relatively isolated geographically. These are areas where exclusion of pathogens by quarantine is a viable means of control. If the pathogen is not present in an area it would be well to keep it out for as long as possible. Since taro is a vegetatively propagated crop the movement of pathogens in planting material is an ever-present threat. Pathotypes may develop in a given area, so even though the disease is present it may be wise to still regulate closely the importation of vegetative planting material. Education of the general public on the dangers of indiscriminant plant movement must accompany the quarantine effort. The effective management of taro diseases requires detailed knowledge of the host, the pathogen, pathogen transmission and dissemination (including vectors), and epidemiology. The rest of this chapter seeks to gather what is known of taro diseases into a single concise summary. DISEASES CAUSED BY BIOTIC

AGENTS

The biotic agents reported to incite diseases in taro are fungi, bacteria, viruses, and nematodes. Although taro is susceptible to attack by at least twenty-three pathogens, only a few cause serious problems that will reduce growth and production of the crop. FUNGAL DISEASES

Taro is damaged by many fungal pathogens distributed in the four main groups of fungi: Phycomycetes, Ascomycetes, Basidiomycetes, and Fungi Imperfecti. The majority of reported diseases throughout the world are caused by fungi. In the Pacific Basin, Pythium corm rot (Trujillo 1967; Plucknett, de la Pena, and Obrero 1970) and Phytophthora leaf blight (Trujillo 1967; Jackson and Gollifer 1975c) are the most serious diseases of the crop. Phytophthora

Leaf Blight (Phytophthora

colocasiae

Rac.)

Raciborski (1900) described the pathogen, Phytophthora colocasiae, causing leaf blight in 1900 from Java. Early Indian epidemics lead one to believe that the pathogen is of Southeast Asian origin. Trujillo (1967) has postulated three routes of pathogen dissemination; (a) from Java to the North Pacific; (b) from Java to the Central Pacific; and (c) from Java to the South Pacific. Movement on the northern route went from Java to Taiwan, where Butler reported it in 1911 (Butler and Kulkarn 1913). From Taiwan it is believed to have moved to Japan and then to Hawaii, arriving probably in the early 1920s. The first report of the disease from the Philippines came in 1916

240

PRODUCTION TECHNOLOGY

(Gomez 1925). Movement into Micronesia then probably came from the Philippines (Trujillo 1967). The most recent spread extends into the South Pacific through New Guinea, Australia, the Solomons, and Fiji, where Parham (1949) reported it present in 1948. The disease has not been reported from Samoa, Tonga, the Cook Islands, the Society Islands, or the Marquesas Islands. Epidemics of leaf blight may occur throughout the year during rainy, overcast weather when night temperatures are low ( 2 0 - 2 2 ° C ) and temperatures during the day are moderate ( 2 5 - 2 8 ° C ) . Entire fields may be blighted in five to seven days under these conditions (Trujillo 1965; Trujillo andAragaki 1964). The early stages of the disease are characterized by small circular water-soaked lesions 1 - 2 cm in diameter, generally dark brown or purple. A clear amber fluid exudes from the center of the lesion. This liquid turns bright yellow or dark purple when it dries. The lesions rapidly enlarge and take on a zonate appearance (fig. 9.1A). The zonation is the result of the temperature-related growth response of the fungus, with rapid growth during the warm days followed by slow growth during the cooler nights. This zonation is accented by sporulation, which takes place at night. The sporangia appear as a white fuzz on both sides of the leaf. The ring of sporangia are particularly prominent in the morning before the sun dries the leaves. After initial establishment lesion development is rapid until the leaf is entirely colonized and collapses (fig. 9.1 B). Under severe conditions the fungus destroys the leaf petiole as well as the lamina and enters the corm causing a firm cream to brownish rot (fig. 9.1C), eventually heading to complete destruction of the plant. The corm rot phase, although not a problem in Hawaii, limits production in the Marianas and the Caroline. Phytophthora rot is a hard, creamy to light brown rot with little or no odor. The difference between healthy and diseased tissue is well-defined (fig. 9.1C). Phytophthora colocasiae is probably the principal cause of storage rots in the Solomon Islands and other islands in Melanesia and Micronesia. Up to 70 percent of the rots in the Solomons are attributed to this fungus (Jackson and Gollifer 1975b). It is not, however, a cause of storage rot in Hawaii. Copper fungicides applied with low volume spraying equipment are effective in Hawaii for control of this disease. A back- mounted knapsack mist blower can cover up to 12.5 meters horizontally with its fungicide valve fully opened and motor accelerated to maximum air speed. For each tank mix, 227 g of basic copper to 7.6 liters of water and 14 ml of spreader sticker is used. The spraying should be done on days when wind velocities are less than 8 kph, with the spray directed downwind. Spray-

242

PRODUCTION TECHNOLOGY

ing should begin when the taro is 4 months old, with application every week during the rainy weather and every two weeks during the dry weather. Fungicide applications should continue until the plants are 9 months old.1 Copper oxychloride applied weekly at a rate of 2.24 kg ai/38 1/ha with a mist sprayer provided control superior to manzeb and captafol in the Solomon Islands (Jackson and Gollifer 1975a). While captafol provided excellent control of Phytophthora leaf blight, it is phytotoxic to taro and therefore dangerous to use (Berquist 1972, 1974). Manzeb provided good control and had a high residual effect without the phytotoxicity of captafol (Berquist 1972, 1974). Chemical control as developed for Hawaiian conditions is not effective in the wet tropics.2 Deshmukh and Chibber (1960) reported the variety Ahina to be resistant to the blight. Paharia and Mathur (1964) found the variety Poonampat to be immune and Sakin V to be resistant to blight in their tests. No resistance has been reported elsewhere in the Pacific Basin (Parris 1941; Hicks 1967). Increasing planting distance from 46 cm to 75 cm reduces blight incidence in Hawaii (Parris 1941). Sanitation by pruning and removing infected leaves biweekly appears to help reduce disease incidence in the Solomons (Jackson and Gollifer 1975a). Exclusion through quarantine will protect areas still free of the pathogen. Phyllosticta

Leaf Spot (Phyllosticta

colocasiophila

Weedon)

Phyllosticta leaf spot can often be seen on dryland taro in Hawaii, especially in the high rainfall areas of the islands. It is also known in American Samoa. Cloudy, rainy weather for a protracted time (2-3 weeks) accompanied by cool winds is conducive to infection and disease development. The disease is limited by hot days and dry cool nights. The spots on the leaves vary from 8 mm to 25 mm or more and are oval or irregular in shape. The young spots are buff to reddish brown. Older spots are dark brown with a chlorotic region surrounding the lesion. The centers of the infected area frequently rot out to produce a shothole-type lesion (fig. 9.2). Phyllosticta spots generally resemble those caused by Phytophthora colocasiae, except for the absence of the whitish fuzz of sporangia produced on Phytophthora colocasiae lesions. Chemicals used for the control of Phytophthora spot can also be used for control of Phyllosticta spot. However, no chemical control is recommended unless Phyllosticta spot is continuously present and causing significant defoliation. Collecting and burning the diseased leaves seems to be of some value. The Hawaiian variety Manini Uliuli is resistant to fungal penetration through the unbroken epidermis (Parris 1941).

Taro Diseases

243

FIGURE 9.2. Phyllosticta spot. Notice the chlorotic halos surrounding the irregulär lesions.

Cladosporium

Leaf Spot (Cladosporium

colocasiae

Sawada)

Cladosporium colocasiae causes a relatively innocuous disease common on dryland taro in Hawaii (Parris 1941). Bugnicourt (1958) reports that C. colocasiae is frequently present in the planting of taro in irrigated terraces of edonia. According to Trujillo (1967), it is present in the New Hebrides, Western and American Samoa, the Carolines, and the Marianas. The disease attacks both wetland and upland taro and occurs mainly on the older leaves. On the upper surface the spot appears as a diffuse light yellow to copper area (fig. 9.3A). On the lower leaf surface the spots

Cladosporium leaf spot: a, chlorotic spot of the upper leaf surface; b, dark brown to black circular spots showing sporulation of the pathogen on the lower leaf surface. FIGURE 9 . 3 .

Taro Diseases

245

are dark brown due to superficial hyphae, sporophores, and conidia of the fungus (fig. 9.3B). The lesions are generally 5 - 1 0 mm in diameter. Since no economic loss has been attributed to the disease, no control measures are needed (Parris 1941). Pythium Rot (Pythium aphanidermatum Fitzpatrick, P. graminicolum Subramaniam, P. splendens Brown, P. irregulare Buisman, P. myriotylum Drechsler, P. carolinianum Matthews, P. ultimum Trow.) Pythium root and corm rot is probably the most widely distributed disease of the crop. Soft rot has been reported from New Caledonia, New Hebrides (Dumbleton 1954), Hawaii (Sedgwick 1902; Carpenter 1919; Parris 1939) Samoa, and Palau (Trujillo 1967), the Solomon Islands (Jackson and Gollifer 1975a), and Puerto Rico (Alvarez-Garcia and Cortes-Monllor 1971). This disease was probably spread with the introduction of the crop. Pythium aphanidermatum, P. graminicolum, and P. splendens have been observed to cause losses of up to 80 percent in Palau, Samoa, and Hawaii (Trujillo 1967). Bugnicourt (1954) has reported heavy losses in New Caledonia due to P. irregulare. Jackson and Gollifer (1975a) find P. myriotylum persistently associated with soft rot in the Solomons, and Ooka and Yamamoto (1979) have noted a prevalence of P. carolinianum in soft rotted material in Hawaii. Conditions required for the occurrence of epidemics of corm soft rot are only vaguely understood. Warm and stagnant water in the paddies of wet-grown taro as well as poor field sanitation have been suggested as important factors contributing to the high incidence of soft rot (Parris 1941; Plucknett and de la Pena 1971; Plucknett, de la Pena, and Obrero 1970). The normally firm flesh of the corm is transformed into a soft, mushy, often malodorous mass (fig. 9.4A). In wetland culture, the taro root system is destroyed except for a small fringe near the apex of the corm. Diseased plants are therefore easily removed from the soil by hand. The plants become stunted, with leaf stalks shortened and leaf blades curled and crinkled, yellowish and spotted (fig. 9.4B). Upon the demise of the main corm the lateral cormels develop roots and remain clustered around the cavity left by the disintegration of the main corm. The skin of the diseased corm usually remains intact until complete disintegration of the interior of the corm has taken place. When the corm is cut open there is usually a sharp line of demarcation between the healthy and diseased tissue (fig. 9.4C). Newly planted setts may be killed before they are able to produce leaves or may be severely stunted.

246

PRODUCTION TECHNOLOGY

FIGURE 9.4. Taro soft rot: a, paddy taro plant variety Lehua Maoli showing stunting and reduction of foliage; b, longitudinal and cross section of corms showing soft rot.

Pythium rot caused by P. splendens is white, dry, and crumbling with a sharply defined, irregular boundary between healthy and decayed tissue. A zone of light brown undecayed tissue is often present in front of the rot. The severity of soft rot may be reduced in soil by incorporating Captan 50 WP at 112 kg formulation/ha into the acid soils before planting. Captan is inactivated in alkaline soils. Setts should be selected carefully to avoid those showing any Pythium infection. The selected setts should then be dipped into a Captan suspension to provide them with protection for a few days after planting (Trujillo 1967). However, chemical control measures utilizing Captan are not always successful in reducing losses (Plucknett and de la Pena 1971; Plucknett, de la Pena and, Obrero 1970). Parris (1941) found that copper sulfate at doses effective for soft rot control were phytotoxic. Resistance to Pythium rot occurs in the Hawaiian varieties Kai Kea and Kai Uliuli (Parris 1941). Others exhibiting some field resistance to

Taro Diseases

247

soft rot are Piko Uaua and Lehua Maoli. 3 T h e cultivar Oga is tolerant to root attacks in the Solomons and is recommended for areas where Pythium root rot is known to be a problem (Jackson and Gollifer 1975b).

Sclerotium or Southern Blight (Sclerotium rolfsii Sacc.). Sexual stage: Pellicularia rolfsii (Curzi) West (syn. Corticium rolfsii Curzi) Sclerotium blight is generally a problem of dryland taro, although wetland taro is frequently infected. This disease has been reported in F i j i (Dumbleton 1954), the Philippines (Fajardo and Mendoza 1935), Hawaii (Parris 1941), and India (Goyal et al. 1974). This disease appears to be one of overmature corms and plant stress. Sclerotia abundantly produced on infected corms persist in the soil, causing serious outbreaks of the disease in warm, wet weather following a significant dry spell. They also float on the water of paddies, infecting the dead petioles of the taro when the opportunity presents itself and subsequently invading the corm and producing a rot in the field and in storage under some conditions. Affected plants are usually stunted and the corms are rotted at the base where abundant sclerotia of the pathogen develop (fig. 9.5). T h e sclerotia are small, almost spherical lemon yellow to dark brown bodies resembling cabbage seeds. The rotted tissue is ocherous to brown and soft with a tendency to stringiness. A dense white mycelium may cover the tissue. In the wetland culture the rot frequently starts at the waterline on the corm rather than at its base. Sclerotium rot of the corm is generally a shallow surface rot occurring below the external mycelial coating of S. rolfsii and occasionally penetrating deeply into the corm as a light pink soft rot with distinct margins. T h e corm consumed by the fungus and sclerotia produced in four to six days. Sclerotium rolfsii may survive saprophytically on plant debris or as sclerotia in the soil. When sufficient moisture is present sclerotia germinate and infect young or old roots, dead leaf petioles, and overmature corms. T h e disease is usually serious during warm wet periods. Flooding of paddy fields in early stages of disease development is an excellent cultural control method in Hawaii. F o r dryland taro, sanitation by pruning and removal of old leaves will reduce disease incidence. Harvesting the taro before it becomes overmature will reduce losses to this disease. Burying plant debris after harvest by deep plowing is suggested for controlling this disease in other crops (Graham, Kreitlow, and Faulkner 1972; Brandes, Cordero, and Skiles 1959). Soil drenches with dicloran and quintozene at 1 1 - 2 2 kg/ha will con-

248

PRODUCTION T E C H N O L O G Y

FIGURE 9.5. Southern blight: taro "huli" rotted by the pathogen. Notice microsclerotia formation on the leaf petioles.

trol this fungus effectively. However, these chemicals are not registered for use on taro in the United States (Trujillo 1967).

Spongy Black Rot (Botryodiplodia theobromae

Pat.)

Botryodiplodia theobromae causes a spongy rot, occasionally becoming dry and powdery, ranging in color from cream to grayish brown and frequently becoming dark blue to black with an indistinct margin between healthy and diseased tissue. T h e fungus is capable of invading undamaged corms under conditions of high relative humidity.

Taro

249

Diseases

FIGURE 9.6. Black rot: base of taro corm showing distinct black zone where the pathogen is active. (Photo courtesy E. E. Trujillo.)

B l a c k R o t (Ceratocystis

fimbriata

Ell. and Halst.)

Ceratocystis fimbriata causes a soft dark to c h a r c o a l black rot with a fragrant b a n a n a odor, starting from natural or m e c h a n i c a l wounds (fig. 9.6) in corms. Rhizopus

R o t (Rhizopus

stolonifer

Sacc.)

In Hawaii, Rhizopus stolonifer has been known to cause serious loss in corms stored at moderate temperatures and high humidities while the taro is awaiting shipment.

250

PRODUCTION TECHNOLOGY

FIGURE 9.7. Rhizopus soft rot: a, taro corm showing fungal growth and sporulation; b, longitudinal section of taro corm showing soft cheesy rot.

Rhizopus rot is a white to cream colored soft rot ranging in consistency from cheesy to watery with a slightly yeasty odor (fig. 9.7A). The skin of the corm generally remains intact until the rot is very advanced. External development of mycelium is sparse, however, sporulation at breaks in the skin and wounds resulting from the removal of cormels are extensive, covering these areas with a black powdery layer (fig. 9.7B). Losses to this disease can be minimized through removal of the roots and soil from the corm, rinsing the corms well with clean water, and dipping them into 0.5 percent solution of NaOCl for approximately one minute, air drying, and storing the corms in a cool, clean area of approximately 50 percent relative humidity (Ooka 1981). Fusarium

Dry Rot (Fusarium

solani

[Mars.] Syn. and Hans.)

Fusarium dry rot is a brown rot, mostly dry and powdery but sometimes becoming wet and soft in later stages, with a distinct margin between healthy and diseased tissues.

Taro Diseases

251

VIRAL DISEASES

Relatively little is known about taro viruses, although methods have been developed for their isolation and they have been studied by electron microscopy (James, Kenten, and Woods 1973; Zettler et al. 1970).

Dasheen Mosaic Dasheen mosaic virus, a flexuous rod 750 nm, was initially described in 1970 as a polyvirus infecting members of the Araceae (Zetter et al. 1970). It has since been detected in taro in Florida (Hartman and Zettler 1972); Egypt (Abo El-Nil and Zettler 1976); Puerto Rico (Alconero and Zettler 1971); Venezuela (De Brot and Ordosgiotti 1974); Japan (Tooyama 1975); the Netherlands (van Hoof 1971); the Solomon Islands (Gollifer and Brown 1972; Kenten and Woods 1973); Fiji (Abo El-Nil, Zettler, and Hiebert 1975); and Hawaii.4 While it has not been documented as reducing yield in taro, it has been shown to adversely affect the growth of Caladium, Dieffenbachia, Philodendron (Hartman and Zettler 1974), and new cocoyam (Volin and Zettler 1976). The virus is well characterized (Hartman 1974; Zettler et al. 1970). Purification techniques for the virus and production of virus specific antisera have been developed (Abo El-Nil, Zettler, and Hiebert 1975). It is a stylet-borne virus carried by aphids (Myzus persicae Sulzer, Aphis craccivora Koch., Aphis gossypii Glov.). The foliar symptoms include a dispersed and veinal mosaic pattern on the leaves (fig. 9.8). Leaf distortion is generally mild to moderate. Plants generally become asymptomatic three to four months after initial symptom expression. Symptom expression seems to be more pronounced during the cooler months of the year in Hawaii. Apparently this virus does not cause appreciable yield reduction in the varieties grown commercially, and the quality of the corm is not affected. Varietal resistance appears to be a good method for reducing the incidence of this disease in taro.

Alomae and Bobone Gollifer and Brown (1972) described for the first time two virus diseases from the Solomon Islands. Alomae, a disease apparently caused by two bacilliform viruses, results in the death of susceptible cultivars (Kenten and Woods 1973; James, Kenten, and Woods 1973). At present this disease is confined to Papua New Guinea and the island of Malaita in the Solomons (Gollifer et al. 1975). The etiology of Alomae requires additional studies. A purification technique to get virus preparations suitable for production of virus-specific antisera as well as for use in biochemical-

252

PRODUCTION TECHNOLOGY

FIGURE 9.8. Dasheen mosaic: symptoms of feather-

ing mosaic and distortion. ly and physically characterizing the particles needs to be developed. Vectors and host ranges, especially of the small bacilliform particles, need to be clarified. E a r l y symptoms of Alomae are a usually conspicuous feathery mosaic of the leaves. Young leaves are often crinkled and fail to open normally. Laminae of malformed leaves are thickened with hypertrophied veins. As the disease progresses, leaves fail to open and begin to die at the tip. Necrosis moves down the petiole and the plant dies. Bobone is similar to Alomae except that the plants affected tend to be more stunted with curled, twisted leaves. The distorted foliage remains dark green. Recovery occurs in four to six weeks. Plants with Bobone contain only the large bacilliform virus. These diseases are perpetuated by planting infected taro setts and possible transmission of the virus particles by insect vectors from older plantings to new plantings. It is suspected that the large bacilliform virus

Taro

253

Diseases

particle is transmitted by the taro planthopper, Tarophagus proserpina (Kirk); the smaller bacilliform particle could be transmitted by mealybugs. Rouging plants infected with Bobone and Alomae to reduce the reservoir of pathogens and the use of resistant varieties appears to be the most practical approach to controlling these diseases. BACTERIAL DISEASES

B a c t e r i a l Soft R o t ( E r w i n i a carotovora chrysanthemi

[L. R . Jones] H o l l a n d ;

E.

Burkholder, Mcfadden, and Dinock)

Bacterial soft rot is a strong smelling watery soft rot ranging in color from white to dark blue. Wounds and bruises caused by the feeding of insects and other animals and those inflicted at harvest are the most common infection court for this disease. Abundant moisture is required for invasion of the bacteria. Control measures therefore include careful handling of corms to minimize injury at harvest, air drying of corms, and storage at low temperatures of only the sound corms. Bacterial Leaf Spot T h e bacterial leaf spot of taro reported from India (Asthana apparently is not very important.

1946)

NEMATODE DISEASES

While several nematode species are commonly reported on taro, little work has been done on the effect of these invertebrates on taro yield. T h e following nematodes have been reported on taro or dasheen in Hawaii: Pratylenchus sp. (Connors 1980); Helicotylenchus sp. (Plant Disease Clinic [PDC] 1981); H. dihystera (Cobb) Sher (Holtzmann 5 ); Rotylenchulus reniformis (PDC 1980, 1981; Holtzmann 6 ); Meloidogyne sp. (Parris 1940; Rabbe 1965; PDC 1980); M. incognita (Kofoid-White) Chitwood (Holtzmann 7 ); M. javanica (Treub) Chitwood (Holtzmann 8 ); Longidarus sylphus Thorne (Holtzmann 9 ); and Tylenchorhynchus sp. (PDC 1981). Meloidogyne spp. (Byars 1917; Nirula 1959), Pratylenchus sp. (Kumar and Souza 1969), and Aphelenchoides sp. (Tandon and Singh 1974) have been reported on taro or dasheen elsewhere. Root-knot nematodes (Meloidogyne spp.) damage dryland taro when the crop is planted in infested soils. Galls on the root and swelling and malformations on the corm are characteristic of attack by this nematode. Severe attacks will stunt the plants and render it chlorotic. Fumigation with dichloropropene, fenamiphos, or D-D (Nemafene) is

254

PRODUCTION TECHNOLOGY

desirable for control of root-knot nematodes in heavily infected soils. These chemicals are not registered in the United States for use on taro. Other root and corm feeding nematodes may also be controlled by soil fumigation. Treatment of dasheen corms with water at 5 0 ° C for 40 minutes kills the nematodes in the tubers. This treatment provides clean planting material. DISEASES OF U N C E R T A I N

CAUSE

T a r o hard rot or "guava seed" is of unknown etiology and only reported from Hawaii where it may cause losses of up to 100 percent (Bowers 1967; HAES 1938; Parris 1941). Trujillo (1967) suggests that damage caused to feeder roots and large roots by Pythium spp. may be responsible for the problem. Hard rot incidence is high where the occurrence of Pythium corm rot is low and vice versa (Parris 1941; Trujillo 1967). It has also been reported that the use of planting material from infected corms increases the disease incidence in the subsequent crop (Parris 1941). This observation suggests a systemic biotic infection. Unfortunately, light microscopy and standard mycological isolation procedures have not produced positive indications of a fungal pathogen thus f a r (Takahashi 1953). 10 Suboptimal levels of oxygen in the paddies have also been advanced as a cause of this condition (HAES 1920). However, taro in dryland culture sometimes exhibits similar symptoms in situations unlikely to be oxygen deficient." The disease destroys the vascular system of the corm, starting with the root traces and working progressively inward. The healthy corm has a smooth skin. The skin of a diseased corm, on the other hand, is barklike, 3 to 6 m m thick, deeply furrowed, crumbly, and coarse. Affected areas of the corm are woody and appear dull. They are filled with walled off vascular elements tan to reddish brown in color, very much like the seed cavity of a cross-sectioned guava (Psidium guajava), thus giving the disease its local n a m e "guava seed" (fig. 9.9). In advanced stages of hard rot all that remains of the corm is a hardened, dark brown to black skeletal framework. Damage to roots by high salt concentrations, whether through intrusion by salt water in paddies lying near sea level or induced by the application of commercial fertilizers, may account for the stratification of the affected areas and the general limiting of the damage to the lower one-third of the corm. Cultural practices to avoid root injury during corm development should be emphasized. There is some indication that liming of the fields is beneficial. Four varieties in the Mana group and Kai Kea are immune to hard rot. Kai Uliuli is resistant to both Pythium rot and h a r d rot (Parris 1941). Ooka 1 2 found H a p u u and Manini Kea to have little hard rot.

Taro Diseases

255

FIGURE 9.9. Hard rot of taro: a, cross section showing off vascular elements; b, longitudinal section showing stratification of hard-rot affected areas.

ABIOTIC DISEASES PHYSIOLOGICAL Starch, present in normal corms, is deficient or absent in those with " l o l i l o l i , " a term used in Hawaii to describe a physiological disorder of taro. While the normal corm is firm, crisp, and resilient to the touch, loliloli taro is soft and spongy and water exudes when affected parts are squeezed. Loliloli taro is the result of withdrawal of starch from the corm. T h i s starch is converted into sugar, which is used by the plant to develop new leaves and other parts. Any action that encourages resumption of vegetative growth in mature taro is likely to result in loliloli taro; therefore, use of nitrogenous fertilizers after the corm has formed or the natural growth-decadence of the plant has started should be avoided to reduce chances of loliloli taro occuring.

256

PRODUCTION TECHNOLOGY

9.10. Glyphosate (Roundup) injury: chlorosis, necrosis, and distortion of the lamina caused by herbicide drifts.

FIGURE

TOXICITIES:

HERBICIDES

Glyphosate Isopropylamine Salt (Roundup®) damage is evidenced by interveinal chlorosis and distortion of the laminae of emerging leaves (fig. 9.10). A high dosage of the chemical will produce shoestringing in the newly emerging leaves and will kill the plant. Taro is very sensitive to this compound and all contact with the chemical should be avoided. Spray drift control with thickening agents such as Airdrop® and spray application during the windless morning hours are precautions well taken when using glyphosate near taro. TOXICITIES:

NUTRIENT

High pH of calcareous soils may induce iron deficiency in taro. Limeinduced chlorosis appears first between the veins of the youngest leaves. The leaves turn from yellowish green to a bleached yellow (fig. 9.11), and the plants may be stunted.

Taro

Diseases

257

F I G U R E 9 . 1 1 . Lime-induced chlorosis in coral soils. Typical interveinal chlorosis or iron deficiency induced by high pH in coral soils. (Photo courtesy E. E. Trujillo.)

T h i s is a p r o b l e m in a l k a l i n e o r c a l c a r e o u s soils. F o l i a r a p p l i c a t i o n of a n a q u e o u s solution of 0 . 5 t o 1.0 p e r c e n t F e r r i c s u l p h a t e , r e p e a t e d as necessary, will c o r r e c t the c o n d i t i o n . NOTES 1. E. E. Trujillo 1975: personal communication. 2. E. E. Trujillo 1978: personal communication. 3. J. J. Ooka 1978, unpublished data, University of Hawaii, Honolulu. 4. J. J. Ooka 1980, unpublished data, University of Hawaii, Honolulu. 5. O. V. Holtzmann 1980: personal communication on nematodes. 6. Ibid. 7. Ibid. 8. Ibid. 9. Ibid. 10. Ooka 1978. 11. Ibid. 12. Ibid.

10 Processed Food James H. Moy Wai K. Nip

TARO has perhaps been prepared or processed into more consumable forms than any other root crop. These include poi (fresh or fermented paste, canned, and canned-acidified), flour, cereal base, beverage powders, chips, sun-dried slices, grits, and drum-dried flakes (Payne, Ley, Akau 1941). Taro is the main staple food for the Pacific regions, where large servings (equivalent to two large potatoes) are common for each adult meal. Many taro varieties are grown for both corm and leaf usage (Martin and Ruberte 1975). Corms may be roasted, boiled, baked, steamed, or fried. In the South Pacific, baked corms constitute a major portion of the meal. In India, the corms are boiled with fish or vegetables for curry. Pulverized cooked corms are mixed with corn meal to make bread in Brazil (Plowman 1969). In the Philippines, the corms are boiled as vegetables or sliced thin and fried to produce chips (Knott and Deanon 1967). Taro is popular in Hawaii as poi and as a dessert, kulolo. In Samoa, taro is made into a sweet dessert. Leaves and petioles are steamed or boiled with meat or fish. They are known as palusami in Samoa, curry bhaji in India, laulau in Hawaii (Miller, Bauer, and Denning 1952), and calalou stew in the West Indies (Martin and Ruberte 1975). Thus, both corms and leaves are utilized for food accepted by consumers.

TARO PASTE Poi, a purplish-gray paste made from taro (mainly var. Lehua Maoli), is sold commercially in plastic bags, jars, or cans in Hawaii. Easily digested and practically nonallergenic, it is an excellent food for people

262

UTILIZATION

with specific health problems and is recommended to patients with food allergies. Patients allergic to certain grains can eat poi with no adverse reaction (Derstine and Rada 1952; Glaser et al. 1967; Roth, Worth, and Lichton 1967). The preparation of poi from taro involves pressure cooking of the corms, washing, peeling, trimming, grinding, straining out the fibrous material, and blending with water to 30 percent total solids ("ready-tomix" poi). This process changes the distribution of the starch components. Lactobacilli fermentation of the poi is usually very rapid within the first twenty-four hours of manufacturing, during which time the acidity increases from a pH of 6.3 (fresh ground taro corms) to a pH of 4.5. Thereafter, the acidity increases gradually until it reaches an average pH of 3.8 by the third day. The shelf life of unrefrigerated poi is three to four days. Refrigeration makes its texture rubbery, changes the eating quality, and is thus not usually used (Allen and Allen 1933). Canned fresh poi is the unfermented product less than four hours old containing not less than 18 percent total solids ("ready-to-eat" poi). In a 566-gm can (U.S. No. 2, 20 ozs.), the thermal process requires cooking for 100 minutes at 116°C (Sherman etal. 1952). Canned-acidified poi is the unfermented product less than four hours old to which 1 percent w/w commercial grade lactic acid (50% lactic acid) has been added. It contains not less than 18 percent total solids. The shelf life of canned poi is comparable to other canned foods (Sherman etal. 1952). Experimental preparations of dehydrated poi were made by freeze drying.1 The product was of high quality and acceptable to a trained taste panel, but it was considered an expensive process for preserving poi. Also experimented with was the use of gamma-radiation to extend the shelf life of poi. It was found that a minimum of 7 kGy (700 krad) would be required to increase the shelf life to seven to ten days (Moy and LeeLoy 1967). TARO

F L O U R

Taro flour has been manufactured in several ways. The process developed by the Hawaii Agricultural Experiment Station was as follows: Raw taro corms were cooked in a pressure retort at 1 0 4 - 1 2 1 °C for one hour, mechanically or hand peeled and washed, ground to "paiai," refrigerated at 2 ° C for thirty-six hours, shredded in a mechanical food shredder or slicer, dried in a recirculation tray-drying cabinet for five to six hours at 6 3 ° C (initial) to 9 3 ° C (final), ground in a hammer mill, sifted through a mechanical sifter with silk or metallic 66-grits gauze, and

Processed Food

263

packaged. Taro flour manufactured by this process was of good quality. It could be reconstituted to fresh, unfermented poi or it could replace up to 20 percent of the wheat flour used in baking (Potgieter 1940; Payne, Ley, and Akau 1941). The only disadvantage of this process was the added cost of refrigeration before drying in order to reduce the gumminess of the intermediate product (paiai). The method developed by the Central Food Technological Research Institute, Mysore, India for making arvi (Colocasia) flour is as follows (Jain, Das, and Lai 1953): Corms were washed, peeled, and cut into 6 mm thick slices. The slices were washed thoroughly to remove mucilageous matter, kept immersed overnight in water, washed again as before, and immersed for another three hours in 0.25 percent bisulfite solution. The slices were blanched in boiling water for five minutes, then sun dried or tunnel dried at 57-60°C. The dried arvi slices were ground, sieved to 4 0 - 5 0 mesh, and packaged. In Western Samoa, taro corms were trimmed, peeled, transversely sliced to 5 mm thick, then air dried for twelve hours at 48 °C and ground. The yield of taro flour was about 25 percent. It has been successfully stored for one year (Pedrana 1979). Taro flour produced by this method is the starting product for baby-weaning food and taro-based bread. A more recent version of preparing taro flour at the Hawaii Agricultural Experiment Station was somewhat similar to the Western Samoa process. Taro corms were peeled, sliced 5 mm thick for air drying (60°C for nine hours) and freeze drying (ten hours), and 2.5 mm thick for solar drying (twelve hours). The dried slices were ground to 4 0 - 6 0 mesh. Quality of the taro flour was stable at 38°C for more than a year, with minor changes in acidity, pigment, moisture content, and with moderate changes in catalase activities and flavor (Moy, Wang, and Nakayama 1977; Moy, Wang, and Nakayama 1979; Moy, Bachman, and Tsai 1980). Through a series of steps including grinding, wet milling, filtration, centrifugation, and drying, Tu and his coworkers (1979) separated 40 percent of the taro starch from a total of 7 0 - 8 0 percent on a dry-weight basis. The taro starch granules formed a clear, stringy paste somewhat resistant to enzyme action, indicating that taro starch could be utilized for both human consumption and industrial use. The residue in the nylon filter bags after drying was ground to flour which contained 6 0 - 7 0 percent starch. Noodles, flakes, cookies, muffins, and biscuits were made experimentally by mixing this raw flour fraction with wheat flour. Results indicated that taro flour could be substituted for part of the wheat flour required for pastry preparation. In a Nigerian process, taro corms and cormels were cleaned, peeled

264

UTILIZATION

raw, cut into chips, parboiled or blanched, then sun dried until the chips could break between the fingers. The dried chips were ground in a mortar. Several rounds of grinding and sifting were made until most of the flour had been extracted. The flour was stored to combat the annual famine, during which time the flour was made into a smooth thick paste in hot water and eaten with rich vegetable soup (Nwana and Onochie 1979).

CEREALS, BREAD AND CAKE, INFANT AND INVALID FOODS In the 1930s, a company called Hawaiian Taro Products, Ltd., was organized in Honolulu after several years of extensive research in the agronomic, nutritional, and processing phases of taro production. The following products were produced: flour, cereals, infant foods, invalid foods, and beverage powders. The baby formula was called Taro-Lactin and contained fully precooked, dehydrated taro; skim milk; unrefined cane juice; and 1.5 percent sodium chloride. It was used either as a gruel or in the preparation of a formula. Commercial pamphlets indicate a similar product line was distributed by Galen Co., Inc., Berkeley, California, also around the late 1930s and the 1940s, under the brand names Poyolin and Poyo-meal. These contained about 60 percent dehydrated poi on a dry-weight basis.

BEVERAGE POWDER A beverage powder using dehydrated, cooked taro as its base was marketed in Hawaii in the 1930s and 1940s under the name Ta-Ro-Co. It was a chocolate-flavored taro beverage with sugar, cocoa, milk, and salt as added ingredients. Although Ta-Ro-Co was intended mainly for use in milk beverages, it also found favorable application as a nourishing and tasteful ingredient in ice creams, puddings, custards, and other preparations. Again, economic reasons probably caused it to disappear from the market.

TARO FLAKES Drum drying has been adapted to dehydrating various root crops such as potato (Cording et al. 1957), sweet potato (Spadaro et al. 1967), pumpkin (Hoover 1973), yam (Onayemi and Potter 1974; Steele and Sammy 1976), and tanier (Rodriguez-Soza and Gonzales 1977). Payne, Ley, and Akau (1941) reported that paiai could be dried on a double-drum dryer with optimum dilution from 10 to 15 percent total

265

Processed Food

solids, steam pressure of 4.93 * 104 to 5.64 x 104 kg/m 2 abs., a drum clearance of less than 3/8 mm and 6 - 8 revolutions per minute. The average yield was about 8 - 9 kg per square meter of drum surface per hour. Coming from the drums in thin sheets and breaking up into fine flakes of very low density, the flakes rehydrated readily. Instant taro flakes were developed by the Food Industry Research and Development Institute in Taiwan and have been manufactured commercially. The corms were washed, abrasive peeled, trimmed, sliced to 1.7 to 2.2 mm thick, steam cooked at 100°C for thirty minutes, pureed to contain 20 percent solid with 5 percent glucose solution, and drum dried at 2 kg internal drum pressure and 2.5 rpm with a 1/4 mm spacing between drums. The reconstituted product had good flavor, texture, and color, but its viscosity was lower than the product made from fresh taro (Hsu and Chiou 1971). In the early 1970s there was interest among some taro growers in Hawaii to increase the cultivation and use of taro. Hing 2 did some preliminary work on drum drying of poi mixed with some tropical fruit purees. Nip recently studied the drum-drying properties of combined taro and tropical fruit purees as well as their storage stability (six months) and acceptability (Nip 1978; Nip 1979). The tropical fruit purees included guava, papaya, pineapple, and mango. It was found that a fruit to taro ratio of 3 to 2 was preferred by the taste panel over that of 1 to 2. In spite of some decreases in ascorbic acid content and the development of browning in some of the stored samples, general acceptability was rated by the taste panel between "like slightly" and "like moderately." Drum-dried taro flakes, without additional ingredients, have a pleasant flavor and may be used in purees, puddings, ice creams, eggnogs, and other drinks. The addition of certain other ingredients gives a product of more universal appeal, however. A formula consisting of paiai, salt, sugar, drimalt, and cocoa mixes readily with milk to give a thick drink of the malted-milk type (Payne, Ley, and Akau 1941). TARO SLICES AND CHIPS Taro can be and has been marketed as chips prepared by deep-fat frying much like the popular potato chips. An important criterion in making acceptable taro chips in this manner, however, is the choice of a variety that will lose the acridity factor (not found in potato) during frying. The alternative approach is to make a taro chip similar to Proctor and Gamble's Pringles, which are flash-fried, reconstituted, dehydrated potato flakes. In Fiji, taro chips were produced by peeling the corms, crushing the

266

UTILIZATION

peeled corms into small pieces, mixing with food preservatives and ingredients, steaming, cooking, and then drying. The dried taro chips, usually about 2 to 3 cm in diameter, were packed into 57-gm cellophane bags. The dried chips were also fried and then packed (Chandra 1979a). In Nigeria, raw taro corms or cormels were cleaned, washed, boiled for three hours, peeled, cut into half-moon slices about 1 cm thick, and sun dried or smoked. Packed in clay pots shielded with dry leaves and sealed with a mixture of smoked banana stems and clay, the dried slices were then stored in w a r m dry places until needed for eating (Nwana and Onochie 1979). In Hawaii, taro chips have been marketed like potato chips. Corms of the Bun-Long variety, known to be the least acrid among the various varieties available in Hawaii, were cleaned, peeled, cut into thin slices, then deep-fat fried and packed in laminated bags.

TARO MEAL, GRITS, OR BREAKFAST FOODS A meal or grit type product from taro was made by Payne, Ley, and Akau (1941). The slices or shredded material was roasted sequentially at 121 °C for thirty minutes, then at 150°C for fifteen minutes, and finally at 177°C for five to fifteen minutes. When ground to the consistency of corn meal or grits, the roasted taro could be converted into a mush by adding hot water, with or without additional cooking. The mush was granular and similar in physical properties to those made from wheat or corn meal. Additionally, the meal or grit could be a pudding base or could replace 10 to 15 percent of wheat flour in making muffins, waffles, and other baked products. Dry breakfast foods were prepared by adding flavoring materials into taro before drying or roasting. Taro shreds, nuts, and flakes, to which malted barley, papaya, banana, sugar, and salt had been added, had nutlike flavors and did not soften in milk and cream. The optimum amount of malted barley in the dry product was approximately 10 percent (Payne, Ley, and Akau. 1941).

CANNED TARO Experiments were conducted at the Hawaii Agricultural Experiment Station to determine the qualities of canned taro in various forms (Payne, Ley, and Akau 1941). Taro corms (var. Pili Uliuli) were first pressure-cooked at 102°C for one-half to one hour. A portion was cut into suitable small pieces, another portion was ground, and a third portion was ground and diluted with water to approximately 20 percent

267

Processed Food

solids. They were then packed into 60.3 mm x 101.6 mm (206 x 400) cans. The cans were vacuum sealed at 253 mm Hg vacuum, preheated at 95°C for a half-hour, then processed at 121 °C for one hour. The aroma and flavor of all the canned samples were preserved to a remarkably high degree. The canned taro was appetizing and very palatable. These researchers claimed that no difficulties should be encountered in canning various forms of taro on a commercial scale.

FROZEN TARO In a Western Samoa process, taro slices were boiled until completely cooked, covered with coconut cream, and then frozen at - 2 0 ° C . However, the taro had the tendency to "bread u p " due to the long cooking time. Taro can also be cooked in the traditional Samoan umu (firepit of heated stones) and then either sliced and poached in styrofoam trays and frozen at - 2 0 ° C . In the case of small corms, they were cooked, packed whole into polyethylene bags, tied with a metal clip, and frozen (Pedrana 1979). In Shanghai, People's Republic of China, a local variety of taro was selected for freezing. The corms were divided into size grades, boiled in hot water (100°C) for three minutes, mechanically peeled, manually selected, packed in small aluminum trays or plastic bags, and quickly frozen for fifty minutes (Plucknett and White 1979).

EXTRUDED PRODUCTS Extruded products (rice, noodles, and macaroni) have been experimentally produced by researchers at the Hawaii Agricultural Experiment Station. The taro flour, prepared from Bun-Long taro corms as described earlier, was mixed with or without the addition of 15 percent (w/w) mung bean flour or 15 percent (w/w) soy protein before extrusion. The dough moisture contents were adjusted to 30 percent or 40 percent (w/w) and dough temperature to 21 °C or 82°C. The extruded samples were air dried at 35°C for eight hours. Results showed that the taste quality of taro macaroni and rice was better than that of taro noodles. The addition of 15 percent mung bean flour to taro improved the firmness of the rice and noodles. Soy protein also improved the texture of taro rice and macaroni with 30 percent dough moisture. The addition of either mung bean or soy protein has little effect on the surface smoothness of these products. The color intensity decreased considerably in taro rice after the addition of soy protein or mung bean flour but only slightly in taro noodles and macaroni (Moy et al. 1980).

268

UTILIZATION

Extruded samples were packed in polyethylene bags and stored at 2°C, 9 0 ± 5 percent relative humidity (RH); 21°C, 7 0 ± 1 0 percent RH; 38°C, 3 3 ± 3 percent RH; and 55°C, 10±1 percent RH. After twelve months of storage, all of the samples stored at 55°C developed a toasted flavor and were judged unacceptable by the taste panel, while those stored at 38 °C or lower temperatures were judged acceptable. With some exceptions, the heat in the 55°C storage increased the chewiness of the products when cooked, degraded the major anthocyanin pigments by changing the products from purple to brown, and dehydrated the samples considerably (Moy et al.). The flavor of most of the extruded taro samples was plain and bland but might be desirable for use as a staple food. However, the color of the taro products was darker than that of the usual staple foods. None of the variables tested could help improve the color significantly. In general, the overall quality of the extruded taro rice, noodles, and macaroni was quite acceptable and stable after they were stored at 38°C or below for twelve months. Their cooking times were shorter than most comparable commercial products. They could thus be considered convenient and energy saving. The benefit of enrichments was to increase the nutritional value of these taro products. SUMMARY

Taro can be made into ten different types of products. Experimental studies indicate that taro can be prepared into dehydrated forms to maintain stability and offer convenience and ease in preparation. It has been demonstrated that stable, intermediate products such as taro flour and dried slices could be prepared and further extruded into convenient, ready-to-use, stable forms such as taro rice, noodles, and macaroni. The short postharvest shelf life of taro corms even when refrigerated makes it essential that practical and economical methods be used to popularize this underutilized tropical root crop.

NOTES 1. J. H. Moy 1967, unpublished data, University of Hawaii, Honolulu. 2. F. S. Hing 1974, unpublished data, University of Hawaii, Honolulu.

11 Animal Feed James R. Carpenter William E. Steinke

W E are in a period of great international anxiety about the world's ability to feed its growing population. In the early 1970s the world food situation was transformed from one of food surpluses and low prices to one of relative food scarcity and high prices. There are varied opinions as to the causes of this rapid change in the world food situation and its likely development in the future. When global utilization of total wheat and coarse grains is separated into feed, industrial use, seed, waste, and food use, it is very likely that feed will be the largest single form of usage (USDA 1980a). In Africa (except South Africa) the use of grain for feed has increased from 0.2 million metric tons in 1965 to 1.2 million in 1975 to 3.8 million in 1979. In Taiwan the use of grain for feed has increased from 0.1 million metric tons in 1965 to 1.1 million in 1975 to 3.5 million in 1979. Feed grain consumption in Oceania (except Australia) has increased from 0.2 million metric tons in 1965 to 0.4 million in 1 9 6 5 - 1 9 7 9 . It is clear that drastic increases in feed grain demand can be projected for Oceania as well as for developing countries in the humid tropics. The soaring demand for food resulting from rapid population growth and rising affluence has begun to outrun the productive capacity of the world's agriculture industries, especially farming. The developing countries in particular have become progressively more dependent on the developed countries for food and fertilizer; however, the abrupt increases in import costs of these commodities may price them beyond the means of many countries. It is believed by many worldwide that there is sufficient land and raw materials for productive inputs and that the food deficits of developing countries could be reduced sharply if they were to employ technologies at a faster rate than they have in the past.

270

UTILIZATION

The most difficult problems, however, are not those of increasing the production of food, but of distributing it properly. Millions of people in the world already suffer from energy and protein malnutrition. In the future, the most likely food shortage will be protein, especially high-quality protein. There is no question as to the desirability of animal protein sources for meeting this demand. In this respect, the need for the efficient utilization of our forage resources and agricultural by-products becomes more critical.

THE POTENTIAL OF TARO AS AN ANIMAL FEED Animal industries have long been hampered in the wet tropics by the inability to produce locally grown feeds. Imported feeds are simply too expensive and in most cases, unavailable. The tropics are generally characterized by subsistence agriculture, vast areas of high rainfall and low soil fertility, and urban centers of high population density. The very characteristics that make them an ideal climate for taro production make them unsuitable for the production of feed grains or more common forages. High rainfall and the common, heavy cloud cover combine to make field curing, and thus long-term storage, of hay unreliable. The comparatively short day-length and low solar irradiation cause reduced yields in most feed grains. Marginal soil fertility due to leaching losses in many areas also reduces yields. Pastures must compete with vegetable production for the most fertile lands, while the steep hillsides and poorer soils cannot support large numbers of animals. Raising cattle, sheep, poultry, or pigs under such conditions is, at best, difficult. Taro has long been a staple food for many countries. Its leaves, stems, and corms have all been prepared and eaten as a vegetable or starch by nearly all of the inhabitants of the tropics and subtropics. Its place in the diet of millions in Oceania and the developing nations of Africa and Asia is well known and documented, and several analyses of taro corms and tops (leaves and petioles) have been carried out. Taro is not only a traditional crop of high value to subsistence farmers, but also a developing commercial crop as well. In many tropical and subtropical areas, large acreages of agricultural lands are used for the production of products that yield vast quantities of both plant residues and processing by-products which are potential feedstuffs for livestock. Taro (Colocasia esculenta) is one of these products; however, it has not been widely used as an animal feed. The acrid principles (see chap. 6) have rendered the leaves, petioles, and corms unacceptable for use an an animal feed without costly, high-energy preparation. At least one case of cattle poisoning from consumption of the raw mate-

Animal Feed

271

rial has been documented (Lazarus, Rajamani, and Nagarajan 1969). There are undocumented cases of use of taro leaves and stems as a pig feed, but these involved cooking the material for long periods of time. This strategy may have been acceptable earlier, but with the current energy situation it clearly is no longer acceptable. Previously, the nutritional value of taro by-products had not been examined very closely; it is only recently that a critical assessment of its nutritional value has begun. Data on the value of taro as an animal feed are quite rare and sketchy. Most data are estimates and do not identify variety. Occasionally the scientific name is not given, thus limiting the usefulness of the data. Several feeding trials have been conducted in the past, but all have used either flour made from the corms or ground corm meal (Mondonedo and Alonte 1931; Fetuga and Oluyemi 1976; Szylit et al. 1977; and Soldevila and Vincente-Chandler 1978). Results of these trials varied. Generally the meal was found to be too low in protein to allow animals to perform well. Supplements had to be added in all cases, both for protein and some essential vitamins and minerals. In 1918, Westgate estimated the digestibility of taro by a comparison with materials of a similar composition. Taro tops (unnamed variety) were described as being composed of 15.46 percent dry matter, 1.38 percent ash, 1.86 percent crude protein, 1.42 percent fiber, 10.29 percent nitrogen-free extract, and 0.49 percent fat. The estimated digestilibity of taro tops was given in terms of digestible nutrients in 45.35 kg of fresh weight (84.54 percent moisture content). Values were 0.54 kg of crude protein, 4.40 kg of carbohydrates, 0.09 kg fat, and thus 5.14 kg of total digestible nutrients. When converted to a dry-weight basis, the digestible protein content was 8 percent of total dry matter and 64 percent of crude protein. The composition and nutritive value of taro leaves were determined by Oyenuga (1959) to be as presented in table 11.1. One of the earliest attempts to feed taro or its products to animals was made in the late 1930s in Hawaii. Bice and Tower (1939) studied the value of taro waste and poi as a feed for poultry. They found that poi was too expensive for its feed value and in fact, added very little feed value for growing chickens. Taro waste, described by them as the peelings and "eye," was found to be less expensive per pound of gain. Gerpacio et al. (1975) and Fetuga and Oluyemi (1976) also reported feeding trials of taro corms to chickens. They reported the lowest daily gain and feed efficiency for chicks fed a diet composed of 50 percent taro meal when compared to a diet of 50 percent yellow maize, 50 percent cassava meal, or 50 percent camote meal. They prepared the meal by taking washed, raw tubers which were then sliced, dried, and ground

272

UTILIZATION TABLE 11.1

COMPOSITION AND NUTRITIVE VALUE OF TARO LEAVES Percent

Dry m a t t e r Crude p r o t e i n True p r o t e i n Ether e x t r a c t Crude f i b e r Nitrogen-free extract Ash ( t o t a l ) Si 1 i c a - f r e e ash D i g e s t i b l e crude p r o t e i n D i g e s t i b l e true protein D i g e s t i b l e ether extract Digestible fiber Digestible nitrogen-free extract Total d i g e s t i b l e n u t r i e n t s

8.23 2^.95 22.53 10.66 12.08 39.89 12.*t2 11.31 17-22 15.55 4.69 9-78 3*1.70 72.25

NOTE: R e p r i n t e d by p e r m i s s i o n o f the publ i s h e r from N i g e r i a ' s Feeding S t u f f s , T h e i r C o m p o s i t i o n and N u t r i t i v e V a l u e , by V. A. Oyenuga ( I b a d a n , N i g e r i a : Ibadan U n i v . P r e s s , 1959).

into a fine meal. The average daily gain when adjusted for initial weight and protein consumed was not significantly different for the 50 percent taro meal diet and the 50 percent cassava meal diet. Similarly, Fetuga and Oluyemi (1976) used a meal made of raw tubers, sliced, dried and then ground into a meal. They substituted this meal for 25 percent and 40 percent of the glucose in a diet of 48 percent glucose, 51.5 percent basal mixture, and 0.5 percent vitamin-mineral premix. They found values for gross energy, metabolizable energy, and metabolizable energy adjusted for nitrogen to be 4 . 1 8 ± . 0 2 , 2 . 8 8 ± . 0 6 and 2 . 8 2 ± .11, respectively, when expressed as kcal/g dry matter. The metabolizable energy represented 68.90 percent±1.14 percent of the gross energy, and they suggested that the low rate of gain may be due to factors that may not be eliminated by cooking. Soldevila and Vincente-Chandler (1978) fed a meal of raw, peeled taro corms to growing pigs but found no gain could be achieved unless a protein supplement was employed. Tannia (Colocasia macrorrhiza) was fed to rats in an attempt to analyze its toxic effects (Seager 1930). The results showed no evidence of poisoning and suggested that all the rats died of protein and vitamin A defi-

Animal Feed

273 TABLE 11.2

TIME TO DEATH FOR RATS FEO TANNIA AND DASHEEN

Feed Boi1ed tannia Unboiled tannia Tannia waste Boiled dasheen

Time to Death days 101 31 8 136

SOURCE: Data from E. A. Seager, "Defective Diet: Notes on the Feeding of Indigenous Rats on Tannia and Other Tubers, with Special Reference to the Question of Toxic Effects," Tropical Agriculture 7:120 (England,

moy.

ciency. Seager theorized that boiling increased starch digestibility and thus time to death. T a b l e 11.2 gives time to death in days for rats on various feeds. T h e potential of taro as a animal feed is too great to be ignored. M a n y people stand to benefit through better nutrition and diet if additional sources of animal feed can be found. Previous a g r o n o m i c studies on t a r o have focused on the yield of corms and cormels that could be achieved. Uses for the petioles and leaf blades were insignificant and sufficient quantities were always available. D a t a on the yield of taro tops were gathered mainly out of scientific curiosity or to help gain insight into the development of the plant. These studies attempted to optimize production of the starchy portion of the plant. (Chapter 7 details the studies done on taro in which yield of corms and cormels was the object of study.) Besides the obvious benefit of producing an animal feed and therefore either a new source of income or the ability to feed more domestic livestock, there are many other benefits that can a c c r u e to taro producers. Improved field sanitation is a m a j o r one. It is believed that discarded, decaying organic matter left in the field aids the spread of corm soft rot (see chap. 9). In current cultivation practices great effort is required to disperse the discarded plant material completely and evenly throughout the soil. Occasionally all plant material is removed from the field prior to the planting of the next crop. Using this material as an animal feed would m a k e the removal from the field beneficial on its own and reduce the subsequent land preparation required.

274

UTILIZATION

ASSESSING T H E Y I E L D , F E R M E N T A T I O N CHARACTERISTICS, AND NUTRITIVE VALUE O F TARO SILAGE YIELD Yield data of the quantity of t a r o tops available and the frequency at which the tops can be cut are largely speculative, based upon informal observations. Apparently taro tops can be harvested a number of times during the life cycle of the plant, and it is a crop that is extremely tolerant of a variety of growing conditions and can be grown for extended periods before replanting. It has been grown and studied for many centuries, and optimum growth conditions o c c u r when average daily temperature is 2 4 ° C and rainfall is at least 2 5 0 c m per year. Rainfall must also be well distributed, with 4 c m per week being the optimal condition. In Hawaii and a few other locations, t a r o is grown in flooded paddies, similar to rice, but the m a j o r i t y of worldwide production occurs under upland conditions. T h e crop is vegetatively propagated and requires a twelve- to fourteen-month growing period under flooded conditions and nine to twelve months under upland conditions. T h e South P a c i f i c Commission ( 1 9 7 1 ) reports yields of Red M a n a u r a t a r o on Moorea Island in F r e n c h Polynesia to vary between 3 8 7 and 2 , 8 5 0 grams of tops per plant. This variation is due to different fertilizer regimes and time to cutting. Spacing in these experimental plots was 8 0 cm by 8 0 c m , thus 1 5 , 6 2 5 plants occupied one hectare. T h e blocks were cut at different ages, varying from 31 to 3 8 weeks. Fertilizer applications varied from none, through the absence of each element, to two levels of potassium. Using the assumption that leaf and top yields decrease with age beyond a certain time, one m a y interpret the South P a c i f i c Commission data to mean that an average yield of 2 kg per plant per 31 weeks is achievable. T h e above assumption on leaf growth is supported by de la Pena and Plucknett ( 1 9 7 2 ) and de la Pena ( 1 9 8 1 ) . T h e y found that the total weight of leaves and petioles was reduced as plants aged beyond approximately three months. T h e m i n i m u m cutting interval of 31 weeks for the South P a c i f i c Commission trial justifies assuming the block with the highest yields to be the first harvested. If we use an average of 2 kg of taro tops per plant per 31 weeks and a spacing of 8 0 cm by 8 0 cm, a yield of 5 2 . 5 metric tons per hectare per year becomes realistic. This is fresh weight of the entire top, petioles, and leaves. Some of the aroids, such as Alocasia, however, can yield as m u c h as 1 6 7 . 8 metric tons of leaves and stems per hectare per year. 1 It is believed that with optimum applications of fertilizer, the yield can be

275

Animal Feed

raised to 226.8 metric tons per hectare per year or the equivalent of 27.2 metric tons dry matter with 34 percent crude protein and 17 percent carbohydrates (Miller 1929, Peters 1958). Table 11.3 is adapted from data given by de la Pena and Plucknett (1972). The total dry weight of taro leaves and petioles (var. Lehua) is presented as a function of time to cutting and nitrogen application rates. All values are in grams dry weight per plant. All plots received a basic treatment of 280 kg/ha each of P and K, except the no-treatment plots. Plant spacing was 45 cm by 60 cm. Using the mean value of 26.6 grams of taro tops per plant at three months of age, a total yield of 3,941 kg per hectare per year can be projected. This is dry weight only and reflects a fresh weight of 10 to 12 times that value, or 39.4 to 47.3 metric tons per hectare per year on a fresh-weight basis. The highest value reported, 55.1 grams per plant, likewise projects to a yield of approximately 8.2 metric tons per hectare per year on a dry-weight basis and 90 metric tons per hectare per year on a fresh-weight basis. The value of 55 grams per plant at three months of age is under the highest rate of nitrogen application. This rate also gave the highest yields of corms, but these are probably not simultaneous goals; the response curve of taro tops to nitrogen and the cost of nitrogen would have to be combined to find the optimum rate of application. These research results

TABLE 11.3

TOTAL DRY WEIGHT OF UPLAND TARO LEAVES AND PETIOLES IN RELATION TO AGE AT CUTTING AND NITROGEN APPLICATION RATES g Dry Matter per Plant

Treatments N kg/ha Nil 0 280 560 1120 Means

Age at Cutting (months) 6 3 9

k.3

3-9 16.2 53.1 55.1 26.6

3.0 3.5 18.9 22.1 23.0 11».1

8.9 14.3 18.0 30.9 31.9 20.8

SOURCE: Adapted from R. S. de la Pena and D. L. Plucknett, "Effects of Nitrogen Fertilization on the Growth, Composition and Yield of Upland and Lowland Taro (Colocasia esculenta)," Experimental Agric. 8:187-19^ (Great Britain, 1972).

276

UTILIZATION

do, however, give an idea of the yield of taro leaves and petioles that can be achieved. Recent experimental data have shown values of approximately 7 metric tons per hectare in a twelve-week period (de la Pena 1981). There is also a big difference in yield among varieties. Lehua Maoli yields between 9 to 14 metric tons per hectare per year fresh weight of tops, while Bun-Long yields somewhere between 16 to 25 metric tons per hectare per year, fresh-weight basis. Quantity of water and fertilizer available for plant use will affect yield. This experiment is still continuing. Over the two-year duration of this experiment, a more accurate value of expected yield per hectare per year should be realized. FERMENTATION

CHARACTERISTICS

Based upon assessments of the potential of taro as an animal feed and the need for some degree of processing for storage and/or neutralization of the acridity, the silage process was determined to be the process most likely to achieve the goals. The high moisture content of the taro tops (up to 88 percent) and the environmental conditions under which it is grown make it very difficult to field-dry taro tops, therefore suggesting that ensiling this product may have some potential for animal feed. It has been previously noted that root crops in general and taro in particular, would be an excellent source of animal feed (Coursey and Halliday 1975). They specifically suggested silage made from the entire Colocasia plant. The silage process is well documented, having been used as a method of preserving green forage for many years. The success of the process must be considered in terms of the efficiency of preservation and the usefulness of the end products as animal feed. The process depends upon lactobacilli acting in anaerobic conditions to lower the pH of the forage through production of lactic and other organic acids to preserve the material. Proper harvesting and packing techniques must be used, so that air is excluded. This will prevent the production of undesirable products such as butyric acid. The process depends upon the readily available carbohydrates in the plant material as an energy source for the lactobacilli. The goal is to have the material ferment quickly and reach a state of equilibrium (Moore 1962). Moore gives the characteristics of good silage as having less than 75 percent moisture, a pH of 4.5 or below, low ammoniacal nitrogen, little or no butyric acid, and a lactic acid content of from 3 to 13 percent on a dry-matter basis. McCullough (1978) presents similar characteristics, which were previously proposed by Breirem and Ulvesli (1954). The lactic acid is the primary constituent that preserves the silage and also has a

Animal Feed

277

positive correlation with animal intakes due to increased palatability. T h e primary factor affecting animal performance is the feeding value of the crop at the time of ensiling. During the past two years at the University of Hawaii, the leaf and petiole of three varieties of taro (Lehua, Bun-Long, and Niue) and the whole plant of a single variety have been successfully ensiled in small laboratory-scale silos ranging in size from 2 to 2 0 8 liters and in experimental trench silos (see fig. 11.1). Special precautions were taken to ensure that the taro leaves and petioles were cut into pieces 2 to 3 cm in length, packed tightly, and sealed to prevent oxygen from entering, as would be done in other operations in which silage is produced commercially. Some fresh taro was allowed to wilt up to 18 to 24 hours without detrimentally affecting silage quality. These trials have yielded a great deal of significant data on several aspects of taro as an animal feed. One of the particularly encouraging results from these trials has been

FIGURE 11.1. Typical cross-sectional view of trench silo. Trench is approximately 0 . 6 m x 1.0 m in size. (From J. K. Wang, W. E . Steinke, and J. R. Carpenter, " F o o d , Feed and Fuel from T a r o , " paper presented at the International Conference on Agricultural Engineering and Agro-Industries in Asia, Bangkok, 1 0 - 1 3 Nov. 1981.)

278

UTILIZATION

either neutralization or destruction of the acrid factor or factors in taro. The raw, unensiled material was quite acrid and caused irritation to workers handling the material. Contact with any portion of the plant material, other than the undamaged leaf or petiole surface, resulted in an itching, burning sensation on the skin. After ensiling, the forage could be handled by laborers with no irritation to the skin. The material could also be eaten without further processing and with no ill effects or acridity. Animals eat the taro silage with no more hesitation than they would any other silage (see chap. 6 for a more complete discussion of mice-feeding trials with ensiled versus unensiled taro). Nagarajan 2 reported that even at 5 percent of the total diet, unensiled taro in their feed is detected and rejected by Swiss-Webster mice. He found, however, that mice consumed good levels of feed when taro silage was included at 10 percent of the diet, which could be an indicator of preference at that level. The series of trials conducted confirmed that the acridity of taro is neutralized or destroyed by the ensiling process. With taro silage at up to 25 percent of their diet, these mice still consumed adequate levels of feed. A comparison of varieties and duration of ensiling indicated no basic varietal differences that could be measured by preference, but did reflect some differences due to length of time in the silos. It was found that 30 days seems to be the optimal period, as greater consumption reflected higher palatability. A visual examination of raw and ensiled taro was also carried out. 3 Whole and intact calcium-containing cells were found to be present in both raw and ensiled taro. The raphides and druses commonly seen in taro were present even after ensiling. The changes due to ensiling, therefore, do not destroy the crystal cells, but still may cause a chemical change. Such a change could deactivate the irritant mechanism or render it harmless. Another problem inherent in the utilization of taro silage as an animal feed is its very high moisture content (up to 90 to 92 percent water). This problem has been minimized by the successful ensiling of taro tops along with other feedstuffs (see table 11.4). The ensiling process also allows the preservation of taro forage without the use of energy for drying. A trial was conducted to determine energy and seepage losses associated with a 26-day ensiling period. During the experiment, small silos similar to those described by Parker (1979) were developed for experimental use. Each silo was made of 10.2 cm (4 in.) schedule 40 polyvinyl chloride (PVC) pipe, with a removable threaded cap at the top to allow for placing material into and withdrawing material from the silo. Each 2-liter micro-silo held approximately 2 kg of material. A perforated false floor was placed 10 cm above the bottom to allow fluid to drain off and be

Animal Feed TABLE 11.A

279 TYPES OF FEEDS SATISFACTORILY ENSILED WITH TARO TOPS

Energy Feeds Ro 11 ed ba r 1 ey Rolled corn Pineapple bran Molasses

Dry Roughages + Grasses Rice straw Guinea grass hay Pangola grass Paragrass

Agricultural By-products Rice bran Chopped banana plant Whole plant sugarcane Seedcane tops Cane trash

collected. A 3-kg weight maintained a steady pressure on the top of the material. After filling, the silo was evacuated both to provide a uniform and consistent degree of compression and to remove oxygen from the silo. Average losses observed were 7.4 percent and 25.9 percent of the initial weight for energy and seepage losses, respectively. Energy losses were low and well within the satisfactory range for silages. Part of the energy loss could be due to the small silo size and large surface area-to-volume ratio. The heat loss in the micro-silo was excessive compared to commercial scale, as more energy was probably required to reach the necessary ensiling temperatures. Losses due to seepage were very high, however. This was to be expected, as the material was very wet going into the silo. The nutrient content of this liquid is not currently known. Spoilage losses were not measured, as the laboratory-scale silos are not capable of giving accurate measurements of these values. However, minimal spoilage losses have been noted with all experimental silos, whether they are the small micro-silos or larger 208-liter drums or trench silos. Figure 11.2 shows the lactic acid levels and pH's of the Lehua leaves during a 30-day fermentation period. Both pH values and organic acid profiles indicated a desirable fermentation. The pH values were 3.70 and 3.95 for the taro top and whole-plant silages, respectively. Lactic acid was 7.78 percent of the dry weight for tops only and 3.63 percent for the whole-plant silage. Acetic acid as a percent of dry weight was 0.48 and 0.78 for taro tops and whole plants, respectively. The ratio of lactic acid to acetic acid in both silages was very good. Propionic acid and butyric acids were present in quantities of less than 0.038 and 0.006 percent dry matter, respectively. The butyric acid was very low considering the high moisture content. These organic acid profiles indicate good fermentation and preservation and would indicate little problem with acceptability by animals. The silage characteristics of taro silage are also similar to those of water hyacinth (see table 11.5).

Day Number

FIGURE 11.2. Lactic acid levels and pH's of Lehua leaves during 30-day fermentation period.

TABLE 11.5

SILAGE CHARACTERISTICS AS RANKED BY PREFERENCES BY CATTLE

Rat i ng pH at day 12 Ash, % DM Lactic acid, % DM Acetic acid, % DM Propionic acid, % DM Butyric acid, % DM Total organic acids, % DM

1 4.23 10.63 24.80 1.60 1.50 1.44 29.34

. ., .

4

4.39 10.73 17.72 1.72 0.77 1.52 21.73

. . .

7

4.53 11.33 6.71 2.41 0.87 2.22 12.21

SOURCE: Adapted from H. T. Byron, J. F. Hentges, Jr., J. D. O'Connell, and L. 0. Bagnall, "Organic Acid Preservation of Waterhyacinth Silage," Hyacinth Control Journal 13:64-66 (1975).

Animal

Feed

281

In another trial, Lehua Maoli, Bun-Long, and Niue varieties of taro tops were ensiled. The pH and lactic acid contents are given in table 11.6. All three varieties ensiled very well, and as the data show, the pH for all varieties leveled off at 3.90 to 4.00 on day 5. The dry-matter content of all three silages was very low (ranging from 8.9 to 12.1 percent), but the lactic acid content was exceptionally high, especially in the BunLong and Niue varieties, which had levels greater than 15 percent of the dry matter. These data confirm what was earlier noted in figure 11.2. The pH dropped very rapidly, indicating a rapid fermentation with the pH peaks at about day 15 of fermentation, and the concentrations of lactic acid were one and a half to three times those found in average corn silages. Because the dry matter of taro silage is very low, a trial was designed in which various feedstuffs such as rice straw, guinea grass hay, dried grains, and sugarcane by-products, and wet feedstuffs such as chopped banana, pangola grass, paragrass (California grass), and molasses were each mixed with fresh taro tops (var. Lehua Maoli) at two levels in an attempt to increase the energy density and dry matter of the ensiled taro. Representative samples of the various taro combinations were taken at days 1, 3, 5, 10, 15, and 30 of the ensiling period to determine pH and lactic acid concentrations. The results are given in table 11.7. As was previously noted in other experiments, the pH after ensiling dropped rapidly and leveled off at about day 5 of the fermentation period. All of the feedstuffs were added at levels that would be effective in raising the dry matter of the silage, and the dry matter results demonstrate that this in fact occurred. The dried grains, hay, and drier byproducts were effective in raising the dry matter to the 2 5 - 3 5 percent range, which is desirable for optimum silage production. All of the combinations ensiled very quickly, had minimum spoilage, and looked and smelled like other silages. Because ensiled taro leaves have a high lactic acid concentration, there was generally a decrease in the lactic acid levels as the quantity of additive was increased. When expressed as grams lactic acid per 100 g silage, the differences in quantity were much less, though in general the trends were the same. NUTRITIVE V A L U E

Chemical Composition Table 11.8 lists the results of proximate and mineral analyses of fresh and ensiled taro tops and whole plants of the Lehua Maoli variety. The fresh and ensiled tops contained very low levels of dry matter. When corms were incorporated in the silage, there was a significant increase

a> C t) ra c •— -C 4-t ra LA TJ t/1 a) M — CM


CU

° Q .

2

> m

"d a; O. o s-

1

:

1

! ° o o C/3

•s

ö

.s

'7,

a .

e

o

o

s

o u O

° « tuo

J= 2 « O Co 3

vi

~a

G

w>

8«

2

c

a

o u

-S 8 uS

"O

g

3

"

-

to

rt

-

8

H

I-

CO CO 2 u]

«

o

-g

E s o o >-* CQ

.

m D „ t/5

V) c/i

O

Oí

£

0) £

£

13.4. Type II schedule of crops (each is one growth cycle). Reprinted by permission of Westview Press from Small-Scale Processing and Storage of Tropical Root Crops, ed. by Donald L. Plucknett, p. 180. © 1979 by Westview Press, Boulder, Colorado. FIGURE

o o o O CM o O vO oí vO — LA Lfí o o-l LT> cí IT»

O O o O CM CM O -3" o — ci CO -3- oí O -3- Oí Cí en r^.\£> LA O LT» CM vû Ci OI Oí

d« Ä« O — -3- o r~.vo O — O vO CM LA-3" Oí Oí o vO Oí NO Oí Oí oo oo Oí Oí Oí Oí O I M N O CM CM CM CO o oí i—

CL O

CM

O O O O •wc — s ra J3 iE r o jtz — i

IIU - O 3 « — 0) -O ü U) - i > o o.

o m ci M sO —

1 4-> 4-» ' i '•—I •—

•M "O (/Ì c a> ra >

nj o X z

ra V a. ra

Q. OI c en •— c 3 i . "O 3 l_ T3 O L_ 4-1 O O 4-> ra O >4. ra — •—

4->

0 o J3 ra ÍD u t— 4-> LTV • m •—

ra 3 O oí co c

u c to Ul "D O

to Qo >

«

-a

D ID U -d 3W o ». £ P

® O.

s

8,

§

1 §• ^ 4J- M [/j ¡3 > © co tn -q -O

2 §

c "¡8 T3 D o O) e o •s l/i w© I s 8.OXI -o "S ü -• 8 o o t

£ «

••8 •• 8

2 c« •. e ^ -o N to O h g o 4)

O LC T _Q U 5

I

o cò

ir>

?

-•8

« u.

o £ fe -a -o to 3 J. O „ o oo tri 03 C O C c/T PH Ç O ^«£> Mk es ^ Dh DK* s s| fc Cu > ^

c œ §

• •

c £3 H'5 ut 5F

m o

Ì"? u « V t u o a e te Ç SO S o « 1 * 1 •5 ° . Ü ^ fe" í s "O 2 ? 3 So ai to PO co _. G C vì«ün O rj u t« ^S D h P fe s £ .1 b Oh >

l/J * V VH Pu, £ Vi 4)

XI o> o>

>

©

o XI

£ O) r-

5Í (N 6

2

Oí

O,

a

.o

-O ÜJ •a s

¿¡ G

3

£

J

^

••

en ~ v

8 a> o >o 'S

r

o c • S

i

CD

••

5

a G o

Q

>

to Xl

o

e "d .a « « »

"o e to W V o c

~ o a eq « "g o Si a. 3 £ O t-H ¿ •• S s 1-1

« 00 8. 2 ••

•g § ag

3

>-

S

S

S

« -a o

»•s

gff

t i en Î —

LO

Ó

Cu 4_r -O "5 "O c while 1970 is estimated.

349

Socio-Economic Aspects of Taro as Food TABLE \ k . k

PRODUCTION RANK SCORE OF SELECTED STAPLE CROPS IN TWO LOCATIONS ( H i g h e s t to Lowest i n Importance)

Rank

Ghana

Fiji

1 2 3 k 5 6

Taro Cassava Yam Maize Sorghum Rice

Cassava Rice Taro Yam Mai ze Sorghum

SOURCE: Data from S. K. K a r i k a r i , "Cocoyam U t i l i z a t i o n in G h a n a , " World Crops 23 (1971); and F i j i Bureau of S t a t i s t i c s , Annual S t a t i s t i c a l A b s t r a c t (1968 c e n s u s ) .

Because the vast majority of taro is produced and consumed on subsistence farms (Chandra 1979a; Onwueme 1978; Karikari 1971), only small quantities are found in local markets and almost no internationalscale market exists. Saint Vincent Islands and Fiji are among the few exporting areas (Onwueme 1978; Chandra 1979a), while Trinidad and Tobago import taro (Onwueme 1978). There are few specific references regarding the economic aspects of taro production in the literature, the majority of which concerns cultural management, harvesting, storage, disease, and pest control problems. TARO IN HAWAII Taro is consumed in the form of poi in Hawaii and was once the basic staple food for the population. The area planted to taro in 1937 was 498 hectares, which declined to 192 hectares by 1965 (Doue 1965). In the 1970s this trend has continued, although much less dramatically, and by 1980 there were 129 hectares of taro produced in the state of Hawaii (table 14.5). The island of Kauai is the major taro producing region in Hawaii. In 1970, growers on Kauai cultivated slightly more than one-third of the land area devoted to taro production in Hawaii and grew over one-half the state production. By 1979, approximately one-half of the land area

350 TABLE

PLANNING AND D E V E L O P M E N T 14.5

TARO PRODUCTION ISLAND O F KAUAI

IN T H E S T A T E OF

Year

State Production (MT)

Kaua i Production (MT)

State Area (ha)

1970 1971 1972 1973 1974 1975

3,850 3,978 4,059 3,815 3,976 3,416

2,070 2,236 2,404 2,132 2,427 1,929

190 194 186 186 186 188

69 87 95 87 81

1976

3,308 3,542 3,456 3,012

2,004 2,186

2,903

2,005

186 190 182 164 129

1977 1978 1979

1980

2,231 1,964

Kaua i Area (ha)

HAWAI

A N D ON

THE

State Yield (kg/ha)

Kauai Yield (kg/ha)

20,263 20,505 21,823

79

20,511 21,376 18,170

30,010 25,704 25,306 24,505 29,960 24,420

77 81

17,785 18,642

26,038 26,992

85 83 85

18,989 18,366

26,255 23,664

22,503

23,587

SOURCES: A d a p t e d f r o m S t a t e of Hawaii D e p t . o f A g r i c u l t u r e , S t a t i s t i c s of H a w a i i a n A g r i c u l t u r e 1974 ( H o n o l u l u : H a w a i i A g r i cultural Reporting Service, 1975); Statistics of Hawaiian A g r i c u l t u r e 1975 ( H o n o l u l u : Hawaii A g r i c u l t u r a l R e p o r t i n g S e r v i c e , 1 9 7 6 ) ; a n d S t a t i s t i c s o f H a w a i i a n A g r i c u l t u r e 1980 ( H o n o l u l u : Hawaii A g r i c u l t u r a l R e p o r t i n g S e r v i c e , 1981).

developed to taro production in Hawaii was on Kauai and about twothirds of the state production was cultivated on Kauai. These production figures reflect the higher yields that Kauai taro growers are able to achieve. The area devoted to taro and the amount of taro produced on Kauai have remained relatively stable during the 1970s, in contrast to the general decline in taro production for the state of Hawaii. In Hawaii, it takes about eight to nine months from planting to harvesting for upland taro, while twelve to eighteen months are needed for flooded taro. However, the yields of upland taro are only one-third to one-half that of wetland taro (Begley, Vieth, and de la Pena 1980). According to the reports done by the University of Hawaii Agricultural Experiment Station, the cost to produce taro varies with the method of cultivation as well as with the environment. For a typical wetland taro grower in Hawaii, the cost of production per hectare per crop cycle is about $4,694.00 in U.S. currency. 1 If twelve months are assumed to be one crop cycle and the average yield is considered—18,642 kg per hec-

Socio-Economic

351

Aspects of Taro as Food TABLE 14.6

COMPARATIVE COSTS OF SELECTED CROPS IN HAWAII

Crop Taro ( s t a t e of Hawaii) Barley Taro ( i s l a n d of Kauai) Corn G r a i n sorghum Wheat Sweet p o t a t o

$/MT 251.79 176.15 173-90 167.34 158.18 147.70 132.28

SOURCE: Data from W. Y. Huang and S. E. O b r i c h , "Feed P o t e n t i a l of Sweet P o t a t o e s i n H a w a i i " ( H o n o l u l u : Hawaii A g r i c u l t u r a l Experiment S t a t i o n , 1979); and G. R. V i e t h , B. W. Beg l e y , and W. Y. Huang, "The Economics of Wetland Taro P r o d u c t i o n i n H a w a i i " ( H o n o l u l u : Hawaii A g r i c u l t u r a l Experiment S t a t i o n , 1980).

tare in 1977—then the cost of taro production ($251.79 per MT) is much higher than other staple crops available in Hawaii (table 14.6). However, if the Kauai yield of 26,992 kg per hectare for 1977 is used in the calculation, the cost is $173.90 per MT (Vieth, Begley, and Huang 1980).

ECONOMIC AND SOCIAL FACTORS IN USE OF TARO AS HUMAN FOOD To determine the market competitiveness of a product, all of the cost components, such as production, processing, storage, and transportation as well as the consumer demand for that product, must be taken into account. One of the major problems associated with taro production is the high labor requirement for planting, weed control, and harvesting. Taro production costs also vary because of regional conditions. Regardless of the scarcity and accuracy of available data, Johnston (1958) has suggested a general ranking of production costs among staple crops (table 14.7). The relative price of taro relative to the prices of other staple crops in Papua New Guinea can be seen in table 14.8. Not only are there big differences in prices between areas, but the relative prices also fluctuate

352

TABLE 14.7

P L A N N I N G AND D E V E L O P M E N T

RELATIVE RANKING OF PRODUCTION COSTS FOR STAPLE CROPS

Rank

Per Hectare

1 2 3 4 5 6 7 8

Yams Sweet potatoes Ta ro Cassava Rice Sorghum Maize Mi]let

Per Ki logram Rice Mi 1 let Sorghum Maize Yams Taro Sweet potatoes Cassava

Per 1000 Calories Yams Rice Mil let Sorghum Taro Mai ze Sweet potatoes Cassava

NOTE: Reprinted by permission of the publisher from The Staple Food Economies of Western Tropiical Africa, by B. F. Johnston (Stanford: Stanford University Press, 1958), p. 144.

considerably. In the Philippines (table 14.9) this fluctuation also exists but is of much smaller magnitude. Relative prices give some objective information indicating consumer preferences. According to USDA data (USDA 1971), the relative price of taro in terms of weights is not high in Ghana and Nigeria. However, Krausz (1974) argued that consumers buy staple foods for the food value, i.e., calories, so that it ranks third and second highest, respectively, in these countries (table 14.10). This implies a potentially favorable environment for the production of taro, since taro is mainly produced by subsistence farmers who seek high-yielding crops with low cost of production. Krausz (1974) has compiled considerable data and stresses that in the future taro will be one of the most favorable crops despite the disadvantages of a rather high cost of production and an uncertainty of market price.

NOTE 1. For a detailed explanation of the cost, see Vieth, Begley, and Huang 1980; and Begley, Vieth, and de la Pena 1980.

TABLE 14.8

PRICES OF STARCHY STAPLES IN PAPUA NEW GUINEA AS PERCENT OF THE COST OF TARO Sweet Potatoes

Taro a

Area

Year

Potatoes

Rice

Port Moresby

1976 1977 1978 1979 1980

100 116 114 125 140

0 7 0 8 3

(A3 (51 (50 (55 (61

8) 2) 0) 1) 5)

57 42 48 46 55

8 3 5 4 4

154 106 106 101 85

6 8 3 4 3

98 73 72 61 56

2 9 5 7 6

Goroka

1976 1977 1978 1979 1980

100 110 119 126 116

0 3 3 3 2

(48 (53 (58 (61 (56

7) 7) 1) 5) 6)

19 18 27 23 27

7 6 2 7 7

105 94 79 66 73

1 5 0 6 8

93 73 64 59 63

8 0 1 6 2

Lae

1976 1977 1978 1979 1980

100 103 117 124 156

0 5 5 9 8

(22 (23 (26 (28 (35

9) 7) 9) 6) 9)

36 40 48 44 44

2 8 3 8 7

214 205 181 171 157

0 6 2 2 6

179 154 133 122 97

0 8 6 4 5

Madang

1976 1977 1978 1979 1980

100 86 76 91 84

0 7 4 1 6

(17 (15 (13 (16 (15

8) 4) 6) 2) 1)

70 82 84 76 70

2 5 7 0 1

281 328 409 348 335

5 8 0 1 1

233 244 275 219 240

7 4 7 1 1

Rabaul

1976 1977 1978 1979 1980

100 116 132 132 121

0 4 3 0 3

(22 (25 (29 (29 (27

2) 8) 4) 3 0)

35 46 39 42 45

1 1 4 6 0

305 224 172 177 173

9 5 0 9 8

191 145 124 118 130

9 7 5 2 2

SOURCE: Data from the publisher of Quarterly Consumer Price Index Bui letin, Papua New Guinea Bureau of Statistics (December Tfffrn a

Figures in the parentheses are deflated prices in toea per kilogram, 100 toea = US$1.47 in December 1981.

TABLE 1 4 . 9

P R I C E S OF STARCH STAPLES IN THE P H I L I P P I N E S AS A PERCENT OF THE COST OF TARO a

Crop Taro Camote Cassava Pao Tugui Ubi

1971

1972

100 (384.0) 91 86.8 84.9 127.0 115.4

100 (391.4) 97.1 84.7 93.6 135.6 120.0

SOURCE: Data from C e l e s t i n o C. O l a l o , " P r o d u c t i o n and H e c t a r a g e o f Root C r o p s i n the P h i l i p p i n e s , 1 9 6 3 " 1 9 7 2 , " i n PCAR Workshop on N a t i o n a l P r i o r i t i e s in P h i l i p p i n e A g r i c u l t u r e , C r o p s R e s e a r c h D i v i s i o n , Workshop S e s s i o n no. 24, Root C r o p s Res e a r c h P a p e r s (Los B a n o s , Laguna: P h i l i p p i n e Council for A g r i c u l t u r a l R e s e a r c h , 1 9 7 5 ) , p. 6 1 . a

F i g u r e s i n the p a r e n t h e s e s d e n o t e the a b s o l u t e p r i c e i n p e s o s per MT.

TABLE 1 4 . 1 0 Country

AVERAGE P R I C E S OF STAPLE CROPS IN 1961 - 1 9 6 5 Crop

US5/MT

US$/1000

Calories

Ghana

Yam Rice Taro Millet Sorghum Maize Cassava

73 149 46 131 130 87 37

.070 .042 .041 .038 .037 .024 .024

Nigeria

Yam Taro Rice Mi 1 l e t Sorghum Cassava Maize

61 50 103 70 70 29 53

.059 .044 .029 .020 .020 .019 .015

SOURCE: U . S . D e p t . o f A g r i c u l t u r e , Economic R e s e a r c h S e r v i c e , I n d i c e s o f A g r i c u l t u r a l P r o d u c t i o n i n A f r i c a and the Near E a s t (1971).

15

Production Management Considerations Jaw-Kai

Wang

AGRICULTURAL production management is probably the most difficult and important phase in the agricultural chain of events that includes research, development, production, and marketing. Good production systems planning can often make production management easier, but it certainly is incapable of saving the production system from bad management. On the other hand, it is not rare to find good management saving the production system from bad planning. That management represents artful application of some principles and procedures is generally accepted. That it is easier to describe these principles and procedures than to give a useful lesson in the art of applying them is also well recognized. Therefore, the usefulness of a discourse on agricultural production systems management seems destined to be somewhat in doubt. Nevertheless, there are a few distinguishing features related to the management of the proposed taro production systems that ought to be delineated.

SMALL FARMER GROUP MANAGEMENT The importance of production scheduling has been emphasized. If there is only one single production entity, such as in a case of a corporate plantation, the enforcement of production scheduling can be relatively simple. However, if the production system is to be made up of a large number of small farmers, then production scheduling can become extremely difficult to enforce. From a single farmer's point of view, it is clear that he should plant and harvest at times when he can maximize his yield. What is good timing for one is, unfortunately, also good timing for near-

356

PLANNING AND DEVELOPMENT

ly everyone in the project. From the vantage point of the overall project, it is clear that proper production scheduling is the only way to insure a relative stable year-round supply and to increase labor and farm equipment utilization efficiencies. A number of management strategies can be employed to increase the likelihood that the desired production schedules will be followed. PRODUCTION CONTRACT

Two types of production contract can be used. First, the farmers may be required to plant and harvest a specified acreage of taro at specified dates, and all of the product will be purchased at specified prices. Alternately, the farmers may be required to deliver a specified amount of taro at specified dates and for a specified price. D I F F E R E N T I A L PRICING

In order to require the farmers to plant and harvest at off-peak seasons, it will be necessary to increase the price of taro in off-seasons, so that on a per hectare basis all farmers will receive approximately the same annual gross income. Of course, this is a difficult task but one that cannot be avoided. CONTROL OF PRODUCTION RESOURCES

The degree to which production resources can be effectively controlled may be difficult to judge. Nevertheless, if one or more of the essential production inputs can be effectively controlled, then it will add greatly to the possibility of successful enforcement of a desirable production schedule. In paddy rice production, the control of irrigation water can be very effective in enforcing the desired production schedule. However, the irrigation system must be designed in such a way as to allow the management to prevent unauthorized distribution of water. Taro is a heavy user of irrigation water, and in some instances water control can be employed to reinforce the production contract. O R G A N I Z E D HARVESTING AND L A N D P R E P A R A T I O N S E R V I C E S

The availability of reasonably priced harvesting and/or land preparation services can be especially effective in persuading farmers to willingly join the desired production schedule. Additionally, harvesting and land preparation service prices can also be varied. Low prices can be used to encourage off-season production. None of the above strategies is without pitfalls and difficulties. It is obviously impossible to come up with a differential pricing schedule that

Production

Management

Considerations

357

will be absolutely fair to everyone, especially when one considers the fact that individual farmers will always differ in their production efficiency and that land itself varies in productivity. These same facts will also affect the results of the contract approach. However, on a large scale, if many small farmers are involved, the resultant variations will not differ much from a centrally managed plantation, and that is perhaps the best one can hope for. It is important, therefore, for the production system planner to review the possible effectiveness of these and other management schemes before proceeding to the final design, so that a system is not designed with an accuracy that is utterly beyond the capability of available management schemes to deliver.

SYSTEM PERFORMANCE EVALUATION Agricultural production systems nearly never perform as planned. Is the system poorly designed or is the system poorly managed? Generally speaking, given the same production environment, the variance in yield per hectare is a good indicator of management. In other words, if soil, water, and fertilization regimes are assumed to be identical, then (the mean value of X¡ > the mean value of Xj) is an indicator that System i is better designed than j, where the mean value of X¡ and the mean value of Xj are average yields; while (Sxj > Sxj), where S represents the standard deviation of yields per unit in kg/hectare, is an indicator that System X¡ is better managed than System Xj. In agricultural production systems it is often difficult to demonstrate that any two systems are identical to each other. The natural variations in soils, pests, diseases, and solar irradiation are often sufficient to rule out the existence of identical large systems, but many systems will have sufficient similarity in production environment that they may be considered similar systems and that the mean value of X and Sx can be used to give relative indications of systems performance. The standard deviation of yield per unit of production area, Sx, is a good index of the within-system performance uniformity. A small Sx indicates that there is little variation within the system; therefore, if the systemwide average yield, the mean value of X, is low, there is a strong likelihood that the system operation is poorly designed. On the other hand, a large Sx indicates a high degree of nonuniformity in the implementation of farming practices. When a system consists of a large number of small farmers, a large Sx generally indicates there is a strong need to strengthen on-the-farm extension education on farming practices, equipment maintenance, and credit management.

358

PLANNING AND DEVELOPMENT

In the above, X is used to indicate yield per unit production area; however, it should be obvious that it could be used to designate whatever is of interest to the manager, such as yield per tractor-hour used and equipment down time. UNCERTAINTIES IN P R O D U C T I O N

Agricultural production systems have always had to operate in the face of environmental uncertainties. Water availability, even in the humid tropics and subtropics, can easily vary by a factor of 2 or 3 on a year-toyear basis. These, and other uncertainties, are generally dealt with in the designing stage, if sufficient data are available. As the production system is being implemented, system performance data must be carefully gathered, especially those performance data that are system dependent, such as equipment breakdown and personnel performance, so that appropriate management policy can be gradually established. For example, at the designing and planning stage, the rainfall and streamflow data are analyzed to establish levels of water availability and their frequency of occurrence. The primary goal is to match the production system to the available water to obtain maximum economic benefit. For instance, in many planning cases an 80 percent level for water availability may be selected, and that means it is anticipated that over a period of fifty years or longer, there will have been sufficient water in four out of five years. When the project is being implemented, the important decision is no longer the selection of design criteria. The important considerations are that water shortages will occur in some years and how they should be dealt with. When there is a 5, 10, or 20 percent water shortage, shall the shortage be spread over the entire project area or shall it be limited to a restricted area? The advantages of alternate drought management policies and whatever is required to implement these alternate policies should be analyzed, so that when water shortages occur, as they surely will, there is an established policy to deal with them. It is especially important to publicize and discuss these policies with farmers, so that they have a good understanding of the problems and proposed solutions. Without the support of the farmers, the majority of policy decisions, no matter how good they may actually be, is doomed to failure.

Afterword

T A R O is a generally neglected crop that is an important staple in tropical countries. It is safe to estimate that 4 0 0 million people use taro in their diets. The importance of a comprehensive research and development program for taro should be viewed in light of a recent National Academy of Science study that points to two important facts. One is that the United States must join the hungry nations to develop an agriculture that can feed the world or face food problems at home. This is because food production in the United States is faltering, yields are no longer increasing, and increased energy inputs are starting to show diminishing returns. Another point made by the study is that over the next twenty-five years the new breadbaskets will be the developing countries. They are the ones with the greatest capacity to increase food production. A corollary to this is that neglected crops like taro have a potential that has not yet been fulfilled. If one takes the trouble to look into the food problems of the South Pacific it becomes immediately evident that they are similar to those elsewhere. Population growth is as rapid as in Asia or South America, where the average annual rate is around 3.5 percent and doubling time is twenty-five years. Resources are dwindling and most of the arable land is in use. Crops have not been improved and people still depend on ancient cultivars and methods. As a result yields are low and being reduced by diseases introduced during the last fifty years or so. As matters now stand there is every reason to believe that the problems will worsen. A comprehensive taro research program should include improvement of (1) cultivars and cultural practices, (2) storage methods, (3) processing, (4) developmental planning, and (5) marketing. T o achieve these

360

Afterword

objectives, the training of scientific and extension personnel must not be overlooked. Since taro is of interest to a wide range of nations in Asia, Africa, and Oceania, the interest and ability of participants to support their own interest in this developmental effort will differ. A flexible format is therefore envisioned for taro research and development programs to allow various degrees of participation by the various participating countries. U.S. university teams can act simply as advisers in certain places, as collaborators in experiment station research efforts in other places, and, in yet other countries, can fully assist a national effort in the development of comprehensive programs in taro production.

Contributors

JOSEPH ARDITTI is a professor in the Department of Developmental and Cell Biology, University of California, Irvine. He received his doctorate from the University of Southern California in Los Angeles in 1965 and joined UCI in 1966. Until he became interested in taro in late 1974 his only research interest was the physiology and biology of orchids. Now he works on both orchids and taro. JAMES R. CARPENTER is an associate animal scientist at the University of Hawaii at Manoa. He received his M.S. degree from the University of Hawaii and Ph.D. from Cornell University. He specializes in ruminant nutrition. His research publications have emphasized the evaluation of tropical forages and agricultural by-products as animal feeds, with special interest in the ensiling process and fiber and protein utilization. FEN-FEN CHANG is a research assistant and doctoral student in the Department of Agricultural and Resource Economics, College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. She received her master's degree in Taiwan, where she was an instructor in economics and land economics at the National Cheng-Chi University in Taipei. Her speciality is production and land economics. RAMON S. D E LA PENA is an associate professor of agronomy at the University of Hawaii. He is a specialist in tropical root crops, particularly taro. He has worked with other tropical crops, including rice, mung beans, winged beans, and corn. He was director of economic development for the county of Kauai, Hawaii, from 1973 to 1974. He has been a consultant to the World Bank and AID in Thailand and to the JARI Proj-

362

Contributors

ect in Brazil. He has served as a panel member in the National Academy of Science workshop on ethanol production for alternate energy and has advised the University of Florida on the research and production potential of taro for the Everglades. He has been editor of the International Society for Tropical Root Crops newsletter since 1980. GERALD ]. L. GRIFFIN is currently the director of the Ecological Materials Research Institute of Brunei University, England. His research interests and consultantships have covered a wide range of topics in the field of plastics technology, particularly the use of plastics in packaging and the development of novel composite materials. He has pioneered the use of surface-treated starches in plastics formulations, work funded by the British Science Research Council, the NATO Foundation, and industrial sources. He is a member of the Royal Society of Chemistry, the Plastics and Rubber Institute, the Royal Microscopical Society, and the Society of Chemical Industry. SALLY HIGA is a research associate in the Department of Agricultural Engineering, College of Tropical Agriculture and H u m a n Resources at the University of Hawaii at Manoa. She received her master's degree in Pacific Islands Studies f r o m the University of Hawaii. PETER A. MADDISON is an entomologist with the Department of Scientific and Industrial Research, Auckland, New Zealand. He is a specialist in pests of tropical crops, particularly in the Pacific region. Since 1969 he has worked with the South Pacific Commission, later the FAO, Rhinoceros Beetle Project in Samoa and the FAO's "Survey of Agricultural Pest and Diseases in the South Pacific Region," surveying pests in seven Pacific island countries. He is currently engaged in writing the report on the pests of the South Pacific region for the survey. His work for the New Zealand government is to survey pests of promising " n e w " horticultural crops in New Zealand and to deal with Pacific island pest problems. WALLACE C. MITCHELL is a professor of entomology at the University of Hawaii at Manoa. He is a specialist in tropical economic entomology, with publications on the biology, behavior, and control of insect pests of fruits, nuts, vegetables, and stored food products. His work has been supported by the Office of Naval Research, the National Science Foundation, the U.S. Department of Agriculture, and both private and governmental sources within the state of Hawaii. He has been a consultant on agricultural administration, production, and entomological problems in Asia, Australia, Central America and Panama, Micronesia, Melanesia, and Polynesia.

Contributors

363

JAMES H. MOY is a professor of food engineering at the University of Hawaii at Manoa. He received his B.S.Ch.E and M.S.Ch.E degrees from the University of Wisconsin-Madison and his Ph.D. in food science from Rutgers University. Specializing in food processing technology, he has worked on tropical fruit irradiation, root crop processing, aquaculture product preservation, and tropical product dehydration, including solar energy utilization. His research support has come from the Atomic Energy Commission; the U.S. Department of Agriculture; Sea Grant; the International Sugar Research Foundation; and the U.S. Department of Energy. He has served as an adviser to research institutes in Taiwan, Thailand, and Venezuela. WAI KIT NIP is an assistant professor of food science and technology at the University of Hawaii at Manoa. He specializes in the handling and processing of various food products. His research has drawn support from the U.S. Departments of Agriculture and Commerce and various sources within the state of Hawaii. JERI J. OOKA is an assistant plant pathologist at the University of Hawaii at Manoa. He received his B.A. and M.S. degrees from the University of Hawaii and was awarded a Ph.D. in plant pathology from the University of Minnesota in 1975. He specializes in fungal diseases of tropical crop plants and ecological epidemology. Currently stationed at the Kauai Branch Station of the Hawaii Agricultural Experiment Stations, he has initiated studies on the epidemology of Exserohilium turcicum, Pythium carolinianum, and the papaya powdery mildew organism. His research into control of Pythium carolinianum incited taro soft rot includes investigations into use of pathogen specific systemic fungicides, pathogen population dynamics, and cultural control strategies. DONALD L. PLUCKNETT is a fellow of the American Society of Agronomy, the Soil Science Society of America, and the American Association for the Advancement of Science and is currently scientific adviser, Consultative Group on International Agricultural Research, World Bank, Washington, D.C. He is a specialist in tropical agriculture, with particular emphasis on tropical root crops and farming systems research. He is currently president of the International Society for Tropical Root Crops. Formerly professor of agronomy and soil science at the University of Hawaii at Manoa, he has also held senior agricultural positions with the Agency for International Development. WILLIAM S. SAKAI is associate professor of horticulture in the College of Agriculture, University of Hawaii at Hilo. He is a plant physiologist

364

Contributors

with special interests in the physiological anatomy of higher plants in the tropics. BLUEBELL R. STANDAL is professor of food science and h u m a n nutrition at the University of Hawaii at Manoa. Her research activities are in protein nutrition, complementation of plant proteins, nutrient evaluation of underutilized tropical plant foods, and nutritional status. She is a consultant on nutrition education to the South Pacific Commission, Noumea, New Caledonia, and to the North Eastern Hills University of Shillong, Meghalaya, India. WILLIAM E. STEINKE is a f a r m safety specialist associated with the Department of Agricultural Engineering at the University of Hawaii at Manoa, where he has also been an assistant professor and a research associate. His research experience has been entirely on taro and other root crops. Work on both his B.S. degree f r o m Michigan State University and M.S. degree f r o m the University of Hawaii emphasized systems analysis as applied to agricultural engineering problems. He has applied the silage process to taro and combinations of taro and other feeds and has worked on the concept of scheduling field activities in tropical agriculture to manipulate yields and harvest schedules to optimize the use of production and processing facilities. MICHAEL S. STRAUSS is an assistant professor in the Department of Biology, Northeastern University, Boston, Massachusetts. He has studied problems associated with tissue culture, seedling variability, and cell culture of taro since 1976. His present research interests include study of the viruses infecting taro in Papua New Guinea and the Solomon Islands, as well as the cell culture of taro and sugarcane. He is also engaged in studies of the physiology of senescence in orchid flowers. LESLIE A. SUNELL received her Ph.D. in developmental and cell biology at the University of California, Irvine, and is now a research associate at Stanford University. Her dissertation research was on the differentiation and structural development of calcium oxalate crystal idioblasts in taro. Her other interests center on the cellular and biophysical bases of morphogenesis in plants. CHUNG-SHIH TANG is a professor in the Department of Agricultural Biochemistry, University of Hawaii at Manoa. He is a biochemist with a special interest in the chemistry of secondary metabolites. His research publications cover subjects in phytotoxic, insecticidal, and germicidal

Contributors

365

compounds in tropical crops and the flavor chemistry of tropical fruits. He is a member of the American Chemical Society, the American Society of Plant Physiologists, and the American Association for the Advancement of Science. G A R Y R. V I E T H is an assistant professor of agricultural economics at the University of Hawaii at Manoa. He is a specialist in agricultural production economics and quantitative methods. His research has included the economic evaluation of many tropical and subtropical crops, including taro production in Hawaii. JAW-KAI WANG is a fellow of the American Society of Agricultural Engineers and professor of agricultural engineering at the University of Hawaii at Manoa. A specialist in agricultural production systems analysis, he has held a wide range of paid consultantships, including service to the Jari Project in Brazil on the development of taro production and World Bank studies relating to agriculture modernization in China. His research has drawn support from the U.S. Departments of Agriculture, Commerce, and State; the Rockefeller Foundation; John Deere International; and other sources within the state of Hawaii. His other interests include irrigated rice production systems design and aquacultural engineering.

Literature Cited

Abdel-Akher, M.; A. M. Youssef; and S. M. Hegazi. 1972. The structure of an arabinogalactan from Colocasia esculenta (taro). Pakistan J. Sci. Ind. Res. 15:363-364. Abo El-Nil, M. M., and F. W. Zettler. 1976. Natural occurrence of dasheen mosaic virus in Egyptian taro, Colocasia antiquorum. Plant Dis. Rep. 60:281-285. Abo El-Nil, M. M.; F. W. Zettler; and E. Hiebert. 1975. Purification of dasheen mosaic virus. Proc. Amer. Phytopathol. Soc. 2:73 (abst.). Abraham, A., and K. Ramachandran. 1960. Growing Colocasia embryos in culture. Curr. Sci. (Bangalore) 29:342-343. Adriano, F. T.; H. T. Ramos; and L. A. Ynalvez. 1932. The proximate analysis of Philippine foods and feeding stuffs. III. Philipp. Agr. 20:530-534. Affandi, D. 1982. Starch carried fire retardants in polyester resins. M.Phil, diss., Brunei University, Uxbridge, England. Agarwal, A. K., and P. Kumar. 1979. Influence of morphactin, coumarin and gibberellic acid on sprouting of seed corms of Colocasia esculenta L. Comp. Physiol. Ecol. 4:198-200. Ahmed, G., and M. M. Rashid. 1975. A comparative study of the gross morphological characters and yield potentialities of the major types of edible aroids of Bangladesh. Bangladesh Hort. 3:15-21. Alamu, S., and C. R. McDavid. 1978a. Effect of time and method of application of gibberellic acid on the growth and promotion and flowering in tannia (Xanthosoma sagittifolium). Trop. Agr. (Trinidad) 55:235-241. Alamu, S., and C. R. McDavid. 1978b. Promotion of flowering in edible aroids by gibberellic acid. Trop. Agr. (Trinidad) 55:81-86. Alconero, R., and F. W. Zettler. 1971. Virus infections of Colocasia and Xanthosoma in Puerto Rico. Plant Dis. Rep. 55:506-508. Allen, O. N., and E. K. Allen. 1933. The manufacturing of poi from taro in Hawaii, with special emphasis upon its fermentation. Hawaii Agr. Exp. Sta. Bull. 70:1-32.

368

Literature

Cited

Al-Rais, A. H.; A. Myers; and L. Watson. 1971. The isolation and properties of oxalate crystals from plants. Ann. Bot. 35:1213-1218. Alvarez-Garcia, L. A., and A. Cortes-Monllor. 1971. Currutaca.- A Pythium soft rot of Xanthosoma and Colocasia spp. in Puerto Rico. J. Agr. Univ. Puerto Rico 55:78-84. Amar, M. 1903. Sur le role de l'oxalate de calcium dan la nutrition des végétaux. Compt. Rend. Acad. Sei. (Paris). 136:901-901. Amin, E. S. 1955. The polysaccharides of Colocasia antiquorum (taro or colocass). J. Chem. Soc. (London) 1955:2441-2445. Anon. 1976. Bright future for high-fructose corn syrup. Chem. Engr. News, 19 April 1976, p. 13. Arditti, J., and M. H. Fisch. 1977. Anthocyanin of the Orchidaceae: distribution, heredity, functions, and localization. In: Orchid Biology Reviews and Perspectives, vol. I, ed. J. Arditti, pp. 116-155. Ithaca: Cornell Univ. Press. Arditti, J., and M. S. Strauss. 1979. Tissue Culture of Taro: A Manual. Information Document 44-1979. Noumea, New Caledonia: South Pacific Commission. Arditti, ]., G. C. Stephens, and M. S. Strauss. 1979. Evidence for genetic variation in two seedling populations of taro, Colocasia esculenta (L.) Schott. Int. Found, for Sei. (Stockholm) Prov. Rep. no. 5, pp. 245-257. Arditti, J.; B. H. Flick; A. Ehmann; and M. H. Fisch. 1975. Orchid phytoalexins. II. Isolation and characterization of possible sterol companions. Amer. J. Bot. 62:738-742. Arnott, H. J. 1966. Studies of calcification in plants. In: Calcified Tissues, ed. H. Fleisch, H. Blackwood, and M. Owen. Berlin: Springer. Arnott, H. J. 1973. Plant calcification. In.- Biological Mineralization, ed. I. Zipkin, pp. 609-627. New York: Wiley. Arnott, H. J. 1976. Calcification in higher plants. In.- The Mechanism of Mineralization in the Vertebrates and Plants, ed. N. Watabe and K. M. Wilbur, pp. 55-78. Columbia: Univ. of South Carolina Press. Arnott, H. J., and F. G. E. Pautard. 1970. Calcification in plants. In: Biological Calcifications: Cellular and Molecular Aspects, ed. H. Schraer, pp. 375-446. New York: Appleton-Century Croft. Asthana, R. P. 1946. Bacterial leaf-spot of arum. Curr. Sei. (Bangalore) 15:356. Banerji, I. 1934. Sterility of the female gametophyte of Colocasia antiquorum. Curr. Sei. 2:432. Banerji, I. 1937. Sterility in Colocasia antiquorum, Schott. J. Indian Bot. Soc. 16:159-164. Barnes, B. A. 1953. The pharmacology and toxicology of certain species of Dieffenbachia. M.S. thesis, Univ. of Florida. Barooah, S. R. 1944. The significance of sapotoxin and C/N ratio in the growing corms of Colocasia. Allahabad Farmer 18:98-100. Barrau, J. 1956. Plantes alimentaires de base des Melanesiens. J. d'Agric. Trop, et Bot. Appl. 3:32-49.

Literature

Cited

369

Barrati, J. 1958. Subsistence agriculture in Melanesia. Bishop Mus. Bull. (Honolulu) 219:39-43. Barrau, J. 1959. Fruits et graines du taro, Colocasia esculenta (L.) Schott. J. d'Agric. Trop. et Bot. Appi. 6:436-438. Barrett, O. W. 1928. The Tropical Crops. New York: Macmillan. Bauer, A.; H. Denning; and C. D. Miller. 1951. Thiamine, riboflavin, and niacin contents of foods commonly used in Hawaii. Rep. Hawaii Agr. Exp. Sta. for the Biennium Ending 30 June 1950, pp. 101 -106. Baybay, D. S. 1922. Storage of some root crops and other perishable farm products. Philipp. Agr. 10:423-440. Beaglehole, J. C.; J. A. Williamson; J. W. Davison; and R. A. Skelton, eds. 1955. The Journals of Captain James Cook on His Voyages of Discovery. I. The Voyage of the Endeavour 1768-1771. Hakluyt Soc. Extra Ser. 34. Cambridge: Cambridge Univ. Press. Beaglehole, J. C.; J. A. Williamson; J. W. Davidson; and R. A. Skelton, eds. 1961. The Journals of Captain James Cook on His Voyages of Discovery. II. The Voyage of the Resolution and Adventure 1772-1775. Hakluyt Soc. Extra Ser. No. 35. Cambridge: Cambridge Univ. Press. Beardsley, J. W. 1955. Fluted scales and their biological control in United States administered Micronesia. Proc. Hawn. Ento. Soc. 15:391-399. Beardsley, J. W. 1963. The Coccoidea of Micronesia (Homoptera). Ph.D. diss., Univ. of Hawaii. Begley, B. W. ; G. R. Vieth; and R. S. de la Pena. 1980. Commercial dryland taro in Hawaii: estimates of the costs of production on small and medium sized farms. Unpublished report of the Dept. of Agr. Econ., Univ. of Hawaii. Berquist, R. R. 1972. Efficacy of fungicides for control of Phytophthora leaf blight of taro. Ann. Bot. (London) 36:281-287. Berquist, R. R. 1974. Effect of fungicide rate, spray interval, timing of spray application, and precipitation in relation to control of Phytophthora leaf blight of taro. Ann. Bot. (London) 38:213-221. Bianchi, F. A. 1940. Some interesting new records in the Thysanoptera. Proc. Hawn. Ento. Soc. 10:375-376. Bianchi, F. A. 1965. New Thysanoptera records from the Caroline and Mariana Islands. Proc. Hawn. Ento. Soc. 19:73-76. Bice, A. M., and B. A. Tower. 1939. Crossbreeding poultry for meat production; including a feeding test for taro waste and poi. Hawaii Agr. Exp. Sta. Bull. 81:1-19. Bigelow, J. 1818. Acridity in Arum. J. Amer. Med. Bot. (Cummings and Hilliard) 1:55. Bishop Museum. 1964. Pest and diseases survey of the Cook Islands. Bishop Mus. Lib. Honolulu. Black, O. F. 1918. Calcium oxalate in the dasheen. Amer. J. Bot. 5:447-451. Booth, R. H. 1974. Post-harvest deterioration of tropical root crops: losses and their control. Trop. Sci. 16:49-63. Bourke, R. Michael. 1975. Food crop farming systems used on the Gazelle Penin-

370

Literature

Cited

sula of New Britain. Proc. 1975 Papua New Guinea Food Crop Conf., Port Moresby, pp. 81-100. Bowers, F. A. 1967. Agricultural history of taro. Univ. Hawaii Coop. Ext. Serv. Misc. Publ. 36:8-13. Bowers, F. A.; D. L. Plucknett; and O. R. Young. 1964. Specific gravity evaluation of corm quality in taro. Hawaii Agr. Exp. Sta. Circ. 61. Brandes, G. A.; T. M. Cordero; and R. L. Skiles, eds. 1959. Compendium of plant diseases. Philadelphia: Rohm and Haas. Brierem, K., andO. Ulvesli. 1954. Meld. Norg. Landhr-Hogstk. 34:373-479. Brouk, B. 1975. Plants Consumed By Man. New York: Academic Press. Brown, Lester R. 1980. Food or fuel: new competition for the world's cropland. Worldwatch Paper 35. Worldwatch Institute, 1776 Massachusetts Avenue NW, Washington, D.C. 20036. Bugnicourt, F. 1954. Phytopathologie. Courr. Cherch. 8:159-186. Bugnicourt, F. 1958. Contribution a l'etude de Cladosporium colocasia Sawada. Rev. Mycol. (Paris) 23:233-236. Butler, E. J., and G. S. Kulkarn. 1913. Colocasia blight caused by Phytophthora colocasiae Rac. Mem. Dept. Agr. in India, Bot. Ser. 5:233-259. Byars, L. P. 1917. A nematode disease of the dasheen and its control by hot water treatment. Phytopathology 7:66. Byron, H. T.; J. F. Hentges, Jr.; J. D. O'Connell; and L. O. Bagnall. 1975. Organic acid preservation of waterhyacinth silage. Hyacinth Control J. 13:64-66. Cable, W. J. 1973. The potassium requirement of taro (Colocasia esculenta [L.] Schott) in solution culture. M.S. thesis, Univ. of Hawaii. Carpenter, C. W. 1919. Preliminary report on root rot in Hawaii. Hawaii Agr. Exp. Sta. Press Bull. 54. Carpenter, J. R.; W. E. Steinke; and L. B. Bruce. 1981. Taro silage: its potential as an animal feed in the tropics. Amer. Soc. Anim. Sci. 53, suppl. no. 1, p. 292 (abst.). Carpenter, J. R.; W. E. Steinke; and J. K. Wang. 1981a. Assessment of nutritive value of taro silage (Colocasia esculenta L. [Schott]). Amer. Soc. Anim. Sci. 53, suppl. no. 1, p. 487 (abst.). Carpenter, J. R.; W. E. Steinke; J.K.Wang. 1981b. Assessment of nutritive value of taro silage (Colocasia esculenta L. [Schott]). Proc. West. Soc. Amer. Soc. Anim. Sci. 32, p. 175. Carson, H. L., and T. Okada. 1980. Drosophilidae associated with flowers in Papua New Guinea. I. Colocasia esculenta. Kontyu (Tokyo) 48:15-29, 28 March 1980. CAST (Council for Agricultural Science and Technology). 1975. Ruminants as food producers. Dept. of Agronomy, Special Publ. no. 4, Iowa State Univ., Ames, Iowa. Chan, H. T.; T. H. C. Kao-Jao; and T. O. M. Nakayama. 1977. Anthocyanin composition of taro. J. Food Sci. 42:19-21. Chandra, S. 1979a. Handling, Storage and Processing of Root Crops in Fiji. In.-

Literature

Cited

371

Small-Scale Processing and Storage of Tropical Root Crops, ed. D. L. Plucknett, pp. 53-63. Westview Trop. Agr. Series no. 1. Boulder, Colorado: Westview Press. Chandra, S. 1979b. Taro research and development in Fiji. Int. Symp. Taro and Cocoyam, Baybay, Philippines. Int. Found. Sci. (Stockholm) Prov. Rep. no. 5 , pp. 55-72. Chang, T. K. 1958. Dispersal of taro in Asia. Ann. Asso. Amer. Geog. 48:255-256. Chappel, H. G. 1927. Jaws and teeth of ancient Hawaiians. Bernice P. Bishop Mus. Mem. (Honolulu) 9:251-268. Chatfield, C., and G. Adams. 1931. Proximate composition of fresh vegetables. U.S. Dept. Agr. no. 146, pp. 1-24. Chen, T. H., and D. L. Day. 1980. Feedlot biogas as process fuel for farm alcohol plants. Paper presented at the Int. Symp. on Biogas, Microalgae and Livestock Wastes, Taipei. Cherian, S.; W. T. Smith, Jr.; and L. P. Stoltz. 1976. Soluble proteins of Dieffenbachia. Trans. Kentucky Acad, of Sci. 37:16-19. Ching, K. W. 1969. Some aspects of the physiological ontogeny of starch, total sugar, protein, leaf and corm of Colocasia esculenta. M.S. thesis, Univ. of Hawaii. Ching, K. W. 1970. Development of starch, protein, leaf and corm in Colocasia esculenta. Proc. 2nd Int. Symp. on Trop. Root and Tuber Crops (1970), vol. 1:143-146. Chowdhury, B., and M. Hussain. 1979. Chemical composition of the edible parts of aroids grown in Bangladesh. Indian J. Agr. Sci. 49:110-115. Chung, H. L. 1929. Utilization and composition of oriental vegetables in Hawaii. Hawaii Agr. Exp. Sta. Bull. 60. Clark, A., and R. B. Waters. 1934. The presence of a sapotoxin in Xanthosoma atrovirens, a tropical food-tuber. Biochem J. 28:1131-1134. Cleare, L. D. 1930. The tannia beetle, Ligyrus ebenus DE G. Agr. J. British Guiana 3:11-23. Cohen, Y.; M. Renveni; and H. Eyal. 1979. The systemic antifungal activity of Ridomil against Phytophthora infestants on tomato plants. Phytopathology 69:645-649. Cohic, F. 1950. Insects injurious to plants grown in Wallis and Futuna. Trop. Agron. 5:563-581. Cohic, F. 1955. Rapport d'une Mission aux Establissements Français de L'oceanie. Fasicule III Enquete sur les parasites animaux des cultures. Office de la Recherche Scientifique et Technique Outre-mer, Institut Français D'Oceanie, Noumea, Nouvelle-Caledonie. Cohic, F. 1956. Parasites Animaux des plantes cultivees en Nouvelle-Caledonie et dépendances. Institut Français D'Oceanie. Collier, H. O. J. 1962. Kinins. Sci. Amer., August, 111-118. Coloroll, Ltd. 1974. Brit. Pat. 1,478,050 and 1,484,833. Concepción, I., and I. S. Cruz. 1961. Amino acid composition of some Philippine plant foods. Philipp. J. Sci. 90:497-516.

372

Literature

Cited

Conners, I. 1980. Updated check list of microorganisms and viruses found in Hawaii. Unpublished manuscript. Dept. Plant Pathology, Univ. of Hawaii Cooper, R. C. 1969. Flowering of taro, Colocasia esculenta (L.) Schott, Araceae, in New Zealand. Ree. Auckland Inst. Mus. 6:403-406. Cording, J., Jr.; M. T. Willard, Jr.; R. K. Eskew; and J.F.Sullivan. 1957. Advances in the dehydration of mashed potatoes by the flake process. Food Technol. 11:236. Coursey, D. G. 1968. The edible aroids. World Crops 20:25-30. Coursey, D. G., and D. Halliday. 1975. Developments in the use of tropical root crops as animal feed. Proc. of the Regional Meeting on the Production of Root Crops, 24-29 November 1975, Suva, Fiji, pp. 139-143. Noumea, New Caledonia: South Pacific Commission. Coursey, D. G., and P. H. Haynes. 1970. Root crops and their potential as food in the tropics. World Crops 22:261-265. Dabek, A. J., and R. T. Plumb. 1975. Viruslike particles in the taro planthopper, Tarophagus proserpina. J. Invert. Pathol. 26:271-272. Dale, P. S., and J. L. Herring. 1960. Pest control in Samoa Tarophagus proserpina, gaogao, taro. Western Samoa Dept. Agr. Forestry and Fisheries Bull, no. 3. De Brot, E. A., and A. Ordosgiotti. 1974. Dasheen mosaic virus infection of Colocasia and Xanthosoma in Venezuela. Plant Dis. Rep. 58:1032-1034. de la Pena, R. S. 1967. Effects of different levels of N, P, and K fertilization on the growth and yield of upland and lowland taro (Colocasia esculenta [L.] Schott, var. Lehua). Ph.D. diss., Univ. of Hawaii. de la Pena, R. S. 1970. The edible aroids in the Asian-Pacific area. Proc. 2nd Int. Symp. on Trop. Root and Tuber Crops (1970), vol. 1:136-140. de la Pena, R. S. 1975. Nitrofen for taro weed control. Univ. Hawaii Coop. Ext. Ser. Circ. 488. de la Pena, R. S. 1981. Unpublished interim report on the response of taro top yield to cutting interval, time to initial cutting, and fertilizer. Coll. Trop. Agr. and Human Resources, Univ. of Hawaii, de la Pena, R. S., and D. L. Plucknett. The response of taro (Colocasia esculenta [L.] Schott) to N, P, and K fertilization under upland and lowland conditions in Hawaii. Proc. 1st Int. Symp. Trop. Root Crops (1967), vol. l(2):70-85. de la Pena, R. S., and D. L. Plucknett. 1972. Effects of nitrogen fertilization on the growth, composition and yield of upland and lowland taro (Colocasia esculenta). Exp. Agr. 8:187-194. de la Pena, R. S.; D. L. Plucknett; and G. H. Shibao. 1973. Application of herbicides through irrigation water for weed control in lowland taro (Colocasia esculenta). Proc. 3rd. Asian-Pac. Weed Sei. Soc. Conf., Kuala Lumpur, 1971, pp. 332-334. de la Pena, R. S.; P. van der Zaag; and R. I. Fox. 1979. The comparative phosphorus requirements of flooded and non-flooded taro. Int. Symp. Taro and Cocoyam, Baybay, Philippines. Int. Found. Sei. (Stockholm) Prov. Rep. no. 5, pp. 223-237.

Literature

Cited

373

Degras, L. M. 1970. Morphology, physiology and selection in three tropical tuber crops. Proc. 2nd Int. Symp. on Trop. Root and Tuber Crops (1970) vol. 1:163-165. Derstine, V., and E. L. Rada. 1952. Some dietetic factors influencing the market for poi in Hawaii. Univ. Hawaii Agr. Econ. Bull. 3. Deshmukh, M. J., and K. N. Chibber. 1960. Field resistance to blight (Phytophthora colocasiae Rac.) in Colocasia antiquorum, Schott. Curr. Sci. (Bangalore) 29:320-321. De Vries, C. A.; J. D. Ferwerda; and M. Flach. 1967. Choice of food crops in relation to actual and potential production in the tropics. Neth. J. Agr. Sci. 15:241-248. Dixon, H. H., and G. J. Dixon. 1931. The exudation of water from the leaf-tips of Colocasia antiquorum Schott. Sci. Proc. Roy. Dublin Soc. 20:7-10. Doue, S . M . I 965. Taro production and acreage trends. Univ. Hawaii Agr. Econ. Coop. Ext. Serv. Drach, G., and W. H. Maloney. 1963. Toxicity of the common houseplant Diffenbachia: report of a case. J. Amer. Med. Asso. 184:1047. Dumbleton, L. J. 1954. A list of plant diseases recorded in South Pacific territories. South Pacific Commision Technical Paper 78. Easton, G. D., and M. E. Nagle. 1981. Potato late blight control by the systemic fungicide Ridomil. Phytopathology 71:214. Eastop, G. D., and Hille Ris Lambers. 1976. Survey of World Aphids. The Hague: Dr. W. Junk b.v. Publishers. El-Habbesha, K. M., and A. G. Behairy. 1973. Root secretion from some vegetable plants. Egypt. J. Bot. 16:349-352. El-Habbesha, K. M.; A. G. Behairy; and M. Abol-Magd. 1976. The relation between method of propagation, plant density and growth, mineral uptake and field of dasheen (Colocasia antiquorum Schott). Scientia Hort. 4:15-22. Emma, Queen of Hawaii. 1836-1885. Observations on the varieties and culture of kalo. Photocopy of holograph. Hawaiian Collection, Hamilton Lib., Univ. of Hawaii. Endrodi, S. 1971. Monographic der Dynastinae. 4. Tribus Pentadontini (papuanische and pazifische Inselwelt) (Coleoptera: Lamellicornia: Melolonthidae). Pacific Insects 13:243-320. Esau, K. 1965. Plant Anatomy. 2nd ed. New York: Wiley. Esquerra, N. M., and B. P. Gabriel. 1969. Insect pests of vegetables. Tech. Bull. 25, Dept. Ento., College Agr., Univ. of Philippines. Fajardo, T. G., and J. M. Mendoza. 1935. Studies on the Sclerotium rolfsii Sacc. Philipp. J. Agric. 1935, pp. 387-424. Falicoff, W.; G. Koide; and P. Takahashi. 1979. Solar/wind handbook for Hawaii, C-250. Hawaii Natural Energy Inst., Univ. of Hawaii. FAO (Food and Agriculture Organization of the United Nations). 1970. Nutritional Studies no. 2. Rome: FAO FAO (Food and Agriculture Organization of the United Nations). 1974. FAO production yearbook 1973. Rome: FAO.

374

Literature

Cited

FAO (Food and Agriculture Organization of the United Nations). 1975. FAO production yearbook 1974. Rome: FAO. FAO (Food and Agriculture Organization of the United Nations). 1976. FAO production yearbook 1975. Rome: FAO. Farih, A.; J. A. Menge; P. H. Tsao; and H. D. Ohr. 1981. Metalaxyl and efosite aluminum for control of Phytophthora gummosis and root rot on citrus. Plant Disease 65:654-657. Feingold, B. F. 1942. A vegetable milk substitute: taro. J. Allergy 13:488-493. Fetuga, B. L., and J. A. Oluyemi. 1976. The metabolizable energy of some tropical tuber meals for chicks. Poultry Sei. 55:868-873. Fiji Bureau of Statistics. 1968. Annual Statistical Abstract. Floch, H. 1957. Carotenes et acide ascrobique dans les feuilles de végétaux Guyanais. J. d'Agric. Trop, et Bot. Appl. 11:527-531. Flood, M. C. 1919. Exudation of water by Colocasia antiquorum. Proc. Roy. Dublin Soc. N.S. 15:506-512. Fochtman, F. W.; J. E. Manno; C. L. Winek; and J. A. Cooper. 1969. Toxicity of the genus Dieffenbachia. Toxicol, and Appl. Pharm. 15:38-45. Food and Nutrition Board, National Research Council, National Academy of Sciences. 1980. Recommended Dietary Allowances. 9th ed. Wash.,D.C. Ford, E. J., Jr. 1955. Notes and exhibitions. Elytroteinus subtruneatus (Fairmaire) reared from taro roots. Proc. Hawn. Ento. Soc. 15:385. Fournier, P. 1952. L'histoire ancienne de la colocase. Bull. Soc. Bot. (Fr.) 99:263-264. Franceschi, V. R., and H. T. Horner. 1980. Calcium oxalate crystals in plants. Bot. Rev. 46:361-428. Frey, A. 1929. Calciumoxalat: Monohydrat and Trihydrat. In: Handbuch der Pflanzenanatomie, ed. K. Linsbauer, Band III/1 a:81 — 100. Berlin: Gebrüder Borntraeger. Frey-Wyssling, A. 1981. Crystallography of the two hydrates of crystalline calcium oxalate in plants. Amer. J. Bot. 68:130-141. Fukushima, E.; S. Iwasa; S. Tokumasu; and M. Iwamasa. 1962. Chromosome numbers of the taro varieties cultivated in Japan. Chromosome Information Service no. 3, pp. 38-39. Fac. Agr., Kyushu Univ., Fukuoka, Japan. Fullaway, D. T. 1937. Notes on the taro leafhopper Megamelus proserpina Kirk. (Delphacidae). Proc. Hawn. Ento. Soc. 9:405-406. Fullaway, D. T. 1939. Paradichlorobenzene formulation for crayfish control. Proc. Hawn. Ento. Soc. 10:413. Fullaway, D. T. 1940. An account of the reduction of the immigrant taro leafhopper (Megamelus proserpina) population to insignificant numbers by the introduction and establishment of the egg-sucking bug Cyrtorhinus gluluus. Proc. Sixth Pac. Sei. Congress 1939 4:345-346. Fullaway, D. T. 1941. A checklist of the parasitic Hymenoptera of the Samoa Islands with descriptions of new species appended. Proc. Hawn. Ento. Soc. 11:41-49. Fullaway, D. T. 1942. A list of parasitic Hymenoptera collected by F. X. Williams in New Caledonia. Proc. Hawn. Ento. Soc. 11:243-47.

Literature

Cited

375

Gaind, K. N.; K. S. Chopra; and A. C. Dua. 1968. Study of the mucilages of corm and tuber of Colocasia esculenta Linn. I. Emulsifying properties. Indian J. Pharm. 30:208-211. Gaind, K. N.; K. C. Chopra; and A. C. Dua. 1969. Mucilages of corm and tuber of Colocasia esculenta Linn. II. Binding properties. Indian J. Pharm. 31:156-158. Gerpacio, A. L.; D. B. Roxas; N. M. Uichanco; N. P. Roxas; C. C. Custudio; C. Mercado; L. A. Gloria; and L. S. Castillo. 1975. Tuber meals as carbohydrate sources in broiler rations. South Pacific Commission Working Paper 30. Presented at the Regional Meeting on the Production of Root Crops, 24-29 November 1975, Suva, Fiji. Ghani, F. D. 1979. The status of Keladi China Colocasia esculenta (L.) Schott cultivation in Peninsula Malaysia. Int. Found, for Sci. (Stockholm) Prov. Rep. no. 5, pp. 35-54. Gibbons, E. G. 1942. On the breeding habits and places of Aedes (Stegomyia) simpsoni Theobald in Uganda. Ann. Trop. Med. Parasitol. 36:151. Gillett, J. D. 1969. Aedes simpsoni in Chaggaland, Tanzania. Ann. Trop. Med. Parasitol. 63:147-156. Glaser, J.; R. A. Lawrence; A. Harrison; and M. R. Ball. 1967. Poi, its use as a food for normal, allergic and potentially allergic infants. Univ. Hawaii Coop. Ext. Ser. Misc. Publ. 36:39-75. Goering, H. K., and P. J. Van Soest. 1970. Forage fiber analyses. U.S. Dept. of Agr., A.R.S. Agr. Handbook no. 379. Goering, K. J. 1971. Properties of the small granule starch from Colocasia esculenta. A comparison of the small granule starch from dasheen tubers with that obtained from cereal type sources. Cereal Sci. Today 16:306. Goering, K. J., and D. L. Brelsford. 1966. New starches. I. The unusual properties of starch from Saponaria vaccaria. Cereal Chem. 43:127-136. Goering, K. J., and B. De Haas. 1972. New Starches. VIII. Properties of the small granule starch from Colocasia esculenta. Cereal Chem. 49:712-719. Goering, K. J., and M. Schuh. 1967. New starches. III. The properties of the starch from Phalaris canariensis. Cereal Chem. 44:532-538. Gollifer, D. E., and J. F. Brown. 1972. Virus diseases of Colocasia esculenta in the British Solomon Islands. Plant Dis. Rep., 56:597-599. Gollifer, D. E.; G. V. H. Jackson; A. J. Dabek; R. T. Plumb; and Y. Y. May. 1975. Taro viruses in the Solomon Islands: symptoms and transmission. South Pacific Commission Working Paper 20. Presented at the Regional Meeting on the Production of Root Crops, 24-29 November 1975, Suva, Fiji. Gomez, E. T. 1925. Blight of Gabi (Phytophthora colocasiae Rac.) in the Philippines. Philipp. Agr. 14:429-440. Gomi, K. 1957. Studies on the drought resistance of Colocasia esculenta Schott. Bull. Fac. Agr., Univ. of Miyazaki 2:43-51. Gopalan, C.; B. V. Rama Sastri; S. C. Balasubramanian. 1977. Nutritive value of Indian foods. National Inst, of Nutrition, Indian Coun. Med. Res., Hyderabad, India.

376

Literature

Cited

Goyal, J. P.; S. M. Naik; V. N. Pathak; H. C. Sharma; and R. Prasada. 1974. Evaluation of some modern fungicides for the control of Sclerotium rolfsii Sacc. inciting the tuber rot of Colocasia antiquorum L. (Arvi). Nova Hedwigia Beiheftezur 47:205-210. Graham, J. H.; K. W. Kreitlow; L. R. Faulkner. 1972. Diseases. In, Alfalfa Science and Technology, ed. C. H. Hanson, pp. 497-526. Amer. Soc. Agron., no. 15. Gray, W. G. 1966. Fungal protein for foods and feeds. I. Introduction. Econ. Bot. 20:89-96. Gray, W. G., and M. O. Abou-El-Seoud. 1966a. Fungal proteins for foods and feeds. II. Whole sweet potato as a substrate. Econ. Bot. 20:119-126. Gray, W. G., and M. O. Abou-El-Seoud. 1966b. Fungal proteins for food and feeds. III. Manioc as a potential crude raw material for tropical areas. Econ. Bot. 20:251-254. Greenwell, A. B. H. 1947. Taro with special reference to its culture and uses in Hawaii. Econ. Bot. 1:276-289. Griffin, G. J. L. 1974. Biodegradable fillers in thermoplastics. Amer. Chem. Soc. Adv. in Chem. 134:159-170. Griffin, G. J. L. 1975. Degradation of polyethylene in compost burial. Preprint volume, 15th Prague Microsymp. Paper G6. Griffin, G. J. L. 1979. Nonfood application of starch with special reference to potential uses of taro. In: Small-Scale Processing and Storage of Tropical Root Crops, ed. Donald L. Plucknett, Westview Trop. Agr. Series, no. 1, pp. 275-299. Boulder, Colorado: Westview Press. Griffin, G. J. L. 1981. United Kingdom patent 1600497. Griffin, G. J. L., and P. S. Nathan. 1976. Enzyme permeability of thin PE membranes. IUPAC Int. Symp. (Stockholm) 1976 (in press). Griffin, G. J. L., and K. Tarverdi. 1981. Macrobiodegradation of thermoplastics. 5th Int. Biodeterioration Symp., Aberdeen. Griffin, G. J. L., and R. Turner. 1978. Macrobiodegradation of Plastics. London: Chapman and Hall. Grubben, G. ]. H. 1977. Tropical vegetables and their genetic resources. AGPE: IBPGR/77/23. Rome: FAO. Gueguen, M. F. 1908. Enations hypophylless du Colocasia esculenta Schott. Bull. Soc. Bot. (Fr.) 55 (Ser. 4, Vol. 8):26-32. Gusten, R. 1968. Studies in the staple food economy of western Nigeria. Nigerian Inst, of Soc. and Econ. Res., Univ. of Ibadan. Habeck, D. H. 1974. Arzama densa as a pest of dasheen. Fla. Entomologist 57:409-410. Haberlandt, G. 1914. Physiological Plant Anatomy. London: Macmillan. Handy, E. S. C. 1940. The Hawaiian planter. I. His plants, and areas of cultivation. Bull. BemiceP. Bishop Mus. (Honolulu) 161:6-130. Hartman, R. D. 1974. Dasheen mosaic virus and other phytophathogens eliminated from caladium, taro and cocoyam. Phytopathology, 64:237-240. Hartman, R. D., and F. W. Zettler. 1972. Dasheen mosaic virus infections in commercial plantings of aroids in Florida. Phytopathology 62:804 (abst.)

Literature

Cited

377

Hartman, R. D., and F. W. Zettler. 1974. Effects of dasheen mosaic virus on yields of caladium, dieffenbachia, philodendron. Phytopathology 64:768 (abst.). Hashad, M. N.; K. R. Stino; and S. I. El Hinnawy. 1956a. Transformation and translocation of carbohydrates in taro plants during growth. Ann. Agr. Sci. Fac. Agr., Ain Shams Univ. (Cairo) 1:261-267. Hashad, M. N.; K. R. Stino; and S. I. El Hinnawy. 1956b. Transformation of carbohydrates in taro corms during storage. Ann. Agr. Sci. Fac. Agr., Ain Shams Univ. (Cairo) 1:269-276. Hawaii Agricultural Experiment Station. 1920. Taro. Rep. Hawaii Agr. Exp. Sta., pp. 39-40. Hawaii Agricultural Experiment Station. 1938. Taro. Rep. Hawaii Agr. Exp. Sta., pp. 36-38, 86-87. Hecker E., and R. Schmidt. 1973. Phorbolesters: the irritants and carcinogens of Croton tiglium L. Fortschritte der Chem. Org. Naturst. 31:360-388. Hellman, N. N.; T. F. Boesch; and E. H. Melvin. 1951. Starch granule swelling in water vapor sorption. J. Amer. Chem. Soc. 74:348. Hicks, P. G. 1967. Resistance of Colocasia esculenta to leaf blight caused by Phytophthora colocasiae. Papua New Guinea Agr. J. 19:1-4. Higashihara, M.; M. Umeki; and T. Yamamoto. 1975. Isolation and some properties of taro root starch. Denpun Kagaku (J. Japan Soc. Starch Sci.) 22:61-65. Hill, A. F. 1939. Nomenclature of taro and its varieties. Bot. Mus. Leaflet, Harvard Univ. 7:113-118. Hill, A. F. 1952. Economic Botany. 2nd ed. New York: McGraw-Hill. Hillman, W. S., and D. D. Culley, Jr. 1978. Duckweeds. Amer. Scientist 66: 442-451. Hinckley, A. D. 1963. Trophic records of some insects, mites and ticks in Fiji. Dept. Agr. Bull. (Fiji) 45. Hodgkinson, A. 1977. Oxalic Acid in Biology and Medicine. New York: Academic Press. Hodgson, H. J. 1976. Forages, ruminant livestock, and food. Bioscience 26:625. Holtman, J. Ben; Leroy K. Pickett; D. L. Armstrong; and Larry J. Connor. 1973. A systematic approach to simulating corn production systems. Trans. Amer. Soc. Agr. Engr. 16:19. Hood, J. Douglas. 1940. Organothrips bianchii. A new Hawaiian thrips from taro. Proc. Hawn. Ento. Soc. 10:423-427. Hopkins, G. H. E. 1927. Pests of economic plants in Samoa and other island groups. Bull. Entomol. Res. 18:23-32. Horwitz, W., ed. 1980. Official methods of analysis of the Association of Official Analytical Chemists. 13thed. AOAC, Washington, D.C. 20044. Hoyt, C. P. 1955. Notes on larvaevoid flies reared from Prodenia litura Fab. and Othreis fullonia (Clerck) larvae in American Samoa. Proc. Hawn. Ento. Soc. 15:419-421. Hsu, H. Y., and K. M. Chiou. 1971. Instant taro powder. I. Comparison of different dehydrating methods. J. Chinese Agr. Chem. Soc. 9:164-166.

378

Literature

Cited

Huang, Wen-Yuan. 1974. Optimal use of Hawaii agricultural reservoir system: a multiple cropping approach. Ph.D. diss., Univ. of Hawaii. Huang, W. Y., and S. E. Olbrich. 1979. Feed potential of sweet potatoes in Hawaii. Dept. paper no. 57, Agr. and Resource Econ., Coll. Trop. Agr. and Human Resources, Univ. of Hawaii. Hunger, R. M., and C. E. Horner. 1981. Control of hop downy mildew with the systemic fungicide metalaxyl. Phytopathology 71:1005. Intengan, C. L.; L. G. Alejo; I. Concepcion; C. Yaptinchay; V. L. Probre; R. D. Slud; and J. D. Manalo. 1923. Composition of Philippine foods. Philipp. J. Sci. 82:227-252. International Board for Plant Genetic Resources. 1980. Descriptors for Colocasia. IBPGR Secretariat, Rome. Izawa, G., and S. Okamoto. 1961. Effect of mineral nutrition on organic constituents in taro plants during growth. Soil and Plant Food 6:127-135. Jackson, G. V. H., and D. E. Gollifer. 1975a. Disease and pest problems of taro (Colocasia esculenta L. Schott) in the British Solomon Islands. PANS 21:45-53. Jackson, G. V. H., and D. E. Gollifer. 1975b. Storage rots of taro (Colocasia esculenta L. Schott) in the British Solomon Islands. Ann. Appl. Biol. 80:217-230. Jackson, G. V. H., and D. E. Gollifer. 1975c. Studies on the taro leaf blight fungus Phytophthora colocasiae in the Solomon Islands. South Pacific Commission Working Paper 18. Presented at the Regional Meeting on the Production of Root Crops, 24-29 November 1975, Suva, Fiji. Jackson, G. V. H., and P. M. Pelomo. 1979. Breeding for resistance to diseases of taro, Colocasia esculenta, in Solomon Islands. Int. Symp. Taro and Cocoyam, Baybay, Philippines. Int. Found. Sci. (Stockholm) Prov. Rep. no. 5, pp. 287-298. Jackson, G. V. H.; E. A. Ball; and J. Arditti. 1977a. Seed germination and seedling proliferation of taro, Colocasia esculenta Schott in vitro. J. Hort. Sci. 52:169-171. Jackson, G. V. H.; E. A. Ball; and J. Arditti. 1977b. Tissue culture of taro, Colocasia esculenta (L.) Schott. J. Hort. Sci. 52:373-382. Jacoby, T. 1972. Nutrition and fertilization of tropical root crops. Actualidades de la Ingenieria Agronomica no. 29, pp. 1-32. Jain, N. L.; D. P. Das; and G. Lai. 1953. Arvi (Colocasia) flour. Indian J. Hort. 10:19-22. James, Mari; R. H. Kenton; and R. E. Woods. 1973. Virus-like particles associated with taro diseases of Colocasia esculenta (L.) Schott in the Solomon Islands. J. Gen. Virology 21:145-153. Jeffers, H. F., and P. H. Haynes. A preliminary study of the nutritive value of some dehydrated tropical roots. Proc. 1st Int. Symp. on Trop. Root Crops (1967) vol. 2(6):72-89. Johnson, L. 1963. Power requirements in rice production. Paper presented at the Conference on Agricultural Engineering Aspects of Rice Production, International Rice Research Institute, Los Banos, Laguna, Philippines. Johnson, M. O., and K. A. Ching. 1918. Composition and digestibility of feeding

Literature

Cited

379

stuffs grown in Hawaii. Hawaii Agr. Exp. Sta. Press Bull. 53:8,10,12,13, 21,23. Johnston, A. 1963. A host list of insects recorded in the South East Asia and Pacific region. Tech. Doc. 33, FAO Plant Protection Comm. for SEA and Pac. Region. Johnston, B. F. 1958. The Staple Food Economies of Western Tropical Africa. California: Stanford Univ. Press. Jones, M. R.; N. P. Larsen; and G. P. Pritchard. 1934. Taro and sweet potatoes versus grain foods in relation to health and dental decay in Hawaii. The Dental Cosmos 76:395-409. Jos, J. S., and S. G. Nair. 1976. Multiple sporocytes in meiotic cells of triploid Colocasia esculenta Linn. Genetica Iberica 28:279-287. Jos, J. S.; K. N. Vasudevan; and M. L. Magoon. 1967. In vitro germination of pollen in aroids. Indian J. Hort. 24:166-172. Jos, J. S.; K. Vijaye; and N. Hrishj. 1979. Major factors limiting seed set in aroids. Int. Symp. Taro and Cocoyam, Baybay, Philippines. Int. Found. Sci. (Stockholm) Prov. Rep. no. 5, pp. 259-267. Kagbo, R. B.; D. L. Plucknett; and W. G. Samford. 1979. Field and related components of flooded taro as affected by land preparation, planting density and planting depth. Int. Symp. Taro and Cocoyam, Baybay, Philippines. Int. Found. Sci. (Stockholm) Prov. Rep. no. 5, pp. 153-165. Karikari, S. K. 1971. Cocoyam utilization in Ghana. World Crops 23. Kato, I., and F. Kamota. 1969. Measurement of évapotranspiration by chamber method and its application. Japan Agr. Res. Quart. 4:27-32. Kato, I.; F. Kamota; Y. Naito; and R. Taniguchi. 1969. Studies on the characteristic features of water consumption in various crops. IV. In the transpiration and évapotranspiration of taro plants. J. Japan Soc. Hort. Sci. 38:60-67. Kawabe, A. 1975. Integration of harvesting and processing of taro by machine. Kikaika-Nogyo (Farming Mechanization) 5:22-24. Kay, D. E. 1973. Root crops. Trop. Prod. Inst. Crop Prod. Dig. 2:71-75, 168-179. Kenten, R. H., and R. E. Woods. 1973. Viruses of Colocasia esculenta and Xanthosoma saggitifolium. PANS 19:38-41. Kikuta, K.; L. D. Whitney; and G. H. Parris. 1938. Seeds and seedlings of the taro, Colocasia esculenta. Amer. J. Bot. 25:186-188. Kirkpatrick, R. M. 1935. Diet in relation to gingivitis. Field observations in New Guinea. J. Amer. Dental Asso. 23:197-206. Knott, J. E., and J. R. Deanon, Jr., eds. 1967. Vegetables in Southeast Asia. Univ. of Philippines, College of Agr., Los Banos, Laguna. Krauss, N. L. H. 1944a. Notes and exhibition. Mites and aphids on taro. Proc. Hawn. Ento. Soc. 12:2,4. Krauss, N. L. H. 1944b. Notes on insects and other arthropods from the islands of Molokai and Maui, Hawaii. Proc. Hawn. Ento. Soc. 12:81. Krauss, N. L. H. 1954. Notes and exhibitions. Crayfish in taro patches. Proc. Hawn. Ento. Soc. 15:279. Krausz, J. P. 1974. Competition among the root and cereal staples in tropical

380

Literature

Cited

agricultural development. Dept. of Agr. Econ. Staff Paper, May 1974. Cornell Univ., Ithaca, New York. Krishnan, Palaniappa. 1976. Evaluation of auger plow for digging wetland taro. Master's thesis, Univ. of Hawaii. Krishnan, R.; M. L. Magoon; and K. Vijaya Bai. 1970a. Desnapsis in Colocasia antiquorum Schott. Genetica (The Hague) 41:170-178. Krishnan, R.; M. L. Magoon; and K. Vijaya Bai. 1970b. Meiosis in desynaptic triploid Colocasia antiquorum Schott. Genetica Iberica 28:279-287. Kubo, P. 1970. The history of taro and taro products in Hawaii. Typescript paper submitted for Hist. 424, Dept. of Hist., Univ. of Hawaii. Kumar, C. R. M., and D. Souza. 1969. A note on Paratylenchus mutabilis Colbran 1968 (Nematoda: Criconematidae) from India. Curr. Sei. (Bangalore) 38:71-72. Ladiera, A. M.; S. O. Andrade; and P. Sawaya. 1975. Studies on Dieffenbachia picta-. Toxic effects in guinea-pigs. Toxicol, and Appl. Pharm. 34: 363-373. Langworthy, C. F., and H. J. Deuel. 1922. Digestibility of raw rice, arrow-root, canna, cassava, taro, tree-fern, and potato starches. J. Biol. Chem. 52:251-261. Larsen, K. 1969. A study of Thai aroids. Dansk. Bat. Ark. 27:39-59. Larsen, N. P.; M. R. Jones; and G. P. Pritchard. 1934. Dental decay as an indicator of a dietary fault. Amer. J. Dis. Children 48:1228-1233. Lazarus, A. E.; S. Rajamani; and V. V. Nagarajan. 1969. Colocasia poisoning in cattle—a case report. Indian Vet. J. 46:170-173. Ledbetter, M. C., and K. R. Porter. 1970. Introduction to the Fine Structure of Plant Cells. Berlin: Springer-Verlag. Lever, R. J. A. W. 1968. A checklist of economic insects and mites on crops in the British Solomon Islands. Tech. Doc. 65, FAO Plant Protection Comm. for SEA and Pac. Region. Lockwood, B. A. 1969. Produce marketing in a Polynesian society. In: Pacific Marketplaces, ed. H. C. Brookfield. Canberra: Australian National Univ. Press. Look, William C. 1949. Notes and exhibitions. Thrips on taro. Proc. Hawn. Ento. Soc. 13:321. Look, William C., and E. L. McAfee. 1944. New host records of aphids in Hawaii. Proc. Hawn. Ento. Soc. 12:99- 111. MacCaughey, V. 1917. The Hawaiian taro as food. Hawn. Forester and Agriculturist 14:265-268. MacCaughey, V., and J. S. Emerson. 1913. The kalo in Hawaii. Hawn. Forester and Agriculturist 10:186-93, 225-31, 280-88, 315-23, 349-58, 371-75; 11:17-23,44-51, 111-22,201-16. MacMasters, M. M.; P. D. Baird; M. M. Holzapfel; and C. E. Rist. 1955. Preparation of starch from Amaranthus cruentus seed. Econ. Bot. 9:300-302. Madaus, G. 1938. Legrbuch der biologischen heilmettal I. Georg Thieme, Leipzig, pp. 766-769. Maddison, P. A. 1979. Pests associated with cassava in the Pacific region. Cassava Newsletter 5:10-14.

Literature

Cited

381

Malcolm, S. H. 1952. Nutrition research conducted in New Hebrides during 1951. South Pacific Commission Technical Paper 23. Malcolm, S. H. 1953. Nutrition investigations in New Caledonia. South Pacific Commission Technical Paper 50. Malcolm, S. H. 1954. Diet and nutrition in American Samoa. South Pacific Commission Technical Paper 63. Malcolm, S. H. 1955. Diet and nutrition in the Trust Territory of the Pacific Islands. South Pacific Commission Technical Paper 83. Malek, A.; R. Begum; and K. Ahmad. 1966. Analysis of some food stuffs of East Pakistan. Pakistan J. Biol. Agr. Sci. 9:25-29. Manser, P. D.; G. H. Plumb; and M. Liengphilavanh. 1968. Preliminary list of insects found on economic crops in Laos. Tech. Doc. 63, FAO Plant Protection Comm. for SEA and Pac. Region. Manson, D. C. M. 1972. A contribution to the study of the genus Rhizoglyphus Acariña Acaridae. Acarologia 13:621-650. Martin, F. W., and R. M. Ruberte. 1975. Edible Leaves of the Tropics. Mayaquez, Puerto Rico: Antillia College Press. Martin, F. W., and W. E. Splittstoesser. 1975. A comparison of total protein and amino acids of tropical roots and and Tubers. Trop. Root and Tuber Crops Newsletter no. 8, pp. 7-15. Massai, E., and J. Barrau. 1956. Food plants of the South Sea Islands. South Pacific Commission Technical Paper 94. Matsumoto, B. M. 1964. Predator-prey relationships between the predator, Cyrtorhinus fulvus Knight and the prey, the taro leafhopper, Tarophagus proserpina (Kirkaldy). M.S. thesis, Univ. of Hawaii. Matsumoto, B. M., and T. Nishida. 1966. Predator-prey investigations on the taro leafhopper and its egg predator. Hawaii Agr. Exp. Sta. Tech. Bull. 64. Mayeda, Yosinori. 1932. Cytological studies in Colocasia. Proc. Crop Sci. (Japan) 4:315-318. McCullough, M. E., ed. 1978. NFIA Literature Review on Fermentation of Silage: A Review. Grants-in-Aid Committee, National Feed Ingredients Association, West Des Moines, Iowa 50265. Middendorf, E. A. 1968. Plants with blowguns. Turtox News 46:162-64. Milfont, W. N. 1978. Prospects of cassava fuel alcohol in Brazil. In.- Cassava Harvesting and Processing, ed. E. J. Weber, James H. Cock, and Amy Chouinard, pp. 46-48. Proc. of a workshop held at CIAT, Cali, Colombia, 24-28 April 1978. IDRC, 114e Ottawa, Canada. Millaud, R. 1952. Insect pests of the food plants of the French colonies of Oceania. Agron. Trop. (Paris) 7:589-600. Miller, C. D. 1927. Food value of poi, taro and limu. Bernice P. Bishop Mus. Bull. 37. Miller, C. D. 1929. Food values of breadfruit, taro leaves, coconut and sugar cane. Bernice P. Bishop Mus. Bull. 64:1-23. Miller, C. D. and B. Branthoover. 1957. Nutritive values of some Hawaii foods. Hawaii Agr. Exp. Sta. Circ. no. 52. Miller, C. D.; A. Bauer; and H. Denning. 1952. Taro as a source of thiamine, riboflavin, and niacin. J. Amer. Dietet. Asso. 28:435-438.

382

Literature

Cited

Mitchell, W. C. 1981. Notes and exhibitions. Echinothrips americanus Morgan 1913. Forthcoming in Proc. Hawn. Ento. Soc. Mitchell, W. C. 1968. Notes and exhibitions. Syrphid larvae on taro. Proc. Hawn. Ento. Soc. 20:18. Miyasaka, S. C., and D. P. Bartholomew. 1979. Calcium nutrition of taro (Colocasia esculenta [L.] Schott). Int. Symp. Taro and Cocoyam, Baybay, Philippines. Int. Found. Sci. (Stockholm) Prov. Rep. no. 5:239-246. Modi, J. D., and P. R. Kulkarni. 1976. New starches: the properties of the starch from Amaranthus paniculatus, Linn. Acta Alimentaro 9:399. Molinyawe, D. C. 1967. Status of root crop research in the Philippines. Proc. 1st Int. Symp. Trop. Root Crops (Trinidad), vol. l(3):69-83. Mollenhauer, H. H., andD. A. Larson. 1966. Developmental changes in raphideforming cells of Vanilla planifolia and Monstera deliciosa. J. Infrastructure Res. 16:55-70. Mondonedo, M., and F. Alonte. 1931. A comparative study of corn, cassava, sweet potatoes, and pong-apong as feeds for swine. Philipp. Agr. 20:113-119. Moore, L. A. 1962. Grass-legume silage. In.- Forages, ed. H. D. Hughes, M. E. Heath, and D. S. Metcalfe, pp. 535-546. Ames: Iowa State Univ. Press. Morey, R. V.; Peart, R. M.; and D. L. Deason. 1971. Corn-growth harvesting and handling simulator. Trans. Amer. Soc. Agr. Engr. 14:326. Moy, J. H., and B. B. Lee Loy. 1967. Shelf life extension of poi by gamma irradiation. UH-235-P5-2, pp. 149-154. Coll. of Trop. Agr. and Human Resources, Univ. of Hawaii. Abstract 10147, in Nucl. Sci. Abst. 23:1039, March 1969. Moy, J. H.; W. Bachman; and W. J. Tsai. 1980. Solar drying of taro roots. Trans, of Amer. Soc. Agr. Engr. 23:242-246. Moy, J. H.; N. T. S. Wang; and T. O. M. Nakayama. 1977. Dehydration and processing problems of taro. Food Sci. 42:917-920. Moy, J. H.; N. T. S. Wang; and T. O. M. Nakayama. 1979. Processing of taro into dehydrated, stable, intermediate products. In: Small-Scale Processing and Storage of Tropical Root Crops, ed. D. L. Plucknett, pp. 223-248. Westview Trop. Agr. Series, no. 1. Boulder, Colorado: Westview Press. Moy, J. H.; W. K. Nip; A. O. Lai; and W. Y. J. Tsai. 1979b. Development of extrudal taro products. Paper presented at the 39th Annual Meeting of Inst, of Food Technologists, 10-13 June 1979, St. Louis, Missouri. Moy, J. H.; W. K. Nip; W. Y. J. Tsai; and A. O. Lai. Storage qualities of extruded taro products. Proc. of the 5th Int. Symp. on Trop. Root Crops, 1980 (Manila-Baybay, Philippines). In press. Moy, J. H.; W. K. Nip; A. O. Lai; W. Y. J. Tsai; and T. O. M. Nakayama. 1980. Development of extruded taro products. J. Food Sci. 45:652-655. Moy, J. H.; B. Shadbolt; G. S. Stoewsand; and T. O. M. Nakayama. 1979. The acridity factors in taro processing. J. Food Proc. and Preserv. 3:139-144. Murai, M.; F. Pen; and C. D. Miller. 1958. Some Tropical South Pacific Island Foods. Honolulu: Univ. Press of Hawaii. Murphy, D. H. 1973. A preliminary list of insects attacking economic plants in

Literature

Cited

383

Singapore. Tech. Doc. 87, FAO Plant Protection Comm. for SEA and Pac. Region. Nahrstedt, A. 1975a. Cyanogenese der Araceen. Phytochemistry 14:1870-71. Nahrstedt, A. 1975b. Triglochinin in Arum Maculatum. Phytochemistry 14: 1870-1871. Nakasuji, F.; H. Yamanaka; and K. Kiritani. 1973. The disturbing effect of Micryphantid spiders on the larval aggregation of the tobacco cutworm, Spodoptera litura (Lepidoptera: Noctuidae). Kontyu (Japan) 41:220-227. Nakasuji, F.; H. Yamanaka; and K. Kiritani. 1976. Predation of larvae of the tobacco cutworm Spodoptera litura (Lepidoptera: Noctuidae by Polistes wasps). Kontyu (Japan) 44:205-213. Nathan, Richard A. 1978. Fuel from sugar crops. Battele Institute Report to U.S. Dept. of Energy. National Academy of Sciences. 1975. Underexploited tropical plants with promising economic value, pp. 37-43. U.S. Acad, of Sci. NCRR (North Central Regional Research) 93. 1975. Livestock waste management with pollution control. MWPS-19. Iowa State Univ. Neal, Marie C. 1965. In Gardens of Hawaii. Bernice P. Bishop Mus. Spec. Publ. 40:130-65. Nesmith, W. C. 1981. Strategy for using metalaxyl in controlling blue mold of burley tobacco. Phytopathology 71:897. Nip, W. K. 1978. Development and storage stability of drum dried guava- and papaya-taro flakes. J. Food Sci. 44:222-225. Nip, W. K. 1979. Drum-dried pineapple-taro and mango-taro flakes. In: SmallScale Processing and Storage of Tropical Root Crops, ed. D. L. Plucknett, pp. 266-274. Westview Trop. Agr. Series, no. 1. Boulder, Colorado: Westview Press. Nirula, N. K. 1959. Root knot nematode on Colocasia Curr. Sci. (Bangalore) 28:125-126. Norman, J. C. 1972. Tropical leafy vegetables in Ghana. World Crops 24:217-218. Nwana, I. E., and B. E. Onochie. 1979. The technical and social problems of taro processing and storage in Nigeria. In: Small-Scale Processing and Storage of Tropical Root Crops, ed. D. L. Plucknett, pp. 100-109. Westview Trop. Agr. Series, no. 1. Boulder, Colorado: Westview Press. Occhini, P., and C. T. Rizzini. 1958. Acao toxica daus sp. de Dieffenbachia. Res. Brasil. Mod. 15:10. O'Connor, B. A. 1969a. A farmer's guide to pest control. Insects and mites. Dept. of Agr. Bull. 42 (Suva, Fiji). O'Connor, B. A. 1969b. Exotic Plant Pests and Diseases. A Handbook. Noumea, New Caledonia: South Pacific Commission. Okamoto, S. 1966. Effect of mineral nutrition on metabolic change induced in crop plant roots. III. Diurnal periodicity in contents of amino nutrogen of bleeding sap from taro plants as affected by potassium and nitrogen. Soil Sci. Plant Nutr. 12:139-143.

384

Literature Cited

Okamoto, S. 1967a. Glycolic acid oxidase activity in crop plants. Soil Sci. Plant Nutr. 1 3 : 1 3 3 - 1 4 2 . Okamoto, S. 1967b. Effects of potassium nutrition on the glycolysis and the krebs cycle in taro plants. Soil Sci. Plant Nutr. 1 3 : 1 4 3 - 1 5 0 . Okamoto, S. 1969a. Effect of mineral nutrition on metabolic changes in crop plant roots. X. Nitrogenous constituents of bleeding nitrate nutrition solutions with a potassium deficiency. Soil Sci. Plant Nutr. 1 5 : 2 3 5 - 2 4 1 . Okamoto, S. 1969b. The respiration in leaf disks from younger taro plants under a moderate potassium deficiency. Soil Sci. Plant Nutr. 1 5 : 2 7 4 - 2 7 9 . Okamoto, S., and G. Izawa. 1963. Effect of mineral nutrition on metabolic changes induced in crop plant roots. I. Diurnal periodicity in contents of nitrogenous constituents of bleeding sap from taro plants in relation to potassium nutrition. Soil Sci. Plant Nutr. 9 : 9 2 - 9 7 . Olalo, Celestino C. 1975. Production and hectarage of root crops in the Philippines, 1 9 6 3 - 1 9 7 2 . In Root Crops, pp. 5 2 - 5 6 , 61. PCAR Crops Res. Div. Res. Papers. Los Banos: Philippine Council for Agricultural Research. Olsen, C. 1939. Absorption of calcium and formation of oxalic acid in higher green plants. Comptes. Rend. Travaux de Lab Carlsberg, Serie Chimique 23:101-124. Onwueme, I. C. 1978. The Tropical Tuber Crops: Yams, Cassava, Sweet Potato, Cocoyams. New York: Wiley. Ooka, J. J. 1981. Rhizopus stolonifer rot of taro. Phytopathology 71:246 (abst.). Ooka, J. J., and K. Y. Matsuura. 1981. Effectiveness of metalaxyl for control of taro soft rot. Phytopathology 71:897. Ooka, J. J., and B. Yamamoto. 1979. Phythium root and corm rot of Colocasia esculenta in Hawaii. Phytopathology 6 9 : 9 1 8 (abst.). Oomen, H. A. P. C., and S. Malcolm. 1958. Nutrition and the Papuan child. South Pacific Commission Technical Paper 118. Osagie, A. U. 1977. Phytosterols in some tropical tubers. 1977. J. Agr. Food Chem. 2 5 : 1 2 2 2 - 1 2 2 3 . Osisigu, I. U. W.; J. O. Uzo; and E. N. Ogochukwu. 1974. The irritant effects of cocoyams. Planta Medica 2 6 : 1 6 6 - 6 9 . Oyenuga, V. A. 1955. The composition and nutritive value of certain feeding stuffs in Nigeria. I. Roots, tubers and green leaves. Empire J. Exp. Agr. 23:81-95. Oyenuga, V. A. 1959. Nigeria's Feeding Stuffs: Their Composition and Nutritive Value. Ibadan: Ibadan Univ. Press. Paharia, K. D., and P. N. Mathur. 1964. Screening of Colocasia varieties for resistance to Colocasia blight (Phytophthora colocasiae Racib.). Sci. Cult. 30:44-46. Paliwal, G. S., and A. K. Kavathekar. 1972. Anatomy of vegetative food storage argans. Acta Agron. Acad. Sci. Hung. 2 1 : 3 1 3 - 3 1 8 . Papua New Guinea Bureau of Statistics. 1976. Quarterly Price Index Bull. Parham, B. E. V. 1949. Annual report of the economic botanist for the year 1948. Fiji Legislative Coun. Paper 2 4 : 3 1 - 3 5 .

Literature Cited

385

Parker, R. B. 1979. Methodology for determining quality silage. National Feed Ingredients Asso., West Des Moines, Iowa 50265. Parris, G. K. 1939. Diseases of taro. In: Report of the Hawaii Agr. Exp. Sta. 1938, pp. 36-38. Parris, G. K. 1940. A check list of fungi, bacteria, nematodes and viruses occurring in Hawaii and their hosts. Plant Dis. Rep. Suppl. 121:11-12. Parris, G. K. 1941. Diseases of taro in Hawaii and their control, with notes on field production. Hawaii Agr. Exp. Sta. Circ. no. 18. Parsons, S. D. 1975. An event-oriented corn production simulation model. Ph.D. diss., Michigan State Univ. Parsons, S. D., and J. B. Holtman. 1976. An event-oriented corn production simulation model. Amer. Soc. Agr. Engr. Paper no. 76-5539. Parsons, S. D.; L. K. Pickett; J. B. Holtman; and R. B. Fridley. 1971. Modelling man, machine and crop relationships for corn combine simulation. Amer. Soc. Agr. Engr. Paper no. 71-625. Patch, Edith M. 1939. Food-plant catalogue of the aphids of the world. Maine Agr. Exp. Sta. Bull. 393, Orono, Maine. Payne, J. H.; G. J. Ley; and G. Akau. 1941. Processing and chemical investigations of taro. Hawaii Agr. Exp. Sta. Bull. 86. PCARR (Philippine Council for Agriculture and Resources Research.) 1977. The Philippines recommends Gabi 1977. PDC (Plant Disease Clinic). 1980. Plant disease clinic report. Univ. Hawaii Coop. Ext. Serv., with the U.S. Dept. of Agr., Honolulu, Hawaii. PDC. 1981. Plant disease clinic report. Univ. Hawaii Coop. Ext. Serv., with the U.S. Dept. of Agr., Honolulu, Hawaii. Pedrana, C. 1979. Processing of root crop products, especially taro and cassava in Western Samoa. In: Small-Scale Processing and Storage of Tropical Root Crops, ed. D. L. Plucknett, pp. 258-265. Westview Trop. Agr. Series, no. 1. Boulder, Colorado: Westview Press. Perry, C. H. 1977. The ecology and control of some taro pests in Papua New Guinea. Agriculture in the Tropics, Univ. of Papua New Guinea, pp. 319-322. Peters, F. E. 1958. The chemical composition of South Pacific foods. South Pacific Commission Technical Paper 115. Peterson, George D., Jr. 1957. Recent additions to the list of insects which attack crops and other important plants in Guam. Proc. Hawn. Ento. Soc. 16:203-207. Phillips, T. P. 1978. Economic implications of new techniques in cassava harvesting and processing. In.- Cassava Harvesting and Processing, ed. E. J. Weber, James H. Cock, and Amy Chouinard, pp. 66-74. Proc. of a workshop held at CIAT, Cali, Colombia, 24-28 April 1978. IDRC, 114e Ottawa, Canada. Plowman, T. 1969. Folk uses of new world aroids. Econ. Bot. 23:97. Plucknett, D. L. 1970. The status and future of the major edible aroids, Colocasia, Xanthosoma, Alocasia, Cyrtosperma and Amorphophallus. Proc. 2nd Int. Symp. on Trop. Root and Tuber Crops (1970), vol. 1:127-135.

386

Literature

Cited

Plucknett, D. L. 1976. Edible aroids: Alocasia, Colocasia, Cyrtosperma, Xanthosoma. In.- Evolution of Crop Plants, ed. N. W. Simmonds, pp. 10-12. Plucknett, D. L., and R. S. de la Pena. 1971. Taro production in Hawaii. World Crops 23:244-249. Plucknett, D. L., and M. S. White. 1979. Storage and processing of taro in the People's Republic of China. In.- Small-Scale Processing and Storage of Tropical Root Crops, ed. D. L. Plucknett, pp. 119-123. Westview Trop. Agr. Series, no. 1. Boulder, Colorado: Westview Press. Plucknett, D. L.; R. S. de la Pena; and F. Obrero. 1970. Taro (Colocasia esculenta), a review. Field Crop Abst. 23:413-426. Plucknett, D. L.; H. C. Ezumah; and R. S. de la Pena. Mechanization of taro culture in Hawaii. Proc. 3rd Int. Symp. Trop. Root Crops, 1973 (in press). Plucknett, D. L.; D. F. Saiki; and T. S. Motooka, eds. 1969. Weed control basic to agriculture development. Proc. of 1st Asian-Pacific Weed Control Interchange, 12-22 June 1967, Univ. of Hawaii, pp. 90-93. Pond, W. G., and J. H. Maner. 1974. Swine Production in Temperate and Tropical Environments. San Francisco: W. H. Freeman and Co. Potgieter, M. 1940. Taro (Colocasia esculenta) as a food. J. Amer. Dietet. Asso. 16:536-540. Price, J. L. 1970. infrastructure of druse crystal idioblasts in leaves of Cercidium floridium. Amer. J. Bot. 57:1004-09. Purseglove, J. W. 1972. Tropical Crops. Monocotyledons 1, pp. 58-75. New York: Wiley. Quisumbing, F. A. 1914. Cultivated aroids. Philipp. Agriculturist and Forester 3:99-110. Rabbe, R. 1965. Check list of microorganisms and viruses found in Hawaii. Unpublished manuscript. Dept. Plant Pathology, Univ. of Hawaii. Raciborski, M. 1900. Parasitic algae and fungi, Java, Batavia. Bull. New York State Mus. 19:189. Rada, E. L. 1952. Mainland market for taro products. Agr. Econ. Dept. Rep. no. 13. Agr. Exp. Sta., Univ. of Hawaii. Radley, J. A. 1940. Starch and its derivatives. Photomicrograph no. 61. London: Chapman and Hall. Rakovan, J.; A. Kovacs; and J. Szujko-Lacza. 1973. Development of idioblasts and raphides in the aerial root of Monstera deliciosa. Liebm. Acta. Biol. Acad. Sci. Hung. 24:103-18. Ramachandran, K. 1978. Cytological studies on South Indian Araceae. Cytologia 43:289-307. Rao, K. K. 1969. Isolation and characterization of taro ferredoxin. Phytochemistry 8:1379-1386. Rao, K. K., and H. Matsubara. 1970. The amino acid sequence of taro ferredoxin. Biochem. Biophys. Res. Comm. 38:500-506. Rashid, M. M., and H.-J. Daunicht. 1979. Chemical composition of nine edible aroid cultivars of Bangladesh. Scientia Horticulturae 10:127-134. Rasper, V. 1969. Investigations on starches from major starch crops grown in Ghana. I. Hot-paste viscosity and gel-forming power. J. Sci. Food Agr. 20:165-171.

Literature

Cited

387

Reddy, D. B. 1970. A preliminary list of pests and diseases of plants in Western Samoa. Tech. Doc. 77, FAO Plant Protection Comm. for SEA and Pac. Region. Reddy, D. B. 1973. Preliminary list of pests and diseases of principal crops in French Polynesia. Tech. Doc. 89, FAO Plant Protection Comm. for SEA and Pac. Region. Reddy, V. B.; W. F. Meredith; and B. T. Brown. 1968. A note on the relationship between corm yield and certain leaf measurements in taro (Colocasia esculenta [L.] Schott). Trop. Agr. (Trinidad) 45:243-245. Reynolds, S. G.; L. Isaako; and G. Michael. 1977. Foliar nutrition of taro (Colocasia esculenta [L.] Schott) in Western Samoa. Regional Meeting on Production of Root Crops. South Pacific Commission Technical Paper 174:68-72. Rodriguez-Sosa, E. J., and M. A. Gonzales. 1977. Preparation of instant tanier (Xanthosoma sagittofolium) flakes. J. Agr. Univ. Puerto Rico 61:26. Rosa, J. 1936. Notes and exhibitions. Ginger weevil in taro. Proc. Hawn. Ento. Soc. 9:138. Roth, A.; R. M. Worth; and I. J. Lichton. 1967. Use of poi in the prevention of allergic diseases in potentially allergic infants. Ann. of Allergy 25: 501-506. Sakai, W. S. 1977. Raphides with hexagonal cross sections in petals of Vanda Miss Joaquim. Proc. 3rd Ann. Big Island Sci. Conf., Hilo, Hawaii, p. 6a. Sakai, W. S. 1979. Aroid root crops, acridity and raphides. In: Tropical Foods: Chemistry and Nutrition, ed. G. E. Inglett and G. Charalambous, pp. 265-278. New York: Academic Press. Sakai, W. S. 1980. Effect of fruit ripening on raphide structure and irritation in Monstera deliciosa. Plant Physiol. 65 (suppl.): 105a. Sakai, W. S., and M. Hanson. 1974. Mature raphide and raphide idioblast structure in plants of the edible aroid genera Colocasia, Alocasia, and Xanthosoma. Ann. Bot. (London) 38:739-748. Sakai, W. S., and M. Nagao. 1980. Raphide structure in Dieffenbachia maculata. J. Amer. Soc. Hort. Sci. 105:124-26. Sakai, W. S.; M. Hanson; and R. C. Jones. 1972. Raphides with barbs and grooves in Xanthosoma sagittifolium (Araceae). Science (Wash., D.C.) 178:314-315. Sakimura, K. 1956. Notes and exhibitions. Scolothrips pallidus (Beach) on taro. Proc. Hawn. Ento. Soc. 16:7. Sakimura, J., and N. L. H. Krauss. 1944. Thrips from Maui and Molokai. Organothrips bianchii Hood on petioles of taro Molokai. Proc. Hawn. Ento. Soc. 12:113-122. Sastrapradja, S., and G. G. Hambali. 1979. Taro (Colocasia spp.) as a source of carbohydrates and vitamins in Indonesian diets. Int. Symp. Taro and Cocoyam, Baybay, Philippines. Int. Found. Sci. (Stockholm) Prov. Rep. no. 5, pp. 17-28. Sato, T.; M. Kawai; and T. Fukuyama. 1978. Studies on matter production of taro plant (Colocasia esculenta Schott) I. Changes with growth in photosynthetic rate of single leaf. Japan J. Crop Sci. 47:425-430.

388

Literature

Cited

Schimper, A. G. W. 1888. Uber Kalkoxalatbildung in der Lanblattern. Botanische Zeitung. 46:65-69. Schoch, T. J. 1964. Iodometric titration of amylose. In.- Methods in Carbohydrate Chemistry, ed. R. I. Whistler, vol. 4:157-160. New York: Academic Press. Schotz, F.; L. Diers; and H. Bathelt. 1970. Zur Feinstrudtur der Raphidenzellen. I. Der Entwicklung der Vakuolen und Raphiden. Z. Pflanzenphysiol. 63:91-113. Seager, E. A. 1930. Defective diet. Notes on the feeding of indigenous rats on tannia and other tubers, with special reference to the question of toxic effects. Trop. Agr. (Trinidad) 7:120-122. Sedgwick, T. F. 1902. The root rot of taro. Hawaii Agr. Exp. Sta. Bull. no. 2. Sharafi, M. 1977. Starch/polystyrene composites. Master's thesis, Brunei Univ., Uxbridge, England. Sharma, S. C.; Y. N. Shukla; and J. S. Tandon. 1972. Constituents of Colocasia formicata, Sagittaria sagittifloria, Arnebia nobilis, Ipomoea paniculata, Rhododendron nivem, Paspalum scrobiculatum, Mundulea sericea and Duabanga sonneratiodes. Phytochemistry 11:2621-2623. Shaw, D. E. 1975. Illustrated notes on flowering, flowers, seed and germination in taro (Colocasia esculenta). Papua New Guinea Dept. Agr., Stock and Fisheries Res. Bull. 13:39-59. Shaw, D. E.; R. T. Plumb; and G. V. H. Jackson. 1979. Virus diseases of taro. Colocasia esculenta and Xanthosoma sp. in Papua New Guinea. Papua New Guinea Agr. J. 30:71-97. Sherman, G. D.; G. W. Duernberg; H. Seagrave-Smith; and T. Shaw. 1952. Food processors' handbook for Hawaiian fruits and vegetables. Hawaii Agr. Exp. Sta. Progress Notes no. 81. Simonds, H. R.; C. Ellis; and C. W. S. Bigelow. 1943. Handbook of Plastics. London: Chapman and Hall. Smee, L. 1965. Insect pests of sweet potato and taro in the territory of Papua New Guinea; their habits and control. Papua New Guinea J. Agr. 17:99-101. Smith, M. R. 1975. Mechanical harvesting of wetland taro. Amer. Soc. Agr. Engr. Paper 75-1024. Smith, M. R. and H. Shen. 1972. Pickup mechanism for harvesting wetland taro. Trans. Amer. Soc. Agr. Engr. 15:1005-1009. Soldevila, M., and J. Vincente-Chandler. 1978. Tanier corms used as feed for growing pigs. ]. Agr. Univ. Puerto Rico 62:283-289. South Pacific Commission. 1971. Taro Information Circ. 34. Spadaro, J. J.; J. I. Wadsworth; G. M. Ziegler; A. S. Gallo; and S. P. Koltum. 1967. Instant sweet potato flakes: processing modifications necessitated by varietal differences. Food Technol. 21:326. Splittstoesser, W. E. 1977. Protein quality of tropical roots and tubers. Hort. Sei. 12:294-298. Splittstoesser, W. E., and F. W. Martin. 1975. The tryptophan content of tropical roots and tubers. Hort. Sei. 10:23-24. Splittstoesser, W. E.; F. W. Martin; and A. M. Rhodes. 1973. The nutritional

Literature

Cited

389

value of some tropical root crops. Proc. Trop. Region. Amer. Soc. Hort. Sci. 17:290-294. Sproat, M. N. 1968. A guide to subsistence agriculture in Micronesia. Agr. Ext. Bull. no. 9, Saipan, Mariana Islands, Trust Territory of the Pacific Islands. Srivastava, A. S.; R. C. Gupta; B. Singh; and S. Ram. 1969. Damage and control of Meloidogyne javanica (Treub) in Colocasia (C. antiquorum). Labdev. J. Sci. and Technol. Part B. Life Sciences 7B:306-307. Srivastava, A. S.; R. S. Verma; and R. C. Pandey. 1971. Comparative efficacy of different nematocides tested against root-knot nematode infesting colocasia (Colocasia antiquorum). Labdev. J. Sci. and Technol. Part B. Life Sciences 9:142-144. Stahl, E. 1920. Zur physiologie und biologie der exkrete. I. Einleitung. Flora 113:1-132. Standal, B. R. 1970. The nature of poi carbohydrates. Proc. 2nd Int. Symp. on Taro Root and Tuber Crops (1970), vol. 1:146-148. Standal, B. R., and G. K. Kian. 1968. Nutritive quality of simulated milk mixtures prepared from tropical plant products. J. Food Sci. 33:426-431. Standal, B. R.; D. R. Bassett; P. B. Blicor; and M. Thorn. 1970. Fatty acids, cholesterol and proximate composition of certain prepared and unprepared foods in Hawaii. Univ. Hawaii Agr. Exp. Sta. Res. Bull. 146. Stanton, W. R. 1978. The biodégradation of starch-filled plastics in Malaya. "Sago 76" Symp. Vol., Kuching, Malaysia. State of Hawaii, Dept. of Agriculture. 1975. Statistics of Hawaii Agriculture 1974. Prepared by the Hawaii Agricultural Reporting Serv. State of Hawaii, Dept. of Agriculture. 1976. Statistics of Hawaiian Agriculture 1975. Prepared by the Hawaii Agricultural Reporting Serv. State of Hawaii, Dept. of Agriculture. 1981. Statistics of Hawaiian Agriculture 1980. Prepared by the Hawaii Agricultural Reporting Serv. Steele, W. J. C., and G. M. Sammy. 1976. The processing potential of yams (Dioscorea spp.). II. Precooked drum dried flakes—instant yams. J. Agr. Univ. Puerto Rico 60:215. Steinfink, H.; F. G. E. Pautard; and H. J. Arnott. 1965. Crystallography of Caoxalates in plants. Amer. J. Bot. 52:613. Steinke, W. E.; J. R. Carpenter; J. K. Wang; and R. S. de la Pena. 1982. Taro silage: a new feed for the humid tropics. Trans, of the Amer. Soc. Agr. Engr. 25:1034-1036, 1040. Steinke, W. E.; J. K. Wang; J. R. Carpenter; and R. S. de la Pena. 1980. Taro silage: an alternative for the wet tropics. Paper presented at the Amer. Soc. Agr. Engr. Meeting, 2-5 December 1980, Chicago. Stoewsand, G. S.; B. Shadbolt; T. O. M. Nakayama; and J. H. Moy. 1979. The acridity factor in taro processing. J. Food Process. Preservation 3:139-44. Stone, ]. H. 1962. Economic plants encountered on the voyage of the Beagle. Econ. Bot. 10:116-126. Strauss, M. S., and J. Arditti. 1979. Seed culture and micropropagatua of taro. Int. Symp. Taro and Cocoyam, Baybay, Philippines. Int. Found. Sci. (Stockholm) Prov. Rep. no. 5, pp. 279-286. Strauss, M. S.; J. D. Michaud; and J. Arditti. 1979. Seed storage and germination

390

Literature

Cited

and seedling proliferation in taro, Colocasia esculenta (L.) Schott. Ann. Bot. 43:603-612. Strauss, M. S.; G. C. Stephens; C. J. Gonzales; and J. Arditti. 1980. Genetic variability in taro, Colocasia esculenta (L.) Schott (Araceae). Ann. Bot. 45:429-437. Suketa, L., and T. Yamamoto. 1975. Effect of atmosphere fluoride on plants. Biological studies on environmental pollution by fluoride. I. J. Agr. Chem. Soc. Japan 49:341-346. Sunell, L. A., and P. L. Healey. 1978. Distribution of calcium oxalate crystals in taro (Colocasia esculenta). Amer. J. Bot. Misc. Pubi. 156:23. Sunell, L. A., and P. L. Healey. 1979. Distribution of calcium oxalate crystal idioblasts in corms of taro (Colocasia esculenta). Amer. J. Bot. 66:1029-1032. Suzuki, M. 1969. Studies on the irritating substance of Pinellia ternata Breitenbach. Arzneimittel-Forschunr. 19:1307-1309. Suzuki, M.; M. Kano; A. Mitani; F. Mochida; and M. Afriki. 1975. The irritant substance, 3, 4-diglycosilicbensaldehyde, in taro, Colocasia antiquorum. J. Japan Soc. Food Nutr. 28:55-59. Swezey, O. H. 1924a. Notes on insect pests in Samoa. Hawn. Planters' Ree. 28:214-219. Swezey, O. H. 1924b. Notes on insect pests in Samoa. Proc. Hawn. Ento. Soc. 5:385-393. Swezey, O. H. 1932. Notes and exhibitions. Taro leafhopper parasites. Proc. Hawn. Ento. Soc. 8:5, 16. Swezey, O. H. 1938. Notes and exhibitions. Hyperparasite of taro leafhopper. Proc. Hawn. Ento. Soc. 10:23. Swezey, O. H. 1940. A survey of the insect pest of cultivated plants in Guam. Hawn. Planters' Ree. 44:151 -182. Swezey, O. H. 1941. Some injurious insects in Samoa which do not occur in the Hawaiian Islands. Proc. Hawn. Ento. Soc. 11:127-130. Swezey, O. H. 1942. Notes on food habits of Lepidoptera in Samoa. Proc. Hawn. Ento. Soc. 11:202-216. Szent-Ivany, J. J. H., and R. R. Stevens. 1966. Insects associated with Coffee arabica and some other crops in the Wan-Bulolo area of New Guinea. Papua New Guinea Agr. J. 18:101-119. Szylit, O.; L. P. Borgida; H. Bewa; R. Charbonniere; and J. Delort-Laval. 1977. Valeur nutrionnelle pour le poulet en croissance, de cinq amylacés tropicaux en relation avec quelques caractéristiques physico-chimiques de leur amidon. Ann. Zootech. 26:547-563. Takahashi, M. 1953. Report of taro diseases in Hawaii. Mimeographed report to the Hawaii Territorial House (HR no. 28). Taki, M.; T. Yamada; and K. Nakaya. 1972. Studies on the mucilage of tubers of Colocasia antiquorum Shott [sic] var. esculanta [sic] Engl. I. Bull. Fac. Agr. Mie Univ. (Japan) 43:105-113. Taleafoa, F. 1975. Marketing of root crops: taro. South Pacific Commission Regional Meeting on the Production of Root Crops. South Pacific Commission Technical Paper 174.

Literature

Cited

391

Tamura, S. 1970. Amino acid composition of food in Japan. Japan Agr. Res. Quart. 5:56-60. Tandon, R. S., and S. P. Singh. 1974. Two new species of the genus Aphelenchoides Fischer (Nematoda, Aphelenchoididae) from the roots of Colocasia antiquorum Schott. Indian J. Entomol. 36:44-50. Tazaki, T. 1939. On the nature of secretion from Colocasia antiquorum var. esculentum. Bot. Mag. (Tokyo) 53:524-533. Theobald, Frederick V. 1929. The Plant Lice or Aphididae of Great Britain. Vol. III. London: Headley Bros. Timberlake, P. H. 1924. Notes on Hawaiian aphidae, with a list of food plants (Homoptera). Proc. Hawn. Ento. Soc. 5:450-460. Tisbe, V. O., and T. G. Cadiz. 1967. Taro or gabi. In: Vegetable Production in South East Asia, ed. J. E. Knott and J. R. Deanon, Jr., pp. 293-300. Los Banos, Laguna: Univ. of the Philippines Coll. Agr. Titschack, E. 1969. Taro thrips, a new pest in Germany. Anz Schadlingskunde und Pflanzenschutz 42:1 -6. Tooyama, A. 1975. Expression of mosiac symptoms on taro plants from Dasheen mosaic virus infected corms. Ann. Phytopathol. Soc. Japan 41:506-507. Trujillo, E. E. 1965. Effects of humidity and temperature on Phytophthora blight of taro. Phytopathology 55:183-188. Trujillo, E. E. Diseases of the genus Colocasia in the Pacific area and their control. Proc. 1st Int. Symp. onTrop. Root Crops (1967), vol. 2(5): 13-18. Trujillo, E. E., and M. Aragaki. 1964. Taro blight and its control. Hawaii Farm Sei. 13:11-13. Tu, C. C.; W. K. Nip; and T. O. M. Nakayama. 1979. Starch and flour from taro. In: Small-Scale Processing and Storage of Tropical Root Crops, ed. Donald L. Plucknett, pp. 249-257. Westview Trop. Agr. Series no. 1. Boulder, Colorado: Westview Press. Uchida, Hajime. 1959. On some collembolans injurious to upland taro Colocasia antiquorum Schott var. esculenta Engler. Japan J. Appl. Ento. Zool. 3:145-146. U. S. Department of Agriculture (USDA). Economic Research Service. 1971. Indices of Agricultural Production in Africa and the Near East. U. S. Department of Agriculture (USDA). 1980a. Foreign Agriculture Circ. FG14-80, World Food and Agriculture Outlook and Situation Board, 1 May 1980. U. S. Department of Agriculture (USDA). 1980b. Small Scale Fuel Alcohol Production, chap. IV. U. S. Department of Commerce, Bureau of Census. 1979. Statistical Abstract of the United States, 10th ed. U. S. Department of Energy (USDE). 1977. Alcohol Fuels Policy Review. U. S. Department of Health, Education and Welfare (USDHEW). 1972. Food Composition Table for Use in East Asia. Usinger, Robert L. 1939. Distribution and host relationships of Cyrtorhinus (Hemiptera: Miridae). Proc. Hawn. Ento. Soc.lO:271-273. van Hoof, H. A. 1971. Zantedeschia aethiopica. In: Ann. Rep. Inst. Planten-

392

Literature Cited

ziektenk, pp. 8 7 - 8 8 . Onderzoek, Binnenhaven 12, Wageningen, The Netherlands. Vasudevan, D. N.; J. S. Jos; and M. L. Magoon. 1968. Radiation-induced mutations in Colocasia esculenta (L.) Schott. Indian J. Hort. 2 5 : 6 6 - 6 9 . Vieth, G. R.; B. W. Begley; and W. Y. Huang. 1980. The economics of wetland taro production in Hawaii. Hawaii Agr. Exp. Sta. Agr. Econ. Dept. Paper 60. Vijaya Bai, K.; M. L. Magoon; and R. Krishnan. 1971. Meiosis and pollen mitosis in diploid and triploid Colocasia antiquorum Schott. Genetica (The Hague) 4 2 : 1 8 7 - 1 9 8 . Volin, R. B., and F. W. Zettler. 1976. Seed propagation of cocoyam, Xanthosoma caracu Koch and Bouche. Hort. Sci. 11:459-460. Von Bargen, K. 1970. Analysis and simulation of a field machine and transport system for row-crop planting. Ph.D. diss., Purdue Univ., West Lafayette, Indiana. Von Bargen, K., and R. M. Peart. 1973. Simulation of field machine and transport activities for a row crop planting system. Trans. Amer. Soc. Agr. Engr. 16:1010. Wada, K.; T. Hase; H. Tokunaga; and H. Matsubara. 1975. Amino acid sequence of spirulina platensis ferredoxin: a far divergency of blue-green algae ferredoxins. Fed. European Biochem Soc. (FEBS) Lett. 5 5 : 1 0 2 - 1 0 4 . Wallace, C. R. 1963. Checklist of Sarawak insects of economic importance. Tech. Doc. 51, FAO Plant Protection Comm. for SEA and Pac. Region. Dieffenbachia Walter, W. G., and P. N. Khanna. 1971. Chemistry of the Aroid I. sequine, amoena, and picta. Econ. Bot. 2 6 : 3 6 4 - 3 7 2 . Wang, J. K., and K. Nagarajan. 1981. An integrated taro production system for the humid tropics. Int. Found, for Sci. (Stockholm) Prov. Rep. no. 11, pp. 234-254. Wang, J. K., and K. K. Otagaki. 1979. An overview: systems approach to root crop research. In: Small-Scale Processing and Storage of Tropical Root Crops, ed. Donald L. Plucknett, pp. 3 - 1 2 . Westview Trop. Agr. Series no. 1. Boulder, Colorado: Westview Press. Wang, J. K., and W. E. Steinke. 1979. Effect of storage on paddy taro production system efficiency. In: Small-Scale Processing and Storage of Tropical Root Crops, ed. Donald L. Plucknett, pp. 169-186. Westview Trop. Agr. Series no. 1. Boulder, Colorado: Westview Press. Wang, J. K.; W. E. Steinke; and ]. R. Carpenter. 1981. Food, feed and fuel from taro. Paper presented at the Int. Conf. on Agricultural Engineering and Agro-Industries in Asia, 1 0 - 1 3 November 1981, Bangkok, Thailand. Wang, J. K., and R. E. Hagan. 1980. Irrigated Rice Production Systems: Design Procedures. Boulder, Colorado: Westview Press. Warid, W. A. 1970. Trends in the production of taro in Egypt (United Arab Republic). Proc. 2nd Int. Symp. on Trop. Root and Tuber Crops (1970), vol. 1:141-42. Warid, W. A. 1973. Production and improvement of edible aroids in Africa. Proc. 2nd Int. Symp. on Trop. Root and Tuber Crops (1970), vol. 2 : 3 9 - 4 4 .

Literature

Cited

393

Watson, L. J. 1970. The legal importance of water requirements of taro Colocasia esculenta in Hawaii. Proc. 2nd Int. Symp. on Trop. Root and Tuber Crops (1970), vol. 1:149-151. Watt, B. K., and A. L. Merrill. 1963. Composition of food. U.S. Dept. of Agriculture Handbook no. 8. Wattendorf, J. 1969. Feinbau and Entwicklung der verkorkten CalcuimoxalatKristalzellen in der Rinde von Larix decidua Mill. Z. Pflanzenphysiol. 60:307-47. Wattendorff, J. 1976. A third type of raphide crystal in the plant kingdom. Planta 130:303-311. Wenkam, N. S., and F. L. Thong. 1969. Sodium and potassium in some Hawaii foods. Hawaii Med. J. 28:209-212. Western Samoa, Dept. of Agriculture, Fisheries and Forests. 1957a. Laufasi Ola Information Circ. Vol. 2(3). Western Samoa, Dept. of Agriculture, Fisheries and Forests. 1957b. Laufasi Ola Information Circ. Vol. 2(7). Westgate, J. M. 1918. Composition and digestibility of feeding stuffs grown in Hawaii. Hawaii Agr. Exp. Sta. Bull. no. 53, pp. 1-26. Whitney, L. D. 1937. Some facts about taro: staff of life in Hawaii. Paradise of the Pacific 49:15,30 (cited in Shaw, 1975). Whitney, L. D.; F. A. I. Bowers; and M. Takahashi. 1939. Taro Varieties in Hawaii. Hawaii Agr. Exp. Sta. Bull. No. 84, Univ. of Hawaii. Whitney, P. J. and W. Williams. 1976. Biodégradation of a polyethylene composite. IUPAC Int. Symp., Stockholm, 1976 (in press). Wilder, G. P. 1923. The taro, or kalo in Hawaii. Prepared for the Univ. Hawaii Ext. Div. (cited in Shaw, 1975). Williams, F. X. 1936. Biological studies in Hawaiian water-loving insects. Proc. Hawn. Ento. Soc. 9:235-349. Willimott, S. G. 1936. A study of Colocasia (Colocasia antiquorum). Cyprus Agr. J. 31:94-108. Wilson, J. E. 1979a. Promotion of flowering and production of seed in cocoyam (Xanthosoma and Colocasia) Int. Symp. Taro and Cocoyam, Baybay, Philippines. Int. Found. Sci. (Stockholm) Prov. Rep. no. 5, pp. 269-277. Wilson, J. E. 1979b. Progress in the breeding of cocoyam (Colocasia and Xanthosoma). Int. Symp. Taro and Cocoyam, Baybay, Philippines. Int. Found. Sci. (Stockholm) Prov. Rep. no. 5, pp. 299-308. Winton, A. L., and K. B. Winton. 1935. Corms, shoots, and petioles of the arum family (Araceae). In: The Structure and Composition of Foods. Vol. II. Vegetables, Legumes and Fruits, pp. 130-134. New York: Wiley. Wolf, M. J.; M. M. MacMasters; and C. E. Rist. 1950. Some characteristics of the starches of three South American seeds used for food. Cereal Chem. 27:219. Wrigley, G. 1969. Tropical Agriculture: The Development of Production. New York: Praeger. Yamanaka, H.; F. Nakasuji; and K. Kiritani. 1972. Life tables of the tobacco

394

Literature

Cited

cutworm, Spodoptera litura (Noctuidae) and an evaluation of the effectiveness of natural enemies. Japan. J. of Appl. Ent. and Zoo. 1 6 : 2 0 5 - 2 1 4 . Yamashita, E., and N. Yoshikawa. 1973. Studies on the mucilage in satoimo (Colocasia antiquorum Schott var. esculenta Engl.) J. Japan Soc. Food Nutr. 2 6 : 3 0 3 - 3 0 7 . Yarbrough, J. A. 1934. Stomatal count of a single leaf of Colocasia. Proc. Iowa Acad. Sci. 4 1 : 7 1 - 7 3 . Yau, C. H. W. ; W. K. Nip; and C. C. Tu. 1979. Correlation of raphides with acridity of taro fraction. Paper presented at the 39th Annual Meeting of Inst, of Food Technologists, St. Louis, Missouri. Yen, D. E., and J. M. Wheeler. 1968. Introduction of taro into the Pacific: the indications of the chromosome numbers. Ethnology 7 : 2 5 9 - 2 6 7 . Yong, C. W. 1971. Yield and growth responses of some leguminous and root crops grown on acid peat to magnesium lime. Malaysian Agr. J. 48:142-157. Young, R. A. 1913. The dasheen, a root crop for the southern states. U.S. Dept. of Agr. Bureau Plant Industry Circ. 1 2 7 : 2 5 - 3 6 . Young, R. A. 1917. The dasheen: its uses and culture. 1916 Yearbook, U.S. Dept. of Agr., pp. 1 9 9 - 2 0 8 . Young, R. A. 1924a. Taros and yantias: promising new food plants for the South. Bull. 1247, U.S. Dept. of Agr. Young, R. A. 1924b. The dasheen: a southern root crop for home use and market. Farmers' Bull. 1396, U.S. Dept. of Agr. Young, R. A. 1936. The dasheen: a southern root crop for home and market. Farmers' Bull. 1924, U.S. Dept. of Agr. Zettler, F. W. ; M. J. Foxe; R. D. Hartman; J. R. Edwardson; and R. C. Christie. 1970. Filamentous viruses infecting dasheen and other araceous plants. Phytopathology 6 0 : 8 9 3 - 8 9 7 .

Index

Acari (mites), 185, 187 Acetic acid, 279, 2 8 0 Acridity, 145, 1 4 8 - 1 6 3 , 265, 2 7 0 - 2 7 1 , 300; chemical theories of, 1 5 6 - 1 6 1 ; dietary effects, 1 5 0 - 1 5 1 , 152, 153; principles, 10, 148, 150, 1 6 1 - 1 6 3 ; and toxicity, 1 4 9 - 1 5 0 , 2 7 2 - 2 7 3 , 278. See also C a l c i u m oxalate crystals Aedes simpsoni, 189 Africa, 7, 14, 145, 269; t a r o p r o d u c t i o n in, 3, 5, 141, 346, 3 4 8 Agricultural p r o d u c t i o n systems. See Prod u c t i o n systems Agriculture, U.S. D e p a r t m e n t of, 3, 1 1 , 2 1 A k a d o p l a n t variety, 173 Alcohol, f r o m taro, 3 0 4 - 3 0 6 , 337, 342-345 Alkaloids, 1 3 6 - 1 3 8 Allergenicity of taro, 147, 2 6 1 - 2 6 2 Alomae disease, 183, 2 5 1 - 2 5 2 , 2 5 3 Alphitobius laevigatus, 190, 191 Amaranthus cruentus starch, 302 Amaranthus leucosperma starch, 302 Amaranthus paniculatus starch, 302 A m e r i c a n Samoa, 3, 243, 261, 2 9 5 - 2 9 7 A m i n o acids, level of: in t a r o plants, 1 0 7 129, 142, 144; in t a r o silage, 285, 286, 287, 2 8 9 A m i n o acid sequence, 43, 46, 47, 74, 75. See also Photosynthesis A m m o n i u m nitrogen, 35 A n i m a l feeds: chemical a n d mineral composition of tropical feedstuffs, 298; c o m p a r i s o n of feed costs, 297; potential

of, f r o m taro, 1 0 - 1 2 , 2 6 9 - 2 7 3 , 2 9 5 297. See also Silage Anthocyanins, levels of, 53, 1 3 6 - 1 3 8 Aphis gossypii, 183 Apii plant variety, 173 Apuwaii plant variety, 145 Araceae family, 3, 14, 17, 141, 1 8 0 - 1 8 1 ; acridity, 148; toxicity, 1 4 9 - 1 5 0 ; yields of, 2 7 4 - 2 7 5 Araimo. See Dasheen p l a n t variety Aroids. See A r a c e a e family Artiodactyla, 188 Ascorbic acid, 142, 143 Asia, t a r o p r o d u c t i o n in, 3, 5, 141, 3 4 8 Asia Vegetable a n d Research Development C e n t e r (AVRDC), T a i w a n , 13 Astacops, 183 Australia, 2 4 0

Bacterial leaf spot, 2 5 3 Bacterial soft rot, 2 5 3 Bangladesh, 14 Big Lehua plant variety, 173 Black rot, 2 4 9 Bobone disease, 183, 251, 2 5 2 - 2 5 3 Botanical N o m e n c l a t u r e , I n t e r n a t i o n a l Rules of, 15 Brachylybas variegatus, 183 Brazil, 261 Bread c o n s u m p t i o n , increase of, 6 - 7 Bun-Long p l a n t variety, 145, 146, 173, 183, 266, 276; in silage experiment, 277, 281, 286, 287

396 Burma, 3 Butyric acid, 279, 280 Cadra cautella, 190 Calcium, 35-36, 57, 297, 346; deficiency, 36 Calcium oxalate crystals, 35, 53, 136138, 142, 146, 147; as cause of acridity, 145, 148, 151-158, 161-162 Canned and frozen foods, 266-267 Carbohydrates, 141, 142 Caroline Islands, 243 Carotenes, 53, 136-138, 142, 143, 146 Cassava, 6, 12-13, 147 Cattle, and animal feed experiments, 280 Central America, 14 Central Food Technological Research Institute, Mysore, India, 263 Chemical constituents, levels of, in plants, 53-55, 89-106 Chickens, and animal feed experiments, 271-272 China, 3, 17, 34 Chlorophyll, level of, in plants, 54, 136-138 Chromosome numbers, 16, 17, 18, 2 9 - 3 0 , 33 Cladosporium leaf spot, 2 4 3 - 2 4 5 Climate; optimum conditions, 167-168, 270, 274; and root crop distribution, 8 Cocoyam, 17, 141. See also Species, nomenclature for Coleopteral (beetles), 184, 187 Collembola (springtails), 187 Colombia, 13 Consumption, worldwide, 5, 359 Cook, Captain James, 3, 34 Cook Islands, 187 Cormels, 19, 23; as animal feed, 273; chemical constituents, 53, 89-139; fertilization effects on, 38, 4 0 - 4 1 , 42, 43, 72-73; nutrients in, 36, 38, 57; planting and harvesting of, 172, 176-177, 178, 179 Corms, 19, 23-26, 141, 346; acridity, 10, 142, 151, 153; as animal feed, 11, 271-273; chemical constituents, 53, 54, 61, 71, 89-140, 142, 147, 316; and chromosomes, 16, 17, 18; diseases in, 174, 236, 239, 240-241, 245-250, 253-255; fertilization effects on, 37-38, 4 0 - 4 1 , 42, 43, 69, 71, 72-73; nutrients in, 38, 61, 142-145; pest damage to, 181, 186-188, 190-191, 214-219; planting and harvesting of, 172, 176-177, 178, 179; as processed

Index food, 261-267 passim; in silage, 281, 285; sprouting in storage, 5 2 - 5 3 , 88; use of, in integrated production, 335-344 Cosmetics, 312 Cytology. See Chromosome numbers Cyrtorhinus fuluus, 184, 189 Cyrtosperma chamissonis, 185 Darwin, Charles, 34 Dasheen mosaic disease, 251, 252 Dasheen plant varieties, 16, 17, 172, 173, 175, 273 Dieffenbachia plant genus, 149, 156, 157, 158-159 Digestibility. See Silages digestibility Diptera (flies), 184, 187 Diseases, causes and controls, 236-257; from bacteria, 239, 253; from fungi, 239-250; from herbicides, 256; from nematodes, 239, 253-254; and pathogens, 236-239; from physical disorder, 255; from soils, 256-257; from uncertain conditions, 254; from viruses, 239, 251-253 Dorylaimide (needle nematodes), 188 Druses. See Calcium oxalate crystals Dryland plants. See Upland plants East Africa, 185 Eddoe, 17. See also Species, nomenclature for Egypt, 14, 34, 251 Ensiling. See Animal feed; Silage, process of Environmental Protection Agency (EPA), 192, 238 Ethanol. See Alcohol Fatty acids, levels of, in plants, 54, 139 Ferredoxin. See Amino acid sequence Fertilization, and plants, 3 7 - 3 9 , 4 1 - 4 3 , 66-69, 274-276 Fiji, 191, 265-266, 337-340, 349; plant diseases in, 240, 247, 251 Florida, 251 Flour, processed from taro, 4, 6 - 7 , 261, 262-264, 267, 268 Flowers, 27-28, 47, 50, 81; and parts, diagram of, 48 Food and Drug Administration (FDA), 192 Food Industry Research and Development Institute, Taiwan, 265 French Polynesia, 274

Index Fuel alcohols, from taro starch, 302, 3 0 4 306; in integrated production system, 335-345 Fungicides, 235, 238, 240, 242 Fungus mycelia, 147 Fusarium dry rot, 250 Galen Co., Inc., Berkeley, California, 264 Geographical history, 3, 14, 34, 141, 346 Germination. See Seeds and seedlings Gesonula punctifrons, 182 Ghana, 349, 352, 354 Glucoside theory, and acridity, 159-161 Glycolic acid oxidase, 37 Glyphosate Isopropylamine Salt, 256 Growth period, 43, 47, 7 6 - 7 7 , 274 Gruiformes (birds), 188 Gryllotalpa africana, 189 "Guava seed." See Hard rot disease Gums. See Mucilages Haokea plant variety, 173, 241 Hapuu plant variety, 173, 254 Hard rot disease, 2 5 4 - 2 5 5 Harvesting, process of, 1 7 5 - 1 7 9 Hawaii, 3, 4 - 5 , 38, 167; animal feeds, 271, 337, 340; food uses in, 3 - 4 , 145, 261, 264, 265, 266, 267; harvesting in, 1 7 5 - 1 7 9 ; lowland planting process, 168, 169, 170, 274; nutrients, 142, 1 4 5 - 1 4 6 ; pests in, 183; production systems in, 7, 3 4 9 - 3 5 l ; t a r o diseases in, 236, 239, 2 4 0 - 2 4 2 , 243, 245, 247, 249, 251, 254, 255; registered pesticides, 235; varieties, 6, 18, 1 7 2 - 1 7 3 , 237, 317 Hawaii Agricultural Experiment Station, 262, 263, 266, 267 Hawaii Island, 173, 175 Hawaiian Taro Products, Ltd., 264 Heliothrips haemorrhoidalis, 183 Hemiptera (Heteroptera) (true bugs), 183, 186, 187 Herbicides, 235, 256 High fructose enriched syrup (HFES), 303-304 Homoptera (aphids, leafhoppers, mealybugs, planthoppers, scales, and whiteflies), 183-184, 186, 187 Huli. See Setts Hymenoptera (ants, bees, wasps), 185, 189 India, 3, 4, 346; food uses in, 141, 261, 263; nutrient composition of taro, 142,

397 143, 1 4 5 - 1 4 6 ; taro diseases in, 239, 247 Indonesia, 3 Infant food, 264 Insecticides, 1 9 1 - 1 9 2 , 235 Insects, 180, 1 8 1 - 1 8 2 , 1 8 9 - 1 9 0 , 191, 2 3 0 - 2 3 3 . See also Pests, plant International Centre for Tropical Agriculture (CIAT), Colombia, 13 International Institute for Tropical Agriculture (UTA), Nigeria, 13 International Potato Centre (CIP), Peru, 13 Invertebrates. See Pests, plant Iodine affinities in starch, 303, 304 Irrigation, process of, 168, 1 7 3 - 1 7 5 , 356, 358; in integrated production system, 317. See also Water relations Ishikawase plant variety, 39 Isopoda (pillbugs, woodlice), 185 Isoptera (termites), 187 Japan, 17, 30; plant diseases in, 239, 251 Java, 239 Kai Kea plant variety, 246, 254 Kai Uliuli plant variety, 173, 246, 254 Kalo (talo), 17. See also Species, nomenclature for Kauai, 173, 175, 177, 287; production on, 6, 3 4 9 - 3 5 1 Lactic acid, level in taro silage, 2 7 6 - 2 7 7 , 279-284 Lambs, and animal feed experiments, 296, 300 Land use, management strategies for, 319, 3 2 0 - 3 2 3 ; Type I, 320, 323, 324, 326, 328, 329, 330, 332; Type II, 320, 323, 325, 326, 327, 328, 330, 331, 332 Lasioderma serricorne, 190, 191 Leaves, 20, 2 1 - 2 3 , 24, 32, 172, 173, 179; acridity, 10, 151, 152; chemical constituents, 53, 8 9 - 1 3 9 ; as cooked food, 4, 141, 261; diseases in, 3 6 - 3 7 , 236, 2 3 9 245, 2 5 1 - 2 5 3 , 2 5 6 - 2 5 7 ; fertilization effects on, 3 7 - 3 8 , 4 0 - 4 3 , 5 8 - 5 9 , 6 2 73; laminae of, 2 1 - 2 2 ; nutrients in, 11, 12, 143, 1 4 5 - 1 4 6 , 147, 271, 272, 346; pest damage to, 182-185, 1 9 3 - 2 1 0 ; and photosynthesis, 39, 4 4 - 4 5 ; in silage, 2 7 4 - 2 7 6 , 2 7 7 - 2 9 5 , 296; stomata of, 21, 23, 39; use of, in integrated production, 3 3 5 - 3 4 4 ; and water content, 3 4 - 3 5 , 316 Leeuwenhoek, Anthony van, 155

398 Lehua Keokeo plant variety, 146, 147, 173 Lehua Maoli plant variety, 6, 1 5 0 - 1 5 1 , 173, 276; diseases of, 241, 2 4 6 - 2 4 7 ; poi production from, 261, 317, 334; in silage experiments, 281, 286, 287, 294 Lehua Palaii plant variety, 173 Lehua plant variety, 277, 279, 280 Lepidoptera (moths and butterflies), 184, 186, 187 Linear programming (LP) model, 321, 333 Linnaeus, Carolus, 14 Loliloli disorder, 255 Lowland plants, 173, 286; comparative costs, 3 5 0 - 3 5 1 ; diseases of, 236, 243; fertilization of, 3 7 - 3 8 , 63, 65, 67; growth of, 3 1 5 - 3 1 6 , 317, 318, 3 2 0 323, 350; irrigation of, 168, 1 7 3 - 1 7 5 , 315; planting and harvesting of, 169170, 1 7 5 - 1 7 6 ; production systems for, 3 2 0 - 3 2 3 , 3 2 6 - 3 2 7 ; and soil, 167, 168, 169; yields from, 317, 318 Lyon Arboretum, plant varieties in, 173 Malaysia, 26, 346 Mana plant group, 18, 254 Manini Kea plant variety, 254 Manini Uliuli plant variety, 242 Mariana Islands, 243 Maui, 173 Maui Lehua plant variety. See Big Lehua plant variety Melanesia, 3, 4, 240 Mice, and animal feed experiments, 150151, 152, 153, 278 Micronesia, 240 Millipedes, 185 Mineral analysis, fresh taro and silage, 281, 285 Minerals, levels of, in plants, 54, 1 3 2 - 1 3 5 Mineral analysis, fresh taro and silage, 281, 285 Mucilages, 25, 5 4 - 5 5 , 312 Myzus persicae, 183 Nematicides, 191, 235 Netherlands, 251 New Caledonia, 30, 245 New Guinea, 191, 240 New Hebrides, 3, 243, 245 New Zealand, 30, 33, 337 Nigeria, 3, 7, 13; processed food in, 2 6 3 264, 266; comparative prices in, 352, 354

Index Nitrogen fertilizer, 35, 3 7 - 3 8 , 4 0 - 4 3 , 64, 65, 7 2 - 7 3 , 2 7 5 - 2 7 6 Niue, 3 Niue plant variety, 277, 281, 286, 287 Nomenclature. See Species, nomenclature for Nutrient, taro, composition of, 1 4 3 - 1 4 4 , 272, 2 8 8 - 2 8 9 Oahu, 173 Oceania, 14, 145, 2 3 9 - 2 4 0 , 269; world production in, 3, 5, 141, 346, 348 Odonata (dragonflies and damselflies), 186 Oga plant variety, 247 Ohe plant variety, 173 Organophosphate insecticides, 191 Organothrips bianchi, 186 Orthoptera (grasshoppers and crickets), 182 Oryzaephilus mercator, 190, 191 Oxalic acid, 35, 1 3 6 - 1 3 8 , 142, 145, 146, 147. See also Calcium oxalate crystals Pacific. See Oceania Papuana, 187 Papua New Guinea, 3, 4, 5; comparative prices in, 3 5 1 - 3 5 2 , 353; taro diseases in, 251 Peru, 13 Pesticides, 181, 1 9 1 - 1 9 2 , 235, 2 5 3 - 2 5 4 Pests, plant, 1 8 0 - 2 3 5 ; classification of, 1 8 0 - 1 8 2 ; control, 192; invertebrates, 180-191 passim, 2 5 3 - 2 5 4 ; parasites and predators of, 1 8 8 - 1 8 9 , 2 2 0 - 2 2 9 ; vertebrates, 180, 181, 185, 188. See also by specific scientific name Petioles, 19, 22, 23, 25, 29, 141, 172, 179; acridity, 10; as animal feed, 272, 297; chemical constituents, 53, 8 9 - 1 3 9 ; fertilization effects on, 38, 4 0 - 4 1 , 42, 70, 2 7 4 - 2 7 6 ; nutrients in, 11, 12, 36, 37, 38, 143, 146; pest damage to, 186, 211-213 Phalaris canariensis starch, 302 Philippines, 3, 30, 167, 191, 261; comparative prices in, 352, 354; taro diseases in, 2 3 9 - 2 4 0 , 247; nutrient composition of taro, 142, 143, 1 4 5 - 1 4 6 ; production in, 346, 347 pH levels, importance of: in disease development, 237, 256, 257; in silage, 276, 2 7 9 - 2 8 4 , 294, 295 Phosphate, 346; as fertilizer, 3 7 - 3 8 , 66-69

399

Index Photosynthesis, process of, 39, 43, 45. See also Amino acid sequence Phytophthora leaf blight, 236, 238, 239-242 Pigments, 1 3 6 - 1 3 8 Pigs, 159, 188; and animal feed experiments, 295, 297, 299, 300; in integrated production system, 3 3 5 - 3 4 5 Piko Eleele plant variety, 173 Piko Kea plant variety, 173 Piko plant group, 18, 21 Piko Uaua plant variety, 2 4 6 - 2 4 7 Planococcus "citri," 183 Plant culture, and other organisms, 1 8 9 190, 2 3 0 - 2 3 4 Planting, process of, 1 6 8 - 1 7 2 Plant parts, diagram of, 19 Plastics, filler for, 3 0 6 - 3 1 2 Plodia interpunctella. 190, 191 Poi, 4, 141, 2 6 1 - 2 6 2 ; as animal feed, 271; as preventer of health problems, 4 - 5 , 147, 2 6 1 - 2 6 2 ; production in Hawaii, 173, 317, 334, 3 4 9 Polynesia, 3, 4, 17, 3 4 6 Porphyria porphyrio, 188 Potassium, 36, 5 8 - 5 9 , 142, 146, 297; deficiency, 3 6 - 3 7 ; as fertilizer, 37, 38, 42, 43, 5 8 - 5 9 , 62, 63 Price of taro, 337, 351, 3 5 3 - 3 5 4 Processed products, 4, 2 6 1 - 2 6 8 ; as beverage powder, 264; canned and frozen, 2 6 6 - 2 6 7 ; as cereals, 264; as extruded foods, 2 6 7 - 2 6 8 ; as flakes, 2 6 4 - 2 6 5 ; as slices and chips, 2 6 5 - 2 6 6 ; and pests of, 1 9 0 - 1 9 1 . See also Flour, processed from taro Production. See Worldwide taro production; Yields Production costs, in Hawaii, 351 Production systems: evaluation, 3 5 7 - 3 5 8 ; goals, 7, 3 1 5 - 3 1 7 , 3 3 3 - 3 3 4 ; integration of, 3 3 4 - 3 4 5 ; management strategies, 3 5 5 - 3 5 7 ; steady supply, 3 2 3 - 3 2 6 Proteins, 147, 270, 297; and acridity, 1 5 8 - 1 5 9 ; levels of, in plant, 11, 53, 1 0 7 - 1 2 9 , 142, 1 4 4 - 1 4 5 , 285, 287, 300, 3 4 6 Proximate analysis of fresh taro and silages, 281 Puerto Rico, 245

Radiation effects, 46, 78 Rainfall, 167, 175, 274; disadvantages of, for field drying, 270, 316; essential to production systems, 3 5 8

Raphides, 24, 26, 27, 53, 142, 1 5 2 - 1 5 8 . See also Calcium oxalate crystals Rats, and animal feed experiments, 1 5 0 151, 152, 153, 2 7 2 - 2 7 3 Red Manaura plant variety, 2 7 4 Red Moi plant variety, 173 Rhizopus rot, 2 4 9 - 2 5 0 Rice starch, 302, 312 Rodentia (porcupines, rats, mice), 185, 188

Root crops, 6; as animal feed, 10; and climate variations, 8; neglect of, 3, 5, 6, 34; research in, need for, 1 2 - 1 3 , 359-360 Roots, 26; diseases in, 174, 236, 2 4 5 - 2 4 7 , 2 5 3 - 2 5 4 , 315; fertilization effects on, 36, 37, 38, 4 0 - 4 1 , 42, 60, 71, 7 2 - 7 3 ; pest damage to, 1 8 6 - 1 8 8 , 2 1 4 - 2 1 9 Saint Vincent Islands, 3 4 9 Samoa. See American Samoa; Western Samoa Saponaria vaccaria starch, 302 Sato Imo, 5 4 - 5 5 Satoimo. See Sato Imo Science, National Academy of, 3 5 9 Sclerotium blight, 2 4 7 - 2 4 8 Seeds and seedlings, 2 8 - 3 3 , 49; germination of, 5 0 - 5 2 , 79, 80, 81 Setts, 170, 172, 177, 178; diseases in, 246, 248; irrigation of, 1 7 3 - 1 7 4 ; spacing of, 1 6 9 - 1 7 0 ; sprouting of, 43, 47, 76-77 Shanghai, People's Republic of China, 267 Sierra Leone, 147 Silage, 300; acridity, 278; fermentation process, 2 7 6 - 2 8 1 ; in vitro true digestibility of silage, 286, 287, 288, 2 9 0 291, 2 9 4 - 2 9 5 , 300; in vivo dry matter digestibility of silage, 2 9 4 - 2 9 5 , 300; nutritive value, 2 8 1 - 2 8 9 , 2 9 0 - 2 9 3 ; palatability and digestibility, 289, 2 9 0 291, 2 9 4 - 2 9 5 ; pH and lactic acid content, 2 8 2 - 2 8 4 ; and production system model, 3 3 3 - 3 4 5 . See also Animal feed Sitophilus oryzae, 190, 191 Soft rot disease, 273 Soil, 3 5 - 3 6 , 167, 1 6 8 - 1 6 9 , 270; diseases in, 191, 253, 2 5 6 - 2 5 7 Solomon Islands, 3, 30, 50, 191, 240, 245; diseases in, 240, 242, 247, 251 South America, 14 Southeast Asia, 14, 145, 3 4 6 Species, nomenclature for, 1 4 - 1 5 , 16, 17, 141 Spodoptera litura, 184, 186, 189

400 Spongy black rot, 248 Sri Lanka, 3 Staple crops, and production costs, comparison of, 3 5 1 - 3 5 4 Starch: fuel alcohols, 3 0 4 - 3 0 6 ; high fructose syrup, 3 0 3 - 3 0 4 ; industrial potential, 3 0 1 - 3 0 2 , 312; plant levels, 43, 54, 141; plastics, 3 0 6 - 3 1 2 ; other uses, 312 Starch particles, size of, 4, 5, 302, 303, 304, 306, 308 Stems. See Petioles Sterols, levels of, in plant, 54, 140 Stylommatophora (snails, slugs), 185, 188 Sugars, levels of, in plant, 43, 54, 55 Sweet potatoes, 5, 6, 12-13, 147, 264 Swine. See Pigs Syrup, high fructose enriched, 3 0 3 - 3 0 4 Tahiti, 5, 145, 146 Taiwan, 13, 265, 269; taro diseases in, 239 Talles (tallus), 17. See also Species, nomenclature for Tannia plant variety, 2 7 2 - 2 7 3 Tapioca starch, 302 Taputimu Experiment Farm, American Samoa, 295 Ta-Ro-Co beverage, 264 Tarophagus proserpina, 183, 184, 186, 189, 253 Taro silages. See Silage Taro tops. See Leaves; Petioles Temperature, starch gelatin, 303; irrigation water, 174, 315 Thailand, 50 Thysanoptera (thrips), 1 8 2 - 1 8 3 , 186 Tiapuli. See Setts Tobago, 349 Tonga, 3 Tooth decay, prevention of, 4 - 5 Tribolium castaneum, 190, 191 Tribolium confusum, 190, 191

Index Trinidad, 349 Tropical Agriculture and Human Resources, College of. University of Hawaii, 11 Tubers. See Corms Tylenchida (root knot nematodes), 188 United States, 3, 4, 147, 304; registered pesticides in, 192 University of California, Irvine, 21 Upland plants, 167, 168, 173, 274, 275, 286; diseases of, 236, 242, 243, 247, 253; fertilization of, 3 7 - 3 8 , 62, 64, 66, 2 7 5 - 2 7 6 ; growth of, 315, 350; planting and harvesting of, 168-171, 178; and water availability, 175, 315 USDA. See Agriculture, U.S. Department of Venezuela, 251 Vertebrates. See Pests, plant Vitamins, levels of, in plants, 54, 130131, 346 Water relations, 276, 315, 358; and plant transpiration, 3 4 - 3 5 , 56. See also Irrigation Western Samoa, 3, 147, 191; food uses in, 261, 263, 267; plant diseases in, 243, 245 West Indies, 16, 17, 159, 261, 346; food uses in, 145, 261 Wetland plants. See Lowland plants White Moi plant variety, 173 Worldwide taro production, 5, 6, 7, 9, 346-349 Yams, 12-13, 264 Yields, taro, 1 6 9 - 1 7 0 , 236, 3 3 7 - 3 3 8 , 347, 350; increase of, with fertilizers, 38, 2 7 4 - 2 7 6 ; from lowland plants, 317, 318; variations in, 6, 3 5 7 - 3 5 8