Sugarcane Crop Logging and Crop Control: Principles and Practices 9780824886066

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Sugarcane CROP LOGGING AND CROP CONTROL: Principles and Practices

SUGARCANE CROP LOGGING AND CROP CONTROL Principles and Practices Harry F, Clements

The University Press of Hawaii Honolulu

Copyright © 1980 by The University Press of Hawaii All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording, or by any information storage or retrieval system, without permission in writing from the publisher. Manufactured in the United States of America Library of Congress Cataloging in Publication Data Clements, Harry F 1901Sugarcane crop logging and crop control. Bibliography: p. Includes indexes. 1. Sugar-cane. 2. Sugar-cane—Research. I. Title. II. Title: Crop logging and crop control. III. Title: Crop control. SB231.C63 633'.61 79-9894 ISBN 0-8248-0508-9 (University Press of Hawaii edition) ISBN 0-273-08469-0 (Pitman Publishing Ltd. edition) The section of Chapter 4 entitled "Recent Improvements in the Prediction Equations" was written by Thomas P. Clements. Bonnie Ching Soo Hoo helped with the computer work for other parts of the same chapter. The section on Photosynthesis in Chapter 5 was written for this book by Hugo P. Kortschak. Robert Suehisa wrote most of Appendix II. Others who collaborated in writing the text were Orlando Sanchez Evers (coauthor of Chapter 12) and John E. Bowen (coauthor of Chapter 13). Charles Bretz prepared all the drawings for Chapters 2 and 3 from materials supplied by the author. Some of the artwork in the other chapters is the work of Tomatsu Nakata. Published in the United States of America by The University Press of Hawaii and in Great Britain and Australia by Pitman Publishing Ltd. Pitman has exclusive sales rights for Britain, Europe, Africa, Australia, and New Zealand. Both publishers may sell their editions in India and South America. The University Press of Hawaii has exclusive sales rights throughout the rest of the world.

To my wife, Louise; to my parents, Frank and Frances Clements; and to my grandmother, Anna Mashek, with whom I lived during adolescence.

Note

Other publications by the author, which should be considered as part of this book, are Technical Bulletins published by the Hawaii Agricultural Experiment Station, University of Hawaii, and, except for the last entry in the following list, may be had by addressing such requests to: College of Tropical Agriculture Publications University of Hawaii Honolulu, Hawaii U.S.A. 96822 Sections of these publications have been adapted and incorporated into this book. Clements, Harry F., G. Shigeura, and E. K. Akamine. 1952. Factors affecting the growth of sugar cane. Hawaii Agr. Exp. Sta. Tech. Bull. 18.90 pp. Clements, Harry F. 1957. Crop-logging of sugar cane: The standard nitrogen index and the normal nitrogen index. Hawaii Agr. Exp. Sta. Tech. Bull. 35.56 pp.

Clements, Harry F. 1970. Crop logging of sugarcane: Nitrogen and potassium requirements and interactions using two varieties. Hawaii Agr. Exp. Sta. Tech. Bull. 81.48 pp. Clements, Harry F., E. W. Putman, R. H. Suehisa, G. L. N. Yee, and M. L. Wehling. 1974. Soil toxicities as causes of sugarcane leaf freckle, macadamia leaf chlorosis (Keaau), and Maui sugarcane growth failure. Hawaii Agr. Exp. Sta. Tech. Bull. 88. 52 pp. Sund, K. A., and Harry F. Clements. 1974. Production of sugarcane under saline desert conditions in Iran. Hawaii Agr. Exp. Sta. Res. Bull. 160. 65 pp. Clements, Harry F. 1975. Flowering of sugarcane: Mechanics and control. Hawaii Agr. Exp. Sta. Tech. Bull. 92. 56 pp. Clements, Harry F. 1976. Life and the wonders of water. Harold L. Lyon Arboretum, Lecture Number Seven. University of Hawaii. 33 pp.

Contents

Foreword by R. R. Panje

ix

Foreword by N. P. Kefford

xi

Preface Acknowledgments

xiii xv

Advice to the Reader

xvii

Units of Measure

xviii

Statistical Signs and Terms

xviii

Terms Used to Designate Experimental Sites in Hawaii

xix

Indexes, Abbreviations, and Special Terms Used in Crop Logging

xix

Introduction: The Crop Logging System Crop Logging Procedures Use of the Log in Guiding the Current Crop Use of the Log in Starting the Next Crop Summary 1

2

Changes in Chemical Composition of Plant Parts As They Age Anatomical Features of Sugarcane 3

The Gross Morphological Development of Sugarcane Parts; Vegetative Propagation; Field Planting Practices 108 General Description of Sugarcane Growth 108 Gliding Growth within the Spindle Cluster 115 Development of a Single Shoot 117 Factors Affecting Germination of Setts 121 Field Practices for Maximum Germination 132 General Summary 142

4

Factors Affecting the Growth of Sugarcane General Ecological Theory Early Studies 1943 Study at Waipio General Correlations of Data Multiple Regressions among Morphological, Physiological, and Ecological Factors and Growth The Growth Equations for Sugarcane

1 2 3 12 15

Sugarcane—Its Classification, Habits, and Uses Systematic Botany of Sugarcane Ecology of Sugarcane Uses and Products of Sugarcane

17 17 25 31

The Structures, Names, and Functions of Sugarcane Parts Introduction: True Seeds and Setts Numbering and Labeling of Sugarcane Parts

48 48 50

56 58

5

Physiologic and Agronomic Aspects of Water and Carbon Dioxide Water: The Preeminent Substance Carbon Dioxide Photosynthesis • Osmosis Water Usage and Function in Sugarcane Growing

144 144 145 148 155

164 170 189 189 194 197 200 206

viii

CONTENTS

Using a Moisture Index for Crop Control Irrigation Effects of Drought on Sugarcane 6

7

8

The Carbohydrates of Sugarcane; Elements of Quality; Methods of Ripening Field-Grown Cane Determination of Sugarcane Carbohydrates Carbohydrate Analysis of All Plant Parts from Crop Start to Harvest The Role of Sucrose in the Life of Sugarcane Quality in Sugarcane Production Deposition of Sugars in Internodes Development of a Ripening Program Plantation Practices for Ripening Cane Importance of Overall Strategy Other Aspects of Quality Control Nitrogen (N) Importance of N to a Crop Losses of N from Fertilizers Residual Effects of Forms of N on Soil pH N Composition of the Various Parts of Sugarcane Plants Selection of a N Index Tissue Critical Levels for N in Sugarcane The Carbohydrate-Nitrogen Balance Concept Need for a New Approach to N Fertilization Interactions of N with Other Nutrients Ammonium vs. Nitrate N in Sand Culture Potassium (K) Importance of K to a Crop K Composition of Sugarcane Parts Selection of a K Index Tissue Comparison of Tissue vs. Other Estimates for K Requirements of Sugarcane Physiology of Ion Absorption by Roots Critical Levels of K for Normal Growth Interactions of N, K, and Varieties (N x K x V) Symptoms of K Deficiency K Fertilization Recommendations

214 219 235

239 239 241 244 245 246 247 254 265 269 272 272 214 276 279 282 285 287 289 307 313 320 320 321 325 328 330 334 336 342 343

9

Phosphorus (P) Importance of P to Plants The Absorption of P by Field Crops of Sugarcane Critical Levels of P in Sugarcane Best Guide to P Nutrition in Sugarcane Effect of Age on P Readings Interaction of P with Other Nutrients Deficiency Symptoms Recommendations for Field Application of P

347 347 351 353 360 361 363 364 364

10 Sulfur (S)

368

11 Calcium (Ca) Importance of Ca to Crops Selection of a Ca Index Tissue Ca Accumulation by Growing Sugarcane Plants A History of Liming Cane Fields in Hawaii The First Steps Toward Solution The Very High Coral Application Experiments Ca Metasilicate Field Experiments Search for the Causes of Leaf Freckling Guides to Follow in Identifying Areas in Need of Ca Metasilicate Ca Deficiency Symptoms

374 374 374 379 381 382 390 403 414 419 419

12 Magnesium (Mg)

423

13 Boron (B)

430

14 Manganese (Mn)

440

15 Iron (Fe)

447

16 Zinc (Zn)

454

17 Copper (Cu)

461

18 Chlorine (CI)

465

19 Molybdenum (Mo)

469

Appendix I. Nutrient Sand Culture Technique and Stock Solution Composition

473

Appendix II. Methods of Chemical Analysis

479

Bibliography

487

Author Index

497

General Index

501

Foreword R. R. Panje

This system of crop-logging was developed by Dr. Clements for ascertaining and providing the optimum irrigational and fertiliser requirements of the sugarcane crop with a view to maintaining a high rate of growth and ensuring a maximum production of cane and sugar from a unit area of land, within the framework of a given combination of varying but uncontrollable environmental conditions. In its approach to the problem of crop production, it represents a radical departure from the conventional method of assessing the fertiliser requirements of crop plants by analyses of the soil. It seeks to employ the plant itself as the indicator of its nutritional status and of its deficiencies, and, through a system of sampling appropriate tissues and analysing them, to provide the deficiencies of elements indicated therein, the aim being to maintain the plant at the most efficient possible rate of its vital functions, so that the maximum outturn of produce can be ensured. The crux of the system has been the selection of the indicator tissues and the assessment of the degree of their reliability as indicators. For providing this basis, an enormous amount of spadework has been done for a period over 30 years by Dr. Clements This Foreword originally appeared in an early version of this book, Sugarcane Nutrition and Culture (Clements, 19596), given as lectures in India.

and his colleagues in selecting the tissues, evolving their index values, and correlating the variation in these with changes in environmental factors, so that a correct assessment of the nutritional level of the plant can be obtained at all stages of the plant's growth. The volume now brought out gives the background of this work, explains the approach to the problem, discusses the results of experiments which led to the formulation of the system of crop-logging in respect of each essential element, and presents the reader with an account of the manner in which the system is to be applied in practice. Dr. Clements' system of crop-logging represents one of the major advances in the application of the principles of plant physiology in the production of crops. While, in principle, it should be adaptable to all crop plants, it is particularly applicable to sugarcane and has been extensively adopted in many of the sugarcane plantations of Hawaii, where it now forms the basis of crop management. It has aroused much interest outside Hawaii, too. While the system is bound to undergo some modification on minor points both in and outside Hawaii, as a system, it has undoubtedly come to stay, and will probaibly influence the trend of scientific agriculture in an increasingly wider field of crop production in the coming decade.

X

The volume now brought out is as well suited to the needs of students and research workers as to those of the sugar estate superintendents and agricultural chemists. Dr. Clements is by profession not merely a scientist, but also a teacher, and has had as much experience in the practical work of sugarcane growing as any plantation manager in Hawaii. His abilities in each of these professional roles are discernible in the contents of the book. . . . The scientist sees a logical exposition of the system, the statistical basis of its evolution being particularly convincing to him. The estate manager finds a ready-

FOREWORD BY R . R . PANJE

made system complete with charts and indexes for his guidance and analytical methods for his immediate adoption in the laboratory. In a lucid . . . style Dr. Clements has unfolded his system to his readers, rational in its approach, firm in its basis, progressive in its development and solid in its achievement. R . R . PANJE

Director Indian Institute of Sugarcane Research, Lucknow January 1,1960

Foreword N. P. Kefford

A dominant theme for agricultural production throughout the world is the utilization of the resources that can influence a crop, such that optimal sustained productivity is obtained. This is the theme of Dr. Clements' book, and it is, therefore, a timely and critical guidepost to the many workers who are now striving toward optimal productivity for specific crops in environments throughout the world. The book provides a comprehensive discussion of the factors within a crop and in the environment of a crop, which can be studied and manipulated, and which can be utilized to achieve optimal sustained yield. Dr. Clements presents a case study of the research and technology necessary for bringing a crop, by successive steps, toward optimal sustained productivity. The specific crop is sugarcane, but the philosophy, approach, principles, and practices apply to all crops, as has already been proven in Hawaii and elsewhere in the world. It is appropriate that the case center upon sugarcane, because it is with this crop in Hawaii that a systematic approach to optimal production first achieved a desirable level of sophistication. The approach of the book as a scientific text is significant. The most common scientific approach is analytical—the taking apart of systems, structures,

and processes and the detailed study of component parts in isolation. Seldom does research take the more difficult path of synthesis—the fitting together of the fragments of knowledge on isolated processes to form a unified, functional whole. Dr. Clements' research achieved this and was proven by the harsh test of crop performance in the field, under a variety of conditions in Hawaii and around the world, requiring a profit to the owners. The book represents a considerable and unique achievement because it is chiefly based upon the original research of the author who was a pioneer and a most successful practitioner of an integrated approach to crop control. The author relates his integrated approach to the productivity of a crop. It is rare that an individual has the critical abilities in the necessary widespread areas of botanical science to make a successful integrated attack. There are many narrow investigations that make an impact on an isolated aspect of productivity. Dr. Clements, on the other hand, has shown an ability to attack each problem that the crop system sets, no matter what the required skills are. In turn, Dr. Clements treats the structure of the sugarcane plant, the processes occurring in the plant, and the factors in the environment pertinent to productivity. For each, their effects upon productivity

xii

FOREWORD BY N. P. KEFFORD

and the interactions between factors are studied and research and agricultural practice be laid out and the means by which the factors may be varied and ad- faced. A cataloguing and criticism of all work on sugarcane productivity is not the role of this work justed to achieve optimal productivity are indicated. In addition to its importance to world concerns for and, in my opinion, would be a much less worthwhile crop production, the book presents Dr. Clements' endeavor for this author. contributions to basic plant science—in plant nutriDr. Clements has given his readers a strongly pertion, nutrient interactions, mineral toxicity, regula- sonal account of his contributions to the botany of tion of development, and morphology. I will make sugarcane and, hence, to the efficiency of sugar prospecific mention only of the latter. The section of the duction. He has achieved a scientifically sound acbook on the development of the sugarcane plant is count, which also permits the reader to see the perdefinitive and beautifully done; the necessary sonality behind the scientific method. The energetic thorough job has not been done before. But it is drive, the persistent experimental approach, the more significant that the morphology of the plant critical evaluation of results, the determination and was studied so that it could become the basis for the confidence that production problems will yield to exunderstanding of the physiology and productivity of perimentation, the persuasion of others in the prothe plant. The book develops this relationship and is duction team to accept new attitudes and apa model for the study of other crop plants. proaches, the need for perspective and a sense of Dr. Clements' extensive studies, which are brought humor—all these are revealed through the reading of together in this book for the first time, extended the text. I believe it is an achievement to present from laboratory studies in plant morphology, devel- sound scientific argument and, at the same time, opment, nutrition, and chemistry to the field. Prob- reveal the humanity that must be behind the scientific lems detected in the field were subject to laboratory method. investigation, and new principles resulting from laboA further achievement of the book is its coverage ratory work were put to trial under the complexity of of the topic from basic studies and their technologifield conditions. Rarely do we find laboratory and cal development to specific practical applications in field studies so closely intertwined; indeed, scientists the field and plantation laboratory. Individuals inare no longer trained to expect or to be capable of, volved in all phases of crop production, from rethis desirable approach. Thus, this book is a case search to practice, can find the message appropriate study of the way in which the scientific method may to their levels. At the same time, all readers will be be applied to and tested by natural system. It is most able to comprehend enough from every section of the important that those responsible for the organization book to be enlightened and to gain useful informaof crop research throughout the world are made tion. aware of the need for this approach. Yet another message to be taken from the book is Readers may be surprised to find that some aspects the mutual profit to be gained from an integrated apof research on sugarcane have been given relatively proach to crop research by a research team involving slight treatment by Dr. Clements. In the instances I the unique resources and attributes of both a univercan think of, this occurs either because the basic sity and an industry. discoveries have had, as yet, no impact on the manipulation of crops for increased productivity or because an effect on productivity has been obtained empiriNOEL P . KEFFORD cally and there is little to relate about processes or A cting Associate Director mechanisms. I believe it is important, when dealing Hawaii Agricultural with such an urgent problem as crop productivity, Experiment Station that the realities of the relationships between basic University of Hawaii

Preface

The world sugarcane producers have been provided with several excellent books on the technical aspects of both the field and the factory. For field practices, in recent years appeared R. P. Humbert's The Growing of Sugar Cane, George Samuels, Foliar Diagnosis for Sugarcane, Alex G. Alexander's Sugarcane Physiology, and Felipe Gomez Alvarez's Caña de Azúcar. All report on the growing of sugarcane, each from a somewhat different viewpoint, and each with a good review of literature: Humbert lists 702 citations; Samuels, 271; Alexander 1,622; and Gomez, 474. In addition to these, the very large volumes the International Society of Sugar Cane Technologists (ISSCT) puts out each 3 years provide anyone interested with easy access to literature dealing not only with agronomy, plant physiology, and biochemistry but also with genetics, plant pathology, entomology, and factory practices. In view of these things, the author's thought is that in this book he should not recite the works of other people but should concentrate on his own findings, views, discoveries, and the strategies learned through years of association with successful plant scientists, business executives, plantation managers, field supervisors, and workmen. On the one hand, his professional life of some SO years includes the academic side of plant physiology and general botany with

teaching, lecturing, and research. On the other hand, he has had many, very intimate contacts with the practical, day-by-day problems of field production, which include not only his early life on a family farm in Wisconsin but also field experimentation and production for large plantation corporations in Hawaii. His development of the system that came to be known as sugarcane crop logging and crop control reflects all these experiences. Literally hundreds of experiments—both in the field and glasshouse—and hundreds of thousands, even millions, of analyses and measurements have led to the system. The author became associated with sugarcane research in 1937 and, until 1943, was at the Manoa Campus of the University of Hawaii with field studies going on at the Waipio as well as Kailua substations on land and facilities provided by the Experiment Station of the Hawaiian Sugar Planters' Association (HSPA). In 1943, he became associated with Castle and Cooke, Ltd., which owned and operated three large plantations: Ewa Plantation Co., an irrigated, highenergy, high-yield plantation on Oahu; Waialua Agricultural Co., also irrigated and also a high-yield plantation on Oahu; and Kohala Sugar Co., near the northern tip of the Island of Hawaii, partly irrigated but in a low-yield area.

xiv In 1946, he was invited to be consultant for Maui Agricultural Co. on the Island of Maui, Hawaii. It was here that he had almost unlimited opportunity to put his ideas into practice. Later, this plantation became a part of Hawaiian Commercial and Sugar Co. (HC&S), and he then served as advisor for the merged plantations. Because of the very marked success of the "log" in raising yields of all the plantations using the system, in 1952, the author was invited to help C. Brewer and Co., Ltd., with some of its field problems. At that time, there were 10 plantations owned and operated by C. Brewer ranging from the very highest producer, Olokele Sugar Co., to a very low sugar producer, Kilauea Sugar Co., both on the Island of Kauai, Hawaii. With these IS sugar plantations producing more than 60 percent of Hawaii's sugar, each with its own types of problems, the author was provided with enormous opportunities, all of which he relished. The results from the Brewer plantations were excellent—the total production of raw sugar rose from about 200,000 tons in 1950 to over 285,000 tons in 1955. After the effects of a severe labor strike wore off, Brewer's Island-wide production increased to 311,000 tons in 1965, the last full year before the author's retirement. During the 1955-1965 period, the sugar produced by each man-year rose from about 42 to about 111 tons. (Included in the number of employees was everyone receiving wages from the

PREFACE

plantation, from the lowest employee to the Manager himself.) The yield of sugar increased from about 7.2 tons per acre (T/A) in 1951 to 11 in 1965. Speaking well for the system as applied now (1975) without its author, and for the many people involved, is the fact that yields on the very difficult high-rainfall areas continue to rise, actually challenging the top yields of irrigated plantations. In the meantime, C. Brewer and Co., Ltd., became interested in foreign operations, and the author was sent to Iran in 1958 to study the potential for sugar production in the very large saline desert area, the Khuzestan. A contract was won, and today there is a very thriving sugarcane plantation there. Later, he became involved with Ingenio San Carlos near Guayaquil, Ecuador. Then, because of the great success of the plantation at Haft Tappeh, Iran, the government of Iraq asked for a similar operation there near the Garden of Eden between the Tigris and Euphrates rivers. In 1966, the author reached retirement age and retired from the University as well as from industry and has devoted all his time to conducting many new experiments designed to provide data on certain points and has been putting this book together—most of which represents his own original work.

HARRY F . CLEMENTS

July 1977

Acknowledgments

To acknowledge all the people important to the development of this program would require a book in itself, but the author wishes to single out the following. Dr. Harold St. John, senior professor and chairman of the Botany Department (emeritus), brought the author to the University of Hawaii in 1937. Dr. Harold L. Lyon, director of the experiment station, Hawaiian Sugar Planters' Association (HSPA), who was eager to get the sugarcane research program started, saw to it that land, labor, and funds were available and during the early years was a bulwark of support and encouragement. In addition to these things, Dr. Lyon, who was an enthusiastic botanist and a friendly man, shared many of his ideas. Dr. E. J. Kraus, professor of botany at the universities of Wisconsin and Chicago, as the author's major professor, planted the idea of crop control in the author's mind while he was still a young graduate student. Dr. David L. Crawford, as president of the University of Hawaii during the early years, provided encouragement and support and had Dr. Oscar Magistad, another fine supporter, set up the Department of Plant Physiology in the Hawaii Agricultural Experiment Station (HAES) so that the author, as

chairman, could get more work done in as short a period of time as possible. Mr. Hamilton P. Agee, one-time director of the experiment station, HSPA, was a consultant with Castle and Cooke, Ltd., and a remarkable strategist at manipulating crops, and it was he who suggested the name "crop log." His strategies and general remarks about people were such as to tide the author over difficult periods when opposition to the program seemed almost unbearable and fatal. One of his guiding tales was that there were four stages through which any new concept will pass if it is successful, and I pass the tale on so that young people everywhere may take advantage of it. The first stage is essentially a blank, hard wall, which says the idea is crazy, it will never work because it cannot work, and this wall is the "cold hand of custom." The next stage represents a slight yielding by admitting that there might be something to it but that it will take so long to put it into effect that the industry by that time will have folded! The third stage says that it probably is good, but it is so academic and impractical that it would cost huge sums of money and labor to operate. And, finally, the fourth stage represents collapse as the critics begin saying "Oh sure, it will work! There's nothing new in it. I used it 50 years ago! I know all about it!"

Mr. Boyd McNaughton came to Hawaii about the same time the author did, and while his forte was

xvi finance and top management, he had a remarkable way of asking questions in the author's field that called for unusual kinds of thinking and always opened new vistas, very stimulating to the author. Later, as one of the leading businessmen in Hawaii and president of C. Brewer and Co., Ltd., he used the author's talents, whatever they were, to the fullest. Mr. James Stopford, the author's immediate superior and executive vice president of C. Brewer and Co., saw to it that the author was provided with company funds after his retirement to continue his studies at the University. Without these funds, much of the work to appear in the chapters to follow could not have been done. Dr. Noel P. Kefford, present chairman of the Botany Department, University of Hawaii, has continued to offer general assistance in the way of welcoming this effort even though many times he must have had his patience tried. He also spent much time and thought in thoroughly reviewing the manuscript, wrote the Foreword, and deserves a halo or two. All the analysts at the crop log laboratory of C. Brewer and Co., Ltd., beginning with Mr. Takashi Nonaka, manager of analytical laboratories; all

ACKNOWLEDGMENTS

the laboratory and secretarial helpers at the University of Hawaii; all the plantation managers, field superintendents, supervisors, and crop control superintendents; all the men responsible for collecting the many thousands of crop log samples in rain or shine from Held experiments as well as regular sampling— to all of these who individually and collectively contributed far more than they knew, go the heartfelt thanks of the author. Various University administrators, particularly the late Dr. Willard Wilson, extended to the author the University facilities after normal retirement by asking that office space, laboratory equipment and space, and secretarial help be provided. Mrs. Betty Someda, as the department secretary, saw to the typing of the several copies of the manuscript. Her knowledge of the form and normal requirements of manuscripts was very necessary to transform the messy copies of longhand given her into the book as the reader sees it now, and she deserves the biggest thanks of all. Finally, Ms. Cynthia L. Garver, who did the final editing, which improved the manuscript greatly, and who was able to do it at minimum cost to the author's nerves, deserves his sincere appreciation.

Advice to the Reader

Anyone wanting to get the most from this book should start by reading the whole of the Preface and the whole of the Introduction, which describes the crop logging system for sugarcane as developed through 36 years of intensive work and application. As he comes to new sections of the log, the reader may wish to go to specific chapters for background information. After becoming familiar with the crop log, its philosophy as well as its thrust, the reader should then start with Chapter 1 and continue through the book. Although this work deals with sugarcane, the material—both principles and practices—is applicable to any crop, although some careful work may be needed to fit the methods to the new crop. Throughout, the chapters detail the kind of work done on sugarcane that might become a pattern for any other crop. Obviously, because of the work already done

on sugarcane, applications to new crops would be relatively simple, since the trial and error approaches would not need to be repeated. One further point: the actual data resulting from the many studies are reported as such rather than as curves. The reason for this is that many students like to recast the data for specific statistical study and that many engineers will need actual numbers for their design work. Thus, the student of botany (plant physiology, ecology, and plant anatomy) will find much to interest him, as will the student in the applied fields, the plantation manager, supervisor, research director, or by-products engineer who will see the basis for his future work. Some readers may wish to go directly to the more basic aspects of a subject, while others may be more interested in the practical aspects. Each will find guidance in the table of contents.

UNITS OF MEASURE No attempt has been made in this book to convert all units to the metric system. Results are recorded in the units used in the actual experiments. In general,

English units were used in field experiments and metric units in laboratory experiments.

VOLUME LENGTH 1 meter (m) = 39.370 inches (based on the length of a 1 cubic centimeter (cc) = 1 milliliter (ml) = .061 in3 metal bar at a specific temperature in Paris) 1 liter (1) = 1.000 cc = .908 dry U.S. quart = 1.057 li1 nanometer (nm) = .000000001 m quid U.S. quart 1 micrometer (^m) = .000001 m 1 U.S. liquid quart = .946 liter 1 millimeter (mm) = .001 m 1 U.S. gallon = 231 in3 = 3.785 liters 1 centimeter (cm) = .01 m = .39 inch 1 decimeter (dm)= .1 m WEIGHT 1 kilometer (km)= 1,000 m = .621 miles 1 gram (g) = weight of 1 ml H 2 0 at maximum density in a vacuum 1 inch= 2.54 cm 1 nanogram (ng) = .000000001 g 1 foot = 30.48 cm 1 microgram (pig)= .000001 g 1 mile= 1.61 km 1 milligram (mg)= .001 g AREA 1 decigram (dg) = .1 g 1 kilogram (kg) = 1,000 g = 2.2046 lb lcm 2 =.155 in2 1 metric ton = 1,000 kg = 2,204.6 lb 1 m 2 = 1.196 yard2 1 are= 100m2 1 English ton (short) = 2,000 lb = 907.2 kg 1 hectare (ha) = 100 ares = 10,000 m2 = 2.47 acres 1 English ton (long) = 2,240 lb = 1,016.06 kg 1 ounce (oz) = 28.35 g 1 acre = 43,560 ft 2 = .405 ha 1 pound (lb) = 16 oz = 453.59 g 1 cuerda (Puerto Rico) = .994 acre 1 arpent (Mauritius) = 1.04 acre

STATISTICAL SIGNS AND TERMS ** = statistical significance beyond the 1% level * = statistical significance between the 5% and 1% levels n.s. = not significant t distribution ("student's t") is a measure of reliability of sample data (a measure of statistical significance) F ratio is obtained by dividing the mean square for treatment by the mean square for error.

LSD = least significant difference HSD = honestly significant difference For a working understanding of these symbols as well as simple correlation, linear regression, curvilinear regression, multiple regression, variance analysis, standard partial regression, etc., the reader is referred to Snedecor and Cochran, Statistical Methods (1967), or any other standard text on statistics.

UNITS OF MEASURE No attempt has been made in this book to convert all units to the metric system. Results are recorded in the units used in the actual experiments. In general,

English units were used in field experiments and metric units in laboratory experiments.

VOLUME LENGTH 1 meter (m) = 39.370 inches (based on the length of a 1 cubic centimeter (cc) = 1 milliliter (ml) = .061 in3 metal bar at a specific temperature in Paris) 1 liter (1) = 1.000 cc = .908 dry U.S. quart = 1.057 li1 nanometer (nm) = .000000001 m quid U.S. quart 1 micrometer (^m) = .000001 m 1 U.S. liquid quart = .946 liter 1 millimeter (mm) = .001 m 1 U.S. gallon = 231 in3 = 3.785 liters 1 centimeter (cm) = .01 m = .39 inch 1 decimeter (dm)= .1 m WEIGHT 1 kilometer (km)= 1,000 m = .621 miles 1 gram (g) = weight of 1 ml H 2 0 at maximum density in a vacuum 1 inch= 2.54 cm 1 nanogram (ng) = .000000001 g 1 foot = 30.48 cm 1 microgram (pig)= .000001 g 1 mile= 1.61 km 1 milligram (mg)= .001 g AREA 1 decigram (dg) = .1 g 1 kilogram (kg) = 1,000 g = 2.2046 lb lcm 2 =.155 in2 1 metric ton = 1,000 kg = 2,204.6 lb 1 m 2 = 1.196 yard2 1 are= 100m2 1 English ton (short) = 2,000 lb = 907.2 kg 1 hectare (ha) = 100 ares = 10,000 m2 = 2.47 acres 1 English ton (long) = 2,240 lb = 1,016.06 kg 1 ounce (oz) = 28.35 g 1 acre = 43,560 ft 2 = .405 ha 1 pound (lb) = 16 oz = 453.59 g 1 cuerda (Puerto Rico) = .994 acre 1 arpent (Mauritius) = 1.04 acre

STATISTICAL SIGNS AND TERMS ** = statistical significance beyond the 1% level * = statistical significance between the 5% and 1% levels n.s. = not significant t distribution ("student's t") is a measure of reliability of sample data (a measure of statistical significance) F ratio is obtained by dividing the mean square for treatment by the mean square for error.

LSD = least significant difference HSD = honestly significant difference For a working understanding of these symbols as well as simple correlation, linear regression, curvilinear regression, multiple regression, variance analysis, standard partial regression, etc., the reader is referred to Snedecor and Cochran, Statistical Methods (1967), or any other standard text on statistics.

TERMS USED TO DESIGNATE EXPERIMENTAL SITES IN HAWAII Central Maui. An irrigated plantation on Maui. Ewa. An irrigated plantation on the south coast of Oahu. Hamakua Coast. Plantations on the northeast coast of Hawaii Island (Honokaa and Paauhau). Hilo Coast. Plantations on the northeast coast of Hawaii Island (Hilo, Onomea, Pepeekeo, and Hakalau). Kailua. A substation of HSPA (Hawaiian Sugar Planters' Association) on Oahu. Ka'u. Pahala and Naalehu plantations on the southwest coast of Hawaii Island. Kilauea. An irrigated plantation on the north coast of Kauai.

Kohala. A plantation on the northern tip of Hawaii Island. Lahaina. A plantation town in West Maui. Naalehu. See Ka'u. Olokele. An irrigated plantation on the southwest coast of Kauai. Pahala. See Ka'u. Waialua. An irrigated plantation on the northwest coast of Oahu. Wailuku. An irrigated plantation in west central Maui. Waipio. A substation of HSPA in central Oahu.

INDEXES, ABBREVIATIONS, AND SPECIAL TERMS USED IN CROP LOGGING INDEXES Phosphorus Index (PI). The phosphorus content of Primary Index. The total sugars content of the young the young sheaths expressed as percentage of sheaths expressed as percentage of dry weight. sugar-free dry weight. Moisture Index (MI). The H 2 0 content of the young 5th P. The phosphorus content of the 5th mature insheaths +3, +4, +5, +6 expressed as percentage of ternode counting down from the oldest living leaf, green weight (also called Sheath Moisture Index). expressed as percentage of dry matter. Sheath Moisture Index. Sec Moisture Index. Standard Phosphorus Index (SPI). The Phosphorus Normal Moisture Index. Derived by equation based Index standardized to given moisture and primary on several factors from best yielding crops of the index levels. particular variety. Amplified Phosphorus Index (API). The product of Nitrogen Index (NI). The total nitrogen content of the Standard Phosphorus Index and the 5th P as the green tissue taken from the center of leaf whole numbers. blades +3, +4, +5, +6 expressed as percentage of Potassium Index (KI). The potassium content of the dry weight. young sheaths expressed as percentage of sugarNormal Nitrogen Index (NN). The Nitrogen Index free dry weight. calculated by an equation for the moisture index K-H 2 0 Index (K-H 2 0). The potassium content of the and age of the particular variety as taken from exyoung sheaths +3, +4, +5, +6 expressed as percentcellent crops, expressed as percentage of dry age of tissue moisture. weight. Other indexes. Indexes for all other elements are exStandard Nitrogen Index (SNI). The Nitrogen Index pressed as percentages or parts per million of calculated for standard moisture levels and ages sugar-free dry weight of the young sheaths. for a given variety.

TERMS USED TO DESIGNATE EXPERIMENTAL SITES IN HAWAII Central Maui. An irrigated plantation on Maui. Ewa. An irrigated plantation on the south coast of Oahu. Hamakua Coast. Plantations on the northeast coast of Hawaii Island (Honokaa and Paauhau). Hilo Coast. Plantations on the northeast coast of Hawaii Island (Hilo, Onomea, Pepeekeo, and Hakalau). Kailua. A substation of HSPA (Hawaiian Sugar Planters' Association) on Oahu. Ka'u. Pahala and Naalehu plantations on the southwest coast of Hawaii Island. Kilauea. An irrigated plantation on the north coast of Kauai.

Kohala. A plantation on the northern tip of Hawaii Island. Lahaina. A plantation town in West Maui. Naalehu. See Ka'u. Olokele. An irrigated plantation on the southwest coast of Kauai. Pahala. See Ka'u. Waialua. An irrigated plantation on the northwest coast of Oahu. Wailuku. An irrigated plantation in west central Maui. Waipio. A substation of HSPA in central Oahu.

INDEXES, ABBREVIATIONS, AND SPECIAL TERMS USED IN CROP LOGGING INDEXES Phosphorus Index (PI). The phosphorus content of Primary Index. The total sugars content of the young the young sheaths expressed as percentage of sheaths expressed as percentage of dry weight. sugar-free dry weight. Moisture Index (MI). The H 2 0 content of the young 5th P. The phosphorus content of the 5th mature insheaths +3, +4, +5, +6 expressed as percentage of ternode counting down from the oldest living leaf, green weight (also called Sheath Moisture Index). expressed as percentage of dry matter. Sheath Moisture Index. Sec Moisture Index. Standard Phosphorus Index (SPI). The Phosphorus Normal Moisture Index. Derived by equation based Index standardized to given moisture and primary on several factors from best yielding crops of the index levels. particular variety. Amplified Phosphorus Index (API). The product of Nitrogen Index (NI). The total nitrogen content of the Standard Phosphorus Index and the 5th P as the green tissue taken from the center of leaf whole numbers. blades +3, +4, +5, +6 expressed as percentage of Potassium Index (KI). The potassium content of the dry weight. young sheaths expressed as percentage of sugarNormal Nitrogen Index (NN). The Nitrogen Index free dry weight. calculated by an equation for the moisture index K-H 2 0 Index (K-H 2 0). The potassium content of the and age of the particular variety as taken from exyoung sheaths +3, +4, +5, +6 expressed as percentcellent crops, expressed as percentage of dry age of tissue moisture. weight. Other indexes. Indexes for all other elements are exStandard Nitrogen Index (SNI). The Nitrogen Index pressed as percentages or parts per million of calculated for standard moisture levels and ages sugar-free dry weight of the young sheaths. for a given variety.

XX

YIELD ABBREVIATIONS Pol % cane. The pol yield (see "Measures of Juice Quality," following) multiplied by 100 and divided by the net cane yield (TCA). This value is approximately the reciprocal of the TCA/TPA. TCA. Tons net cane per acre. Non-cane material is estimated and deducted. The trash estimate includes leafy trash, dead cane, rocks, soil, etc., and is not very precise. TCAM. Tons net cane per acre divided by the age of the crop in months. TC/TS. Tons cane per unit divided by the tons of 96° sugar produced. This is an estimate of quality. The lower the ratio the better the quality; it may range from less than 6.0 to over 15.0. TPA. Tons pol per acre, an estimate of the sucrose in the cane juice. This value is usually much larger than actual yield, since mill losses are not considered. TP AM. Tons pol per acre divided by the age in months.

INDEXES, ABBREVIATIONS, AND SPECIAL TERMS

TRS. For field yields in some parts of the world, the actually recovered and refined sugar per acre. TSA. For field yields, the actually recovered sugar converted to 96° raw sugar value per acre. TSAM. Tons 96° sugar per acre divided by crop age in months. Yield % cane (Y t -^"^¿JL ö •> _

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2-30. Plane 4, longitudinal section through the water parenchyma showing the upper epidermis as the bulliform cells with little or no cuticle, the lower epidermis with a thick cuticle and stomata, and an interveinal bundle in cross section. The rest of the mesophyll is made up of very large parenchymatous cells, or water parenchyma. The upper ones are without chloroplasts, and the lower ones with a few. FIGURE

74 thick-walled living cells. Next to each layer of fibers is the single layer of starch-containing sheath cells, then more fibers of pericyclic or phloem origin. It is to be noted that no chlorenchyma is evident in this view. The phloem is made up of the very long sieve tubes and companion cells. As seen in Fig. 2-27, plane number 1 did not go through the metaxylem vessels but does show scalariform xylem cells and the protoxylem vessel, which, in the section drawn, was entire and its thickenings annular. Plane 2 goes through the metaxylem, as shown in Fig. 2-28. Here the epidermal cells are very like those shown in Fig. 2-27, except that the particular strip of the lower epidermis does not show the connector cells. It is to be noted that neither of these two figures shows stomata, since they do not occur opposite the bundles. Within the epidermal layers are the fiber groups, as seen before, and the two views of the starch sheath cells, within which are the very large metaxylem vessels with their scalariform thickenings and a few tracheids similarly thickened. The clear spaces in the vessels represent walls that were cut away in the sectioning. Actually, the thickenings are uniform over the entire walls of the vessels. In the figure, below the xylem is the phloem with its nucleilacking sieve tubes and the nuclei-containing companion cells. Between the phloem and the sheath in this section are some fibers that may be considered as being of either phloem or pericyclic origin. The need for argument can be dispelled by referring to them as bast fibers. Plane 3 is shown in Fig. 2-29 and, except for the small interveinal bundle shown in cross section, is made up entirely of fairly well ventilated chlorenchyma, but this is where sucrose is made! The intercellular spaces are all a part of one large empty space, in which are suspended the various cells making up the mesophyll, that is continuous with the outside atmosphere by way of the stomata, two of which are seen at the bottom in longitudinal section. The epidermises are well covered with the waxy cuticle. In Plane 4, shown in Fig. 2-30, however, are seen the bulliform cells at the top with the water parenchyma extending to the bottom epidermis, which

CHAPTER 2

contains three stomata in longitudinal view. Chloroplasts are present in the lower water parenchyma, but none are in the upper part. At the left, is a cross section of an interveinal bundle surrounded not by starch sheath cells but by what might be called thickwalled parenchyma. A xylem cell is showing, as well as a sieve tube and companion cell. Figure 2-31 is a perspective, three-dimensional drawing of a sugarcane leaf showing all tissues in their relationships to each other, and effectively summarizes the section on the blade anatomy. It should be pointed out that the chlorenchyma, when shown in three dimensions, is made up of a single type of cell, whereas when viewed as in Fig. 2-24, it appears as though there are two types. Leaf Sheath Anatomy In view of the ecological preferences shown by sugarcane, it is not surprising to find such large spaces in the sheath (Figs. 2-32 and 2-33). These, as with other hydrophytes, undoubtedly add to the buoyancy of cane under flooded conditions. They arise as a result of tissue breakdown as the sheath enlarges and are already evident in sheath 0. Although no studies were made, it is not unlikely that gases from the intercellular space system of the leaf gather in these spaces and prevent the greentops from drowning. Bundles of collenchyma are found under the upper (or inner) epidermis, which is made up of thin-walled cells. Sclerenchyma is found inside the lower (or outer) epidermis and is made up of thick-walled, long cells. The bundles are stacked two to three high, each one containing all the normal elements except lacking a clearly defined endodermis or starch sheath. Actually, the function of the sheath is not only to connect the blade with the stem; because the sheaths at the top of the central axis clasp each other very tightly, they are the only support the young succulent stem farther down has. This function requires marked strength distributed circumferentially as well as longitudinally. After very severe wind storms, the fact that any cane tops remain unbroken is a tribute to the clasping tenacity and general strength of the sheaths. Often, of course, cane tops are broken off,

STRUCTURES, NAMES, AND FUNCTIONS OF SUGARCANE PARTS

75

FIGURE 2-31. Perspective drawing of the leaf blade anatomy showing all tissues in three dimensions, as well as the aeration system.

and often, too, internodes that were +4 or +5 during the severe storm were caused to bend almost to the breaking point, and when they emerge as mature they retain the bend (Fig. 2-34) within the internode. Curvatures caused by tropistic stimuli result from adjustments at the nodes rather than the internodes. The outer epidermis (Fig. 2-35) shows two distinctly different types of cell arrangements. There are the layers of cells with the wavy walls with silica and connector cells in between. These types are separated from each other by very heavily staining strips, which occur opposite the stacks of bundles as shown in Fig.

2-33. The hairs, shown as the blank space in Fig. 2-35, are very narrow, thick-walled, and very long and stiff, and they point upward—probably also taking part in moving the tissue upward in the growth process in the spindle cluster. On either side of these strips is a row of stomata, larger than those found on the blade. On the right side of Fig. 2-35 is a distinct arrangement of cells, which suggests a chimney pore found in some plants. No special study was made of this, however, even though there were many of them present. They may be a part of the aerenchyma of the sheath allowing air to enter or to escape.

76

CHAPTER 2

FIGURE 2-32. Top: Cross section of a very young sheath before the large air spaces form. Bottom: Cross section of a mature sheath showing the large air spaces and the stacked bundles. The large air spaces indicate the hydromorphic nature of the plant. When filled with air they help buoy up the plant.

Clones differ in the persistence of the sheaths. Some called "self stripping," such as 'H37-1933', drop the whole leaf, including the sheath, fairly early and create a substantial mat of dead leaves by harvest time. This characteristic has advantages as well as disadvantages. Where preharvest fires are a part of the operation and the mat is dry, very little trash will get to the mill. On the other hand, if there has been rain, it takes a long time for the mat to dry out, and "clean burns" are more infrequent. A clone on which the dead leaves persist generally gives good fires, although, rather commonly, the adhering sheaths are not burned off and go through the

crushers. Self-stripping canes are much more susceptible to rat and other small animal damage than are the so-called "trashy" canes, the ones to which the dead sheaths adhere. If a burning leaf comes off during a cane fire, it will sail through the air for some distance and become a fire hazard. Stem Anatomy Stems of sugarcane are made up of nodes and internodes and usually are single. On occasion a twin stem may be seen (Fig. 2-36). Immediately above each node is a band in which numerous primordia of sett roots are formed. Above this root band is the growth

STRUCTURES, NAMES, AND FUNCTIONS OF SUGARCANE PARTS

77

FIGURE 2-34. A bend in an internode caused by a severe storm when this internode was either +3 or +4, still very immature.

FIGURE 2-33. Cross section of a sheath, more highly magnified.

ring, which may still be actively dividing as the intercalary meristem, or, if it has ceased this activity, it will remain as a distinct but thin line around the stem. Thus, each stem section is made up of a node with a bud at the side and the internode below ending up with the root band just above the next node. Although, in general, all cane stems are much alike, there are many differences in color—yellow,

green, purple, pink, and various combinations of these. Some stems are very thin and fibrous, while others, especially those of the noble canes, are very thick and the storage tissue relatively soft, so that they are commonly used as chewing canes. Some canes retain their leaf sheaths; others drop theirs. The way in which a cane lodges is of very great importance in the production of old, and therefore large, crops. If a cane crashes down, it usually means that the cane has broken free from the stool; in going down in a crash, the stool may very well tear itself loose from most of its roots, as well. As other canes fall later, they tend to bury the first ones, which then turn sour and die. Not infrequently, when a field has lodged in a storm, what was one day a beautiful field of uniformly tall cane will the next day be flat on the ground. If canes grown in soft soils have all gone down in the same direction, when growth resumes, the tops will lift upward and little damage results, However, should the stalks crisscross one another, when the stalks underneath begin to lift because of the activity of the meristems at nodes +5 to +9, they will break off and the cane will die, primarily because the weight upon them is so great. Much of the dead cane at harvest comes about this way. Some clones have a much less tough connection to the stool than others and break off very easily. Such

78

CHAPTER 2

FIGURE 2-35. Surface view of the outer epidermis of a sheath. The clear space is actually filled with long stiff hairs. Note the large chimney pore formation.

scattered throughout the cross section of the stem (Fig. 2-37). The four squares (A, B, C, D) (Figs. 2-38 to 2-41, inclusive) represent areas from which detailed cross-sectional drawings were made. The outermost section (Fig. 2-38) is a cross section of the stem rind made up of the very thick-walled epidermis, inside which are the cells of a mature internode. There are many layers of thick-walled mechanical tissue, collenchyma, which gives strength to the stem Cross Sections of the Stem and toughness to the rind. On canes of colors other Anatomically, the sugarcane is a meristele; that is, than green, these collenchyma cells carry the anthounlike bamboo and the cereal grains as well as many cyanin colors dissolved in their cell content. These other grasses that have their bundles arranged in colored canes, as well as those which are only green, more or less a single ring (siphonostele) leaving the have chlorophyll in chloroplasts in about the fourth center of the stem hollow, sugarcane has its bundles and fifth or deeper layers of cells. As can be seen, canes will have much dead cane at harvest. Some canes, however, such as 'H37-1933', do have a tough connection to the stool but, as they grow and become heavy, they tend to "squat" down and do not crash. This is a very desirable character and probably accounts in good part for the high yields established by that plant. In other words, whatever growth is made is retained until harvest as living cane full of sugar.

STRUCTURES, NAMES, AND FUNCTIONS OF SUGARCANE PARTS

FIGURE 2-36. Most cane stalks are single, but on occasion a twin stem can be found. Such an occurrence begins in the meristem where, for some reason, two buds are formed at a tip instead of one.

such internode tissue made up of thick-walled cells would yield up its juices to cane crushers very reluctantly unless chopped into very fine pieces. The outer bundles shown are leaf traces, which would enter the leaf at the next node perhaps after branching. The larger bundles within would also branch and some parts of the bundles would enter leaves on either side; hence, nutrients entering a set of roots on one side of the plant would very soon, because of the branching bundles, be distributed throughout the whole cane top. The bundle shown in Fig. 2-39 has a mass of mechanical cells surrounding it, but these bundles have no starch sheaths such as were seen in the leaf. Occasionally, starch may be seen in and about the lateral buds and also in the nodes. Starch, of course, getting into the mill is the cause of slow settling of the extracted mixed juices as well as adding to the difficulties of filtration and formation of normal sucrose crystals in the boiling house and is very

79

undesirable. The protoxylem cells are very often absent from the outermost bundles, and the metaxylem vessels are somewhat smaller than those found farther in. The sucrose-storing cells (parenchyma) are slightly thickened, more so than those farther in but much less so than those making up the rind. The bundles shown are typical cane stem bundles being without a starch sheath, but containing protoxylem cells or their remnants in the gaps left when they were stretched beyond the breaking point as well as the metaxylem tissue, which includes the two very large vessels and small living xylem cells in between. The phloem is very prominent with its sieve tubes and companion cells and what appear to be fiber cells as well as collenchyma. Figure 2-40 shows the large, thin-walled, sucrosestoring parenchyma cells, which make up the major portion of the stem. The bundle shown is typical of stem bundles being without a starch sheath but containing proto- and metaxylem cells. Sometimes, as shown also in Fig. 2-39, the protoxylem may appear as a gap, within which may be seen remnants of the original protoxylem vessels that have been torn as a result of the stresses put upon them by the elongating internodes at early stages. Sometimes only portions of the annular thickenings may remain. The bundle is provided with strengthening tissues including collenchyma and fibers. Figure 2-41 shows the innermost portion of the stalk. The sucrose-storage cells here are the thinnest of the whole cross section. The bundle is like the others already shown. In normal growing cane from the field there should be no breakdown of the central tissue as is shown in Fig. 2-41, but where cane has been grown under conditions of high moisture, high N, and high temperature, as well as some other as yet unknown conditions, growth is so rapid and the circumferential size increase so great that the innermost parenchyma does not receive building material fast enough to keep up and begins to break down and gives the impression of pithiness, which may reach the point of complete breakdown leaving a central cavity referred to as "piping," a very undesirable growth condition. Usually such canes will show

2-37. A diagrammatic view of a stem showing the distribution of the bundles throughout the cross section. The rectangles show the location of the four cross-sectional views (A, B, C, D); the two short lines show the radial views (A, C); and the three short lines show the tangential views (A, B, C). (Figs. 2-38 to 2-40) FIGURE

2-38. Cross section of the rind, Rectangle A, Fig. 2-37, showing the epidermis, collenchyma, two rows of chlorenchyma, and several leaf traces, as well as bundles of the stem. FIGURE

8l

STRUCTURES, NAMES, A N D FUNCTIONS OF SUGARCANE PARTS

2-39. Cross section, showing a portion of the stem about one-third of the way in, Rectangle B, with the single bundle surrounded by the large, thin-walled parenchyma cells which contain the stored sucrose and which, because of their thinness, are easily crushed. Immediately around the bundle are many thickened cells, some of which are bast fibers and some collenchyma. In such bundles it is not uncommon to see that the protoxylem has been destroyed in the elongating process, but in its place is a gap. Occasionally, pieces of the annular thickening may be seen. The two large vessels are the conduits for water and soil solutes moving upward. Finally, the phloem, made up of sieve tubes and companion cells, is the tissue through which organic substances such as sucrose move upward or downward to points of utilization or storage. FIGURE

2-40. Cross section of Rectangle C is very similar to Fig. 2-39 except that the parenchyma cells are larger and have thinner walls. FIGURE

82

CHAPTER 2

FIQURE 2-41. Cross section of Rectangle D is from the innermost part of the stem and has very large, thinwalled, sucrose-storage cells. The upper left part of this section shows the breakdown of cells brought on by high N, moisture, and temperature resulting in very lush growth. As the outer cells of the stem enlarge rapidly, the innermost cells cannot keep up and hence collapse, giving rise to pithiness, which, if extreme, leaves a central hole or a pipe—hence, it is called piping, a very undesirable trait.

relatively low sucrose and high reducing sugars, as well as other impurities. The very young bundle shown in Fig. 2-42 is from the lower middle of the +4 internode, which is in its grand period of growth. A protoxylem gap is making its appearance because the oldest protoxylem cell has already been torn, but the oldest cell of the protoxylem is still a living cell, as are both the metaxylem cells. The protophloem is shown as a distinct tissue being made up of some bast fiber, as well as of sieve tube cells. In some cases, the sieve tube portion of the protophloem is crushed and lies dead between the metaphloem and the bast. Inside the protophloem the metaphloem is developing into the large sieve tube cells and the much smaller companion cells. Between the metaphloem and metaxylem are two layers of cells, suggesting a cambium tissue, which, when the bundle is mature, appears as thickened cells bordering on the phloem but extending across the space between the two large metaxylem cells (Figs. 2-40-2-42). The cells that will become the mechanical tissue of the bundle are already formed but have not yet begun to thicken.

FIGURE 2-42. A very young bundle from internode +4, showing protophloem and protoxylem and the developing metaphloem and metaxylem. Cambium-like cells appear between these last two cell types.

Longitudinal Tangential Sections of the Stem The spots from which tangential drawings were made are shown in Fig. 2-37. A surface view of the stem epidermis made up largely of thickened, elongated, somewhat pitted cells with their wavy walls separated

STRUCTURES, NAMES, AND FUNCTIONS OF SUGARCANE PARTS

83

FIGURE 2-43. A tangential view of the stem epidermis showing the numerous elongate cells with undulating walls and very numerous pits. The short connecting cells are either cork or silica cells. One stoma shows.

lengthwise by connector cells including both silica and cork types is shown in Fig. 2-43. Usually the stem epidermis is heavily waxed and contains only a very few stomata, which are very different from the foliar stomata; compare Fig. 2-44 with Fig. 2-45, which is a lower epidermal stoma of a leaf. Fig. 2-46 shows other epidermal cells of the stem. Tangential longitudinal views of the internal stem tissues are shown in Figs. 2-47 and 2-48. Figure 2-47 is about one-third of the way toward the stem center and Fig. 2-48 is about two-thirds of the way (see Fig. 2-37). Figure 2-47 is a section through two neighboring bundles and the sucrose-storing tissue in between. The parenchyma cells are larger here than nearer the outside but smaller than farther in. The bundle on the right shows mechanical tissue on either side of the

xylem tissue. The two pitted metaxylem cells are separated by a protoxylem cell with its annular thickening and also two or three scalariform elements. The metaxylem cell on the right shows a partial cross wall leaving the dead xylem cells as a vessel or a tube, which is very efficient in conducting water and primary inorganic nutrients from the roots toward the growing top. At higher levels in the plant it is not unlikely that some organic nutrients are also moved upward in these cells—especially since sugarcane converts the inorganic N absorbed from the soil to organic in its roots. The bundle on the left of Fig. 2-47 shows the mechanical tissues on either side of the phloem portion. The sieve tubes are very long but without nuclei, while the narrower companion cells, which contain

CHAPTER 2

FIGURE

rnata.

FIGURE 2-43. A lower epidermal stoma of a leaf (note contrast with Fig. 2-44).

2-44 A and B. Two different appearing stem sto-

2-46. The long, pitted, undulating cells with two connector cells in between. FIGURE

STRUCTURES, NAMES, AND FUNCTIONS OF SUGARCANE PARTS

85

FIGURE 2-47. Inner stem tangential view at B and C of Fig. 2-37. In this view, the sucrose-storage cells are rectangular and thin walled. On the left, the section includes a portion of the phloem with sieve tubes and companion cells, as well as fibers. On the right, the section shows the xylem of a neighboring vein showing the large vessels and a smaller one with the annular thickening and some mechanical tissue.

FIGURE 2-48. Inner stem tangential view of B and C (Fig. 2-37), showing a section farther in through the xylem.

86

nuclei, are shorter, as are also the cells of the phloem parenchyma. Figure 2-48 shows two large pitted metaxylem vessels separated by a smaller protoxylem vessel with its annular thickenings. The sucrose-storing parenchyma is separated from the xylem by living fiber cells. In all drawings showing xylem vessels, living cells with wet walls surround and therefore seal the vessels against the inward movement of air, which would incapacitate the vessels as water-conducting tubes. Longitudinal Radial Views of the Stem Two radial longitudinal views of the cane stem are shown in Figs. 2-49 and 2-50 {see Fig. 2-46 for orientation). Figure 2-49 shows the epidermis with its long cells connected by short silica and cork cells. Some three or four cells inside the epidermis can be seen the chloroplast tissue, which, in addition to cytoplasmic pigments such as anthocyans, contains the chlorophyll and carotinoid complements in chloroplasts. The bundle fibers are shown outside a very thin layer of phloem, then the metaxylem vessels and parenchyma, then fibers again, and, finally, the long, narrow sucrose-storing cells. Inward is another bundle with bast fibers, phloem, scalariform, and pitted metaxylem elements, more mechanical tissue, and then again more parenchyma cells, which are wider than those close to the epidermis. Figure 2-50 is much closer to the center of the stem and shows the parenchyma to be made of much wider but shorter cells than those in Fig. 2-49. The bundle in the view was sliced down the middle so that more phloem is shown, but no metaxylem vessels. Instead, some protoxylem elements appear with their annular thickenings and also a protoxylem gap with a few remnants of the annular thickenings scattered about. These gaps extend only to the nodes but do not go through them. On either side of the gap are a few scalariform elements of the xylem. Three-Dimensional View of the Stem Finally, in Fig. 2-51 is a three-dimensional summary of Figs. 2-37 to 2-50 showing all the various elements

CHAPTER 2

making up the inner stem. It is desirable at this point to visualize the activities of such a structure. All of the cells shown are living except for the xylem tubes. During the day, water is being pulled upward through the vessels by the leaf cells that surround the xylem. As the negative pressure intensifies, some water is withdrawn from adjoining tissues (see Chapter 5). Sometimes this negative tension is so intense that an adjoining thin-walled cell may be sucked into the water tube and will grow inside it. Such structures are called "tyloses" and they will decrease the water movement in that element (Figs. 2-52 to 2-54). During the night, a point is reached where the roots are pushing water into the system from the bottom faster than the tops require it, and, hence, an excess of water in the xylem results in a positive pressure that will be exuded from the edges of the leaves as water of guttation carrying with it whatever soil nutrients may be dissolved in it. Much of this water of guttation is exuded into the space between the tightly clasping sheaths and the stem. Such water is quickly reabsorbed the next day. By and large, the direction of water movement is upward; however, should the plant be under severe stress, and should water be applied to the leaves in the form of rain or sprinkler water, it is more than likely that, at the upper part of the stem, water will be moving downward through the xylem until the water deficits are equalized. In the phloem sieve tubes, on the other hand, evidence is very abundant that water movement does not occur except over very short distances, perhaps only intracellular^, equalizing local deficits; organic materials in solutions, however, do move in either direction independently of the water. Since the sugarcane plant assimilates its inorganic N into organic forms in the roots, movement upward of amino acids, organic acids, and so on very likely takes place in the same sieve tubes as those in which sugar is moving downward from the source in the leaves to the sinks in the stem and roots. The movements in the sieve tubes are bidirectional. The living cells surrounding these conducting tissues also require food and water and are supplied directly in a lateral move-

87

2 - 4 9 . Radial longitudinal view, showing the epidermis, with its long narrow cells separated by one to three short connector cells, then some mechanical tissue, chlorenchyma, then a slice through one side of xylem but missing the phloem, then sucrose-storage parenchyma. FIGURE

FIGURE 2-50. Radial longitudinal view, farther inward, showing a section through the phloem and protoxylem.

FIGURE 2-51. A three-dimensional drawing of the sugarcane stem showing all elements: sucrose-storage cells, fiber cells, phloem cells, the very large vessels (actually tubes now, since the cross walls have disappeared), some xylem fibers, a protoxylem element with its annular thickenings, and a protoxylem gap. Note how well sealed-in the conducting cells of xylem and phloem are by living cells, thus preventing inward passage of air that would incapacitate the elements.

STRUCTURES, NAMES, AND FUNCTIONS OF SUGARCANE PARTS

FIGURE 2-52. A protoxylem cell that was under a severe negative pressure and pulled into itself a portion of an adjoining thin-walled cell—a tylose.

FIGURE 2-53. A protoxylem cell with a thin-walled cell growing within it—a tylose.

89

RGURE 2-54. The annular thickenings of a protoxylem cell that are breaking apart leaving the tylose exposed.

ment, in either direction or both simultaneously. Thus, there is much activity going on! When such a cane stem goes through the disintegrator in the milling process, the bundle tissues are quite resistant and come out as long toothpick-like pieces, while the thin-walled parenchyma is well chewed up. It would be ideal if each such cell could be cut across, thus emptying its contents into the water. Root System and Anatomy The root system of sugarcane, is similar to the fibrous systems of other grasses. Like them, when sugarcane is propagated from its true seed, its first root is the primary root, which in turn gives rise to secondary roots and these to tertiary, and so on. When sugarcane is propagated by use of setts, there is, in the technical sense, no primary root at all. The only true primary root comes from an embryo. Sett roots are adventitious, which, by definition, are produced from structures other than roots, that is, stems or leaves. It seems to me that these simple definitions should be adhered to. The primordia of the sett roots are to be found in the root band located just above each node, or it would be better to say at the very

90 bottom of the internode and below the growth ring (Fig. 2-55). When a sett is put to germinate, the sett roots begin growth at the same time that the bud begins growth. Depending on growing conditions, all the primordia or very few of them, or none of them may produce roots. Although these roots may become very long and much branched and may persist for a very long time, their well-being does not appear to be crucial to the welfare of the shoot that arises from the adjacent bud, since the resulting shoot develops its own root system very soon (Fig. 2-56). This very young shoot is already producing one root of its own, also adventitious, which will be a part of the permanent root system. A factor contributing to the earliness of shoot-root appearance has to do with the nature of the shoot growth, whether straight or curved. If the sett is placed so that the most terminal bud is up, shoot roots will appear later than if the bud is on the side or underneath; curved growth of the shoot hastens the appearance of its roots. Undoubtedly this behavior is related to the downward movement of auxin from the terminal meristem of the shoot, which, if it is diverted because of a curved stem, reacts to form roots from the curve. In Fig. 2-56, it can be noted that, although the first sett roots have already developed a sizable root system with many branches, new sett roots are continuing to be produced. Figure 2-57 shows a tangled mass of sett roots with several shoot roots beginning to grow. In general, more sett roots are formed from the most basal root band of the sett than from the most terminal one as FIGURE 2-55. A sett beginning germination. On this sett, the sett roots appear first at the bottom of the root band. FIGURE 2-56. Close-up view of a node with a shoot and sett roots. Note the emergence of a shoot root and also of new sett roots among the old. FIGURE 2-57. A three-bud sett showing a shoot at the top, twin shoots on the middle node, and no shoot on the basal node. Contrariwise, the top node has no sett roots, the second node has heavy sett root development with several shoot roots beginning, and the basal node has very heavy sett root development.

CHAPTER 2

STRUCTURES, NAMES, AND FUNCTIONS OF SUGARCANE PARTS

91

seen in the figure. The uppermost node (Fig. 2-57) some 5 square feet. At the 1-foot level, although has no sett roots, even though it already carries a there were many roots across the entire interrow, the shoot, while the oldest one has a very heavy devel- roots were more directly under each line of cane; but opment of sett roots but no shoot. The twin shoot at the 20-inch level and below, the roots were uniphenomenon developing from the middle node is formly distributed throughout the soil mass. To see not particularly common, but the shoots come from these roots directly leaves little doubt as to their two separate buds that were formed in the meriste- capacity to absorb both water and nutrients to very matic tip of the stalk from which this particular sett great depths. Quite obviously, roots will develop to was cut. great depths if the soil preparation and nutrition are adequate. Extensiveness of the Root System The depth and spread of roots in the soil are matters Satisfactory preparation of the soil involves the production of much importance to the grower, not only for ir- of a root environment for the cane plant which will make development vigorous and easy. Although we have rigation and fertilizer placement but also for an its heard much about how most of the roots of the plant are in understanding of the plant's reaction to unfavorable the upper foot of soil, those of us who have bothered to dig climatic circumstances. To this end, excavation work to find where they really are have been able to report a was undertaken in an unirrigated field of cane dense network in the upper three to four feet with a thin('H31-1389') (Clements et al., 1952). The field was ning out toward much lower depths. Because all these exroots [Fig. 2-59] must connect with the parent on the crest of a hill, and the cane, a second ratoon, tensive plant, obviously there are more main lines of roots under was about 3 months old. A trench was dug from the the stool than at a distance from it, but to argue that side of the hill into the field to a depth of about 6 feet therefore most of the feeder roots are limited to the upper below the level of the cane stools. The cane lines had foot is like arguing that because there are more railroad been planted 5 feet apart. Digging of the tunnel pro- tracks per square mile of area around a freight terminal gressed to the point within the field where the study most of the freight is gathered from that area. (Clements, 1948) was to begin; then, instead of cutting down the soil profile, digging took the form of tunneling under the Evans in Mauritius (1934, 1935, and 1937) found soil mass containing the roots. The idea was to get roots as far down as 19 feet. He also noted that roots under the field and then to work upward with small from a 'Uba' stool could be found between the sechand implements (screwdrivers and ice picks) by ond and third cane rows away. loosening the soil and allowing the roots to hang out Clearly it is to the plant's advantage to have as exof the ceiling of the tunnel. One very impressive tensive a root system as possible. If the soil is very feature of the roots at this depth was their fragility: compact so that root development is restricted, it even with the greatest of care, it was impossible to means that irrigation will have to be far more freprevent breakage of large numbers of the roots. quent than where the root permeated soil volume is The results of this excavation were otherwise very large. It is also advantageous to have the roots exsatisfactory. At the 6-foot level, below the stool, tracting essential materials from a large volume of several roots emerged: three were large and black soil. with many branches and many white root tips breakOn the other hand, if the soil is sandy and loose, ing through the blackened cortex (Fig. 2-58). These exactly the opposite approach is needed. Effort must roots originated in the pericycle opposite the proto- be expended to reduce the rate of drainage to hold xylem points and remained alive for a very long time the applied water and nutrients in the root zone for after the cortex blackened and died. At the 20-inch longer periods of time. Building up the water-holding level, hanging down from the ceiling of the excava- capacity of the soil is called for, but the means are tion were 186 roots, large and small, in an area of not readily available. Much effort has been expended

CHAPTER 2

92

2 - 5 8 . An old blackened root with one welldeveloped young root and several others breaking through the old root, which obviously is very much alive. FIGURE

preserving the cane trash at harvest for plowing under or returning the bagasse to the fields. Yet careful work done here has shown that, in irrigated areas exposed to bright sunshine and high temperatures, the organic material added disappears within a 6-month period. In cloudy, cool areas where rainfall is moderate to heavy, the added material may last as long as a year. Obviously, the cost of the operation is not justified. It seems far better to continue to apply water and nutrients as needed to grow the best possible crops of cane; the resulting root systems left throughout the soil profile to great depths will gradually raise the water-holding capacity and improve the root environment to the point where yields can be high. Sugarcane has a remarkable and longrange beneficial effect on the soil environment, and, because of the density of the root distribution, organic matter is so uniformly distributed that probably not a cubic centimeter of soil is without some root remnant. While most of this carbonaceous material disappears, as noted above, for added organic matter, the final forms of humin slowly build up throughout the mass to accomplish the desired end. One other approach toward improvement of sandy or very porous soils is being tried in the Philippines, where labor is abundant and therefore cheap: an impervious layer of tar or rubberized cement is inserted

2-59. A great mass of roots dropping out of the soil ceiling. Even though they appear to be white in the photograph, they were mostly a shiny black. All were very much alive, as shown by a very white pericycle within, from which numerous secondary roots were originating. This picture was taken after a cut through the cane field had been made for a road. The lower part of the picture is 8 feet below the line of cane stools from which the roots came.

FIGURE

some 4 to 5 feet below the soil surface. The cost for most agricultural areas, of course, would be prohibitive. To illustrate that roots are actively absorbing to greater depths than the first foot, Fig. 2-60, representing the extraction of water from a field from two soil depths—0 to 18 inches and 18 to 36 inches—is inserted. Augers were used to take soil samples twice each week throughout the whole cycle of several

93

STRUCTURES, NAMES, A N D FUNCTIONS OF SUGARCANE PARTS

MAY

JUNE

JULY 1 9

AUGUST 4

SEPT

5

2-60. Soil moisture data for a 5-month period at the end of a cane crop, representing the 0- to 18-inch and 18- to 36-inch layers of soil sampled twice each week. In general, the two layers dry and wet about equally. In July 1.16 inches of rain fell, and it appears that it was retained by the upper layer. From the time of the rain to the time that the moisture level of the top layer began to decline, absorption in the lower level stopped. By September 20, the moisture in the lower level was about the same as in the upper. At this point the field was very dry. FIGURE

crops, and moisture determinations were made. Results for a 5-month period at the end of the crop showed that the rates of extraction were about the same for both layers. In July, a rain fell, which, for the most part, was contained in the upper 18 inches. Growth of new roots is important because of the way the tips develop. Figure 2-61 is the tip of an aerial root with a good development of root hairs. Figure 2-62 is the same type of root under very moist, quiet air conditions. The drop of water is actually a drop of slime with the feel of albumin. It no doubt arises as a result of the disintegration of the root cap cells, which, because of the excessive hydrature, burst and release their cytoplasm, which then becomes a sort of adhesive material. If these root tips touch an object, be it wall, rock, or iron pipe, they will stick to the object and, when they dry out, be firmly stuck on, continuing their growth while adhering to the object. It is also most likely that this same process occurs in the soil and is the manner in which the root not only slips through the soil as it grows but also becomes a firm part of the moisture-soil-rootcytoplasm continuum. Figure 2-63 is a general view of canes in a very moist atmosphere, resulting in

development of many aerial roots, a very undesirable situation. Evans (1935, 1937) in Mauritius and Hudson (1964) in Barbados undertook very thorough studies of the root systems of several clones. Evans' general method was to plant several setts of the particular clone 9 feet apart in all directions to give each root system opportunity for full development. When the study was to begin, six concentric zones 1 foot wide with the stool at the center were laid out. The outside volume beyond the 6-foot ring was treated as the seventh zone. When digging began, this volume of soil to a depth of 1 foot was taken up first, then, successively, the various foot layers down to 6 feet. Then the sixth inner concentric zones were taken up, first to a depth of 1 foot, then, successively, the various foot layers down to 6 feet. The roots recovered in each zonal layer were divided into four classes, depending on their diameters. Class I roots were the thin, fibrous roots, which were removed. Class II roots measured less than 1 mm in diameter and averaged 0.8 mm. Class III roots measured between 1.0 and 2.5 mm in diameter and averaged 1.7 mm. Class IV roots were all those in excess of 2.5 mm—the

94

CHAPTER 2

class average being 3.5 mm. The root volume by class was determined, and, using the average diameter, the lengths were calculated. Estimates of root hair surface areas were also made. A summary of root length, their surface area, and the surface area of the root hairs is given in Table 2-4. The data show that for 'POJ-2878' in the 9-foot circle to a depth of 6 feet occupied by each stool there was a total root length of 810,911 cm. The 254 ft 2 of soil area had below it, including the root hairs, over 300,000 cm2 of root surface. There are in such a welldeveloped root mass about 1.3 acres of root surface FIGURE 2 - 6 1 . An aerial adventitious root with a strong area per acre of land occupied by canes. development of root hairs. Earlier in this chapter it was shown that the leaf area for one cane stalk was 8,751 cm2. Since there are about three stalks per running foot of line and about 9,000 feet of line per acre, the total leaf area/acre of such plants is about 236 million cm2, or 5.84 acres of leaf area over each acre of land. Thus, the leaf/root ratio is about 4.5. Evans, using several different clones reports ratios of 1.96, 0.844, and 5.14. Undoubtedly, these ratios are all very important to an assessment of varietal performance. Much error probably exists in these estimates, not only in determining the active root surfaces at any one moment but also in determining the activity of the existing FIGURE 2-62. A sugarcane root holding a large slime drop, which will make the root adhere to anything it touches. root area. If one were to limit root activity only to the white tips and the zones immediately behind them, the ratios would be very large. But so far no precise work has been done with sugarcane to determine the activity of the blackened roots. The assumption has usually been made that these are not active in the absorption either of water or salts. Work done by Kramer (1946), however, using tagged water as well as inorganic solutes, showed that absorption was very considerable even through the thick bark of old roots of trees. Even with cane roots, soil profile studies undertaken during winter periods showed no white tips to depths of 4 to 5 feet, and yet, when such fields were fertilized, the cane quickly greened up, showing absorption of nitrogen; the fact that the crop was not wilted meant the absorption of water FIGURE 2-63. An aerial root with numerous slime drops was actively going on through the blackened cortex. growing in a very moist atmosphere.

95

STRUCTURES, NAMES, AND FUNCTIONS OF SUGARCANE PARTS TABLE 2 - 4 .

SUMMARY OF LENGTHS, SURFACE AREAS OF THE FOUR CLASSES OF ROOTS, AND ROOT HAIRS

L a t e r a l d i s t a n c e from s t o o l (feet)

2-3

85,301 15,086 7,938 3,409 5,365 3,339

83,959 18,493 4,859 8,338 9,336 4,071

47,890 21,551 1,521 868 395 370

89,039 18,811 2,298 390 236 162

73,957 15,961 1,971 440 703 339

120,438

129,056

72,685

119,936

93,371

Total 0-1 1-2 2-3 3-4 4-5 5-6 Total

3-4 length o f

S u r f a c e area o f r o o t s , 0-1 1-2 2-3 3-4 4-5 5-6 Total

4-5

6-9

Total

51,871 28,761 2,976 838 406 403

125,659 53,399 6,521 2,360 1,151 1,190

566,766 172,062 28,084 16,643 17,592 9,874

85,255

190,280

811,021

5-6

r o o t s (cm)

e x c l u d i n g root

h a i r s (cm 2 )

20,758 5,076 2,933 1,176 1,201 863

12,188 5,884 1,317 1,806 2,526 1,091

7,773 6,516 421 286 153 140

14,255 6,346 561 135 88 65

13,099 5,199 659 110 153 130

9,643 9,443 1,296 278 131 170

20,636 17,560 2,544 570 430 460

98,352 56,024 9,731 4,361 4,682 2,919

32,007

24,812

15,289

21,450

19,350

20,961

42,200

176,069

Total area o f root 0-1 1-2 2-3 3-4 4-5 5-6

(feet)

1-2

0-1

(,P0J-2878')

h a i r s (cm 2 )

14,923 2,134 1,241 446 842 531

13,331 2,646 636 1,296 1,430 585

7,626 3,119 210 88 47 45

14,741 3,086 286 43 28 20

11,768 2,138 288 30 48 41

7,218 4,011 479 88 40 54

19,633 7,826 964 757 135 151

89,240 24,960 4,104 2,748 2,570 1 ,427

Total

20,117

19,924

11,135

18,204

14,313

11,890

29,466

125,049

Comb i ned areas

52,124

M,736

26,424

39,654

33,663

32,851

71,666

301,118

Source: From E v a n s , 1937P e r m i s s i o n to use these data was g r a n t e d by R. A n t o i n e , D i r e c t o r o f Sugar I n d u s t r y Research I n s t i t u t e , M a u r i t i u s .

Structure of Sugarcane Roots Roots, in general, are much less diverse in their structure than other plant organs. This is so probably because the environments of roots through the ages have been less subject to change. The root of sugarcane in longitudinal sections is shown in Figs. 2-64, 2-65, and 2-66. At the apex of the root (Fig. 2-64), the densest portion shows the promeristem in the center, which gives

rise to the several histogens. The procambium gives rise to the central cylinder. On either side of the cylinder is the periblem, which ultimately forms the cortex and pith. Outward from the periblem is the dermatogen, which later becomes the epidermis, and outward from the promeristem is the calyptrogen, which becomes the root cap. In either direction from this highly meristematic region are the primary tissues that arise from their corresponding histogen. The calyptrogen becomes the root cap, which in

96

CHAPTER 2

FIGURE 2-64. A longitudinal section of a cane root showing root cap, the protodermis, the epidermis, the ground parenchyma, fragments of the root cap, the apical cell, the central cylinder, and the cortex.

sugarcane has a relatively short life. Its cells enlarge and usually are crushed against the soil particles and thus "lubricate" the way for the root (Fig. 2-62). The procambium gives rise to the primary tissues of the stele, the pericycle, the protoxylem cells which mature early as well as the protophloem, followed by the metaxylem and metaphloem. Commonly the pericycle may become fibrous. Figure 2-65 is a longitudinal section that goes directly through the proto- and metaxylem but misses the phloem. The epidermis still retains some of its dense cytoplasm, inside of which is the cortical tissue. It is in this region that most of the absorption takes place (water and nutrients). It should be noted that in this view an aerenchyma does not show so that osmotic activities can be maximal without any "free space." In this section, the endodermis, except that by definition it is the innermost layer of the cortex, does not show, but the elongate cells outside the protoxylem are the pericycle. Inside the pericycle are the

conducting tissues, the narrow but long protoxylem cells, the greatly enlarged metaxylem vessels, and finally the pith. Figure 2-66 shows the root at a slightly older stage where root hairs are numerous. Where there is super abundance of moisture and lack of air, these hairs will not form at all; but, under ordinary field and meso- or xerophytic conditions, as has already been shown, they will greatly increase the absorptive area of the roots. Although in the figure the hairs are relatively short, their lengths may actually exceed the diameter of the root (see Fig. 2-67 and Table 2-4 for extent of surface increase). In drawings of root hairs they are usually shown as extending centrally from the cell. This is very rare in actual occurrence. Sometimes a cell may "burst" to produce an extrusion so that its entire base is about the size of the hair, but usually the most acropetal portion of the cell is the base of the root hair, probably because this is the last part of the cell wall to become rigid. Root

:

c

!

1

1 0

•

• - -1

0

— • —H

Q

DERMATOGE

ROOT

CAP STELE OF

ROOT MERISTEM

OLD

ROOT

STELE (PERICYCLE VASCULAR

GROUND (CORTEX

& ELEMENT

PARENCHYM

& ENDODERMIS)!

PERICYCLE

EPIDERMIS

CORTEX

FIGURE 2-73. A s e c o n d a r y r o o t b r e a k i n g o r digesting its w a y o u t of t h e p a r e n t r o o t , b u t s h o w i n g all t h e essentials of a r o o t m e r i s t e m . N o t e h o w t h e space is b e i n g filled b y t h e d o w n w a r d g r o w t h of t h e g r o u n d p a r e n c h y m a .

Survival of Roots after Harvest It is generally recognized that perennial plants, such as sugarcane, have perennial root systems. Yet, some people argue that, as soon as cane is harvested, the roots die and only as new top growth develops, will new roots develop. Through the years, many demonstrations have been set up bearing on this point.

Evans (1934) undertook a solution of this matter by cutting off the stool of 'POJ-213' but letting the roots be. After 2 days of thorough watering and leaving the distal portions of the roots undisturbed, some 70 surface roots at the end of one night had exuded "over a litre of liquid." Collections of exudates from shallow and deep roots were analyzed for a variety of elements over a period of many days. He reported

STRUCTURES, NAMES, AND FUNCTIONS OF SUGARCANE PARTS

i. Ä

ROURE 2-74. Section through a mature secondary root showing the space completely filled now, and also the establishment of the contact between the stele of the secondary root and stele of the older root.

that severed roots left undisturbed remained alive and functional for "at least 1 month." Earlier root studies (Clements et al., 1952) carried on at Kailua on the Island of Oahu, Hawaii, showed persistence of living roots of the first ratoon at about 3 months of age of a second ratoon. In one case, a very black and large root with new secondary roots coming through the blackened cortex was traced all the way to its attachment to a stubble that obviously came from the plant crop. Since the plant itself is a perennial, its roots also are. If the canes are cut off, then the stool will bleed, and, after a while, new shoots form, each of which will ultimately develop a root system of its own. If canes are cut off several

103

feet from the ground and new shoots develop, these shoots will feed the old roots and keep them alive for a very long time. To determine root activity of harvested cane stools, a special study was undertaken using potted plants which had been a part of another study. To avoid the criticism that even dead roots will act as an osmometer, several such undisturbed potted stools were autoclaved at 15 lb. pressure for 1 hour. At no time after this treatment was there any suggestion of exudate. Another test was conducted by letting the potted and fertilized stools grow and develop secondary shoots. Exudation stopped very quickly, suggesting that the roots were dead, but, in this case, when the small rootless shoots were removed, exudation resumed. This indicates that by a cross transfer of tension, the young shoots pulled the water from the old roots directly to themselves, for it will still be some time before the new shoot-root system will develop and function. The next phase in this study consisted of taking a large number of cane stools that had been grown in concrete pots (12x12 inches) for a period of about 10 months. The canes were cut off, rubber tubes were slipped over the cut ends of the stubble, and the exudate was collected. There were three parts to the experiment: (1) four pots were allowed to produce sucker shoots freely; (2) six pots were cultured so that LiNO) could be added at various stages to determine, if possible, the length of time the roots continued active absorption; and (3) 48 pots were randomly divided into six treatments: I, check; II, fertilized lightly with Mg(N03)2; III, fertilized with K 2 S0 4 ; IV, fertilized with KH 2 P0 4 ; V, fertilized with KN0 3 , and VI, fertilized with KNOa + KH 2 P0 4 . These were applied as dry salts and watered in. There were eight replications. The objective was to follow exudation to determine the amount, the duration, and the effect of any of the added salts. Part 1. Exudation in one of the I-treatment pots stopped at the end of 21 days, in two others after 42 days, and in one after 56 days. At this point, all the shoots of treatment I were removed. Exudation did not resume. In contrast, however, the check (CK)

104

CHAPTER 2

1

1

1

1

1

1

1

1 1

1

1

1

1

1

1

1

1

1

1

1

1

I

1 1

KH2 PO4 ^

^

^

^

CK K 2 S0 4

-

MG(N0 3 ) 2

Js

KNO3+KH2PO4 "

7 1 1 1 I 1 1 I I I 17 24 I 8 15 22 29 5 12 19 26 3 . JL . 1 1 T~ MAY JUNE APR.

KNO3

10 17 24 31 7 14 21 28 4 1 . I JULY AUG.

11 18 25 2 9 L T SEPT. OCT.

1964 FIGURE 2-75. Results of a root exudation study. Each curve represents the number of liters of water exuded from eight stools of cane in culture pots with the indicated salts applied as a fertilizer. Exudation finally ceased on October 2, S.S months after the start.

treatment III, which was also a check for treatment I, may be seen from Fig. 2-75 to have exuded 5,314 cc for each replicate up until October 2, whereas the four pots in treatment I averaged a total of 1,018 cc per pot and stopped 4 months sooner. It can only be conjectured that the shoots that were allowed to grow

in the treatment I had exhausted the food supply of the old roots since the check roots in treatment III continued to exude for 4 additional months. Part 2. At the start, LiN0 3 was applied to one of the six cultures and exudates collected separately. After 2 weeks, the treated exudates contained 20 ppm

STRUCTURES, NAMES, AND FUNCTIONS OF SUGARCANE PARTS

of Li, and the untreated contained 1 ppm. At this point, a second culture was treated, and 1 month later exudate from culture I contained 4 ppm; culture II, 9 ppm; and the check, 0.5 ppm. At this point, a third culture was treated, and 1 month later exudate from culture I showed 2.0 ppm of Li; culture II, 2.4 ppm; culture III, 14.6 ppm; and the check, 0.0 ppm. At this point, cultures V and VI were treated, and on July 24, the exudate from culture I showed 2 ppm; culture III, 15 ppm; and cultures V and VI, 13.5 ppm. Quite obviously, the roots were still capable of accumulating LiN0 3 even after 3 months, during which no new shoots were allowed to develop. Part 3. The results for Part 3 are shown in Fig. 2-75. After 5.5 months, the roots finally stopped exuding solution. During this time, no new shoots were permitted to grow. It would appear reasonable to assume that, had the original stalks been cut high, 2 to 3 feet from the ground, and allowed to develop lalas to feed the old roots but no suckers to develop new roots, the old roots would have kept going for a very long time. The various treatments had no positive effects. The KH 2 P0 4 treatment was not significantly different from the check or from K 2 S0 4 , and the three bottom treatments, though significantly worse than the first three, all detracted from the vitality of the roots, possibly due to increased osmotic pressure of the soil solution. Another test of the vitality of roots following harvest was done in the field at Hilo Sugar Company. Here, several young field men felt very strongly that after harvest the field should be ripped deeply not only to introduce air into the soil but also to cut the roots to force them to branch. The extreme was reached when a cultivator was designed to rip about 18 to 20 inches deep down the middle of the interrow on either side of the cane row. At the bottom of the vertical ripper, a shoe was designed to spread about a foot horizontally but with a wing toward its rear. The wing would lift the soil 2 to 3 inches and then, after the cultivator passed, the soil would drop back. The final stage was achieved when the two shoes of the two uprights were connected with a horizontal cut-

105

ting bar. When the machine with all of these things was put together and pulled by a fast-traveling power unit, the effect on the cane line of stubble was to cause it to jump and then roll from side to side. This gadget came to be known as the "Hilo Rock-andRoller," and was considered the thing. As is common on commercial plantations in Hawaii, when such a departure from normal is made, the agriculturist proceeds to install experiments, either with precise experimental design or merely for observational purposes. The test planned included hand cutting a plot of cane and throwing the cane out of the plot to achieve minimum interference with the ratoon. This plot received no ratooning of any kind except hand fertilization and weed control by knapsack. Another plot similarly harvested was subsoiled in every other line, then another in every line, and finally was given the "rock-and-roll" treatment. In a little while, it was quite evident that the least done was the best for the following ratoon growth. At about 3 months, the first plot was closing in, while the last-treated plot had hardly begun to grow. In fact, one could take hold of the shoots and lift the whole stool out of the soil, since no new roots had yet formed. At Paauhau, the agriculturist made similar studies and found much the same, except that in addition he noted that, when a root was cut, not only did the distal portion of the root die but it died all the way back to the stool as well. In the early days of irrigated cane production, when harvesting was all done by hand and the cane carried by people into the cane car, there was very little disturbance of the soil except that caused by the railroad tracks. The banks that had been flattened somewhat by the cane cutters and the cane loaders (hapaiko men) were restored by workers with hoes pulling the soil up out of the bottom of the furrow to the top. At Ewa Plantation, as many as 17 ratoons followed a single plowing and planting. Gaps in the lines were filled, but there weren't many of them, and yields continued to be excellent. Mechanical cultivators were not allowed in the field because they would disarrange the lines for the irrigator.

io6 Quite obviously, ratoon cultivation is of no benefit to root systems of cane. In fact, this applies to more crops than just sugarcane. More than SS years ago, work with corn at the University of Illinois demonstrated that the less disturbance of the soil, the better the crop grew. There had been the old belief, amounting almost to fanaticism, that a successful corn crop needed a certain number of interrow cultivations; as many as eight per crop were specified. An experiment was set up with several treatments: the check received no treatment—that is, the weeds were allowed to grow; another treatment called for shaving off the weeds at the soil surface with as little disturbance as possible; and another called for the standard cultivation practice. As with cane, the least soil disturbance gave the best yield. Allowing the weeds to grow, of course, was the worst, but cultivating was much worse than keeping the plots free of weeds without soil disturbance. Another benefit from cultivation was supposed to be the mulch created at the soil surface to preserve soil moisture. Yet the U.S. Department of Agriculture Soil Conservation Service people, working with the fine soil of the Palouse hills in southeastern Washington, showed that the 1 of 3 years devoted to fallow with surface mulching of the soil not only resulted in severe erosion but also left less moisture in the soil than was left when a leguminous crop was grown either as a cover crop or as a regular crop. The benefit to a crop following a fallow year was traced to the nitrification that occurred. The point can thus be raised—is there ever a condition that justifies cultivating after a cane harvest or plowing after one or two ratoons? As far as irrigated cane is concerned, when harvested, operations needed are those associated with reshaping the lines for irrigation. If the field is an unirrigated one, harvested under very dry conditions, no operation is needed; but if the soil was wet during harvest and compaction has resulted, subsoiling is probably helpful in aerating the soil, although if the compaction is severe and extensive, deep plowing and planting anew is the better procedure. Some plantations on the wet Hilo

CHAPTER 2

coast plow and plant along the infield roads where most harvesting and loading activities center, more or less regularly after each crop. The areas farther away from the roads, if not damaged, are ratooned. Much, of course, depends on the soil type. Another area where a very light cultivation is justified is in plant fields. As will be seen in Chapter 3, it is essential to plant cane setts in the bottom of a fairly deep furrow but covering the setts only moderately. This leaves a bank in the interrow. If harvesting requires a flat surface, then a light cultivator passed through the field when the cane is some 2 to 2 Vi feet tall will accomplish two purposes: while knocking down the bank and moving the soil into the cane line, it not only levels the field but also, if properly timed, accomplishes a weeding operation. Finally, if harvesting on a wet field has not caused compaction damage or rutting, by the time all the operations are completed, including the final raking of the stalks that were not picked up in the regular harvesting, the soil surface is fairly smooth and often even shiny. A rain on such a surface will cause a heavy run-off and ultimately much small gully erosion. A light cultivation to rough up the surface helps to prevent this. Considerable information relative to the persistence of cane roots after harvest has come from the root laboratory developed in South Africa at Mount Edgecombe by Glover (1967, 1968a, 1968b), patterned after one at the East Mailing Research Station in England. At Mount Edgecombe, a trench 7 feet deep x 7 feet wide was dug, and the sides were provided with glass windows through which roots could be watched and reached for treatments of various sorts. A roof and a floor were also provided to provide darkness as well as prevent contamination. Cane is planted in rows paralleling the trench, and the root performance can be watched through the windows inside the trench. One experiment pertinent to the problem at hand involved harvesting the crop and then observing the old roots. The roots slowed elongating immediately and stopped completely between 2 and 5 days later, confirming Hudson's work (1964) in Barbados. Forty-four days after harvest

STRUCTURES, NAMES, AND FUNCTIONS OF SUGARCANE PARTS

when the ratoons had produced adequate foliage for sampling, Glover applied 50 microliters of 32 P solution directly to the surface of an old root. A fine hypodermic syringe droplet spread into a fine film over the surface of the old root, which was vertically as well as laterally far below the new roots coming from the ratoon shoots. Several such placements

107

were made. Five days after treatment the treated plants were sampled and high counts of the tracer were found. It is evident from the report that extreme caution was taken in this experiment and that if a clincher is needed for the conclusion that the old roots continue to function long after harvest this one is it, and a very sophisticated one, too!

CHAPTER 3

The Gross Morphological Development of Sugarcane Parts; Vegetative Propagation; and Field Planting Practices

GENERAL DESCRIPTION OF SUGARCANE GROWTH In the growth of cane parts, each part has a time cycle to run. If the emergence of new parts is rapid because of excellent growing conditions, growth activities continue in morphologically more distant parts than where growth conditions are less favorable. The elongation of the sugarcane stem is accomplished by the activities of the intercalary meristems of the stem and by the elongation of the cells that originate from them. Figure 3-1 is a diagram of the growing stem of the cane plant. The leaves are numbered in the order used in selecting blade and sheath samples for analysis of moisture and other factors. Thus, the most recently emerged leaf, often showing as a slender, needle-like projection coming from within the folds of the next older leaf, is +1; the leaves are numbered downward (see Chapter 2). With variety 'H32-8560', as with other varieties, leaves older than +3 usually have their dewlaps exposed, while the dewlaps of leaves +1 and +2 are still enclosed in the spindle cluster. The dewlap of +3 is likely to show in winter months, while in summer it may be still enclosed. Sometimes even +4 is still enclosed. Growth of the various parts of the cane tops was determined in a study of groups of 10 tops of

'H32-8560'. These tops were dissected, and various leaf blades, leaf sheaths, and stem internodes were measured. Each time, 10 other plants were selected, appropriately labeled, and allowed to remain in the field for a month or so. From such data it was possible to determine the time and extent of growth of the various parts. Growth of Leaf Blades and Sheaths—Summer and Winter The measurements determined from the study in 1941 are reported in Tables 3-1 and 3-2. Both leaves TABLE 3 - 1 .

GROWTH (cm) OF LEAF BLADES IN SUMMER OVER A 28-DAY PERIOD (average o f 10 p l a n t s )

Leaf blade number +1 +2 +3

TABLE 3 - 2 .

1941

August 25,

1941

150 ± 3.9 191 ± 3-1 169 ± 2.It 185 ± 3 - 5 No f u r t h e r change

GROWTH (cm) OF LEAF BLADES IN WINTER OVER A 48-DAY PERIOD (average o f 10 p l a n t s )

Leaf blade number +1 +2

J u l y 28,

January 19, 1942 1 ± 3.6 178 ± 4 . 3

March 9 ,

1942

181 ± 4 . 9 181 ± 4.2

DEVELOPMENT OF CANE PARTS; VEGETATIVE PROPAGATION; PLANTING PRACTICES

O

-a

'I • .

-4-6-7-1-1

IOÇ

-I

3-1. A separation of aerial parts of the cane plant. Numbers in boldface designate the node, internode, sheath, and blade beginning with the spindle as +1. Numbers beside each part are the lengths, in cm.

FIGURE

+ 1 and +2 showed significant increases in growth, but the older leaves did not. In winter months maturity is achieved at an earlier stage, so far as reference to emergence is concerned, but, of course, at a slower rate: thus, in the January and March measurements, only leaf blade +1 showed growth.

After a leaf blade has completed its emergence so that its dewlap shows above the spindle cluster, there is no further elongation of the blade even though growth of the blade continues after the dewlap has been formed within the cluster. Within the spindle cluster, blades vary in length from a few microns for

no

CHAPTER 3

KEY TO ABBREVIATIONS USED IN FIGURES FOR CHAPTER 3

ar au b cb cbs cpb in

li n 1rs 2rs ps rb

aborted ratoon auricle bud cormbud corm bud sucker corm bud enlarging internode

ligule node 1st ratoon shoot 2d ratoon shoot primary shoot rootband

leaf - 7 to full length for leaf +2. In between, the blades elongate rapidly. Studies made on cross sections ('H37-1933') of the spindle cluster at the level of the very tip of the stem show that the sheaths are formed very early; in fact, preliminary work shows that the second member, - 6 , of the cluster already has sheath characteristics. With - 5 , there is no longer any question of it. Hence, essentially all the elongation of the blade occurs after the leaf joint with its ligule and dewlap have formed. It appears that the blade is formed at the meristem and elongates only a few cells before its tip is picked up by the growing cluster, and from then on the blade tip moves upward with the cluster, while the TABLE 3 - 3 .

GROWTH (cm) OF LEAF SHEATHS IN SUMMER OVER A 28-DAY PERIOD ( a v e r a g e o f 10 p l a n t s )

L e a f s h e a t h number +1 +2 +3 +4 +5 +6

TABLE 3 - 4 .

1.4 14.6 33.1 32.3 32.1

1941

± 0.2 ± 2.4 ± 0.5 ± 0.5 ±0.6 No f u r t h e r

August 25, 36-8 36-7 36.1 36.2 35-8 change

± ± ± ± ±

1 1 0.8 1.0 0.9 0.9 0.8

GROWTH (cm) OF LEAF SHEATHS IN WINTER OVER A 48-DAY PERIOD ( a v e r a g e o f 10 p l a n t s )

L e a f s h e a t h number +1 +2 +3 +4

J u l y 28,

November

17,

1941

1.3 ± 0 . 2 17-7 ± 2 . 6 27.4 ± 0 . 2 No f u r t h e r

J a n u a r y 26,

1942

27.4 ± 0 . 6 28.9 ± 0.5 29.0 ± 0.5 change

sp sr ssp ssr tsr vb

sett sett roots secondary shoots secondary shoot ratoons tertiary shoot ratoon vegetative bud

sheath forms at the base and then grows very little until after the associated blade has completed its elongation and becomes +1 or +2. At this point, the sheath begins to elongate. Groups of cells that become the bundles can be seen in sheath - 6 . Number - 5 shows the bundles with some mature xylem cells; leaf sheaths - 4 and - 3 show the various tissues well formed. Similar measurements of leaf sheaths are shown in Tables 3-3 and 3-4. Leaf sheaths, although formed very early, at - 6 , begin their major extension when the attached blades have about finished their growth. Leaf sheath+1 may be less than a cm in length when its blade tip begins to emerge from the spindle cluster. Its grand period of growth begins at about this stage, and by the time it becomes sheath +3 it has about completed its growth. In the summer, however, growth continues slowly until it becomes sheath +5. In winter, the growth cycle is completed before the sheath has become sheath +3. Important to the methods to be presented in Chapters 7-19 is the variation in size, area, and drymatter composition of the blades and sheaths of a given stalk. In Table 3-5 are recorded pertinent data taken from blades of an 'H53-263' plant about 7 months of age grown in sand culture in a glasshouse. In this table are given the dimensions of the blades beginning with the spindle leaf as +1 and including all the larger dead blades. The earliest formed blades found at the bottom of the stalk were already decomposing. Although variations occur, the blade area of this variety ('H53-263') down to the 23rd blade averaged 566 cm2 per leaf. It increases from the very

DEVELOPMENT OF CANE PARTS; VEGETATIVE PROPAGATION; PLANTING PRACTICES TABLE 3-5.

SIZE AND WEIGHT OF SUCCESSIVE LEAF BLADESi ON A GIVEN STALK OF 'H53-263 •

Width 3 Leaf no.

At joint

+1 2 3 1. 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

6.0 5.0 4.9 5.1 5.0 5.1 5.2 5.5 5.3 5.2 4.7 4.9 4.4 4.4 4.2 4.3 3.9 4.1 3.7 3.7 3.3 3.7 3.0 2.0 2.5 a

number number larger •> c

III

(cm) At haifway 5.3 5.8 5.9 5.9 5.6 5.5 5.9 6.0 5.7 6.0 5.5 5.4 5.3 5.8 5.4 5.3 4.9 4.9 4.5 4.4 4.5 4.0 3.4 2.0 2.5

Length 3 (cm) 93.6 122.0 136.0 134.5 134.0 133.0 130.3 123.0 123.6 120.0 118.3 118.0 122.0 127.0 128.7 C 131.0 142.4 143.0 145.0 159.0 161.2 146.5 143.4 118.0 122.0

lj Area (cm*)

Dry wt. of blade (g)

562 611 666 686 670 678 678 678 655 624 556 570 537 559 541 563 555 586 537 588 532 542 430 236 305

4.43 4.90 6.52 6.84 6.52 5.86 6.44 6.42 6.34 6.12 5.84 5.27 5.00 5.62 5.65 6.08 5.85 5.55 5.71 5.55 5.19 4.25 3.76 2.33 2.80

Moisture (% green wt.) 69.6 66.3 67-3 66.6 67.0 71.1 68.5 68.2 68.1 67.5 66.0 66.5 65.3 62.8 58.7 57.8 60.3 42.0 9.6 9.2 8.3 8.1 7.8 6.8 6.7

Dry wt. of area (mg/cm2) 7.9 8.0 9.8 10.0 9.5 8.6 9.5 9.5 9.7 9.8 10.5 9.1 9.3 10.1 10.4 10.7 10.5 9.5 10.6 9.4 9.8 7.8 8.7 9.9 9.2

The first number Is the width of the leaf about 3 cm above the leaf joint; the second is the width about one-half to two-thirds of the way toward the leaf tip; and the third is the length of the blade from the joint to the tip. The second value usually is the of the first two, but, In this case, the blade has not yet fully formed. The area Is the product of the first width by the length. Leaf 15 and all leaves below it (16-25) were dead.

early leaves (+24 and +25) up to the leaves produced at 5 to 7 months. Leaves +1 and +2 are not yet fully developed. The moisture level of the blades remains relatively the same down to the point where the leaf edges are beginning to die (+13 and +14), followed by the whole blades, and finally even the midribs, which are last to die, +19 and on. Interesting is the fact that leaves +15 to +18 inclusive, although apparently dead, continue to receive moisture from within the plant since they contain almost normal levels of water. When death exists for a month or so, however, the moisture level drops to that obtained only from the atmosphere. The dry weight of the blades, expressed as mg/cm1, although fluctuating, remains at about the same general level. Thus, in later chapters where nutrient levels, expressed as the percentage of dry weight, rise or fall in the leaf blades, it will be due to a change in the actual level of

the nutrient and not to a change in the dry-weight base. Table 3-6 records similar data for the sheaths detached from the blades in Table 3-5. The trends are much the same as shown by the blades. Leaf-Blade Area The leaf-blade area of a cane leaf is approximated rather well simply by multiplying the length of the blade from the ligule up to the tip by the width some 2 to 3 cm above the ligule. The tapering toward the tip appears to be offset by the broadening of the leaf from the base upward. The size of the leaf is determined largely by the variety, age, moisture content, and nutrient status of the plant. The earliest individual leaves on a germinating plant appear with no blade, being simply a sheathlike organ clasping the inner sheaths. Thus, for

CHAPTER 3

112

TABLE 3-6.

SIZE AND WEIGHT OF SUCCESSIVE SHEATHS ON A GIVEN STALK OF 'H53"263'

Leaf no.

Length (cm)

Width (cm)

Area (cm^)

Dry wt. of sheath (g)

+1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 a 16 17 18 19 20 21 22 23 24 25

9.0 17.0 25.8 27.8 27.0 27.0 27.5 27-5 25.0 27.0 26.0 24.5 25.5 23.5 24.7 25.0 27.0 27.0 25.5 27.5 27.5 29.6 31.0 29.5 30.0

5.8 5.3 6.3 6.5 6.8 .6.8 6.8 6.5 6.7 7.3 7.1 6.8 6.5 5.7 5.4 4.7 4.7 4.7 5.4 5.8 5.7 5.7 5.0 3.7 3.5

52 90 163 181 184 184 187 179 168 197 185 167 166 134 133 118 127 127 138 160 157 169 155 109 105

1.00 2.98 4.22 4.53 4.91 4.95 4.62 4.38 4.37 4.08 3.68 3.41 3.40 3.19 3.34 3.52 3.30 3.08 3.00 3.05 2.30 2.59 2.33 2.18

a

Moisture (% green wt.)

-

-

82.9 83.2 74.9 71.9 70.3 70.8 71.7 69.4 68.1 62.9 65.2 61.7 56.1 46.5 46.0 46.1 28.9 9.9 9.4 7.6 6.4 7.2 6.8 5.6

Dry wt. (mg/cm^) 11.1 18.3 18.3 23.3 24.6 26.7 26.5 25.8 26.1 22.2 22.1 22.0 20.5 25.4 24.0 28.3 27.7 26.0 22.3 18.7 19.4 13.6 16.7 21.4 20.8

Leaf 15 and all leaves below it (16-25) were dead.

'H31-1389', the leaf-blade area per leaf starts from 0 and increases to a maximum of over 1,000 cm2 during the "boom" stage of growth when moisture and nutrient levels are high. Leaves emerge at a very rapid rate in young plants, far in excess of the rate of leaf dying; but after the cane stem appears with fully developed internodes, the rates of leaf emergence at the tip and of leaf-dying at the base are more or less synchronized until the period of ripening, when the leaf-dying rate increases over the rate of emergence. To be sure, the plant meets any drought very quickly by reducing its leaf area, accomplished not only by a slowing down of leaf emergence, but also by an acceleration of the leaf-dying and by the rolling of the living leaves. The reverse situation obtains when the plant passes from a drought period into good growing conditions. During the middle of the plant's cycle, there are from 12 to 16 fully expanded leaves. The oldest leaves are usually partially torn loose from the stem. Under conditions favorable to maximum leaf emergence and retention, there may be a leaf area as high

as 16,000 cm2 stalk, although averages are considerably lower. The average maximum leaf area per stalk in one study was 9,108 ± 347 cm2 attained in July when the crop was 1 year old; when the crop was 4 months old, the leaf area was 4,344 ± 122 cm2. Leaf area increased gradually to the maximum, after which it dropped off, first slowly and then, as ripening was undertaken, rapidly until there were only some four or five leaves remaining. Internodes and Circumference In referring internodes to leaf numbers, it is assumed that the internode below a particular leaf connection is associated with it. The assumption is based on general botanical theory and on the fact that considerably higher correlations were found between final actual lengths of sheaths with internodes below than with internodes above. Thus, in one study conducted under greenhouse conditions with variety 'H-109', the correlation between sheath length and length of the internode above the attachment was 0.62, which, in this case, was not significant; the cor-

"3

DEVELOPMENT OF CANE PARTS; VEGETATIVE PROPAGATION; PLANTING PRACTICES

FIGURE

3-2. P r o -

jection drawing of an apical meristem with its young meristematic leaf primordia. Note the distinct layer of cells below the outer tunica layer, which probably represents the first stage in the flowering cycle. (See Clements, 1975.)

relation between sheath length and length of the internode below was 0.95, which was highly significant. Internode measurements are shown in Table 3-7. Just as the sheaths took up growth activity when the blades were finished with it, the internodes take over from the sheaths. The total vertical growth made during a period of 6 weeks is contributed to by several intercalary meristems. In the course of growth from May 29 to July 13, 1942, for instance, TABLE 3-7.

GROWTH (cm) OF INTERNODES OVER A 45-DAY PERIOD (average of 10 plants)

Internode number 0 +1 +2 +3

+k

+5 +6

May 29, 19^2 0.08 0.20 0.36 1.1 2.5 5.2 5.8

± ± ± ± ± ± ±

0.03 0.01 0.02 0.03 0.26 0.62 0.62

July 13, 19^2 7.A 10.1 10.1 8.6 7.2 6.8 7.1

± ± + ± ± ± ±

1.3 1.3 1.0 0.6 0.5 0.6 0.6

internodes of leaves 0, +1, +2, +3, and +4 made major contributions. It is also apparent that at any one instant, the internodes of leaves 0, +1, and +2 are not yet elongating significantly: the internode of leaf +3 is entering the grand period of growth, the internode of leaf +4 is in the middle of its grand period, and the internodes of leaves +5 and +6 are approaching senility. The nodal plates show clearly as strata (Fig. 3-2) before the internode begins elongation, and, of course, the leaf blade associated with it is already mature. The intercalary meristem just below each one becomes active in cell multiplication. The cells near the upper nodal plate mature, while cell formation and elongation of cells continues at the bottom end just above the next older nodal plate. Maturation at the upper end of an internode is very advanced, while elongation activity continues at a lower level in the same internode. In this part of the cane, susceptibility to breakage in storms is great.

ii4 Stalk Circumference Increase in stalk circumference begins at the very tip of the meristem (Fig. 3-3). The internode of leaf+4 is already past the grand period of growth in circumference, but growth continues on a decreasing scale for several more internodes, depending somewhat on the season of the year. Sometimes this growth actually tears the attached leaf sheath base loose from the node, particularly at the edges. Normally these edges overlap considerably in the region of the elongating cane, clockwise at one node and counterclockwise at the next. As growth in circumference continues, the overlap of the attached base of the sheath is less and less marked, and sometimes, with especially thick stalks, the edges may no longer touch. It is apparent that the base of the leaf sheath at the point of attachment also increases in circumference, although more frequently it tears away, leading to the drying of the blade edges. In some varieties (such as 'H32-8560'), this increase is in keeping with the increase of stem enlargement, and, hence, the sheath may remain firmly attached to the node long after it is dead. In other varieties (such as the self-stripping varieties,

Photomicrograph of a longitudinal section of a stem tip showing the very small apical meristem enclosed by the leaves formed by it and the development of the intercalary meristems (the light horizontal areas) beneath each nodal plate (the dark layers). Traversing both areas are the young developing vascular bundles. (Photo by M. S. Canny) FIGURE 3 - 3 .

CHAPTER 3

'H37-1933', for example), this is less true; the sheath is torn from its attachment and falls off. Apical Meristem As shown in Figs. 3-2 and 3-3, the apical meristem of the stem is a small, dome-like mass of tissue. It is made up of the meristematic cells, which ultimately develop into the leaves, lateral buds, and the primary tissues of the stem. For the most part, the tunica appears as three layers of cells, and these are distinct from the corpus. Figure 3-2 shows a distinct second layer, which probably is the first suggestion that a blossom is to develop. The number of leaves attached to this meristematic stem tip varies somewhat from the very young plant to the fully developed growing plant. Counts of these leaves were made in an earlier study with 'H31-1389' (Clements, 19406) at Waipio and at Kailua, on the Island of Oahu, Hawaii. Ten meristematic tips were obtained from each of four plots at intervals of about a month. In all cases, when the plants were about 3 months of age there were eight leaves in the meristem above the point of attachment of leaf +1. Leaves emerge from the spindle cluster at a more rapid rate during this period of growth than later on. The meristem itself enlarges beyond this point; and when the growing mechanism is fully established, the meristem has 10 or 11 leaves developing from it at any one time. The number appears to be a constant for a given variety, whether growing in a high-energy atmosphere (Waipio) or a lower one (Kailua). Thus, the average of 500 tips examined from Waipio was 10.37 leaves per tip, while the same number of counts taken on parallel dates at Kailua averaged 10.26 leaves per tip. In this respect, there is no difference between plant and ratoon crops. Since the number of leaves above the node carrying leaf +1 appears to be a constant after the growing meristem achieves full stature, it follows that the rate of leaf primordia development by the meristem is accurately reflected by the rate of leaf emergence from the spindle cluster. Therefore, by determining the rate of leaf emergence from the spindle cluster, it is possible to determine the activity of the meristem and

"5

DEVELOPMENT OF CANE PARTS; VEGETATIVE PROPAGATION; PLANTING PRACTICES

inferentially the vigor of the plant, although, as will be seen later, there are some exceptions. This is indeed a very great convenience to the investigator! Of great interest to the students of translocation is the situation revealed in Figs. 3-2 and 3-3. Even though leaf blades +2 and +3 are rather fully expanded, the vascular connections to them from the stem are still embryonic and, hence, very poorly developed. The eight leaves enclosed within +1 require considerable quantities of nutrients, both organic and inorganic, as well as water, to enable their growth, and all of this translocation has to be by way of relatively undeveloped tissues. GLIDING GROWTH WITHIN THE SPINDLE CLUSTER Studies (Clements et al., 1952) were directed toward the nature of the so-called gliding growth of cane parts. Using a cork borer, small punches were made through the spindle cluster. These were examined 24 hours later to determine where gliding occurred. In all the tops examined, leaf +1 and all its enclosed members grew at the same pace. In a few, leaf+2 and all its enclosed members, including +1, grew at the same rate. The factor effective here was the actual age of +1. Thus, if leaf +1 had emerged within the previous few days, all parts within +2 and including it grew uniformly. If leaf+1 was very near in time to becoming +2 then the equal growth applied to leaf+1 and its enclosed members. Therefore, within leaf + 1 or +2, depending on the particular moment, there was no vertical gliding of individual members; all parts grew upward at the same rate as the outermost member. As the outermost member began to approach its final length, it began to lag behind the next inner members. This was the point of gliding, but is more a case of being left behind. There appeared to be no gliding upward, since the entire central core made up of sheaths and the very young blades in the tip just being picked up by the cluster grew at a uniform rate. A priori consideration would lead to the surmise that within leaf+1 or +2, depending on which one is the outermost member of the growing spindle cluster

at a particular moment, there must be five other leaf blades taking part in this growth. By use of the sheath and blade measurements reported in the first part of this chapter, it is apparent that their ratio approaches 6:1. Since there is no gliding within, it must mean that from the time the tip of a leaf primordium is caught up by the upward growing cluster and the time that it is exposed as a fully grown leaf blade, six successive sheaths have taken part in carrying it forward. Dissection verifies this to be correct, and, as should be the case, the length of the blade should approximate the total of the length of the six older sheaths. One such dissected top yielded the data shown in Table 3-8. Leaf blade +2 measures 176 cm. If it is assumed that it has completed its growth, it should approximate 177.9 cm, the sum of the lengths of the previous six sheaths, that is, sheaths +3 to +8, inclusive. Departures are brought on by variations in the time the primordium is caught up by the growing cluster and also by the amount of growth taking place in the blade after it is released by the cluster. At a particular moment, growth of leaf blades is confined to leaf +1 or +2 and all those blades within it. When the blades have substantially completed their growth, corresponding sheaths take it up. Thus, at a particular moment sheaths of leaves +1, +2, and TABLE 3-8.

Leaf number + 13 + 12 + 11 + 10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1 0 - 1 - 2 - 3

RELATION OF SHEATH LENGTH TO BLADE LENGTH

Length of blade 3 (cm)

176.0 140.0 105.0 73.0 36.0 1.5

Length of sheath (cm) 34.3 32.3 25.4 24.8 25.3 26.5 30.8 27.2 31.2 31.0 31.2 7.3 1.4 0.4

a Blade lengths for older leaves (13"3) are not included because the leaf tips had been broken by winds.

n6

CHAPTER 3

FIGURE 3-5. Detail of a joint (outside dewlap) between blade and sheath. The sheath shows the presence of an auricle. The membranous ligule is attached to the joint inside at the bottom of the blade and clasps the next inner sheath upward.

3-4. Detail of two sheaths clasped about the enclosed leaf parts. Each sheath has an auricle.

FIGURE

+3 are growing; +1 is just becoming active, +2 is very active, and +3 has just completed its heavy growth. When the sheaths become senile, their corresponding internodes become active. When sheath +3 has about reached its full growth, the internode below leaf+3 is about to enter its grand period of growth; +4 is in the middle of it, and while internodes +5 and +6 may still show traces of growth, they are now at the end of their cycles. Since growth of the spindle cluster is effected by cell activity above the actual stem meristem, all the members reach approximately the same dewlap level as the outer members. Separation of levels of consecutive dewlaps takes place between +3 and +4 and is brought about by the growth of internode +3, which, as it grows, raises everything attached to node +3 and above. Since one or more internodes below +3 are still growing, dewlaps of the corresponding sheaths are being moved farther and farther apart. Thus, except for small seasonal changes in lengths of dewlaps, growth measurements made from a fixed ground point up to the topmost visible dewlap actually represent stem elongation only, even though the topmost visible dewlap is one full sheath length above the stem meristem.

The sheath portion of the leaf plays a most important part in supporting the cane top. Figure 3-4 shows a solid mass of sheaths, one within the other. At a lower level, the stem tip and below it the elongated cane would be inside, supported by the sheaths, which are very tightly clasped together. Figure 3-5 shows the detail of the leaf joint (dewlap). The blade and sheath are separated by a thin membranous collar of tissue, the ligule, which very firmly clasps the stem. This clasp is further strengthened by the dewlap, and together the ligule and dewlap form a very firm, hermetical seal giving protection to the inner parts. The name "dewlap" seems inept for describing the joint between the blade and sheath. It would more appropriately apply to the ligule, which, when firmly clasping the next inner member, would serve as a seal against leakage of dew or rain and yet Artschwager (1925), who began the use of the term, clearly showed it to represent the joint, or the brown tissue on the outside of the leaf. Shown also in Figs. 3-4 and 3-5 are auricles, upward-pointing projections of the sheath edge, which have no apparent function. Many clones show no projections at all. The auricle is probably simply the result of the way the particular clone unrolls its leaves. That the sheath at the point of the topmost visible dewlap clasps the inner tissue very firmly is nicely shown by the so-called "growth marks" on the most exposed sheath (Fig. 3-6). As the vertical growth pressure builds up, the clasp loses its grip for a moment, and a surge of growth follows. Again the clasp

DEVELOPMENT OF CANE PARTS; VEGETATIVE PROPAGATION; PLANTING PRACTICES

117

tassels, and, hence, blossoming would not develop to confuse the study. In germination, the bud begins to swell and the meristem within the bud becomes active 3 days after planting (Fig. 3-8). During this active period, profound changes occur in the physiology of the sett. Prior to cutting the cane, the sett is a part of the vertical stem that supports the cane leaves and top, transporting water and nutrients upward and the inhibitors, which keep the lateral buds dormant, downward. After cutting and planting, the bud is no longer inhibited, and, hence, it begins to develop meristematic leaves and to mobilize the food it requires from the sett. Also during this period, soil FIGURE 3-6. "Growth marks," showing as slightly darker organisms attracted to the food source begin to inhorizontal bars on the sheath at left, result from the com- vade the sett from both ends. Six days after planting pression or removal of some epidermal wax by the clasping (Fig. 3-9), the bud is considerably enlarged, and the dewlap. sett roots arising from the root band of the stem, takes hold at the larger diameter until it is again where they existed as dormant tips, become active. broken, and so it continues, until a series of horizon- Now there is little difference in bud growth, whether tal marks are left, which the field man watches as top or side. Nine days after planting (Fig. 3-10), difevidence of rapid daily growth. The "growth marks" ferences in the position of the bud begin to show. as used here should not be confused with the growth Where the bud is on top, the shoot is straight, though ring that appears on the stem just above the root slightly off-vertical at the start; on the side, growth band after internode elongation has stopped. This curvature is apparent, the total shoot growth is growth ring is the thin line separating the root band somewhat slower, and sett root growth is stronger. from the remnant of the intercalary meristem, Twelve days after planting (Fig. 3-11), these difwhereas the "growth mark" is the impression on the ferences are greater, with evidence of early superior rooting of the bud on the side. From this time on, waxy epidermis left by the clasp of the sheaths. vertical elongation becomes rapid, and the shoots push through the soil surface. Figures 3-12 and 3-13 DEVELOPMENT OF A SINGLE SHOOT FROM at IS days and 18 days after planting, respectively, 0 TO 43 DAYS In Figs. 3-7 to 3-17, inclusive, are shown the progres- show the first shoot roots developing from the curve sive stages of development of the bud on a single bud in the growth coming from the side of the sett. This is one big advantage of planting with the bud to the sett. side. Even though there is a tendency for the early In Fig. 3-7 is shown a bud in two views, side and shoot growth to be somewhat slower than from the top, at the time of planting. Although the sett is bud on the top, because of faster root development in drawn accurately as it was, it would have been better both sett and shoot roots, later growth more than to cut the piece so that one-third of its length had catches up. At 21 days after planting (Fig. 3-14), the been above the bud and two-thirds below. Experience top leaf begins to unfold and then to separate into has shown this to give stronger germination since the distinct leaves (Fig. 3-15 and 3-16). The stalk (Fig. nutrient passageways to the bud seem more strongly 3-17), about 4Vi feet from top to bottom, may be connected to the internode below the bud. The varieseen when the boom stage of growth is well along and ty used for this series was 'H51-4336' because it never

RGURE 3-7. 'H51-4336' sett at time of planting (August 5, 1966). The bud is /,-inch thick. Each was planted with the bud in the indicated position.

FIGURE 3 - 8 . Three days after planting (August 8, 1966), each bud has doubled its thickness to V* inch.

FIGURE 3-9. Sue days after planting (August 11,1966), the bud is a small shoot, 3/4-inch long, and sett roots appear.

3-10. Nine days after planting (August 14, 1966), each shoot is 1 % inches long. The bud on the bottom sett is also developing some shoot roots.

FIGURE

FIGURE

3-11. Twelve days after planting (August 17,1966), the shoot on the top sett is \Vi inches tall. Note the large root development of the bud on the bottom sett, a condition associated with planting the sett with the bud on the side or underneath.

FIGURE 3-12. Fifteen days after planting (August 20, 1966), the plants are 4% inches tall. Note the sharpness of the tips. When germinating in a soil with a dry crust, the sharp point exudes water by guttation, which softens the crust.

3-13. Eighteen days after planting (August 23, 1966), the plant on the top sett is VA inches tall. FIGURE

3-14. Twenty-one days after planting (August 26, 1966), leaves are beginning to unfold. The plant on the top sett is 9 inches tall and already has three leaves.

FIGURE

FIGURE 3-15. Twenty-four days after planting (August 29, 1966), the plant is 193A inches tall and at the four-leaf stage.

FIGURE 3-16. Forty-three days after planting (September 17, 1966), the plant is 25 inches tall and at the five-leaf stage.

FIGURE 3-17. The well-developed cane top with a full complement of living leaves, showing the spindle leaf (+1) as a small pointed projection from the unrolling edge o f + 2 (56 inches from bottom to top). The number beside each sheath applies not only to it, but also to the blade and the internode below the node to which the sheath is attached.

DEVELOPMENT OF CANE PARTS; VEGETATIVE PROPAGATION; PLANTING PRACTICES TABLE 3--9.

121

GERMINABILITY OF SINGLE BUD SETTS

Buds on top

Buds on the side

Bud no.

Shoot length (cm)

Days to emerge

Shoot length (cm)

+ 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

37.5 46.3 51.5 1(8.7 35.7 39.0 35.0 36.3 35.5 30.6 29.1 25.8 25.9 25.1 25.1 25.6 25.1 26.7 27.6 30.6 26.9 32. i»

9.0 8.1 6.9 6.8 6.7 6.8 7. 4 7.5 8.5 9.1 9.7 9.5 11.0 12.2 13.0 13.1 11.8 12.2 12.1 12.6 12.9 14.2

44.0 48.8 50.0 49.6 44.7 41.3 36.3 39.6 35.3 35.7 36.5 29.9 34.9 27-7 25.7 25.9 29.1 28.1 26.8 27-3 31.7 27.9

Average

32.45

10.5

35.6

Buds underneath Shoot length (cm)

Days to emerge

13.4 12.4 10.9 11.7 12.2 12.3 12.9 13.9 14.3 15.7 15.5 19.3 20.8 23.7 23.3 24.5 27.7 27.7 23.6 25.0 25.3 30.0

42.0 54.5 57-2 45.2 38.5 40.1 38.3 34.3 36.3 35.6 32.6 30.1 26.2 21.9 23.7 28.6 29.5 30.4 32.2 27.3 29.9 30.9

14.8 14.3 14.4 15.2 16.9 15.8 17.7 19.1 21.5 22.2 24.8 26.3 31.6 31.3 32.8 31.8 31.5 30.1 30.1 33.4 32.3 33.0

18.8

34.8

24.6

Days to emerge

the field is closed-in. In well-nourished plants at any were made daily. After 9 weeks, the plants were one time, as many as 17 to 20 green leaves may be removed from the flats and measured (Table 3-9). seen on a stalk, counting downward from the spindle It is evident that all the buds of a stalk are capable leaf as +1, each enclosing a bud. of germination if healthy, that is unbroken or undamaged by bud insects. It is also evident that the FACTORS AFFECTING GERMINATION older the bud of a stalk, the slower is the rate of gerOF SETTS mination and the subsequent growth. Emergence is Position of Buds hastened if the sett is planted with the bud up, The germinability of buds from a given stalk varies although the subsequent growth is somewhat slower considerably from the top to the bottom (Clements, for reasons that will be evident shortly. If the bud is 1940a). Beginning with the bud enclosed by leaf +7, on the underside of a one-bud sett, it takes more than 30 stalks having undamaged buds were selected for a twice as long for the shoot to emerge, but subsequent 1939 study, and each stalk was cut into single bud shoot growth is good. As might be anticipated, when pieces. Younger buds than +9 are immature and easi- the bud is on the side, results are intermediate. ly damaged; under field conditions, however, they The best performance, regardless of bud position, would be enclosed by their sheaths. The buds were is from the bud enclosed by leaf +9, which is fully put to germinate in soil in flats under favorable con- developed without hardening having set in. Buds ditions of sunlight, temperature, and water. In the younger than this take longer to germinate and grow first set, all the setts were planted with the bud on the less rapidly, probably because they require some time upside; in the second, all were on the downside; and to reach the initial growth stage of +9. Buds older in the third, all were on the side. Germination counts than +9, which are still enclosed by a leaf, also per-

122

CHAPTER 3

FIGURE 3-18. One-bud setts were placed to germinate with the bud on top (A), on the side (B), and underneath (C). Growth in each is about the same, but notice the development of shoot roots on the two where there is a curve in the growth.

form very well, although a slowing down with age is where they occurred, although their length is not invery apparent. Buds whose enclosing leaves have dicated. fallen require about twice as many days for emergence and grow about half as fast, although all of One-Bud Setts them are capable of good later growth if properly In Table 3-10, data are presented for one-bud setts treated and fertilized. taken from the top (I), middle (II), and bottom thirds (III) of the cane. Germination of the one-bud setts Number of Buds per Sett and Sett Age taken from the top third of the stalk was perfect, In an effort to determine the best number of buds per whether the bud was up, down, or on the side (Fig. sett, 10-month-old, well-cultured field cane was cut 3-18). Of interest is the earlier development of roots and divided into top, middle, and bottom thirds where the germinating shoot comes from the side or (Clements, 1940a). These, in turn, were cut into one- underneath resulting in a curved growth, which bud, two-bud, and so on, setts and were put to germi- always favors root development at that point. When nate in flats containing fertile, well-drained garden the shoot developed from an up bud, the appearance soil. Three bud positions were used: the terminal bud of its roots was delayed. up, down, and to the side. After 44 days, the plants Later work was done with one-bud setts because of were lifted and shoots measured from the seed piece the interest in the industry to save planting material to the tip of the longest leaf. Figures 3-18 to 3-22 and to place each bud at a precise distance from the show the results, each shoot drawn from an actual next, as occurs with seed crops, such as corn and and typical photograph but drawn to the average sugar beets. The results showed that the one-bud setts length of all the shoots of each treatment but only should be cut so that about one-third of the total from the young setts obtained from the top third of length is above the bud and two-thirds below. The the stalk (age I). For the illustrations, all the sett vascular connections from a bud were stronger to the roots were removed, and the shoot roots are drawn internode below the bud and, hence, provided nour-

DEVELOPMENT OF CANE PARTS; VEGETATIVE PROPAGATION; PLANTING PRACTICES

123

FIGURE 3-19. Two-bud setts were placed to germinate with the terminal bud up (A), to the side (B), and down (C). Where the terminal bud is up, its growth is strong, but the down bud grows poorly. Where the terminal bud is down, some of the shoots do relatively well, although the second bud grows very well.

obtains with the three buds on the side.

fourth shoots in B are smaller than the first two, showing that as more buds are included, there is a suppression of not only the down buds but also the basal buds.

completely suppressed; it will probably fail to survive the early competition.

DEVELOPMENT OF CANE PARTS; VEGETATIVE PROPAGATION; PLANTING PRACTICES TABLE 3-10.

PERFORMANCE OF ONE-BUD SETTS OF THREE AGES AND THREE POSITIONS (average of 50 setts in each category)

Age of sett

Position of first bud

Emergence

(%)

Length of shoot (cm)

Up Down Side

100 100 100

70 70 75

1 1 1 1 1 1

Up Down Side

96 94 96

46 38 51

1 1 1 1 1 1 1 1 1

Up Down Side

80 90 90

33 33 31

Young 1 1 1 Middle

Old

TABLE 3-11

PERFORMANCE OF TWO-BUD SETTS OF THREE AGES AND THREE POSITIONS (average of 25 setts, 50 buds, in each category)

Length of shoot (cm) Age of sett

Position of first bud

Emergence

m

First

Second

Up Down Side

66 94 100

76 48 70

21 72 56

1 1 1 1 1 1

Up Down Side

70 88 94

53 32 1(8

19 48

120

90 $ o tr.

o

60

FIGURE 4-7. Relation between sheath moisture and growth units.

30

76

80

78

SHEATH TABLE 4-11.

Crop year 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945. 1946* 1949

82

83.45 83.55 83.75 83.45 82.97 82.53 83.73 85.12 84.65 84.18 84.51 87.71 85.23 85.75 85.04 85.16 84.88 84.88 84.98 83.54

88

MOISTURE

RELATION BETWEEN MAXIMUM TEMPERATURE AND YIELD OF SUGAR AT EWA PLANTATION COMPANY, 1928-1949

Mean maximum temperature (°F)

86

84

Yield (TSAM) .557 .560 .578 • 551 • 570 .574 .556 .503 .489 .509 .515 .525 .535 .491 .500 .428 .447 .449 .463 .576

-.782. b i Two strike-affected years are not included--1947, 1948.

ing the hotter years than during the cool years; because of economic factors, however, the reverse was actually the case. Sheath Moisture and Growth In Fig. 4-7, the relation between tissue moisture and growth units is shown to be curvilinear, although again a straight line is adequate for most purposes. Thus the correlation of a straight line and the actual points is .969, while that for the curve is .986. From the high moisture levels down to 78.0, the points arrange themselves on a linear basis; of course, this is the range of greatest consequence to growth. In order to maintain moisture levels at 86 to 88 percent, young plants must be adequately provided with soil moisture and with excellent mineral nutrition and must be kept completely free of competition from weeds. Usually, after a crop is a year old, such high moisture levels are practically impossible to achieve and also undesirable, the normal range being from 80 to 83

164

CHAPTER 4

£00

300

AGE

IN

DAYS

percent. As harvest approaches, the moisture level is reduced, and, of course, with it growth slows down. Some fields may be found which, because of poor timing of irrigation and fertilization and weeding, have low moisture levels when a little more precision in field operations would raise the moisture level and with it the growth rate. Actually, the most important single physiological factor in cane production is the sheath moisture level. Age, Height, and Growth It is common knowledge that young cane plants 2 to 3 months of age grow at a faster rate than older plants. The relation of age to the rate of elongation is shown in Fig. 4-8. The downward break in the curve is sharp until the plant is about 7 months old, when the rate of elongation drops off very gradually to about age 20 months. Actually, there is no good reason why age of itself should be strongly and inversely related to growth. Since the older plant is taller, it is probably length of stem rather than age that becomes the limiting factor in growth (Fig. 4-9). The simple correlation between age of plant and length of plant is .973 (rt - 1,373), so that, within a given ecological area, it is immaterial whether age or height of the plant is used once the

relationship is established for that area. If one compares the growth made in a high-energy area with that in a low-energy area, however, it is evident that it would be safer to use height rather than age. In the Waipio study, the height of plants shows a simple correlation with growth units of-.671, while age shows a simple correlation of-.648, only slightly less. Minimum Temperature and Growth The relation between growth units and the minimum temperature experienced during the Waipio study is shown in Fig. 4-10 to be linear. Light and Growth When growth units are classified according to amounts of radiation per day, the relationship is positive and linear (Fig. 4-11). MULTIPLE REGRESSIONS AMONG MORPHOLOGICAL, PHYSIOLOGICAL, AND ECOLOGICAL FACTORS AND GROWTH Evaluating the relative influences of climate and physiology leads to an equation that can be used in conjunction with sugarcane production to predict yields and evaluate practices.

165

FACTORS AFFECTING GROWTH OF SUGARCANE

ROUSE 4-9. Relation between plant height and growth units. Although the curve is a better fit it is only slightly better than the straight line.

GROWTH HEIGHT

UNITS IN

CMS

Relation between minimum temperature and growth units.

FIGURE 4 - 1 0 .

zoo

275

390

425

500

575

650

725

166

CHAPTER 4

700-

600

500

< o

O

400

m

300-

O


ISH 8,'26/5 S,kNPL: v •A 1(IT (9:

4

JAN

11

IB 25

4

FEB

11 18 2 5

I

MAR

8

15 2 2 29

6

APR

13 2 0 2 7

MAY

3

10

17 24

1

JUN

6

15 2 2 2 9

JUL

3

10

17 24 31

AUG

1 K

\

s

\ V

s

O S Tu

2

50Í-I

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CHAPTER»

Potassium (K)

IMPORTANCE OF K TO A CROP The chemical symbol for potassium, K, is taken from the old, now obsolete word for alkali, "kali." Whereas K is not needed by animals but is indispensable to plants, sodium (Na) is indispensable to animals and is not only nonessential to plants, but in more than trace amounts is toxic. These two elements along with calcium (Ca) (Chapter 11) and magnesium (Mg) (Chapter 12) make up the four cations that can accumulate under arid conditions and produce saline or alkaline conditions very harmful to plant growth (Sund and Clements, 1974). Of the four, only Na is not essential to plant growth, although it can replace small amounts of K in the metabolism of some plants. Sugarcane requires very large amounts of K, as will be seen shortly, and yet specific functions for K have not been established. Of the essential elements, K occurs in highest amounts, and caused Liebig (1871, cited from Palladin, 1923) to class sugarcane in the group of K plants. Under certain conditions, silica is more abundant in cane, but it has not been established as essential. Should it prove to be so, the amount actually needed would very likely place it in the minor elements category (see Chapter 11).

No involvement of K in specific metabolic functions has been demonstrated. Attempts have been made to associate it with translocation, photosynthesis, enzyme systems, respiration, and so on, but these attempts have no objective, logical, or reasonable supporting data. There is no question about K's indispensability to plant life, and, of course, if it is absent, the plant cannot function properly, and hence, essentially all its various processes are likely to be affected. But such effects cannot be attributed directly to K. The need for balancing di- and polyvalent ions with monovalent ions in maintaining a dispersion of the colloids of protoplasm has long been known, and it is probably in this category that K performs its major function. The unanswered question why K should be indispensable to plants and Na to animals, but not vice versa, prevents the solution of the problem from being simple. Hydrated K ions occupy less space than Na ions and much less than in solutions, and this may cause a better fitting together of essential parts of plants that make up the surfaces on which reactions take place. But rubidium is only slightly smaller than K, and, although it performs somewhat as K does, it cannot be substituted for it as an essential element. K also is closely related to quality of germination.

POTASSIUM TABLE 8-1.

321

POTASSIUM CONTENT OF SUGARCANE PARTS (percentage of dry matter, except young sheaths b )—'H32-8560', WAIPIO PLOT B

Year: Plant part

1943

Age (months): 2 . 8 3 Date: 9/24

Meristem and elongating cane Spindle cluster Young blades Green lisaf cane blades Young sheaths Young sheaths b Old sheaths Green leaf cane Top internodes 15th 3 nternodes 14th 3 n te m o d e s 13th 3 nternodes 12th 3 nternodes 11th 3 nternodes 10th 3 nternodes 9th 3 nternodes 8th 3 nternodes 7th 3 nternodes 6th 3 nternodes 5th 3 nternodes 4th 3 nternodes 3rd 3 nternodes 2nd 3 nternodes 1st 3 nternodes Bottommost internodes

5.30 2.67 1.70 1.06 2.93 3.31 1.62 2.85

1944

1945

5.17 12/3

7.50 2/11

10.17 4/21

12.50 6/30

14.83 9/8

17.13 11/17

19.47 1/26

21.80 4/6

5.38 2.45 1.78 1.38 2.92 3.09 1.89 2.67 1.49

5.42 2.35 1.92 1.44 2.81 3.09 2.04 2.66 1.87

4.48 2.14 1.67 1.33 2.66 2.88 1.95 2.09 1.15

5.15 2.31 1.60 1.41 2.71 2.91 2.03 2.08

3.88 1.99 1.65 1.12 2.56 2.79 1.84 1.69 1.18

5.07 2.36 1.53 1.19 2.57 2.74 1.87 2.07 1.47

4.88 2.25 1.82 1.37 2.86 3.06 2.10 2.52 1.59

5.05 2.28 1.81 1.46 2.81 3.00 2.46 3.32 1.39

1.10 -99 .87 .86 .84 .91 .66 .42

1.20 1.08 .93 .87 .74 .59 .62 .68 .71 .65 , .52 .31

1.25 .98 .77 .72 .72 .67 .60 .67 .79 .77 .80 .65 .42

1.27 1.17 .93 .85 .75 • 72 .78 .67 .70 .73 .78 .79 .66 .64

1.27 .81

.70 1.00 .54

.88 .77 .57 .36

1.29 1.04 .92 1.07 .77 .52 .31

24.13 6/15 3 2 1 1 2 2 2 1 1 1

55 07 65 31 48 77 05 78 12 07 95 90 90 78 73 74 75 68 67 71 73 86 90 72 51

^ A blank space means the indicated plant part was not present. Percentage of sugar-free dry matter.

Time and again at a plantation when setts were planted but germinated erratically, the trouble was traced to a low K log for the crop at the time the planting material was cut. K COMPOSITION OF SUGARCANE PARTS Field-Grown Cane As already described in Chapter 4, beginning in 1938, cane plantings of 'H31-1389' were made in each quarter of the year at two places, Kailua and Waipio, both on the Island of Oahu. Later, a series of 'H32-8560' was similarly grown, but only at Waipio. Collections of stalks from the ground level up were made on more or less a monthly basis. Five such stalks were taken from each crop each time. The samples were taken apart as shown in Table 8-1, dried for green- and dry-weight data, ground in a Wiley mill, and analyzed for N, P, K, Ca, and the various sugars and polysaccharides. The data in

Table 8-1 are the K values expressed as percentage of the dry matter. To conserve space, beginning with the first collection September 24, 1943, values are reported only for every other collection, although analyses for all collections were made. This set of data is from a plant crop of 'H32-8560' grown at Waipio. The data show the relative constancy of the K level of each organ or tissue. The level in the meristem is always very high—in fact, as will be seen later, if there is a shortage of K, more of it is moved out of the aging tissue into the meristem. Young leaves contain more K than old leaves; sheaths contain more than their corresponding blades. Of the cane tissues, the elongating cane (here combined with the meristem) is highest next to the meristem, then the green leaf cane, and so on down the stem. Thus, the K level lowers as the organ ages. Some of the lowering of K is due as much to the rise of dry matter as to actual

322

CHAPTER 8

TABLE 8-2.

POTASSIUM CONTENT OF SUGARCANE PARTS (percentage of tissue moisture)—'H32-8560', WAIPIO PLOT B

1944

1943

1945

Plant part

9/24

12/3

2/11

4/21

6/30

9/8

11/17

1/26

4/6

6/15

Meristem and elongating cane Spindle cluster Young blades Old blades Young sheaths Old sheaths Green leaf cane Top internodes 15th 3 internodes 14th 3 internodes 13th 3 internodes 12th 3 internodes 11th 3 internodes 10th 3 internodes 9th 3 internodes 8th 3 internodes 7th 3 internodes 6th 3 internodes 5th 3 internodes 4th 3 internodes 3rd 3 internodes 2nd 3 internodes 1st 3 internodes Bottommost internodes

.424 .524 .515 .393 .523 .360 .385

.387 .490 .593 .511 .521 .474 .460 .304

.441 .511 .607 • 533 .582 .498 .563 .468

.424 .522 .618 .578 .619 .542 .348 .348

.387 .513 .640 .641 .565 .615 .325

• 343 .510 .660 .487 • 569 .497 .245 • 257

.393 .524 .638 .567 .571 .534 .247 .253

.444 .523 .650 .596 .665 .568 .371 .361

.447 • 530 .696 .664 .611 .631 .438 .448

.275 .275 .281 .287 .313 .325 .244 .168

.245 .284 .282 .272 .247 .211 .221 .234 .254 .241 .208 .155

.347 .306 .266 .257 .257 .248 .231 .248 .282 .275 .286 .250 .183

.438 .418 .344 .327 .288 .267 .300 .268 .280 .292 .300 .304 .275 .256

.428 .609 .750 .624 .653 .641 .336 .350 .382 .365 .360 .346 .300 .281 .274 .278 .262 .268 .284 .292 .331 .333 .277 .222

a

.231

.760 .333 .225

.293 .285 .228 .157

.371 .368 .390 .308 .217 .148

A blank space means the indicated plant part was not present.

removal of the element. Some fluctuations occur as a result of growing conditions favoring growth or causing growth to slow down. When reported on a dryweight basis, the K level will fall as a drought develops because of the accumulation of dry matter. Because of this, it became desirable to report the K index on a tissue moisture basis. In the earlier years, a drought would drop the K level, suggesting a need for fertilization, and yet, because of the drought, the fertilizer would never reach the roots. When reported on a tissue moisture basis, a drought that automatically reduced the tissue moisture raised the K level and at least prevented the crop control superintendent from wasting money on potash. The data in Table 8-1 are reported in Table 8-2 on the tissue moisture basis, not to be confused with the green-weight basis. Thus, when reporting on the drymatter basis, the amount of the element in grams is divided by the weight of the original sample, including the element itself. If reported on the greenweight basis, the amount of the element is divided by the total fresh weight making up the sample. If reported on the tissue moisture basis, the amount of

the element is divided by the weight of the water associated originally with the dry matter used in the analysis. Thus, the total green weight of a sample equals the sum of the dry matter and of the water contained in the original tissue. Analytical data may be reported on any of these bases. For example, assume a leaf weighing 100 grams is oven-dried and then weighs 20 grams; thus, the 80 grams evaporated away is labeled "water," even though undoubtedly some semi-volatile compounds also disappeared. Suppose a 2-gram sample of dry material, or /10 of the total leaf, was used for analysis, and assume that the analysis of the sample showed 0.2 grams total carbohydrates. Were it the desire of the analyst to report the result, he could report it as 2 grams/leaf, or 0.2 x 100/10 = 2 percent on the green-weight basis, or 0.2 x 100/2 = 10 percent on the dry-weight basis, or 0.2 x 100/8 = 2.5 percent on the tissue moisture basis. If one chooses to report all the K data on the tissue moisture basis, the simplest procedure is to make up a table including a broad range in tissue moisture, from 68 to 89 percent, and in K, from 0.2 to 5.0 percent of the dry weight, and thus eliminate

POTASSIUM TABLE 8 - 3 .

323 POTASSIUM CONTENT OF SUGARCANE PARTS (percentage of dry weight) IN RELATION TO LEVEL OF K IN THE SAND CULTURE—'H32-8560'

Culture number Plant part

3

Meristematic matter Spindle cluster Young blades--bottom Young b l a d e s — m i d d l e Young blades--top Old b l a d e s — b o t t o m Old b l a d e s — m i d d l e Old b l a d e s — t o p Very old b l a d e s — b o t t o m Very old b l a d e s — m i d d l e Very old b l a d e s — t o p Dead b l a d e s — b o t t o m Dead b l a d e s — m i d d l e Dead b l a d e s — t o p Young sheaths Old sheaths Very old sheaths Dead sheaths Elongating cane Green leaf c a n e — t o p Green leaf c a n e — b o t t o m Old cane a

0

1

3.13 1.45 .43 .49 .38 .20 .22 .27

4.44 1.81 1.05 .66 .71

.08 .09 .09 .78 .11

.13 .14 .17 .80 .11

.07 .68 .18

.21 .60 .18

.11

.12

.26

.26 .41

2 5.20 1.79 1.34 .98 .85 .65 .40 .50 .31 .27 .45 .16 .11 .15 1.25 .40 .09 .15 1.30 .18 .10 .07

3 6.04 1.89 1.74 1.13 1.20 .74 .45 .65 .39 .29 .46 .20 .14 .26 1.51 .70 .34 .29 2.58 .56 .22 .09

4 5.77 1.93 1.78 1.25 1.26 1.04 .58 .74 .41 .26 .49 .31 .18 .26 1.69 .96 .41 .32 2.76 .94 .35 .12

5 5.97 2.03 1.79 1.38 1.28 1.09 .73 .88 .45 .31 .43 .41 .22 .25 1.74 1.13 .45 .64 3.10 1.03 .41 .16

6

7

6.53 2.06 1.85 1.48 1.44 1.40 .95 .94 .61 .46 .49 .63 .39 .33 1.84 1.54 .78 .73 3.10 1.11 .50 .33

6.95 1.98 1.85 1.41 1.49 1.50 .96 .98 .60 .38 .50 .79 .38 .36 2.03 1.78 .84 .95 3.29 1.41 .66 .39

8

6.78 2.05 1.95 1.46 1.51 1.65 1.00 1.01 .81 .39 .53 .91 .54 .40 1.90 1.81 1.08 1.41 3.18 1.49 .91 .48

10

12

6.75 2.00 1.88 1.66 1.56 1.89 1.40 1.29 1.11 .69 .79 1.10 .64 .41 2.26 1.83 1.68 1.55 4.19 1.59 .86 .51

5.95 2.05 1.98 1.69 1.79 1.88 1.30 1.06 .83 .53 .61 .96 .45 .31 2.50 1.85 1.36 1.29 3.40 1.56 .96 .61

A blank space means the indicated plant part was not present.

the need to calculate each time. Such a table appears will be presented as percentage of dry matter (Table in Clements (19596) pages xlvi and xlvii, and also in 8-3) and percentage of tissue moisture (Table 8-4). Samuels (1969) page 338. Samuels gives a simple The sand was washed with 3N HN0 3 , and purified equation for the conversion, of which the following chemicals were used. Culture no. 8 received a total of 15.369 grams K, as shown in Appendix I (Table Apis a slightly altered version: pendix 1-4). Culture no. zero received no K, and each of the cultures in between, starting with no. 1, which K-H 2 0 = KVo (dry matter) x (100 ~ Sheath moisture) received 1.921 grams K, received the incremental inSheath moisture crease. As in the N series, culture no. 10 received two Thus if the sheath moisture on a green-weight basis is increments over no. 8, and no. 12 received two more 80 percent and the K is 2 percent on a dry-weight increments. The dry-matter growth curve is shown in Fig. 8-1. The zero-K culture achieved considerable basis, then growth, but this was due to the K residue in the sett and whatever contamination there was. The general K-HjO = 2 x ( 1 0 0 ~ 8 °) or 2 x 0.25, or 0.50 percent rate of reduction in growth increases with increasing 80 amounts of the nutrients, and the result approaches In this particular crop, no potash fertilizer was added that postulated by Mitscherlich (1909). The K levels reported on a dry-weight basis (Table since none was needed because the water used for ir8-3) as usual show very high readings for highrigation was pumped water, relatively rich in K. moisture tissues, such as the meristematic material, Sand Culture Cane elongating cane, and spindle cluster. Unlike the less Before discussing Tables 8-1 and 8-2 further, data mobile elements within the plant, K levels are highest collected from a K-deficiency series in sand culture in the young leaves and drop off sharply as the leaves

CHAPTER 8

324 TABLE 8-4.

THE SAME DATA AS IN TABLE 8-3 REPORTED ON A K-HjO BASIS

C u l t u r e number Plant

part

Meristematic matter Spindle c l u s t e r Young b l a d e s — b o t t o m Young b l a d e s — m i d d l e Young b l a d e s — t o p Old b l a d e s — b o t t o m Old b l a d e s — m i d d l e Old b l a d e s — t o p Very o l d b l a d e s — b o t t o m Very o l d b l a d e s — m i d d l e Very o l d b l a d e s — t o p Dead b l a d e s — b o t t o m Dead b l a d e s — m i d d l e Dead b l a d e s — t o p Young s h e a t h s Old s h e a t h s Very o l d s h e a t h s Dead s h e a t h s Elongating cane Green l e a f c a n e — t o p Green l e a f c a n e — b o t t o m Old c a n e

0

1

.226 .348 .415 .200 .200 .096 • I'll .320

.225 .601 .427 .299 .348 .129 .145 .353

.380 • 390 .'»19 .318 .037

.388 .488 .669 .225 .053

.226 .085 .037

.921 .097 .048

.025

.035

2 .415 .444 .457 .397 .363 .299 .197 .265 .152 .149 .328 .766 .700 .810 .260 .123 .048 .882 .144 .028 .023 .023

3

4

5

6

7

8

10

12

.579 .551 .702 • 507 .561 .346 .250 .393 .205 .175 .329 1.156 1.029 1.24 .477 .304 .207 2.30 .344 .117 .059 .031

.517 • 550 .704 .553 .560 • 477 .259 .402 .208 .150 • 347 1.09 • 77 1.24 .479 .362 .219 1.48 .348 .182 .108 .043

.557 .573 .694 .588 .574 .463 .356 .481 .214 .185 .279 1.10 1.24 1.18 .486 .415 .258 4.03 .389 .204 .126 .057

• 570 .557 .703 .635 .623 .565 • 391 .454 .263 .224 .304 1.77 1.60 1.69 .493 .510 .361 3.28 .382 .214 .144 .100

.537 .559 .698 .629 .668 .528 .412 .465 .273 .198 .301 4.97 2.84 2.75 .553 .614 .427 5.83 .420 .289 .212 .132

.580 .603 .744 .611 .651 .642 .457 .488 .377 .203 .317 1.94 1.32 1.21 .540 .624 .504 4.26 .397 .269 .236 .153

.598 .550 .749 .703 .666 .682 .583 .576 .459 .307 • 371 .411 2.27 1.87 .533 • 535 .629 7.87 .483 .249 .207 .171

.561 .579 .750 .695 .711 .676 .539 .507 .365 .264 .386 .400 1.92 1.99 .548 .552 .683 6.58 .419 .276 .256 .198

age. For example, the bottom third of the dead leaves showed 0.08 percent K (dry-weight basis), one-fifth as much as in the bottom third of the young blades. As the K levels are raised, the amounts remaining in the dead leaves are relatively much higher. Culture no. 8 shows the bottom third of the dead leaves to retain 0.91 percent K versus 1.95 percent K in the bottom third of the young blades, a ratio nearer 1:2. Although K is considered a very mobile cation, not all of it is so. The dead blades still retain considerable quantities of the elements that would be very useful elsewhere, and this immobile residue increases as the amounts of K added increase, even though deficiencies exist. What it is that immobilizes this K fraction is not known at this time, but a possibility exists that it has become a part of some other immobile compound, perhaps organic, or that it is merely occluded within cell bodies such as the plastids. The drop in K occurs as the tissues age. Thus, old leaves (+7, +8, +9, and+10) lose more than half their K to the younger top growth (see Table 8-2). As the old leaves become very old, they release still more K. Thus, this K recycling is a very desirable process since it reduces the full impact of a deficiency. It is interesting to note that the mature cane from treatment

nos. zero and 1 contain more K than nos. 2 and 3, which are left with the lowest residues of all. Just as the cane tissues give up most of their K during a deficiency, they also serve as storage tissue for K when its supply is excessive. The elongating cane for culture no. zero (Table 8-2) contains 0.68 percent K, but 3 to 4 percent in culture nos. S to 12. Just as it is desirable to maintain adequate levels for full growth, it is undesirable to exceed these levels since Tables 8-2 and 8-3 show that the excess K is stored especially in the cane, even though all tissues to some extent act as storage tissues. As noted in Chapter 6, this K, along with sucrose, finds its way into the boilinghouse of the mill and causes problems there. In Table 8-5 summary data of the 1972 sand culture series are presented. Culture no. zero (without any added K) produced 452 grams dry matter, which contained 0.6280 gram K derived from the setts, as well as contamination. This value is used as a blank and is added to each. Each sett contained an average of 0.2159 gram K as actually determined. Thus, the three setts left per culture would add 0.6477 gram K. The K still remaining in the rather completely deteriorated sett at harvest was not determined, but it seems rather clear that most of the blank came from

325

POTASSIUM TABLE 8-5.

RESPONSES OF SUGARCANE GROWN data)

IN SAND CULTURE TO INCREASING QUANTITIES OF ADDED K (summary

Culture no.

K added + blank (g)

K recovered (g)

K recovered

m

Dry matter/culture (g)

Dry matter/g absorbed K (g)

0 1 2 3 4 5 6 7 8 10 12

0.628 2.579 4.490 6.3913 8.3124 10.2335 12.1546 14.0757 15.9968 19.839 23.6812

0.6280 1.9284 3.2039 5.5045 7.5780 10.4734 11.0897 12.0177 14.4826 15.4653 18.1630

74.8 71-4 86.1 91.2 102.3 91.2 85.4 90.5 78.0 76.7

452 857 1,375 1,593 1.870 2,097 1,920 1.891 1,916 1,895 2,111

720 444 429 289 247 200 173 157 132 123 116

the setts. The deionized water used was very pure (12 to 18 megohms), and the air in the glasshouse was relatively clean, as shown by apparent lack of dust particles on the leaves and floor, the latter being flooded for about 8 hours every day with running tap water, not only to help with cleanliness but also for temperature control. It seems odd that culture nos. 1, 2, and 3 failed to use a higher percentage of the K provided them since they were all deficient. Perhaps the deficiency itself so reduced the vigor of the plants that they were less capable of absorption than culture nos. 5 to 12. Although culture nos. 5 and 12 gave the highest actual yields, Fig. 8-1 shows the calculated growth curve for all the cultures (not including roots) and shows the actual high point being reached by culture no. 8. Although adequacy of levels will be discussed a little later, all the cultures from nos. 5 to 12 show the young-sheath levels to be very near to the presently accepted standard for the field (see below). SELECTION OF A K INDEX TISSUE TheKIndex During the early history of crop logging, the index tissue found most suitable for K was made up of the young sheaths (+3, +4, +5, and +6); the K was reported as the percentage of sugar-free dry matter. The reason for basing it upon the sugar-free dry weight was that these sheaths varied quite considerably in their sugar content, as will be noted later, and, because of this, the K index would also vary

even though the K nutrition of the plant remained the same. Furthermore, the residual dry weight is not very subject to change, being made up of cell walls and such. The young sheaths were selected from a very large mass of data taken from some 8 years of field-grown cane. Each month or so, collections were made and the plants separated into their several parts as described earlier. Among other things, these parts were analyzed for K, and then the K content of the working tissues of the plants was determined. These tissues included the photosynthetic, growing, and sugar storage tissues. To have a practical system that can be used by plantations, it is necessary to have a simple, yet completely accurate, system. There is no point in making a lot of collections of material and using fast, though cheap and inaccurate, methods, as has been the case with many systems in use. In Table 8-6 are recorded simple correlations made from data obtained from a S experiment grown in sand culture. As is customary, the experimental plants subjected to any nutrient variable were separated into their many parts, and complete nutrient analyses were made of each part. Even though K was added equally to all cultures, the data are useful for index selections. In this case, the K composition of each of four possible index tissues (young bladesmiddle portion only, young sheaths, elongating cane, and meristematic tissues) was used, and the K level (percentage of dry weight) of each was correlated with the K level (percentage of dry weight) of the photosynthetic tissue (all the green blades), the

700

E = I80.90I7 + I02.5758X-5.8377X Ì 600

-

R 2 =.8385** F = 20.7628**

.60 I

500 -

.55 .50

< CL

>

400

K-H 2 0= .1450+.0950 X-.0053 X 2 R 2 = .9260** F = 39.34**

300 -

.45 .40 .35

OC o

.30 200

.25 .20 .15 .10

,05 10

SAND CULTURE NUMBERS FIGURE 8-1. The upper curve, read off the left-hand scale, shows final dry weight per plant, including roots, of plants grown in sand culture with K - H 2 0 added by increments of 1.921 g/culture (culture nos. 0 to 10). The lower curve, read off the right-hand scale, indicates that .5570 K - H 2 0 is the critical level for K-H 2 0.

TABLE 8-6.

CORRELATIONS BETWEEN EACH OF THE POSSIBLE INDEX TISSUES AND EACH OF THE "WORK" TISSUES AND THEIR r 2 l s SUMMED

Possible index tissue

"Work" tissue

Young blade middle

All green blades Young cane Green leaf c a n e — t o p Roots Whole plant Dead 1 eaves Elongating cane

.9603** .9200** .7708** .9260** .9217** .6415** .9192**

5.3262

Young sheaths .9137** .8904** .9509** .8928** .9413** .5552* .9l»98**

5-4254

Elongating cane

Meristem

.8964** .9371** .9543** .9378** .9297** .4780* 1.0000**

.3342 .2060 .2896 .1945 .2652 .4195 .2263

5.5647

.5733

POTASSIUM TABLE 8 - 7 .

327 t_ VALUES FOR THE REGRESSIONS BETWEEN THE POSSIBLE INDEX TISSUES AND EACH OF THE MAIN THREE "WORK" TISSUES (K Index expressed as the K content of the young sheaths expressed on sugar-free dry-weight basis)

Possible index tissue

"Work" tissue Green leaf cane—top

Meristem and elongating cane

Dry cane

Old sheaths

8.52** 6.68** 8.39**

6.38**

3.98** 3.87** 10.13** 4.43**

3-** 2.25* 5.35** 1.27

K index

9.97**

9.47**

6.17**

Young blades Old blades Young sheaths

storage tissue, the young cane, the roots, the whole plant, and, finally, the dead leaf blades and sheaths. In the latter measurement, the leaf, as it ages, is tied securely to the cane so that it cannot fall off and be confused with other dead leaves and also so that it dies a natural death. From the correlations in Table 8-6, it is clear that the meristematic tissue is not at all suitable as an index tissue for K—not a single correlation was significant. The other three tissues were essentially equal, as shown by the Yr2 values with the elongating cane being slightly better than the young sheaths, which are better than the young blades. Part of the reason for the superiority of the elongating cane is the perfect correlation with itself. When it is not included, the 1r2's between the young blades, the young sheaths, and the elongating cane and each of the tissues except elongating cane are 4.4812, 4.5233, and 4.5647, respectively, showing that any one of these could be used as a reliable indicator of the K levels in the plant. Other uses for the sheath, however, make it a desirable choice, as will be seen in all the chapters dealing with nutrients. In actual use, the K index was the percentage of K expressed on the sugar-free dryweight basis. In Table 8-7 the superiority of the K index from field-grown cane is rather nicely shown. The blade tissues were the entire blades including the midribs. In Table 8-8 are given the R"s as well as the F values for the K content of tissue or organ and the treatment number as developed in sand culture. Sev-

TABLE 8-8.

THE R AND £ VALUES BETWEEN THE K CONTENT OF EACH OF THE SEVERAL PLANT PARTS AND SAND CULTURE TREATMENTS

Plant part Meri stem Spindle cluster Young b l a d e s — b o t t o m Young b1ades--middle Young b l a d e s — t o p Old blades--bottom Old b l a d e s — m i d d l e Old blades--top Very old b l a d e s — b o t t o m Very old b l a d e s — m i d d l e Very old blades--top Dead b l a d e s — b o t t o m Dead b1ades*-middle Dead blades--top Young sheaths Old sheaths Very old sheaths Dead sheaths Elongating cane Green leaf c a n e — t o p Green leaf cane--bottom Old cane

R2

F va 1 ue

.7110 • 7309 .9305 .8839 .8989 .9140 • 7613 .9088 .4082 .6581 .1805 .1950 .3880 .0432 .9674 .9675 .9465 .0099 .6412 .9593 .9773 .9703

9.84** 10.86** 55.26** 30.45** 35.56** 42.50** 12.76** 39.86** 2.07 5-77* 0.66 0.96 2.53* 0.18 118.70** 119.0769** 53.07** 0.0399 7.14* 94.28** 129.158** 130.68**

eral points of interest are revealed. The meristem and spindle cluster continue to be poor indicators of the K levels, even though the R's are highly significant. Unlike many other elements, the young blades reflect the levels of K in the culture better than the older blades, which as they age, lose more of their K not only to the younger leaves but also particularly to the sheath and stem tissues that reflect supply levels with very high precision. The fact that the dead blades and dead sheaths show no correlation at all with supply is

328 quite unlike the situation with several other elements, as will be seen in subsequent chapters, and points to the removal of K as death approaches. All the living sheaths, irrespective of age, are excellent index possibilities, as are the three oldest stem categories. The old cane with its F value of 130.68 reflects the supply levels well. The bottom green leaf cane also has a very high F value. These things point to the need for great care in applying K to a field because most of it will be in the cane stalk juice and will get into the processing plant along with the sucrose to complicate the work of the sugar boiler. The two best tissues other than cane are the young sheaths (+3, +4, +5, and +6) and the old sheaths (+7, +8, +9, and + 10). The young sheaths were selected over the others because they are always present, even during severe drought periods, and because they are usually enclosed by other sheaths, thus being cleaner than the old sheaths.

CHAPTER 8

the growth curve for the 1972 K series, shows the K-H 2 0 curve for the several treatments. Obviously, there is a very good correlation (r2 = + .9260, r = + .960). COMPARISON OF TISSUE VS. OTHER ESTIMATES FOR K REQUIREMENTS OF SUGARCANE Mitscherlich Testing When the work on crop logging began, some use in Hawaii was also being made of the Mitscherlich (1909) techniques and of soil analysis. Mitscherlich testing was abandoned rather soon for a very simple reason: unlike the fields in Germany, where the method had success but where climatic conditions for the various fields were much the same in any one season, in Hawaii each field had a different climate. Thus, in Hawaii soil samples were taken. At Kohala, for example, the maximum yield because of climate was of the order of 5 to 7 TSA for a particular field; from Ewa, a hot bright area, the maximum yield for a particular field reached 17 to 18 TSA. These soil samples were sent to the Makiki station in Honolulu for the actual determination. The soils were treated with the various fertilizer combinations called for, placed into Mitscherlich pots with drainage catchment for return to the culture, seeded with the indicator (usually Napier- or Sudangrass), and placed into small glasshouses for a certain growth period. On the basis of the results, recommendations were returned to the two plantations. Thus, the weaknesses of the method as applied to Hawaii are easily apparent. Soils from totally different climates were brought to a third climate, very warm and mostly clear, and an indicator plant was used, not the actual crop plant, sugarcane.

The K-H 2 0 Index As time went on, however, certain discrepancies developed. The K index associated with growth responses seemed to vary for different varieties. Also, during drought periods, the index dropped into deficiency levels, and yet, when the drought was broken, the K index levels rose above normal. While working with several varieties on another problem, it was noted that sheath tissue moisture levels differed by variety somewhat, even though the varieties were growing together in the same field. Analysis of the aqueous extract used for sugar determinations showed that essentially all the K present in the sheaths was also water soluble, and so it was soon found that varietal differences for K disappeared when K was reported as percentage of the tissue moisture. The designation K-H 2 0 was thereafter used to indicate this change in base. Since the sugar Soil Analysis Estimates of Nutrients content expressed on the moisture basis changes The second approach, soil analysis, was based on relatively little from culture to culture, the K-H 2 0 is dried soil, which, in itself, completely changes some simply the K content expressed as the percentage of of our soils irreversibly from plastic to crystalline. the tissue moisture, not of the green weight. The soil sample would be extracted with sulfuric acid It is now necessary to present data showing that the as used by Truog (1951, 1953) for P for the crops in K-H 2 0 value of the young sheaths is better than that the north central part of the United States. This of other tissues. Figure 8-1, in addition to showing method, when applied to sugarcane soils in sub-

329

POTASSIUM

tropical Hawaii, showed P levels so low that readings were not possible. Hence, the acid concentration was greatly increased until the extracted P at least came into the range. Truog had set 20 ppm as the adequacy level for his rather short-lived crops—oats, wheat, com, and so on. This same level, but obtained with the very strong acid, was adopted at first for sugarcane. Experiments were installed in commercial fields and yields obtained. Available K was determined by use of the acetate method. At first some effort was expended on soil N, but even the more recent crystallizable N concept proved to be essentially not only useless but dangerous. Very little work was done with Ca, and at first 100 lb/acre was used as the critical level. During the decade prior to the start of crop logging, the industry installed many field experiments testing varieties, amounts and timing of fertilizers, and so on. When soil analysis came into use, plantations tried to correlate the results. In one case in particular, soil analysis showed the K level of a near growth failure area in Held Iole 3 at Kohala Sugar Company, Island of Hawaii, to be adequate, but the cane failed to grow normally. It germinated, but then the shoots, instead of growing vertically, grew horizontally for a short while to a length of about 2 ft and then stopped altogether. Pathologists could find no pathogenic organism, but the condition was nonetheless considered a disease. Analysis of a sheath sample taken showed the K index to be 0.17—the most extreme deficiency I have ever noted, even lower than those obtained in three generations of minus-K culture solution. Perhaps the unusual growth pattern involves a remote function of K. In Table 8-9 are listed some fields at Kohala Sugar Company together with the soil analysis of each for "available K 2 0 " expressed in lb/acre, the amount of K2O applied on the basis of the analysis, and then the three consecutive K-index readings for the same field. At that time, 250 lb. available K 2 0 and 2.2S percent were considered adequate amounts for the K index. The agriculturist in charge, one of the most careful, called for 53 lb. K 2 0/acre (100 lb. KC1) when his readings were below 250 lb. and nothing when they were above. When these crops were ready for crop

TABLE 8-9.

Field Iole 3A Niulii 17 Niulii 39 Halawa 3 Union 5 Halelua 5 Nunulu 7C Alaalae 1A Alaalae 7

COMPARISON OF SOIL ANALYSIS AND THE K INDEX FOR GUIDANCE IN FERTILIZATION AT KOHALA, ISLAND OF HAWAII

K index (reading number)

"Available K2O1' (lb./acre)

K2O applied (lb./acre)

75 75 175 225 275 250 100 425 475

53 53 53 53 0 0 53 0 0

1 1.72 3.12 1.50 3.20 1.98 1.68 2.95 3.10 2.25

2 0.85 2.06 1.61 2.96 2.15 1.76 2.87 2.98 2.11»

3 0.72 2.35 1.45 2.57 1.98 2.03 2.42

log sampling, samples taken at 5-week intervals at midcrop as part of the early research program were sent to the University of Hawaii plant physiology laboratory for analysis. Obviously, there is little similarity between the results of the soil analyst and of the plant. Field Iole 3A was very low on both bases, but obviously 53 lb. K 2 0/acre was of little value; yet the agriculturist had no real basis for determining the amount to put on because Field Niulii 17, which showed less than 75 lb. of available soil K 2 0 with 53 lb. K 2 0 added, showed relatively high tissue readings. And so it was understandable that the industry was soon disillusioned with soil analysis. One particularly pertinent demonstration occurred at Paauhau where the agriculturist installed a factorial experiment involving P and K, each at three levels—0, 200, and 400 lb. P 2 0 5 and KjO, respectively (Table 8-10). Soil samples were sent to the central laboratory for analysis, and the Truog P showed 38 to 44 ppm, which was considered high above the set 20 ppm level. The ammonium acetate method showed exchangeable K to range from 140 to 180 ppm, whereas at that time 100 ppm were considered adequate. Thus, the recommendation to the plantation was that the area was not well suited to the experiment since the soil P was twice as high as needed and the soil K 2 0 was between 1.4 and 1.8 times as high as needed. Fortunately, the experiment was already installed, and 2 years later the harvest results showed how wrong the soil estimates were, which probably accounts for the indifference developed by

330

CHAPTER 8

TABLE 8 - 1 0 .

Treatment

EFFECT OF THREE L E V E L S OF POTASH AND THREE L E V E L S OF PHOSPHATE ON Y I E L D OF SUGAR PER A C R E 3 , PAAUHAU, ISLAND OF HAWAII

p2o5 (lb./acre)

A

0 200

B C 3

uoo

TSA 8.1 8.8 9.0

Treatment

K L M

k2o

(lb./acre) 0 200

AOO

TSA 7.7 8.3 10.0

LSD = 0 . 5 .

the plantations in following "handed-down" recom- cane plant with its very extensive root system is a mendations. The 400-lb. P 2 0 5 treatment was much more thorough sampler of the heterogeneous significantly better than the zero-pound and some- mass called "soil" than is a chemist's probe some 2 what better, though not significantly, than the 200- inches x 2 or 3 ft. In a heterogeneous soil medium lb., which, however, was significantly better than the that is not abundantly supplied with a particular zero-pound. The 400-lb. treatment of KjO was nutrient, roots that strike an area containing greater significantly better than either of the other two, and amounts of the element multiply rapidly and thorthe 200-lb. treatment was significantly better than the oughly saturate the area, and thereby they absorb a zero treatment and very significantly poorer than the great deal more of the element than from other parts 400-lb. treatment. of the soil mass. Many other such cases have been cited (Clements, Another important reason for the lack of correla19596, 19626). An outstanding case had to do with tion is the use by the chemist of rather concentrated Napiergrass grown on a field on the University of acids, bases, or salts for extraction. Of course the Hawaii campus and also one at Poamoho, Oahu. plant never uses these; instead it expends energy in The late Robert Lindner, formerly an associate of the the absorptive process which the chemist cannot imauthor, discovered that these fields were listed by the itate at all, but more on this later. In Chapter 11, soil chemist as low potash fields, yet no response had where data on toxic elements are reported, soil been noted when potash was applied. This was samples are used that were soaked in deionized water understandable when tissue analysis showed extreme- and after a time autoclaved for 1 hour at 15 lb. presly high K levels. Another case was picked up at sure. The result of this on release of the pressure was Waimanalo where the soil K was reported as high, to thoroughly separate all the soil particles and exbut a definite response to K on papayas was noted. tract the soluble material at the natural soil pH. Soil Mg as well as even soil Ca have given similar er- When acid extractants were used on similar soils, the roneous results, as will be seen in later chapters. amount of the toxic element obtained was related to Thus, my view is that soil analysis for determination the concentration and quantity of the acid even of the nutrient requirements of crops is a complete where toxicity under natural field conditions because waste of time and money and also dangerous since of a favorable pH and amounts of Ca was not manilosses of yield frequently occur of which the grower is fest. not even aware. However, as was seen in Chapter 5 for water and as will be seen in Chapter 11 for toxic PHYSIOLOGY OF ION ABSORPTION BY elements and salinity, soil analysis is indispensable in ROOTS identifying edaphic problems. The first extensive and perhaps still the broadest Why do soil analyses fail? Why should soil analysis work on salt absorption by roots was that by Hoagbe so poor and does this failure add to our under- land and Broyer (1936). Their data will be repeated standing of crop production? It seems obvious that a here because they are so fundamental and compre-

POTASSIUM TABLE 8-11.

331 REPRODUCIBILITY OF ABSORPTION DATA (absorption period 27 hours)

Set

Concentrated K (me/1 iter)

Initial

A B

23-7 22.9

At end of absorption period

A

85-0 85.5 83.5 85-0 87.5 88.0 85.O 85.O

Condition

B C D

Accumulated K (me/1 iter)

Average

Source:

-

62..0 61. 0 6 It..1) 61. 7

62.3

Hoagland and Broyer, 1936.

hensive. This work followed the important works of Steward (1933) and his co-workers (Steward et al., 1936) and devised a technique to control all the essential variables and so they were able to get reproducible results (Table 8-11). Their use of excised root systems of barley over short periods eliminated all the complications brought on by the top. Seeds of a particular barley variety were soaked in tap water overnight, spread out over a cheesecloth net and covered with another, and placed in a warm, constanttemperature (about 25° C) dark room. After some 7 days, the plants that had been in the light for about 3 more days were selected for uniformity and placed in the supporting holes of a cork. Nonabsorbent cotton was used to firm up the plant's position. The corks were placed in holes of the cover of an enamelware pan capable of holding 168 plants. The pan contained 3,800 cc of a culture solution. The study called for both low-salt and high-salt root systems, produced by increasing or decreasing the number of applications of nutrient solution. The nutrient solution was aerated. The roots were cut off the plant just below the seed contact point and washed in distilled water twice, centrifuged gently to dispel adherent water, and then placed into the aerated experimental solutions in batches of 168 root systems. At the required time, the roots were removed, washed, and again centrifuged. At this point, green weights of the roots were recorded, and the roots were frozen in

closed jars at -15°C for 48 hours or more. Records of the volume of the culture solution as well as its composition were maintained. To obtain sap, the frozen roots were quickly thawed and the sap was expressed in a mechanical press. Since, in their day, radioactive salts were not available, Hoagland and Broyer (1936) frequently used the bromide ion, which does not occur naturally and which fortunately did not seem to affect the functioning of the living tissue. Importance of Oxygen Quite obviously, Hoagland and Broyer's techniques were of high quality, so that several points about nutrient absorption were established. The first such study involved two experiments (Table 8-12): experiment A compared absorption with and without a stream of air going through the solution; experiment B involved the same set-up but with a stream of N2 gas. In other words, the question was, how essential is oxygen to the absorption process? Experiment A shows that 0 2 increased the absorption of both K and halide (Br + CI) by about the same amount. Without air through experiment A, there was a small gain of K and rather a substantial gain of the anions Br and CI, indicating the individuality of the ions in their responses. In experiment B there was a slight loss of K when N was bubbled through, but an appreciable gain for Br and CI as in A without air.

CHAPTER 8

332

TABLE 8 - 1 2 .

KBr ACCUMULATION BY BARLEY ROOTS WITH AND WITHOUT A I R AND A COMPARISON WITH PURE N £

Composition of (me/liter) Growth c o n d i t i o n Experiment

A:

absorption

B:

absorption

period 9

Initial After absorption

period

After absorption

period with

Source:

Halide

15.A 72.5 17.2

0.7 57.2 10.2

28.7 27.9 27.7 89.3 81.3

1.6 7.0 6.It 3 0 . Ii 30.8

NO,

Accumulated in (me/liter) K

Halide

sap

NO.

p e r i o d 2*4 h o u r s

Initial A f t e r a b s o r p t i o n with a stream of a i r A f t e r a b s o r p t i o n without a stream of a i r Experiment

K

sap

with

56.5 9.5

hours

A B A B

i air

H o a g l a n d and B r o y e r ,

-

57.. 1 1..8

0. 1 0. 1 0. 0 21. 6 2 0 ..5

-0. 8 - 1 ..0 60. 6 62.,6

5-It k.8 28.8 29.2

0.0 -0.1 21.5

20.>t

1936.

The second solution had also been given some ni- mine whether subjecting excised roots to N2 caused trate, but a definite gain was again shown with the some irreversible effects on the absorption process. halides. The authors reported that some nitrate was These results are in Table 8-14. In this experiment the absorbed but does not show in the table because it air as well as the N2 gas were purified with respect to was immediately reduced to another form within the C0 2 , and N2 was purified with respect to 0 2 . The K root. After air was bubbled through B there was absorption was completely suppressed by N2 but Br again a great increase in both sets of anions, in- absorption continued at about 12 percent of the nordicating very clearly the dependence, at least in part, mal rate in air, which the authors state is about the of the absorption process on respiratory activity. concentration of the anion in the external solution. Also, the cation K is much more dependent on this When the roots were allowed to absorb in N2 bubbling for 6 hours and then restored to 6 hours of than the anions N0 3 , CI, and Br. Hoagland and Broyer's (1936) next effort added aerated absorption, the return of absorptive activities further evidence that the plant's respiration was in- did not reach normal, although it reached about 87 volved in the absorption process by associating the percent of normal for K and 66.5 percent for Br. utilization of 0 2 with the release of C0 2 by the ex- Whether this failure to return to normal was a percised roots. The results of this study with barley root manent effect of the N2 treatment or one indicating systems followed those obtained earlier by Steward the need for more time or the development of a short(1933) as reported by Steward and Sutcliffe (1959) age of carbohydrates was not discussed. There was a who used potato tuber tissue (Table 8-13). Although reduction of respiratory activity of some 76 percent, the presence of 0 2 contamination may be the cause of which also can be a reflection of the above points. the C0 2 production in N2, it may also be that some anaerobic respiration is going on. It is important to Effect of C0 2 on Ion Absorption note that the ratios of C0 2 relative to the 0 2 output Another point directly applicable to roots of crop are about the same for both plants which are widely plants growing in a soil is that C0 2 to the extent of 10 separated phylogenetically. This observation, along percent and even 20 percent when mixed with air did with many others, points to the general application not affect the absorption of ions. Very likely the C0 2 of these results, at least to land plants. concentration in certain soils devoid of 0 2 (such as Hoagland and Broyer (1936) next sought to deter- can be found in Hydrol Humic Latosols), under very

333

POTASSIUM TABLE 8-13.

CARBON DIOXIDE PRODUCTION BY EXCISED BARLEY ROOTS AND DISCS OF POTATO TISSUE AS INFLUENCED BY OXYGEN SUPPLY

Condition

C0 2 /g fresh tissue/hr. (mg)

Relative to air as 100

0.73** 0.282 0.183 0.086

100 38 100

-

-

-

5.96*

VK VN^K VN K. 7 q 1 l

6.67* 8.08* 5.00

-

-

-

29.58** 5.70*

-

-

-

-

-

-

-

-

Sheath H20 C.V.

(1)

87-6 .70

86.5 .77

81.5 1.19

81.1 1.7

79.3 80.2 80.9 81.6

81.7

80.6

80.2 80.9 81.* 81.9

8.0910 k. 92*

K

-

81.1 81.6 81.9 82.2

Mean

10/3/67 ( 1 3 - 9 months)

39.8^** 52.37** 7.83* 7.83* 29.22**

5.83'° 2*1.79** 6.89*

Kl i

Y

values)

1 1

N

X

-

80.8 1.19

than one producing light tonnage, although there is rigated fields with many knolls that were exposed to no precise relationship between the two. Potassium wind, good sugar-producing varieties failed to levels do vary from variety to variety, but early in my "close-in" even after the expenditure of much effort studies, I became aware that adequate K levels, when and money. When the better parts of the field were expressed on the K-H 2 0 basis, were essentially the already closed-in, these areas remained open, and at same for all varieties, even though some varieties can harvest there were mostly weeds. Hence, for several absorb more K from a given field than others. The years this variety was used in these spots, and even K-H 2 0 readings for the two varieties used in this though its quality was poor, it still gave more sugar study as shown in Table 8-17 are 0.520 and 0.534. than the better variety, which failed in its competiAlthough the difference seems very small, and for tion with weeds. practical purposes it is not important, as shown in Table 8-16 the difference is highly significant Tissue Moisture as Affected by N x K x V Treatments statistically. Since growth is influenced by both N and K, it can be Occasionally one finds a variety that seems un- anticipated that tissue moisture is also affected. In usually capable at finding K in the soil and absorbs Table 8-20 are shown the effects on tissue moisture much higher levels of K than other varieties. Usually noted in the N x K x V experiment. All three such clones are discarded for other reasons—one treatments, as well as some interactions among them, such cane was 'H40-1179', which was an extremely affect moisture levels. Data in Table 8-21 show the heavy grower but produced relatively little sugar. Its statistics of the general effects as averages of the actual K index levels were very high. For rocky, unir- three main collections. Comparing these data with

CHAPTER 8

33« TABLE 8 - 2 2 .

VARIANCE DATA FOR TOTAL SUGARS OF THE SHEATHS ( £ v a l u e s )

(12/1/66 ( 3 . 9 months)

Source N. . N" Nq KC K"

1/19/67 (5.5 months)

7/28/67 (11.8 months)

8.7310

:2o10 11.80* 187.11** 13.13**

355.10** 19.89**

c JliKll

49.36**

27.92**

Total sugars C.V. ( * )

TABLE 8 - 2 3 .

index

(avg.)

8.02 9.1

229.40** 26.92** 11.42** 4.77* 18.30**

7.21 13.8

A B C D

148.48** 8.49* 24.40**

61.29**

12.78**

24.70** 9.20 7.3

9.60 12.2

8.70 7.2

TOTAL SUGARS OF THE SHEATHS AS INFLUENCED BY EXPERIMENTAL TREATMENTS (percentage o f dry m a t t e r , average o f three)

K_0 treatment N treatment

10/3/67 (13.9 months)

20.56*

9

K

Mean

8/24/67 (12.7 months)

Variety

Variety

II

III

IV

Mean

N treatment

X

Y

Mean

KjO treatment

X

10.5 10.9 11.2 11.8

9.3 8.7 9.5 9.5

8.4 8.5 8.2 8.8

8.2 7.6 8.0 7.9

9.1 8.9 9.2 9.5

A B C D

9.5 9.4 9.6 9-9

8.7 8.4 8.8 9.1

9.1 8.9 9.2 9.5

I M III IV

11.5 9.8 8.9 8.3

10.7 8.7 8.0 7.5

11.1

9.2

8.5

7.9

9.6

8.7

9-6

8.7

I

Mean

the pol percent cane data in Table 7-32 reveals one rather striking thing—although the KiO treatments affected tissue moisture exactly the same as did the N treatments (80.2 to 81.9 percent in each case), only the N treatments significantly affected quality, showing that quality in this high-rainfall area is essentially a matter of juice purity and not Brix. Pol percent cane declined steadily from 12.83 percent for the low-N treatment to 11.49 percent for the high-, while there was an inconsistent change in the K 2 0 treatments from 12.01 to 12.21 percent. Although variety Y had a lower moisture content, which is very significant statistically, it did not show a significant difference in quality. Total Sugars of Sheaths as Affected by N x K x V Treatments The level of total sugars in the sheaths (percentage of dry matter), along with tissue moisture, has been very useful in reflecting the well-being of the plant or

Mean

Y

Mean 11.1 9.2 8.5 7.9

fitness to a particular environment and has been named the primary index (Clements and Kubota, 1943). If the total sugar level is high, the plant is growing less well than could be expected for the energy available. If the level is low, growth tends to be more rapid than justified by good quality. (Variance data are given in Table 8-22 and actual levels in Table 8-23.) A high level, however, does not mean high-level storage of sucrose in the stalk, or vice versa; it indicates the balance existing between growth and carbohydrate utilization and between carbohydrate production and translocation. In general, lowering the moisture level raises the total sugars. It is probable that because K deficiencies markedly lower tissue moisture, they raise the total sugar level. Nitrogen deficiencies, however, also lower tissue moisture but usually raise the total sugars, even though slightly. A more common reaction is that as increased N is associated with deepening greenness of the leaves, thus as N stimulates

339

POTASSIUM TABLE 8-24.

Factor

Beta -.8532

-.4274

+.2190

-.0889

K-H2O

-.2193

-.1131

Maximum temperature Age Green weight Minimum temperature

-.4081

-.3503

-.3353

-.0370

+.1665

-.0802

+.0391

-.2333

VARIANCE ANALYSIS DATA FOR API LEVELS FOR THREE COLLECTIONS (only significant £ values shown)

1/lW

Source

r

Sheath H 2 0 Leaf nitrogen

a

TABLE 8-25.

STANDARD PARTIAL REGRESSIONS AND SIMPLE CORRELATIONS OF CERTAIN FACTORS ON THE TOTAL SUGARS OF THE SHEATHS 3

114.00** 23.44** 20.65**

N. . N1'

tf.

V1' VN,,

d.f.

=

7

and

8,735;

R

=

.5029**;

F

49.54** 13-81* 5.63* 8.77**

-

6.30* 5.52*

-

"

3,814 23.1

3,687 26.67

3,736 25.1

value =

10/3/67 (13-9 months)

96.07** 40.71**

-

API (avg.) C.V. (%) 2

8/24/67 (12.7 months)

(11.8 months)

1,262.6?**.

TABLE 8 - 2 6 .

API READING AS INFLUENCED BY EXPERIMENTAL TREATMENTS

Variety

K^0 treatment N treatment A B C D

Mean

1

H

III

IV

Mean

5,614

5,460

5,044

4,947

5,266

4,495

3,123

3,369

3,342

3,582

3,502

3,114

2,829

2,739

3,046

3,807

3,005

2,566

2,975

3,088

4,355

3,676

3,452

3,501

Variiety

N treatment

X

Y

A B C D

5,956 3,772 3,109 3,194

4,576 3,392 2,984 2,982

4,008

3,483

photosynthesis, there is an actual rise in the total sugar production and, hence, in sheath level. The data in the tables verify these points: (1) N is positively, though weakly, related to total sugar level; (2) K is negatively but strongly related to total sugar level; and (3) since the total sugar level reflects the wellbeing of the plant, it is not surprising that the two .varieties differ. Even though the difference is small, it is highly significant throughout. In an effort to determine the usefulness of the primary index, crop logs of record yields for each field on three large plantations in Hawaii were assembled, and the total sugar levels were analyzed using the stepwise regression method. Growing conditions varied from the very hot, irrigated, highyielding Olokele area through a medium climate, high-rainfall Hilo location to the cool, highelevation, unirrigated Pahala section. The total degrees of freedom were 8,742. The analysis is in Table 8-24. Because the plantations did not have adequate measurements of sunlight, this factor could not

Mean 5,266 3,582 3,046 3,088

K20 treatment 1 III IV Mean

X

Y

Mean

4,543 3.980 3,819 3,690

4,166 3.371 3,985 3,311

4,355 3,676 3,452 3,501

4,008

3.483

be included. Actually, sunlight gives a strong positive correlation, as well as partial regression, on the total sugar level of the sheaths; despite this, however, the effect of sunlight is largely assumed by the maximum temperatures. The primary index is very useful in diagnosing the fitness of the crop to its environment. API as Affected by N x K x v Treatments The amplified phosphorus index (API) represents a combination reading (see Chapter 9). The P content of the sheath is standardized to a common moisture and total sugar level and that of the fifth mature internode is expressed as percentage of dry matter. Two representative values obtained, for example, could be 0.085 and 0.030 percent, respectively. The two members are then treated as whole numbers and multiplied (85 x 30= 2,550). The product is the API. It has been very useful for guidance in phosphate fertilization. Variance data and API readings are shown in Tables 8-25 and 8-26. Only the three main collections are included, since the stem tissue was not

340

CHAPTER 8

TABLE 8 - 2 7 -

VARIANCE ANALYSIS DATA FOR THE E F F E C T S OF TREATMENTS ON THE Ca INDEXES

Source

12/1/66 ( 3 . 9 months)

1/19/67 ( 5 . 5 months)

2 5 . 14* 79.02**

76.08*

21.89*

K Kq

V° VN VK ! vn !k . 1

91.91* 4 . 71* 4.47*

8/24/67 (12.7 months)

values)

10/3/67 (13.9 months)

27.87*

40.70*

56.09*

87.78 8.89 7.48 49.70

72.61** 9.81**

54.20*

23.08*

142.51**

4.28* 7.28*

VNI 1 V q

Ca i n d e x C . V . (%)

7/28/67 (11.8 months)

(F

4.59*

(avg.)

.405 8.8

.398 10.1

.303 12.3

available earlier. It will be noted that the C.V. percentages are very high. As Gowing (1968) has shown, transforming the data to square roots or logs greatly reduces the percentages, if it is important to do so. To avoid any possibility of a P deficiency, in the experimental area 600 lb. P2Os were applied under the setts at planting time. This amount greatly exceeds, in the order of 10 times, the amount actually absorbed by the crop. Soil fixation in the experimental area is very high, but once root development is strong, the crop obtains adequate supplies. To insure good root development (Clements et al., 1974), 3 tons Ca metasilicate/acre were applied and rotovated into the soil. Thus, the data in Tables 8-25 and 8-26 should represent direct effects rather than just variation due to dilution by growth. The dominant influence on P absorption is N, and the influence is strongly negative, mostly linear but showing curvilinear trends as well. Potassium fertilization has a negative influence also, but not so strongly significant. The varieties also vary in their abilities to absorb P. In view of the strong negative effect of N on P uptake, it is very essential that wherever a crop is to be forced with high amounts of N, appropriate levels of P be maintained. For example, the treatments that gave the highest cane tonnages, D-III, D-IV, C-III, and C-IV, had API readings just above the critical level, which is in the 2,400 to 2,500 range. Of particular importance is the significance of the dif-

.302 8.5

.285 9-2

ferences in API by variety. Soil analysis would not show that! Ca Levels as Affected by N x K x V Treatments Although Ca (Ca content as percentage of sugar-free dry matter of the sheaths) is an essential element, its function is satisfied at relatively low levels of the element. By far the greatest role is that of offsetting toxicity effects of soil elements. Thus, maintaining a high level of Ca is desirable if maximum yields are to be obtained. A Ca metasilicate treatment, as well as the use of monocalcium phosphate, should maintain adequate Ca indexes. Calcium-index levels between 0.17 and 0.20 are adequate for Ca as a nutrient, and Tables 8-27 and 8-28 show the effects of treatment. The overall effect of N treatment, as in other plants (Emmert, 1961; Prevot and Ollagnier, 1961; Johansen et al., 1968) is the enhancement of Ca absorption, for the most part in linear fashion, but partially quadratic. Conversely, the effect of K 2 0 treatment is strongly negative, also mostly linear with some curvilinear effects. This is a fortunate situation and emphasizes the need for synchronized fertilization with both N and K if the Ca status is to remain acceptable. Calcium builds up where N applications are not balanced with K, and drops off markedly where K is applied excessively without N. But comparing the A-I treatment with the D-IV, Ca is shown as not being affected. Varieties again show different absorption abilities for Ca, with 'H54-775' (Y) being

POTASSIUM TABLE 8-28.

34I CALCIUM INDEX READINGS AS INFLUENCED BY EXPERIMENTAL TREATMENTS (percentage of sugar-free dry weight)

K 0 treatment

Variety

Variety

treatment

1

II

111

IV

Mean

treatment

X

Y

Mean

treatment

X

Y

Mean

A B C D

• 309 .331 .367 . 345

.274 .309 .340 .310

.233 .296 .330 .296

.219 .281 .305 .299

.259 . 304 • 336 .313

A B C D

.240 .274 .302 .286

.277 .334 .368 .339

.259 .304 • 335 .313

1 11 111 IV

.317 .276 .265 .245

.359 .341 »313 .307

.338 .308 .289 .276

.338

• 308

.289

.276

.276

.330

.276

.330

Mean

TABLE 8-29.

12/1/66 (3.9 months)

Kli 11

1/19/67 (5.5 months)

_

_

_

-

64.93** 11.76** 6.80* 10.78**

-

-

-

-

5.51* 11.92** 7.32* 8.74** 15.93** 8.13*

K

-

n li

VK VN{ |K,; VNK.. 1 1 Mg index (avg.) C.V. (2)

TABLE 8-30.

.IM 13.6

.135 9.2

A B C D

Mean

8/24/67 (12.7 months)

10/3/67 (13-9 months)

15.40* 26.86** 13.25**

27.67**

.102 9.3

MAGNESIUM INDEX READINGS AS INFLUENCED BY EXPERIMENTAL TREATMENTS

KgO treatment N treatment

7/28/67 (11.8 months)

70.77**

N

K

Mean

VARIANCE ANALYSIS DATA FOR THE EFFECTS OF EXPERIMENTAL TREATMENTS ON THE Mg INDEXES (£ values)

Source

N v in 1

Mean

1

11

111

IV

Mean

N treatment

.075 .076 .086 .083

A B C D

.083 .088 .098 .097

.073 .075 .088 .078

.073 .070 .075 .074

.071 .069 .085 .084

.092

.078

.073

.077

Mean

able to absorb much more than 'H53-263' (X), perhaps explaining to some degree why the former does better in the more acid, high-elevation soils. Mg Levels as Affected by N x K x V Treatments Although the MgO content of the original lavas is substantial, because of the heavy rainfall and heavy crop production Mg-index levels (Mg content as percentage of sugar-free dry matter of the sheaths) are

. -

-

-

-

-

-

6.02*

-

-

-

4.71*

.081 10.6

.057 13.7

(percentage of sugar-free dry weight)

Variety

k2o

,

Variety

X

Y

Mean

treatment

X

Y

Mean

.080 .078 .089 .087

.070 .073 .082 .079

.075 .076 .086 .083

11 111 IV

.101 .083 .074 .076

.082 .073 .071 .078

.092 .078 .073 .077

.OB'!

.076

.OB'»

.076

Mean

becoming more and more critical in several of the high-rainfall areas such as that in which this experiment was performed. While 0.075 percent Mg is considered adequate, many crop log readings are lower. Part of this is due to the use of higher purity fertilizers and part to the lack of Mg fertilization. The responses of the Mg index to the treatments in this experiment are shown in Tables 8-29 and 8-30. The levels shown are fairly close to the 0.075 level,

CHAPTER 8

342 TABLE 8-31.

t_ VALUES OF CERTAIN FACTORS AND THEIR RELATIVE IMPORTANCE AS THEY AFFECT THE K-HjO LEVELS OF FIELD-GROWN CANE

Factor

'H53-263' and

Sheath moisture Age Leaf nitrogen Total sugars Growth rate Light intensity Minimum temperature Maximum temperature

? d. f. 8 and d_.F. 8 and The number determined by the

-6.01** 3.77** 3.18** -2.87** -2.98** -.98 .95 -.40

,

H5'i-775 ,a (l) c (2) (3) (5) (4) (6) (7) (8)

'H49-5 -8.18** 5.06** 7.13** -2.46* -5.26** -6.03** .05 .35

,b (l) c (5) (2) (6) (4) (3) (8) (7)

540. 2,986. in parentheses is the rating of each factor as size of the t.

although C-IV and D-IV are above standard. Quite obviously, a general application of Mg should have been made. Although the same general relationships hold for Mg as for Ca, the positive effect for N is less marked for Mg, as is also the negative effect for K. For K, only at the two low-N levels is there a consistent downward regression. At the two higher N treatments, the effect of K on Mg is curvilinear. The varieties also show a weaker reaction, and opposite to that for Ca, as might be anticipated.

commercial varieties as grown at Pepeekeo Sugar Company. Only the t values are shown together with the sign (+ or - ) of the regression coefficients. There is a rather marked similarity in the two sets of data. The one striking dissimilarity is that light intensity is not important for the K-H 2 0 level in 'H53-263' or 'H54-775', but it is very important for 'H49-5'. Temperatures, although usually very dominant, are not important here. The dominant factors are sheath moisture, age, and leaf N. Sheath moisture is negative in its effect for at least two reasons: Other Indexes (1) the higher the sheath moisture, the faster the In addition to the data already presented, the follow- growth rate, and (2) since it is reported as K-H 2 0, obing materials together with their mean values were viously, the higher the moisture level, the lower the determined: molybdenum (0.35 ppm), boron (2.0 reading. ppm), manganese (255.0 ppm), sulfur (0.319 perThe correlation with age is positive, as might be cent), silica (2.22 percent) and sheath aluminum (9.0 anticipated. As the plant ages, its sheath moisture ppm). None of these were significantly affected by tends to drop; also, with time, the total K amount treatment except Mn, which showed some very in- within the plant continues to increase and, hence, consistent responses to all three treatments. The through its recycling, causes the K-H 2 0 to rise levels shown are normal for sugarcane except for toward maturity. It is very important that K fertilizaMn, which is high, only about 20 to 25 ppm being tion be carried on early in the crop's life. normal. SYMPTOMS OF K DEFICIENCY Factors Other Than Soil Supply Affecting the K-H 2 0 By the time deficiency symptoms for any nutrient apLevels pear, substantial irretrievable growth losses have alWhen working with a particular element, it is very ready occurred. Extreme deficiency symptoms are desirable to have some knowledge about factors shown for K (Fig. 8-2, in color section) as developed other than soil supply that affect its level. In Table in sand culture. 8-31 are reported the multiple regression results for Dieback of the leaf tips is probably the first sympeight factors on the K-H 2 0 index for two dominant tom to appear, followed by similar dying downward

POTASSIUM

along the leaf edges. This is very marked as the leaves get older. Even + 1 and +2 show the tip dieback. As the intensity of the deficiency heightens, small reddish-brown dots appear along the underside of the midribs; the dots become very numerous from +2 all the way down. Then the reddish spots appear on leaf edges; then they spread to the whole blade. With time, these spots (not so much those on the midrib) begin to enlarge, the green tissue becomes yellowish, and the leaf dies very much earlier than those in cultures adequately supplied with K. Usually in these sand cultures, the complete nutrient cultures will have as many as 14 to 16 living broad leaves in contrast to the leaves shown in the figures where +7 and +8 are much narrower and are very nearly dead. Typically, the stalks are only about onehalf as thick as normal. In field cane, K-deficiency symptoms include a fan-shaped leafy top with the leaves standing out very stiffly, very like ripening cane. Culture nos. 1 and 2 (see Tables 8-3 to £-5 and Fig. 8-3) showed the symptoms also but less severe than for zero culture. Culture no. 3 showed symptoms on an occasional old leaf, but, except for size, the other leaves appeared slightly off-color. Culture nos. 4 and up appeared normal. Yet the growth, as shown in Fig. 8-1, is about 70 percent of normal for culture no. 3, demonstrating the futility of relying on apparent symptoms for diagnosis. Despite these severe foliar symptoms, the total number of leaves produced per plant was affected relatively little, although the number alive at any one time is small. The number of leaves per plant beginning in zero culture at the time of the death of plants was 20.7 for culture no. 1; 21.7 for no. 2; 22.2 for no. 3; 21.3 for no. 4; 21.0 for no. 5; 20.7 for no. 6; 22.0 for no. 7; 22.0 for no. 8 (the best culture); 21.0 for no. 10. Two effects of a K deficiency already pointed out are lowering the moisture level of the plant and, in extreme cases, causing horizontal growth rather than vertical. One rather rare but nonetheless striking Kdeficiency symptom in the field involves a young crop, perhaps 2 to 4 months old. Often a heavy fertilizer application involving N and K has just been made, followed by a torrential downpour. After

343 about 2 weeks, the young plants in the fertile hollows of a hilly field will slow their growth rate, and go offcolor, while those on the higher points of the field will have been growing normally and are closing-in. Foliar analysis will show very low K-H 2 0 levels. The only interpretation, of course, is that the heavy rain caused heavy surface flow of water down the low areas and created a sheet of flowing water and the loss of the fertilizer. On the knolls and high points, the rain, although as heavy as elsewhere, did not reach the point of running off and hence soaked into the soil taking the very soluble fertilizers with it. K FERTILIZATION RECOMMENDATIONS The interactions between K and N and between each of these and tissue moisture point to the necessity of first providing the crop with enough water so that a high sheath moisture can be maintained. To achieve the latter, the N level must be maintained at the NN for the variety as determined by the formula developed for the particular variety when it was producing record crops. Then, assuming there are no other nutrient deficiencies, K has to be provided to maintain the N index at normal. In the experiment reported, the K-H 2 0 levels associated with top yields varied between 0.518 and 0.564 (see Table 8-19). Higher levels are also shown, but, as shown in Table 7-37, where the K-H 2 0 levels are very high, the plant is experiencing a severe N deficiency or a severe drought. When a cane plant is very young (1 to 6 months), because of its high moisture level, its early K requirements are high, as shown in Fig. 8-3. At no time did the 0-lb. treatment reach into the adequacy zone. The 250- and 500-lb. treatments reached adequacy at about 9 to 11 months. The 750-lb. treatment gave the highest yield when associated with the very highest N amount. The 750-lb. curve, except for one brief period at 3.9 months, was within or actually above the 0.500 to 0.560 range. The dates of application of both K and N were made on August 30 and October 4,1966, and March 7 and July 27, 1967. One-fifth of the indicated amounts of both N and K was applied each time. Early in the life of the plant the K-H 2 0 is low, not only because of high tissue moisture but also because of lack of absorbed K. Once certain mini-

344

CHAPTER 8 1966

FIGURE 8-3. The actual

K-H,0

curves for variety 'H53-263', plotted from readings taken at various times throughout the crop season. The range between .500 and .560 shows the area within which K levels are adequate if N fertilization is correct. One-fifth of the total N and K fertilizers was added on each of the following dates: 8/30, 10/4, 12/13

1967

1968

o X ai

(1966), 3 / 7 , and 7 / 2 7 (1967).

mum levels are reached, recycling of the absorbed K reducing sugars and highly significant curvilinear inmakes it possible for the plant to maintain relatively crease of sucrose, both very desirable things. Howhigh K levels in its active tissues even without further ever, culture nos. 4 through 7 are about the same, applications. Because of this, early applications are showing that if the K levels are adequate for growth very essential. Thus, in the experiment, up until Feb- (culture no. 8) nothing is gained in sucrose storage by ruary 24, applying potash fertilizer at the rate called applying an excess of potash. The relationship befor by the 750-lb/acre treatment satisfied the early re- tween the sucrose percentage of the old cane and the quirements. By this time, three of the Ave applica- K-H 2 0 index is a n r value of .8816*"*, somewhat better than the .6601 shown in Table 8-31. tions had already been made, for a total of 450 lb. As shown in Table 7-33, K affects purity in a posiThe effect of K on total tonnage of sugar storage is somewhat less than its direct effect on growth. As tive way, but only by a point or two. The greatest efshown in Table 7-31, the yield of TPA ranged from fect of K is on growth itself, as shown in the Pepee12.48 for the zero-K plots up to 14.15 for the 750-lb. keo experiment, and this, in turn, means greater K 2 0 level, and the difference was very significant. In vigor, which, in turn, means a greater photosynthetic Table 8-32 are shown three values, r, R2, a n d F , for rate and more storage tissue. If K is limiting, not only reducing sugars, sucrose, and total sugars between will the K-H 2 0 level reflect the situation, but tissue the K culture number and the particular carbohy- moisture will drop and the total sugar level of the drate. There seems little relation between the culture sheaths will rise rapidly, as shown in Tables 8-20 and number and carbohydrate content of any of the three 8-23. This has been used by some as partial proof immature storage tissues, but the old cane storage of that K specifically is involved in the translocation of sugars is affected in two ways. First there is a highly carbohydrates, which probably is not the case since significant curvilinear reduction in the amounts of one primary effect of a K deficiency is a loss of tissue

345

POTASSIUM TABLE 8 - 3 2 .

EFFECT OF K LEVELS ON THE STORAGE OF SUGARS

IN CANE O F V A R I O U S A G E S , A N D S T A T I S T I C A L

Culture

number

Statistics

10

S t e m part Reducing Elongating cane Green leaf c a n e - - t o p Green leaf c a n e - - b o t t o m Mi 1lable cane

DATA

12.5

14.6 13.2 -

8.8

5.2

17-9

18.5 30.9

26.3

44.1

15.4 15.4 16.9 8.0

15.5 14.6 8.0 3.?

15.1 19-9 26.4 40.9

18.1 26. A 40.7 50.3

sugars

15.4 14.8 7.3 3.0

15 6 14..6 6 .6 3 ,0

15.7 14.8 7.8 34

14..0 11. 4 6.,5 3 0

14.9 15.8 8.1 3.4

14. 3 15. 8 10. 6 4..0

-.4219 • 3713 -.3226 -.6781*

.4466 .1401 .7372 .7500

2 7 10

16.9 26.8 43.9 52.8

14.6 25.9 42.1 49.8

13.6 29.2 44.5 54.2

15.1 22.5 37-7 50.9

12.4 20.0 34.9 49.2

-.8083** -.0100 .1649 .6601*

.6710 .3172 .7332 .8275

6.1185* 1.6259 6.8703* 16.7898*

30.5 42.0 52.0 55.8

28.5 42.0 53-3

30.8

27.3

.8067** .1025 .0364 .6464*

.7022

7.0738* 2.3091 5.5775* 15-6152*

.5702

Sucrose Elongating cane Green leaf cane--top G r e e n leaf c a n e — b o t t o m Mi I lable cane

17.0 25.4 43.3 53.7

Total E l o n g a t i n g cane G r e e n leaf c a n e — t o p Green leaf c a n e - - b o t t o m Hi Ilable cane

31.3 36.5

34.3 45.9 51-5

31-3 36.8 43.8 51.0

34.5 42.3 50.8 56.8

sugars

33.3 41.5 52.8 59.5

30.5 42.8 52.8 58.5

moisture, which then causes a rise in sugar level. The primary index rises and falls as the general vigor of the plant falls and rises, as can be associated with the adequacy of K—among other factors (see Tables 8-21 and 8-22). Since the N level is high at the start of the crop and drops as the crop ages, one would expect the N regression on K-H 2 0 to be negative. However, as was shown in Table 7-17, since N moves up and down with tissue moisture and since the moisture effect is dominant, the N effect is positive throughout the crop's life. The final molasses product is commonly used in commerce for fermentation, fertilizer, and animal feed. For fertilizer, however, its use can only be justified when its price is relatively lower than the useful inorganic nutrients it contains (Table 8-33). One sample of blackstrap was obtained from Haft Tappeh, Iran and one from Belle Glade, Florida. The minor elements seem very high, but the molasses contains compounds not only from the fields in which the cane was grown but also from contamination in the mill where Cu, Zn, and Fe equipment is in common use. Its use to provide organic matter is never justified, since any good cane crop, if properly fer-

60.0

39-5 47.8 57.0

36.8

47.3 55.8

.3975 .6905 .8169

tilized, leaves behind in its root system more organic matter, which is much better distributed than any application of molasses, bagasse, and even green manuring crops. So far as animal feed is concerned, molasses is excellent as a partial supplement but if fed too heavily causes very marked liquidity of excrement in cattle, pigs, and poultry. Some have taken advantage of this—feeding molasses along with other essentials to hogs, whose manure is such that it flows into a gutter and from there into a tank, thence into a tank truck that takes it to the field and runs it into the irrigation supply ditch, or directly into the planting furrow; or it may be sprayed over the cane plants. At the time I saw this, the hope was that the fertilizer value would pay for the operation and the meat produced would be secondary. Although growing a leguminous green manuring crop is in common use in many parts of the world, its use to provide N as well as to bring K and P into the upper profile is another example of false reasoning. It takes 4 to 6 months to grow such a crop and another 4 to 6 months after it is turned under before it is rotted enough to allow for planting a crop. Thus, about 1 year is wasted or lost for crop production. Even where the yield of sugar is only 3 to 4 tons/acre,

CHAPTER 8

346

TABLE 8-33-

PARTIAL LIST OF INORGANIC CONSTITUENTS AND TOTAL N AND S OF TWO MOLASSES SAMPLES 3 (Haft Tappeh, Iran, and Belle Glade, Florida, U.S.A.)

Dry-weight basis Substance

Haft Tappeh

Fresh-weight

Florida

Haft Tappeh

basis Florida

Percentage Water Total ash Insoluble ash Soluble ash Phosphorus Potass i um Ni trogen--total Sul f u r — t o t a l CaIc i um Magnes i um Sod i um Chloride S i 1 i ca

i»8.7 18.69 4.21 lit. 48 • 093 7.26 .64 1.03 1.06 .66 .19 • 70 .41

49.8 17.32 3.66 13.66 .074 6.68 1.49 1.02 1.10 .55 .18 .70 .22

32.7 12.57 2.83 9.74 .062 4.89 .43 .69 .71 .45 .13 .47 .28

33.2 11.54 2.44 9.10 .050 4.46 .99 .68 • 74 .37 . 12 .47 .14

Parts per mi 11 ion Nitrate N Copper Zinc Manganese 1 ron Boron

4.3 14.2 10.8 16.0 184.0 5.2

4.6 18.2 13-8 11.9 141.0 4.7

2.9 9.6 7.2 10.7 124.0 3-5

3.1 12.1 9.2 7.9 94.0 3.2

a Robert Suehisa, analyst, followed the methods in Chapter 31 of the Official Methods of Analysis of the A.O.A.C., 12th Edition, 1975, pp. 56*»596. Published by the Association, Washington, D.C.

the value of the crop lost would have provided all the fertilizer materials needed without the loss of any time. If animal production is part of the operation then, instead of turning the crop under, animals should be allowed to graze upon it and their manures would still provide the crop nutrients of the original crop—except for the small amounts removed by animal growth itself. The common K fertilization practice in Hawaii is to use muriate of potash (KC1) or sulfate of potash (K2SO 106 99

Per ton net cane P

f^O^

.23 .18 .16 .16 .45 .42 .40 .34

.53 .41 .37 .37 1-03 .96 .92 .78

^2^5 removed per acre (net cane) 42 33 38 21 52 -a

Yield data for the last three ratoons were not obtained.

and P 2 0 3 actually used per ton of net cane yielded at by a labor strike in the summer of 1946. Crop log Waipio and Kailua, plant and ratoon, as well as the samples were taken on three consecutive dates during total P2Os removed per acre by the crops, but not in- the strike and complete analysis was made, including cluding the roots. Kailua Plot D plant crop was able sheath moisture, P, N, Ca, K, and Mg. These were to get only 0.16 lb. P for each ton of net cane, and set up for statistical study, first for each of the two only 21 lb. P 2 0 5 were removed per acre. Obviously, plantations and finally combined for both plantathe crop suffered for lack of P. At Waipio, Plot RA tions. The standard partial regressions were all highly absorbed 0.44 lb. P/ton net cane, and Plot C re- significant statistically, but when at first one, then moved 130 lb. P 2 0 5 /acre, about six times more than another, and so on of the cations and N were Kailua Plot D. The considerable increase in the dropped from the calculations, the change in the R2 number of pounds of P for the Kailua ratoon over was negligible, and only sheath moisture and total the plant crop emphasizes the value of an established sugars remained as useful factors. root system at the start of the ratoon crop. When the statistical work was done for N (see Chapter 7), the objective was to ascertain the need CRITICAL LEVELS OF P IN SUGARCANE for additional applications during the life of the current crop on a month-by-month basis. The point was It is always necessary to know whether any factors to determine the "normal" N (NN) at each sample other than supply of the element affect the selected index level and, if so, to develop corrective formulae. collection. Also there was need for knowing what a (At first, merely the P content of the young sheaths particular reading would be, were the tissue moisture on a sugar-free dry-weight basis was the index.) Early and age something other than that observed, and so in the development of the crop control program, the concept of the "standard" N level was intromany phosphate experiments were installed in fields duced. In the case of P, it is desirable only to stanat Kohala and also at Waialua on the Islands of dardize the P levels to constant moisture and total Hawaii and Oahu, respectively; later, many more sugar levels. Experience has shown it best to apply all were installed along the Hilo and Hamakua coasts. of any phosphate fertilizer under the setts at planting The installations at Kohala were exposed to a severe time or beside the stools of a ratoon at the start. It is natural drought, and the ones at irrigated Waialua therefore necessary to obtain the needed information were subjected to an even greater drought brought on from the previous crop. The data collected from the

354

CHAPTER 9

Kohala and Waialua experiments served for the calculation of the Standard Phosphorus Index (SPI) which came out to be

TABLE 9 - 7 .

SPI = PI - 0.004603M, - 0.00271575, + 0.40054 Actual Actual Actual P index sheath total moisture sugars

Treatment 3

Thus, the standard moisture was 81.0 percent, and the standard total sugar was 10.2 percent. The value obtained for Af, and TS, is added to or subtracted from the PI (P index). The general formula which may be used to standardize the PI to any other value is

K

npn

K

P

n ? A! KP? kIp 1 W

TABLE

9-8.

Treatment 3 K p

on

KP?

^

K PU 2 1 a

K index .96 1.02 2.45 1.89 2.74 2.44

75.5 75.6 76.8 76.4 77.1 76.6

P index .074 .082 .074

.078

.079 .073

TSA 5.49 5.09 7.02 7.49 9.23 8.55

C E R T A I N CROP LOG DATA AND F I N A L Y I E L D ( t o n s c a n e p e r a c r e ) FOR THE K AND P E X P E R I M E N T AT HALAWA 5 , KOHALA

Sheath moisture 75.0 74.9 75.5 75.5 76.0 75.7

K index 1.93 1.63 2.48

2.51

2.77 2.78

P index .076 .084 .076 .079 .073 .076

TCA 65.0 56.8 74.8 71.5 79.8 72.0

Treatments the same a s in T a b l e 9~7.

TABLE 9 - 9 .

Under Drought Conditions The need for standardizing is nicely pointed up by the results of the Kohala field experiments from which samples were collected during the drought period. The experiments were factorials involving three levels of K 2 0 per acre (0, 75, and 150 lb.) and two levels of P2Os (0 and 100 lb.). Pertinent data are in Tables 9-7 and 9-8. In both experiments, the highest yields were obtained for the K2P0 treatment, showing that there was no effect of P but only for K 2 0, and yet the P index was below the accepted level of 0.080 even though the sheath moisture levels were all well below the 81.0 percent tissue moisture. The observed P indexes of the sheaths for the 1944 experiments show the levels to be above 0.080 but for Hawi and Halawa in 1946 below. Union 5 showed the observed P index to be above 0.080 in both years, but this field was irrigated. By standardizing the P indexes for all three fields, SPI's are shown to be well above normal and

Sheath moisture

' KQ 0 l b . K^O per a c r e ; K|1 — 7 5 l b . K?0 per a c r e ; K 2 — 1 5 0 l b . KjO per a c r e ; P 0 - - B lb. P 2 0 5 per a c r e ; PC-- 1 0 0 l b . PJOJ per a c r e .

SPI = PI + 0.004603 {M2 - A/,) + 0.002715(752 - TS,)

in which the Af2 and TS2 are the desired standards for moisture and total sugars, respectively. For the standard used here, 81.0 is substituted for Af2 and 10.2 is substituted for TS2, so the equation becomes the simpler one given above for which a table can be prepared, and thus we avoid the need for frequent calculations.

C E R T A I N CROP LOG DATA AND F I N A L Y I E L D ( t o n s s u g a r p e r a c r e ) FOR THE K AND P E X P E R I M E N T AT HAWI 1 , KOHALA

OBSERVED P INDEX R E A D I N G S AND THE CORRESPONDING S T A N D A R D I Z E D P INDEX ( S P I ) R E A D I N G S FOR THREE PLANT ( 1 9 4 4 ) AND RATOON (19i«6) CROPS

Plant crops Field

PI

SPI

Ratoon crops PI

SPI

Hawi 1 Halawa 5 Union 5

.086 .086 .098

.094 .091 .095

.076 .077 .097

.087 .089 .098

Mean

.090

.093

.083

.091

also to be very nearly the same for both years (see Table 9-9). Under High-Rainfall Conditions Many P experiments were conducted along the wet Hilo coast, and all of them were crop logged so that a mass of data was available for study. To determine factors other than supply affecting the P index, a statistical study was set up with the P level of the

PHOSPHORUS

young sheaths expressed on a sugar-free dry-weight basis used as the dependent variable, and five independent variables were used, as shown in Table 9-10. Thus, these five factors accounted for 40 percent of the variability shown by the P index and justify the use of a corrective formula. In order to simplify, stepwise regression was used, and the most important factor, as clearly shown in the table, is sheath moisture. The/? 2 was .369783, practically all of the total. The second factor added was the Mg index, and these two factors, moisture and Mg, raised the/? 2 to .398011. Adding the Ca index raised theR 1 to .404466, and although this was a highly significant gain, the total effect on the/? 2 was only .006455. Age was the fourth factor but was not significant; and the total sugars, which were important in the hot, droughtridden areas, were without influence in the cool wet areas. The data in Table 9-10 show that sheath moisture, Mg, and Ca are all significant. The equation for that combination is SPI = PI + 0.002884(Af2 - A/,) + 0.06479(Mgi - A/gO+O.OlDOSCCdfi-C«,)

355 0.011305C«, + 0.246907. In this equation the SPI is the standard phosphorus index (standardized to a moisture level of 82.0 percent, to a Mg-index level of 0.1090, and to a Ca-index level of 0.2936). The PI index is the actual P content of the sheaths, expressed as percentage of the sugar-free dry weight. The two-factor equation is SPI = P, - 0.003133M, - 0.070315Afgi + 0.264648 The symbols have the same meaning as before. The simplest way to use a two-factor equation is to construct a table using a wide range of moisture levels, say from 75 to 90 percent at 0.5 intervals, and also a wide range of the second factor. Then it will be necessary only to refer to the table and find the correction factor, which will be added to or subtracted from the observed P content (P index). The improvement in yields resulting from the introduction and use of the SPI was marked, but as time went on, it was obvious that still something more was needed.

In Water Culture A study of P as a nutrient within the plant The mean sheath moisture for the data used was ('H31-1389') was undertaken (Clements, 1958). 82.0132 (Mi), the mean Mg index was 0.108999 Four-gallon crocks were used with Hoagland's solu(Mg2 ), and the mean Ca index was 0.293593 (Ca2 ). tion (Hoagland and Davis, 1929), and since the Substituting these values: pumped tap water on the University of Hawaii campus was essentially free of P, it was used instead of SPI = PI + 0.002884(82.0132- M,) distilled water. Continuous aeration was provided, + 0.064790(0.108999- Mg,) and pH adjustments were made daily. Four germi+ 0.011305(0.293593- Cat ) nated cane plants were provided each crock. SoluClearing, SPI = PI - 0.002884M, - 0.06479QAig, - tions were changed weekly, and at the start, all the cultures were given complete nutrient solutions. When the plants were 3 months old, differential TABLE 9-10. FACTORS AFFECTING THE P INDEX IN HIGH-RAINFALL treatments were begun. AREAS3 On October 1, 1942, one culture of four plants was harvested and taken apart, weighed, chopped, dried, Factor Beta r t value and ground for analysis. Weights and the API Age -.2540 .0186 1.21 readings are recorded in Table 9-11 in addition to the Sheath H20 .6081 27.60** .4935 Total sugars -.0005 -.0026 .04 P content of the various tissues. At the time of this Calcium index 6.06** .3993 .0973 first harvest, 10 cultures were selected at random and Magnesium index .1706 11.11** .4143 became Series A, which continued to have its solu3 n^ = 3,201; 1(34.9**; R2 = .401(936. tions changed as for the X series but which was

356

C H A P T E R

TABLE 9-11.

PHOSPHORUS CONTENT OF SUGARCANE PARTS FOR WATER CULTURE SERIES X, A, AND D, THE AMPLIFIED P INDEX (API) READINGS, AND DRY WEIGHT TOTAL PER PLANT TOP AT HARVEST. SERIES A PLANTS RECEIVED PHOSPHATES UNTIL OCTOBER 1 AND SERIES D, UNTIL DECEMBER 26 BUT NONE THEREAFTER. (Intervening months are skipped to save space.)

Series X

Series D

Series A

10/1 19^2

11/27

1/22 1943

3/19

10/5

10/30 1942

II/27

1/22 1943

3/19

10/5

1/22 1943

3/19

10/5

.600 .210 .188 .163

.688 .213 .138 .125 .068 .110 .060 .035 .263 .085 .048

.550 .200 .096 .133 • 053 .098 .053 .031 .226 .060 • 055

• 413 .163 .113 .073 .043 .073 .041 .024 .233 .060 .056

.375 .181 .148 .118 .063 .109 .120 .033 .146 .088 .063 .075 .070 .068 .088 .078 .085 .083 .070 .070 .070 .073 .078 .068 .118 .108 .146 .078 .158

.525 .146 .108 . 100 .047 .068 .048 .034 .165 .044 .030

.413 .117 .070 .063 .022 .050 .031 .014 .140 .025 .020

.300 .088 .060 .044 .033 .038 .028 .017 .090 .023 .010

.129 .070 .041 .023 .013 .025 .024 .009 .090 .022 .014

• 338b .200 • 163 .275 .053 .173 .135 .013 .206 .275 .023

• 500 .175 .129 .083 .040 .070 .048 .024 .200 .053 .036

.400 .133 .083 .060 .028 .044 .029 .020 .115 .023 .016

.267 .083 .055 .038 .014 .033 .022 .009 .054 .031 .013

.055 .104

.014 .015 .018 .031 .040 .113

.010 .009 .009 .008 .009 .009 .008 .007 .007 .008 .008 .007 .009 .014 .078

P content Meri stem Spindle cluster Young blades Old blades Dead blades Young sheaths Old sheaths Dead sheaths Elongating cane Green leaf cane Top internodes 17th 3 internodes 3 16th 3 internodes 15th 3 internodes 14th 3 internodes 13th 3 internodes 12th 3 internodes 11th 3 internodes 10th 3 internodes 9th 3 internodes 8th 3 internodes 7th 3 internodes 6th 3 internodes 5th 3 internodes 4th 3 internodes 3rd 3 internodes 2nd 3 internodes 1st 3 internodes Roots

.142 .167

.049 .060 .121

.050 .053 .065 • 154

.059 .058 .068 .120 .080 .121

API

16,756

6,693

4,700

5,192

9,225

40

152

157

248

257

Dry w t . / D l a n t

9

-

.128 .115 -

.250 • 133 -

.022 .012 .016 .019 .018 .016 .018 .023 .024 .110

.014 .049 .055 .142

.015 .018 .028 .083

.013 .011 .012 .020 .078

.010 .010 .009 .009 .012 .060

3,080

630

429

340

3,586

2,870

616

330

82

116

92

41

46

168

180

92

tOD

A blank space means the indicated plant part was not present. On July 9, the remaining A cultures were given a complete nutrient solution including phosphates.

denied any more phosphate until at the very end. On series are omitted simply to save space. The Series X October 30, 1942, another culture of four plants was data are the alternate month-by-month analyses of harvested from each series, the complete nutrient (X) four plants, each time separated into the indicated and also from the first P series (A), and eight more parts. Although some other analyses also were made, cultures were chosen at random from (X) and labeled no significant trends or interactions developed. Series (B) and denied P from then on. Similar shifts away A data started from October 30 and represented from P were made on November 27, December 26, cultures taken out of Series X on October 1, and January 22, 1943, February 19, and March 19, and denied P from that date on. Comparing the October all the cultures were continued until October 5. 30 data for Series A with those in Series X for the The P composition of the various parts of the plant same date reveals how quickly the P dropped in all are shown only for Series X, A, and D. The other tissues, reflecting recycling from the maturing tissue

PHOSPHORUS

357

to the new growth which continued to develop. Be- much more phosphate than the A plants and survived ginning in January, however, growth slowed, and by much better, although they too suffered an abrupt this time, the P content of the meristem was reduced loss in growth rate after July 9. In both the A and D to about one-half, the blade and sheath tissues to series when the P content of the dead sheaths and old about one-third, the cane tissues to about one-fourth cane dropped to 0.007 to 0.009 percent, no further that in the corresponding X parts. By July 9, the circulation of phosphate occurred, the young upper plants were beginning to deteriorate, only a few green tissues being unable to attract any more of the leaves remained, and there was a marked increase in nutrient from the old, senescent tissues. The dead the rate of old leaves dying. The meristem was so blades retained more P than the dead sheaths or old small that not enough material was available for cane. Comparing the P content of the dead blades analysis with the methods then used. The young with the young living blades (0.019 versus 0.129) blades and sheaths at this point contained only about leads to the conclusion that about 85 percent of the one-fourth as much P as the corresponding parts in phosphate in young tissue is mobile whereas in the the X series, but the old cane tissues contained only old cane (0.007 versus 0.133) about 95 percent is one-tenth to one-fifteenth as much P as their mobile. Undoubtedly, this characteristic pattern accounterparts in Series X, which points to the well- counts for the experimental results obtained comknown fact that the more vigorous top tissues are monly in the field. In most experiments involving more efficient at accumulating nutrients, and they phosphate, the treated plots are often beginning to will accumulate at the expense of those in the old lodge while the zero-plot plants are still very small tissues if they are mobile. The amounts of P remain- and the stand very open, but as the roots of these ing in the dead leaves and sheaths remained more or plants extend themselves more and begin to "locate" less constant at 0.009 to 0.010 percent, indicating this phosphate in the soil, the top growth accelerates to residual portion to be permanently fixed, most prob- the point that in most of these experiments at harvest ably as part of the complex organic compounds mak- there is no difference in yield. Why these plants accelerate so rapidly and outpace the controls is probing up cell membranes, nuclei, and so on. By July 9th, the plants of Series A were in such bad ably due to this recycling, but why the treated plants condition that death was about to ensue, and, hence, do not continue their feist pace has so far defied soluthe remaining cultures were returned to a complete tion. There is a possibility that a plant at a lownutrient solution. The response was very rapid. By phosphate level during a deficiency period accumuOctober 5, the young top parts increased in P much lates other growth factors and when a "working faster than the old cane: the young blades and quantity" of P is in circulation, growth is accelerated sheaths increased about five to six times in P content, well beyond the normal. the green leaf cane more than 10 times, and the old Because the very great reduction of the phosphate cane between two and three times. One marked de- level in the older stem tissues results in the P levels of velopment was the very rapid emergence of a lala at the top growing tissues being relatively higher than each and every node on the plant, including those in justified by the actual phosphate regime, it may be the greentop still enclosed. Thus, the entry into the desirable in arriving at a P index to use both types of buds of the inorganic phosphate broke their dorman- tissues in one way or another. cy. The role of the phosphate here was to energize the At the bottom of Table 9-11 are given the API metabolism described earlier in this chapter. readings for each collection and below this the The data for Series D show much the same trends average dry weight per plant top. The API's for as A, but because the Series D plants were larger Series X started at a very high level—16,756—and when they were transferred from X, they contained continued throughout well above the minima set.

CHAPTER 9

35» TABLE 9 - 1 2 .

TOTAL NUMBER OF LEAVES PRODUCED PER PLANT IN SAND CULTURE IN RELATION TO THE P LEVEL OF YOUNG SHEATHS IN RESPONSE TO VARIOUS FRACTIONAL P LEVELS

P treatment 0 Leaves produced Phosphorus c o n t e n t o f young s h e a t h s (% dry w e i g h t )

1/64

1/16

6

15

17

20

22

22

22

.025

.031

.056

.128

.225

.259

.312

Series A, however, just 1 month after being denied P, dropped to 3,080, which was still adequate for normal growth, as shown by dry weight per top (82 for A versus 59 for X). By November 27, however, the API dropped to a deficiency level of 630. The dry weight value also dropped (116 versus 152) and continued to drop to the very low API's of 340 and 338 and dry weight values of 41 and 27, respectively. As pointed out above, on July 9 the plants were near exhaustion and death so they were given a complete nutrient solution, including phosphate, and all the lateral buds began to grow. Although the API jumped to 3,586, total dry matter increased very little. The freshly grown lalas were not included. Similar data for Series D show similar trends. Thus, the API in Series X on December 26 when plants were taken for Series D was 8,024, a relatively very high value. A month later, on January 22, the API of the X plants was 4,700, still very high but well down. The Series D equivalent on January 22 was down to 2,870. Growth for D was 168 and for X, 157. Although the API for D was only 1,219 on February 19, the growth rate continued to be higher than for X, but the API, as well as the growth, dropped sharply from then on. Ratios between nutrients per se usually add more confusion than light, but since the stem levels of P added a large factor of response variability, the thought developed that using the SPI as one aspect and the P as percentage of dry weight of the stem (to be specific, mature internode+5 counting down from the last living leaf) as the second and multiplying these values as whole numbers would give quite a sensitive indicator of the P regime. This has turned out to be the case. Thus, an SPI of 0.110 and a fifth in-

l/l)

1/2

1

X2

ternode P of 0.030 become 110 x 30, or 3,300, and, because the operation resulted in an amplification, the resulting product is called the amplified P index, or the API. One suggestion that the API is better than any other index is that, since phosphate ions circulate very rapidly through the plant, two site determinations give a better estimate of what is in the top as well as what is in circulation and thus a better estimate of the whole. In Sand Culture Using the techniques described in Appendix I, several series were conducted for each of the several nutrients, including P. In some of these, the normal level of P was referred to as P = 1, and then the P for the next culture was one-half as much, referred to as P = Vi, then P = 1/4, y„ yl6t %4, y,t„ and zero. As indicated in Appendix I, usually the nutrients were applied in five separate doses. The sand used was acid washed, and the major chemicals were purified. Deionized water with a purity range from 18 megohms down to about 4 was applied as needed. Leaf counts were made weekly. Phosphorus like N, but unlike essentially all the other nutrients, markedly affected the production of leaves, as shown in Table 9-12. Actually, P = 0 and P = y,2, died quite early in the series and P = '/,4 was in great distress at harvest. Another approach with sand culture was to use 10 increment levels starting with P = 0 and then adding a uniform increment of 0.4289 gram P per culture up through no. 8 and then a double increment to P = 10 and again to P = 12. Analytical results for P composition are in Table 9-13. The general distribution of P is especially interesting in this table. The growing point or the meristem reaches adequate amounts

359

PHOSPHORUS TABLE 9-13.

PHOSPHORUS CONTENT (percentage of dry weight) OF SUGARCANE PARTS (sand culture)

Culture no. Plant part Meristem Spindle cluster Young blades—bottom Young blades—middle Young blades—top Old blades—bottom Old blades—middle Old blades—top Dead blades—bottom Dead blades—middle Dead blades—top Young sheaths Old sheaths Dead sheaths Elongating cane Green leaf cane Old cane

TABLE 9-1 It.

0

1

.100 .050 .042 .033 .040 -

.017 .016 .030 .026 -

.011 .065 -

.016

2 .460 .106 .052 .079 . 104 .034 .039 .053 .014 .015 .022 .041 .025 .011 .102 .025 .014

.400 .111 .062 .067 .067 -

.017 .019 .030 .045 -

.017 .099 -

.021

3 .582 .194 .106 .125 .150 .062 .081 .083 .019 .022 .048 .076 .046 .017 .159 .054 .022

1

( .646 .206 .129 .137 .146 .074 .071 .092 .021 .031 .071 .089 .039 .019 .206 .082 .031

5

6

.682 .202 .144 .125 .137 .074 .072 .084 .026 .041 .089 .087 .044 .021 .212 .112 .037

.659 .225 .162 .154 .166 .109 .094 .114 .041 .052 .109 .121 .055 .025 .275 .159 .048

7

8 .655 .212 .156 .134 .134

.631 .237 .187 .152 .127

-

-

-

-

-

.057 .077 .144 .115 -

.038 .244 -

.068

-

.162 .190 .259 .181 -

.067 .312 -

.127

10

12

.650 .252 .252 .214 .186 .265 .192 .142 .231 .225 .252 .252 .220 .095 .337 .262 .156

.617 .246 .234 .209 .300 .246 .223 .209 .225 .209 .219 .269 .227 .104 .375 .284 .152

CORRELATIONS BETWEEN THE P CONTENT OF EACH POSSIBLE INDEX TISSUE AND VARIOUS "WORK" TISSUES 3

"Work" tissue Possible index tissue Meristem Young blades Old blades Spindle cluster Young sheaths Phosphorus index Old sheaths Green leaf cane a

Dead leaves

Whole plant

Green top

Growing stem

Immature cane

^ Er

.910 .893 .930 .892 .939 .936 .793 .868

.922 .924 .929 .898 .954 .951 .856 .932

.874 .936 .928 .885 .968 .966 .883 .969

.854 .868 .845 .833 .893 .898 .865 .924

.703 .852 .877 .918 .900 .891 .702 .835

3.6656 4.0066 4.0723 3.9219 4.3363 4.3139 3.3823 4.1120

All correlations are highly significant.

in culture no. 4, and the plateau is maintained at about the same level throughout, even though the supply up to culture no. 12 is tripled. The young and old leaf blades continue to gain P to the highest culture. The same is true for the young and old sheaths and elongating, young, and old cane, suggesting a form of storage or luxury consumption. The P levels of several plant divisions were determined from individual tissue analysis and weighted according to the dry-matter weights of the various parts. For example, in Table 9-14 are shown the correlations between each of the potential index tissues listed on the left with each of the plant divisions listed

across the top. The P index shown is the P content of the young sheaths, expressed on a sugar-free dryweight basis. The data used represented P values from extreme deficiency to excessive levels, and, because of the wide range, the correlations are all good. The young sheaths (+3, +4, +5, and +6) give the best complex evaluation and when expressed as percentage of sugar-free dry weight, the P index is next best; but in cases where the total sugars of the sheaths vary a great deal, the P index is always best of all. In this study, the meristem is next to last. In nearly all cases, the meristem has been very poor as an index tissue. The green leaf cane compares favor-

36O

CHAPTER 9

ably, followed by the blades, spindle cluster, meri- and the old sheaths. Any or all of these tissues could be used since all the correlations of these four tissues stem, and, finally, old sheaths. In another study, the results obtained showed the are extremely high, and occasions may well arise young sheaths to be superior to the green leaf cane where one tissue could be more advantageously used (Table 9-15). The values shown, even though very than the others. For example, were one interested in significant, are low, largely because the range in P repeated samplings of a given stool of cane or even of a single stalk, he could use the old sheaths or old levels was quite narrow. Another way to determine the best index tissue is blades—middle without injuring the plant. Even the to correlate the levels of the various possible tissues dead sheaths could be used, provided they were with the treatments imposed in controlled experi- secured to the plant so that death would come about ments. Simple and multiple correlations are shown in naturally. Because of general experience, the young Table 9-16. It is at once evident that all tissues are af- sheaths are being used because they are more refected by the phosphate treatments and that the cur- moved from storm damage and dust and because vilinear regressions are generally better than the they are always present. The other three tissues are at linear. The four leading tissues are the old blades- times lacking because of storms and commonly the middle, the old blades—bottom, the young sheaths, old sheaths enclose severe mealy bug attacks. TABLE 9 - 1 5 .

CORRELATIONS BETWEEN TWO P O S S I B L E AND FOUR PLANT PARTS (n - 2 6 3 ) a

Possible Index tissue

Meri stem

Green leaf cane Young sheaths

.677 .795

a

INDEX

Plant part Young Old blades blades .528 .792

• 325 .522

TISSUES

Mature cane .789 .615

All correlations are highly significant.

TABLE 9 - 1 6 .

CORRELATION DATA BETWEEN P L E V E L S OF VARIOUS T I S S U E S AND THE 11 P TREATMENTS, FROM NONE TO E X C E S S I V E , SHOWN IN TABLE 9 - 1 3

Plant part Merlstem Spindle cluster Young blades—bottom Young blades—middle Young blades—top Old blades—bottom Old blades—middle Old blades—top Dead blades—bottom Dead blades—middle Dead blades—top Young sheaths Old sheaths Dead sheaths Elongating cane Green leaf cane—top Old cane

£

.6184 n.s. .9406** .9569** .9088« .8668** .9957** .9891** .8287** .3209 n.s. .8468** .9571** .9850** .9759** .7782** .8571** .9618** .62l n.s.

Correlation R* .6599 .9570 .9520 .8450 .8377 .9949 .9967 .8666 .5559 .9043 .9283 .9708 .9837 .9008 .7351 .9689 .6192

F va 1ue

BEST GUIDE TO P NUTRITION IN SUGARCANE One special sample collection taken July 23, 1962 from Pepeekeo (Expt. 98 AP x A coral) included P analysis of leaves, sheaths, fifth internodes, and root bands. These were all put through statistical analysis, and the results follow in Tables 9-17 to 9-23. These data were taken from the second ratoon. The phosphate and coral were applied at the start of the plant crops, and none was applied later. The P content of the fifth mature internode is the best of the single tissues in this experiment. The SPI is a marked improvement over the young sheath P alone and the TABLE 9 - 1 7 .

PHOSPHORUS INDEX READINGS ( p e r c e n t a g e o f s u g a r f r e e d r y w e i g h t ) OF SHEATHS + 3 , + 4 , + 5 AND + 6 FOR A PHOSPHATE X CORAL STONE F I E L D E X P E R I M E N T

6.79* 77.90** 69.41** 19.03** Coral stone treatment*1 18.07** p 585.24** 2°5 a treatment K L M 906.09** 19.49** 4.38 n.s. A .071 .073 .073 33.07** B .074 .074 .078 45.21** C .080 .076 .077 116.76** 151.73** 31.78** Mean .076 .074 .076 9.71** 77.99** 5.69* J A—0 lb. P205/acre; B--200 Ib.; C--400 lb. K—0 lb. coral stone/acre; L--1 ton; M—2 tons.

Mean .072 .075 .078 n.s.

PHOSPHORUS TABLE 9 - 1 8 .

36l

SPI

READINGS FOR THE SAME DATA AS IN TABLE 9 " 1 7

K

L

A B C

.083 .083 .090

.079 .081 .083

.079 .083 .085

.080 .082 .086

.085

.081

.082

r_ - 7 . 9 0 * "

M

Mean

Coral P2O5 treatment

K

A B C

.209 .212 .217 .212

Mean TABLE 9 - 1 9 .

PHOSPHORUS CONTENT ( p e r c e n t a g e o f d r y w e i g h t ) OF THE 5TH MATURE INTERNODES IN THE SAME EXPERIMENT AS IN TABLE 9 " 1 7

Coral P205 treatment

C

Mean

P205 treatment A B C

.032

.021 .023 .026

.020 .023 .025

.022 .025 .027

.028

.023

.022

F-9.38**

API READINGS IN THE SAME EXPERIMENT AS IN TABLE 9 - 1 7

Coral stone treatment p2o5

K

L

M

A B C

2,129 2,296 2,894

1,682 1,880 2,114

1,537 1,897 2,075

1,782 2,024 2,360

2,439

1,891

1,835

F = IO.38**

TABLE 9 - 2 1 .

ROOT BAND A P I TABLE 9 - 1 7

Coral

Mean

IN THE SAME EXPERIMENT AS

stone

IN

treatment

P205 treatment

K

L

M

A B C

4,085 4,274 5,369

3,135 3,738 3,684

2,852 3,470 3,714

4,574

3,517

3,344

Mean

IN

s t o n e treatment M

Mean

.205 .210 .216

.203 .209 .217

.205 .210 .216

.210

.209

L

£ -

ROOT BAND P INDEX (percentage o f d r y w e i g h t ) SAME EXPERIMENT AS IN TABLE 9 - 1 7

5.48*

IN THE

Coral s t o n e treatment

M

treatment

Mean

TABLE 9 - 2 3 .

treatment

L

.026 .028

TABLE 9 - 2 0 .

stone

K

A B

Mean

YOUNG BLADE P INDEX ( p e r c e n t a g e o f d r y w e i g h t ) THE SAME EXPERIMENT AS IN TABLE 9 " 1 7

Coral stone treatment

p205 treatment

Mean

TABLE 9 - 2 2 .

Mean

K

L

M

.049 .051 .053

.040 .046 .043

.036 .042 .041

.053

-043

.041

Mean .042 .046 .049 £=6.02*

API using the fifth internode P, and the young sheath P is best of all. One further advantage in using the two tissues is that in some experiments the fifth P is better than the sheath P and in others it is reversed. The young leaves or rootbands offer no advantages. The larger significance of the API, however, is that it combines the P levels in the high-P regions, the top, with those in the low, the cane. When there is an excess of P, both readings are high, but where there is a degree of deficiency, the top P drops only slightly, if at all, because it removes more of the P from the c a n e thereby causing a steeper gradient and hence a larger API difference. Here then, again, advantage is taken of a fundamental fact.

Mean 3,356 3,826 4,254

£ -

7.21**

EFFECT OF AGE ON P READINGS Within a period of a month or so, the age of a crop is not an important factor for P. In order to measure the P index during the period of maximum growth, as has been shown above, a schedule was worked out

CHAPTER 9

362 TABLE 9-24.

SCHEDULE FOR THE THREE CONSECUTIVE SAMPLINGS IN HAWAII TO OBTAIN AN ADEQUATE MEASURE OF P

Sampling date 3 For fields started in January February March Apr! 1 May June July August September October November December a

Same or next year Same Same Same Next Next Next Next Next Next Next Next Next

year year year year year year year year year year year year

• 1 October October November May May May June June July August August September

2 (9) (8) (7) (13) (12) (11) (11) (10) (10) (10) (9) (9)

November November December June June June July July August September September October

3 (10) (9) (8) (14) (13) (12) (12) (11) (11) (11) (10) (10)

and

December December January July July July August August September October October November

(11) (10) (9) (15) (14) (13) (13) (11) (12) (12) (11) (11)

Numbers In parentheses after each month represent the age (In months) of the crop at that

time.

for sampling. It should be understood that separate sampling for P alone was not made, but that the three regular crop log samples collected during the critical periods were analyzed, not only for the usual N, K, H 2 0, and total sugars of the sheath but also for P as well as all the other elements: S, Ca, Mg, and all the minor elements. The actual dates for these three consecutive samples varied according to the time of start of the crop (Table 9-24). It is noteworthy that the range of ages of these samples for a whole plantation is reduced to 7 to IS months, even for crops grown as long as 36 to 40 months. For this reason, age per se is not a factor. This schedule places the P samples in the period of maximum absorption and avoids the cold soil months of February through April during which P absorption is erratic—sometimes higher than normal, because of reduced growth brought on by unfavorable atmospheric conditions with the soil still warm, and sometimes less than normal, especially in March and April when the soils are at below normal temperatures but the atmospheric conditions are becoming favorable for rapid growth. Applying the API method to the Waipio and Kailua data reported upon earlier, but only to those three samples falling into the timing schedule shown in Table 9-24, results in the data shown in Table 9-2S. Clearly, the Waipio plots were enjoying a much

TABLE 9-25.

API READINGS FOR THE WAIPIO AND KAILUA CROPS OF 1 H31-1389' AND 'H32-8560' (plant and first ratoons)

-

Plant 1

Plot

First

sample 2

1

3

ratoon 2

sample 3

•H31 - 1 3 8 9 ' Wa i p i o

A B C D

4,680 4,158 3,944 7,030

5,980 4.557 3.910 7,488

5.508 4.368 4.455 8.883

9,379 5,460 9,240 12,075

6,960 4,905 12,800 7,446

9,125 9,417 11,315 5.840

Kai 1 ua

A 6 C D

1,295 924 992 1.343

1,100 1,302 1,508 1,944

1,972 880 2,175 1,296

3,392 1,938 2,059 2,275

2,600 2,560 3,198 2,080

5,166 1,680 3,465 2,628

Waipio

A B C D

10,208 10,682 4,850 4,550

6,875 9,525 7,056 4,429

8,160 8,755 8,064 5,184

12,870 8,400 9,990 7,137

10,965 7.657 8,418 9,280

'H32-8560' 11,610 7,410 10,275 7,490

richer P nutrition than the Kailua plots. Also, in general, the ratoons were considerably higher in P than the corresponding plant crops, reflecting the well-developed root system at the start of the ratoon as compared with the lack of one early in the plant crops. The 'H32-8560' plots were not exactly the same pieces of land as used for the 'H31-1389'. Thus, 'H32-8560* plot A was occupied by both A and B in the earlier crop; plot B was C and D of the earlier crop; but plots C and D were on adjacent but dif-

363

PHOSPHORUS

ferent land. It is interesting to note how different the absorption abilities of the two varieties are, which shows still another weakness of soil analysis. INTERACTION OF P WITH OTHER NUTRIENTS Since the young sheaths generally appear to be either the best or very nearly the best index tissue for each of the many nutrients, they were examined for reactions to the P treatments in sand culture that ranged from zero to eight by the uniform increment of 0.4289 gram P/culture. Culture no. 10 received 0.8578 gram more P than no. 8, and no. 12 received 0.8578 gram more P than no. 10. All other nutrients were applied equally to all cultures as shown in Appendix I (Appendix Table 1-3). In this sand culture series, there was a very significant growth response as well as a rise in the P level of all parts of the plant. Except for the old blades (pee Table 9-16), the young sheaths showed the best F value (lie^*" 1 '), better than that of the young blades—middle (19.04**), (Table 9-26). Manganese was the only element showing interaction, being somewhat depressed by P. This has previously been noted and probably represents a part of the early TABLE 9-26.

INTERACTION O F OTHER NUTRIENTS WITH THE PHOSPHATE TREATMENTS IN SAND CULTURE

Nutrient and plant part P—young blades P—young sheaths N—young sheaths N--young blades—middle K index S index Ca index Mg index Fe i ndex Mn index Cu index Zn index CI index B index Total sugars—sheaths Reducing sugars—elongating cane Reducing sugars—old cane Sucrose—elongating cane Sucrose—old cane Sucrose—green leaf cane—top Total sugars—elongating cane Total sugars—green leaf cane—top Total sugars—old cane

r .9088** .9850** -.4011 -.3016 -.526 -.3268 -.2649 -.5001 -.07 -.47 -.3479 -.4106 .6317* -.3300 .6773* .2777 -.8053 .4820 .2793 -.5113 .4504 .3400 • 3245

R2

F

.8477 .9708 .4173 .3147 .543 .2929 • 3344 .4790 .04 • 590 .1423 .4899 .5181 .1377 .5915 .2728 .8933 .2346 .4031 • 7053 .3369 .2843 .1100

19.04** 116.36** 2.50 1.61 4.16 1.45 1.75 3.22 .14 5.03* .58 3.36 3-76 .48 5.06* 1.31 29.30** .37 2.36 7.18* 4.07 1.39 .37

response to phosphate by young cane plants growing in toxic soils. So far as carbohydrates are concerned, the total sugars of the sheath show a significant rise with added phosphate, and, more importantly, the reducing sugars of the old cane are very significantly lowered (F = 29.30) by the rising P treatments, and the sucrose content of the young green leaf cane is significantly raised. Although there is a general increase in sucrose in the old cane with increasing phosphate, it does not reach statistical significance in this series. In another sand culture series, P was applied according to the following, 2 times normal, normal, Vi, V*, A, V\t,'/12,y64,'Ai»normal, and zero. The zero cultures and the %2, normal cultures died very early and hence were not included in the data to follow. The experiment was run in quadruplicate, but each four were combined at harvest and treated as a single sample. In Table 9-27 a comparative summary is given in which each element is compared for each treatment as the percentage of its composition in the P-l culture, which in this series is considered the normal complete solution. Not all the elements showed decided trends—Ca, Mg, S0 4 S, and Cu. Organic S showed a slight positive trend. Of course, P and growth showed strong positive trends. The others all showed strong negative trends—particularly Mn and Al, two toxic elements—pointing again to one beneficial role of P fixation by the soil. To be sure, the negative trends may be no more than a result of the very slow growth with absorption continuing, albeit at a slower-than-normal rate. One thing stands out in Table 9-27 and that is the variety of responses. The P distribution within the cultured cane plants showed that P is quite mobile. The meristem of P = yt, had more than one-half that of the P = 1 or P = 2 treatments, while the dead sheaths had left only oneseventeenth to one-sixty-seventh the amount of P contained in the P = 1 and P = 2 culture sheaths. P = !4, which produced as much growth as the best, had only 0.04 percent P left in the old cane. The P left in the dead blades and dead sheaths probably represents that contained in the complex compounds of the pro-

CHAPTER 9

3 6 4

TABLE 9 - 2 7 -

COMPARATIVE SUMMARY OF DRY WEIGHTS ( g ) , GROWTH, AND THE SEVERAL NUTRIENTS AS PERCENTAGE OF THE CORRESPONDING DATUM FOR CULTURE PI

Fractional Cri t e r i o n

phosphate

treatment

P2

PI

Pl/2

PIA

PI/8

Pl/16

Pl/32

755 107

704 100

639 91

726 103

698 99

356 51

112 16

89 13

ijor elements K PI) P N Ca Mg CI SO^-S

106 196 80 108 100 106 83

100 100 100 100 100 100 100

1

114

65 108 138 140 134 122

33 131 135 120 126 102

143 20 128 94 107 84 76

212 23 180 92 107 152 80

330 5 253 127 140 274 86

324 6 289 132 167 328 92

inor Cu Fe Mn Zn B Al

54 86 116 109 97 113

100 100 100 100 100 100

54 130 155 125 97 126

61 101 156 131 103 207

40 107 192 116 82 413

43 173 311 108 86 762

55 199 610 157 295 371

54 321 652 254 266 489

•y w t . •owth

(g p e r PI)

pot)

Pl/64

elements

toplast and is permanently fixed until the plant either is destroyed by fire or by microorganisms. DEFICIENCY SYMPTOMS As is the case with all other nutrients, reliance on visual symptoms of deficiency is certain to result in growth losses. Thus, in the water as well as sand culture series, only the extremely low cultures showed what might be called deficiency symptoms; namely, the much smaller and fewer leaves tend to be a darker green than those in the complete cultures. As with other nutrients as well as water, P deficiency also is associated with lack of tillering. The only reliable way to identify P deficiency is through chemical analysis of the young sheaths and the fifth mature internodes. RECOMMENDATIONS FOR FIELD APPLICATION OF P Complexities of the Problem As evidenced by the above studies, the P level needed for full growth has been very difficult to establish with the same degree of accuracy as for K, for example. There seem to be several reasons for this. First, the amount of phosphate in the soil is enormous. If it

were readily available to the plant, there probably would be little need to apply more for centuries. But this reserve is well fixed—some by the plant and animal life of the soil; some held in an insoluble state by such cations as Fe, Mn, and Al; some as part of phytic acid complexes; some within the colloidal and crystalline structures making up the soil; and some still tied up in the nitrogenous complexes originating from decaying root and other plant remains. It is not unlikely that some day it will be possible to unlock some of the fixed phosphate by the addition of specific enzyme systems such as the plant uses to change the fixed phosphates in its buds and seeds to the inorganic and mobile forms, or at least by some sophisticated means to imitate this process. Dean (1938) estimated that contained in a particular agricultural soil on Kauai were 2,000 ppm P. Hilgard (1906) estimated the P 2 O s content of five local soils ranged from 0.19 to 0.97 percent. An acre-foot of such Hawaiian crop soils weighs between 2 and 3 million pounds. Thus, the amount of elemental P in the top foot of soil ranges from 0.8 to as much as 6.3 tons/acre. As already shown, P absorption by cane increases with moisture, Mg, and Ca. Long ago Truog (1953) urged the liming of soil to maintain a

365

PHOSPHORUS

pH in the 6.5 to 7.0 range to aid the plants in getting the fixed phosphate. In Hawaii, fields in the range of pH 5.8 to 6.5 generally do not require phosphate fertilizers. On many of these fields the API reaches over 15,000 to 20,000. In the early years of the sugar industry, there seemed little need for phosphate, probably because a particular irrigated Held might be ratooned more or less permanently. This was possible because of hand cutting of the cane and reshaping of cane lines with hand hoes that caused very little or no damage to the root system. In the wet, unirrigated areas, the cane was hand cut and carried (hapaiko) by humans, either to ox carts or to water flumes that delivered the cane to the mill. It was only when there was to be a complete change of variety that plowing was needed. The tremendous increase in labor cost, however, resulted in the desperate need for labor-saving equipment, which did a great deal of damage to the Held, necessitating frequent plowing and renewal of cane stands. It is only with the start of a crop that phosphate additions are noticeably helpful, and this undoubtedly is related to the fact that between the start of germination and up to about 12 months of age the root surface in contact with the soil is building up to the point where it is large enough to extract in toto adequate supplies of phosphate even from that very tightly fixed. These are the factors that make simple solutions to phosphate fertilization difficult. For example, the experiment at Pepeekeo involving amounts of phosphate and of coral stone showed an enormous difference in cane growth for the phosphate through the first 10 months. The results were so striking that it was freely predicted by the many visitors that the zero phosphate plots would be growth failures by harvest time. In fact, it led one confident person to promise that he would "eat the cane" if the differences at harvest were not extremely great. Yet at harvest there was no difference! Minoru Isobe (personal communication) experienced the same type of disappointment with a phosphate experiment on an irrigated plantation. The differences at 12 months, as shown in Fig. 9-2, are highly significant, being of the

130

< O

1400

1600

1800

2000

2200

API RGURE 9-2. Readings from an amounts-of-P experiment in a Low Humic Latosol at 10 to 12 months of age. The growth difference was great and highly significant. The API readings followed the amounts closely and also reflected the growth differences. Yet at 24 months the differences in growth were greatly lessened.

order of 26 percent more for the highest API plot over the lowest. Yet at harvest this difference was reduced to about 7 percent. Although the cane yield just reached the 5 percent significance level, the pol yield did not. Then at the other extreme of conditions is that found in the Khuzestan of Iran where the cane first showed extremely low API readings, which called for heavy phosphate applications. Yet experiments failed to show any visual response by cane to phosphate fertilization but very marked response by legumes. However, management persisted in applying phosphate, and over the years, the API readings rose, as did the yields of sugar (Sund and Clements, 1974). Despite these several areas of uncertainties, the field superintendent wants to know how much and what kind of phosphate fertilizer should be put onto the field that he is beginning to plant "tomorrow morning," since P should go on under the setts. Any plant physiologist who takes his position seriously

366

must provide an answer that combines all the available knowledge. Soil analysis has been not only useless, but dangerously inaccurate, as already pointed out (see Chapter 8). The best basis for recommendations is the API record for the previous crop combined with a knowledge of plant behavior in experiments already conducted. It is most useful to install observation tests near the road so that they can be observed daily by top management. Three to four short lines of cane should be left without phosphate if the field is receiving it, but with phosphate if the field is not receiving it. Sheath and fifth internode samples should be taken at the appropriate time as is done for the field. In this way, the crop control superintendent develops an understanding of what to expect. Amounts and Forms of P Fertilizers to Use

All fields are sampled for P according to the time schedule (see Table 9-12), and three consecutive samples are taken. These API readings become the basis for the phosphate fertilizer recommendation for the next crop. In addition, the fundamental behavior of the cane absorption of phosphates is recognized; namely, that a plant crop in its first year generally fails to achieve the level it will later on. In Hawaii, for the most part, these analyses are made the year before the crop is harvested, so that rather close estimates of the phosphate needed can be arrived at by the end of year prior to harvest, and all fertilizers needed for the coming year can be planned for. Usually the crop logs are studied by the crop control office, and then recommendations to management and the operating staff are made at a meeting where all the evidence is looked at by everyone and a free discussion results in firm decisions. Where there are disagreements, experiments to be installed are planned for the particular field. If a particular field is a ratoon but is to be plowed and planted after the coming harvest, the API readings of the current ratoon are divided by two and if the answer is in excess of 2,500, then no phosphate is called for the next plant crop. If the number falls between 1,800 and 2,500,200 lb. P2Os are called for; if

CHAPTER 9

the number is less than 1,800,400 lb. P2Os are called for. If the number is very low and the field very acid (below 5.8), then liming should be undertaken also (see Chapter 11). If the current crop being sampled is either a plant or ratoon, and if the next crop is to be a ratoon, and if the API readings exceed 2,500, then, no P 2 0 3 is called for. If the readings are below 2,500, then 200 lb. P 2 0 9 can be applied, preferably in a shallow furrow on only one side of the stool, thus doing least damage to the old roots. If there are gaps in the ratoon cane lines that need filling in with new setts, the phosphate applied should follow the recommendations as for a plant crop. The form of phosphate to use is determined largely by the soil pH. If the pH is 6.5 or above, a soluble phosphate should be used—mono- or diammonium phosphate can be used, although such fields usually will not need phosphate. But even where the API's are high, the observation tests should be installed providing the same amount of N as is used in the field. Nitrogen carried by phosphate is probably the best for certain troublesome fields (Clements et al., 1974). Where the pH is between 5.8 and 6.5 and phosphate is actually called for, monocalcium phosphate is best because it is usually cheapest because of lower shipping charges. Where the pH is below 5.8, then no ammoniacal fertilizers of any kind should be used without applying proper amounts of neutralizing materials—either Ca metasilicate or carbonate or dolomite limestone {see Chapters 11 and 12). The form of phosphate to use though should be simple superphosphate—a mixture of Ca phosphate and gypsum. If the soil is very acid, raw rock phosphate can be used, but recognition should be given the possibility of fluoride toxicity, and efforts should be undertaken to correct the soil acidity. Where unpelleted mixtures of N, P, and K are used for placement under the setts, "caking" commonly results. Variations in application methods have developed to avoid "caking." One is to apply the N and P as a mix and then apply muriate of potash as a surface application 2 to 3 weeks later with more N.

PHOSPHORUS

Another calk for applying a granular phosphate fertilizer to deep irrigation lines by airplane. Although this is a broadcast application, because of the steep sides of the cane furrows, in effect the phosphate slides down the bank and when the first water is applied, more soil slides down and forms a talus, which

367 covers not only the setts but also the fertilizer. The N and K fertilizers as needed are then applied with either the second or third irrigation. Still another method calls for broadcasting finely ground raw rock phosphate after plowing but before the final operation of rototilling or disk harrowing.

CHAPTER 10

Sulfur (S)

ESSENTIALITY OF S FOR LIFE The essentiality of sulfur (S) for plant and animal life has been known for a very long time, even though the specific roles played by the element are not even now fully understood. It is known that S is a component of three amino acids—cystine, cysteine, and methionine. Of these, cysteine is essential to all living things and is formed from sulfate S in a metabolism in which ATP is an active participant and in which S04= changes from the inorganic anion to a reduced - S H group in the amino acid HSCH2CHNH2COOH— cysteine (Wilson, 1962). Somewhat as is the case with P, S is capable of high-energy bonding, thus enabling it to take part in the synthesis of high-energy compounds at ordinary temperatures. The relative amounts of S in organic and inorganic forms are not very well known. Statements are rather common that "most" of the S is in organic form and relatively little exists as the sulfate, although it is thought that whatever transport of S occurs is in the inorganic form. The amount of S in various plant proteins varies from about 0.003 to 7.2 percent (Miller, 1938). The Cruciferae are especially rich in organic S, and grasses in general are very low. Assuming that 0.6 percent of the protein in sugarcane plant parts is S

(which may be much too high), then calculations from the N percentage to protein show complete nutrient solution plants to contain about 48 mg organic S out of a total S content per plant of 428.3 mg, or about 11.2 percent. All the rest probably is sulfate S existing in solution as the divalent anion. To check this point, water extracts of dried material were made, filtered, and treated with barium chloride. Heavy white precipitates resulted, indicating the presence of very substantial amounts of inorganic S. The sulfate ion, along with all the other inorganic anions and cations, make up the vacuolar "saline" that is needed to maintain the physical state of cytoplasm. That this portion of the S in sugarcane also is essential is shown by the fact that growth continues to increase with added increments of S beyond the point at which the protein requirements are satisfied. For example, the zero-S (Table 10-1) culture plants contained 39.38 mg organic S (calculated from the N content), while the complete culture contained 48 mg but was about two and a half times heavier. Table 10-1 shows that in extreme deficiency, the plant, as is the case with Mg and chlorophyll, uses whatever S it has to produce the essential S-containing protein with very little left over for the sulfate anions. Growth as dry matter continues to build up to the complete nutrient culture no. 8 (see later).

369

SULFUR TABLE 10-1.

SULFUR CONTENT OF SUGARCANE PARTS GROWN AT FIVE DIFFERENT LEVELS OF NUTRIENT S FROM NONE TO A COMPLETE NUTRIENT (percentage of dry weight)

S Level Plant part

0

1/64

1/16

1/4

Complete

Meristem Spindle cluster Young b l a d e s — b o t t o m Young blades—middle Young blades--top Old blades—bottom Old blades—middle Old b l a d e s — t o p Very old b l a d e s — b o t t o m Very old blades—middle Very old b l a d e s — t o p Dead blades—bottom Dead blades—middle Dead b l a d e s — t o p Young sheaths Old sheaths Very old sheaths Dead sheaths Elongating cane Green leaf c a n e — t o p Green leaf c a n e — b o t t o m Old cane Roots

.227 .064 .046 .061 .056 .049 .053 .064 .064 .053 .081 .079 .086 .114 .008 .031 .032 .075 .037 .028 .024 .024 .071

.244 .043 .046 .056 .056 .049 .046 .086 .056 .056 .094 .096 .094 .102 .040 .037 .040 .064 .031 • 033 .024 .031 .079

.234 .046 .049 .062 .071 .053 .075 .086 .058 .064 . 106 . 122 .090 .118 .033 .040 .031 .112 .053 .032 .035 .024 .086

.277 .075 .078 .080 .132 .086 .090 .109 .140 .106 .098 .208 .174 .163 .082 .082 .168 .330 .090 .046 .037 .049 .082

.342 . 122 .144 .114 .116 .168 . 129 .129 .272 .239 .242 .520 • 352 .321 .243 .348 .461 .690 .165 .118 .086 .106 .296

Grams S per plant

.0514

.0773

-1003

.1739

.4283

DISTRIBUTION OF S IN A SUGARCANE PLANT A sand culture study was undertaken to ascertain the distribution of S in all the various organs and tissues of 'H53-263'. The plants were grown in partially washed silica sand in a relatively low glasshouse, fully exposed to the outside air often contaminated with S0 2 from volcanic mist. Sometimes the S0 2 is so strong that fields of cane 40 to SO miles from the volcano area will be bleached from a deep green to straw color in a matter of a week or so. While the S cultures were grown more than 200 miles from the volcano area, if the wind direction is favorable a very strong sulfurous haze develops. Ten cultures were set up in quadruplicate, ranging in added nutrient sulfate from zero to 6.148 grams elemental S. The data for five of these cultures are in Table 10-1. The complete culture received a full complement of S, while the others received the indicated

fractional amounts. In the actual study, there were five other cultures as well—Xz«, Yn, lA, and lA of the complete, and two times the complete. The data for these are not shown for space reasons. The response to the increasing levels of added S is general. As the tissues age, S builds up, pointing to at least a partial immobility of the water soluble sulfate once it is incorporated into the tissues. The distribution pattern of the S in the leaves from bottom to top follows that of K, probably pointing to its existence as K 2 S0 4 . The high levels of S in the cane tissues also indicate an association with K as well as Na, both of which, when in excess, accumulate in cane tissue. If the SO«" is in solution as K and Na salts, its immobility is difficult to understand. SELECTION OF A S INDEX TISSUE Correlations between the S content of the several "work" tissues and that of each of the several possible index tissues were determined from data obtained

370 TABLE 10-2.

CHAPTER 10 CORRELATIONS BETWEEN S CONTENT OF CERTAIN "WORK" TISSUES AND POSSIBLE INDEX TISSUES

Possible index tissue "Work" tissue

Young sheaths

Green cane top All blades Young cane stem Old cane Dead tissues Roots Spindle cluster

.9459** .8336** .8768** .1238 .4256 .2619 .8356**

Er 2

3.3217

Elongating cane .9303** .7780** .8467** .1117 .3201 .3900 .8922**

3.2507

Young blades .8982** .9366 .8275** .0839 .5576* .0875 .9021** 3.5081

Heristem

Old sheaths

Dead blades

.8271** .8005** .7668** . 1245 .4199 .5136* .7739**

.9312** .8364** .8960** .3027 .5074* .2455 .8255**

•5435* .6404** .6025* .5115* .9830** .1097 .3217

2.9674

3.4603

in sand culture (Table 10-2). It is evident that for S, the young and old sheaths, the elongating cane, and the young blades are about equal in their correlations with major work tissues, and any one could be used as an index to S fertilization. It is curious that none of the index tissues correlate well with the S in the old cane, dead leaves, or roots, probably a result of the accumulation of excessive supplies of S in those parts at the higher treatment levels. Another approach to this index selection involves the correlation of the S content of the various possible tissues and the S treatments imposed (Table 10-3). Any of the plant parts indicated would be completely satisfactory. For general field sampling, the young sheaths, elongating cane, or young blades—middle, in addition, are partly covered and, hence, are cleaner than the blades. The young elongating cane is completely enclosed. The old and very old plant parts are also very reliable, but they are not always present. The relationships between S treatment and the nutrient contents are shown in Table 10-4. The nature of each regression and its significance are shown in Table 10-5. The analyses shown do not include the S = 2 culture because growth there was stunted, and, hence, the analytical results were not meaningful. Sulfur levels in the cultures strongly affected the S levels of the sheaths and the dry-matter yield of the cane plants. The leaf N correlates, of course, with the off-color caused by a S deficiency. The fact that such

2.4120

off-color cannot be corrected by N fertilization suggests a role of S in N metabolism as related to chlorophyll formation. Sulfur affected Mn negatively and very strongly. The same is true of the cane P, although it did not affect the sheath P. Both Mg and K were negatively affected. The K level was strongly affected, but Mg was not. Other nutrient elements listed in Table 10-4 were not significantly affected. Zinc and Ca were both affected positively but not very strongly. RELATION BETWEEN S LEVELS AND GROWTH Another sand culture series provided the yield data in Table 10-6. Culture nos. 8 and 9 provided the heaviest growth, but culture no. 10 showed a sharp drop. The S contents of the young sheaths for culture nos. 8 and 9 were 0.126 and 0.202 percent, respectively. Expressing these on a sugar-free dry-weight basis, the S index range is 0.138 to 0.220 for an average value of 0.179, although these two data are not very reliable. A ratoon crop was harvested in 1973 after a plant crop. The stools were removed and washed relatively free of sand and then transferred to new sand. Not all these cultures were harvested, but those that were gave the yields shown in Table 10-7. Culture no. 1 received no S except that resulting from contamination, and culture no. 8 received the full complement

SULFUR TABLE 10-3.

CORRELATION DATA BETWEEN S CONTENT OF CERTAIN TISSUES AND S TREATMENTS IN SAND CULTURE

Plant part

r

R2

F va 1 ue

Young sheaths Old sheaths Elongating cane Young blades—middle Old blades—middle Very old blades—middle Dead blades—middle

+.8635** +.7597** +.8333** +.8443** +.8922** +.8696** +.8571**

+.9334 +.9083 +.9386 +.9318 +.9271 +.9448 +.9737

42.0248** 29.7080** 45.8838** 40.9754** 38.1692** 51.3281** 111.1987**

TABLE 10-4.

INTERACTION BETWEEN S TREATMENT AND EACH OF THE OTHER NUTRIENT INDEXES AND TOTAL DRY WEIGHT (see Table 10-5 for statistics)

S treatment Plant part and nutrient index Sheaths—SOj,-S (%) B l a d e s — N {X) Old c a n e — C a n e P (%) Young s h e a t h s — M n (ppm) Young s h e a t h s — M g (%) Young sheaths — K {%) Young s h e a t h s — F e (ppm) Young s h e a t h s — B (ppm) Young s h e a t h s — Z n (ppm) Young s h e a t h s — C u (ppm) Young s h e a t h s — P (%) Young s h e a t h s — C a (%) Dry weight of plant

TABLE 10-5.

0

1/128

1/64

1/32

1/16

1/8

1/4

1/2

.008 .92 .22 56 .099 2.89 35 5.6 18 14 .23 .234

.021 .98 .20 42 .061 .280 44 5.2 14 10 .17 .241

.040 .90 .18 39 .051 2.52 40 2.7 15 8 .18 .206

.031 1.00 .18 36 .059 2.45 42 5.6 18 8 .19 .254

.033 1.14 .16 31 .058 2.22 32 5.0 17 8 .18 .289

.041 1.22 .16 23 .048 2.09 41 3.1 21 9 .17 .282

.082 1.37 .13 24 .059 2.30 31 3.3 28 11 .20 .318

.126 1.59 .12 17 .048 2.14 43 4.2 29 8 .16 .326

.243 1.27 .07 23 .056 2.02 33 4.8 21 7 .14 .294

ill

150

169

170

200

215

221

251

243

INTERACTIONS SHOWN IN TABLE 10-4 EXPRESSED IN CORRELATION DATA

Yield (dry matter per plant) Sulfate sulfur (%) Leaf nitrogen (%) Manganese (ppm) Old cane phosphorus (%) Potassium (%) Magnesium (%) Zinc (ppm) Calcium (3>)

+.9746** +.8635** +.8662** -.9348** -.9629** -.9244** -.6108 n.s. +.7404* +.8446**

.9690 .9334 • 7507 .9490 .9540 .9216 .6650 .5516 .7166

93.77** 42.02** 9.03* 55.82** 62.28*** 35-27** 5.96* 3.69 7.59*

1

372

CHAPTER

TABLE 10-6.

Culture no. 1 2 3 4 5 6 7 8 9 10

GROWTH (dry weight per plant), S CONTENT PER PLANT, AND S CONTENT OF YOUNG SHEATHS AS AFFECTED BY S TREATMENT

Dry wt. per plant (g, avg. of 8) 111 150 169 170 200 215 221 251 243 122

S content per plant (mg)

S content of young sheaths 1% dry matter)

51 60 77 75 100 117 185 331 428 481

.008 .021 .040 .031 .033 .041 .082 .126 .202 .585

10

SYMPTOMS OF S DEFICIENCY AND EXCESS S-deficient plants take on an off-color appearance; that is, the young leaves at first appear chlorotic, which may be relatively slight but as it intensifies a yellow color becomes intense and when viewed in a general way is very much like the pictures (Figs. 10-1 and 10-2, both in color section). The old leaves usually are greener than the young, reflecting the lack of mobility of S in the plant, and the top third is usually more chlorotic than the bottom two-thirds. Figure 10-2 shows three very deficient cane tops with a normal leaf insert for contrast. Often a suggestion of redness over the chlorosis appears.

The plants reported on in Table 10-1 were observed closely for symptom development. When the young plants were at the six- to seven-leaf stage, the zero Dry wt. per cultures showed a marked yellowing of the young culture blades and the older leaves were somewhat greener. Culture no. S index (9) There was a slight tendency for the distal thirds of the 1 90 .033 leaves to be less green than the lower portions. The 2 1163 .063 .044 3 1495 yellowing was somewhat like that for Fe but was not 5 1685 .139 due to that, since the plants of another parallel series 8 1800 .211 treated exactly like the S series, except for S, were a Cultures no. 1 were very stunted and had no mature cane. rich dark green. The lighter colored leaves showed some sunburning damage. When the plants were of a complete nutrient solution—5.125 grams S as somewhat older, the leaves were photographed (Fig. sulfate. Assuming that culture no. 8 had produced 10-3, in color section). The first leaf from the left maximum growth, the young sheath S index of 0.211, shows the left side dark green and the right side expressed on a sugar-free dry-weight basis, verifies striped. The second leaf has normal color on both sides of the midrib, but a light green stripe on each the levels shown in previous tables. Leaf counts were made weekly from February 1 edge. Leaf number 3 is striped throughout. Leaf until May 9, 1973. The zero treatment, which pro- number 4 is a normal check taken from the complete duced only 5 percent as much dry matter (pee Table nutrient culture. Leaf number 5 shows the left 10-7) as the complete nutrient control, produced 18.3 margin chlorotic, left center normal green, and the leaves, whereas the complete nutrient control pro- right half streaked. Leaf number 6 shows a dark duced 18.6 leaves. The growth data shown in Table green stripe left of center and all the rest either evenly 10-6 were taken from plants in which the zero-S treat- chlorotic or streaked. Leaf number 7 is another norment plants produced 18.0 leaves and the complete mal leaf taken from the complete nutrient culture. culture produced 17.5 leaves, and yet the zero culture Leaf number 8 shows streaking on the right side with produced only about 45 percent as much dry matter. its left side and right edge being dark green. Thus, S, as is true of several other nutrients, seems to It is evident that these symptoms, while produced have little or no effect on the rate of leaf production. by a complete lack or shortage of S, might easily be TABLE 10-7.

DRY WEIGHTS (g) OF CERTAIN CULTURES AND THE S INDEX (ratoon crop), AS AFFECTED BY S TREATMENT

a

a

SULFUR

373

mistaken for mild symptoms of several other ele- fact that fertilizers there over the years have been the ments. A sheath analysis is needed to verify the cause very pure anhydrous ammonia, muriate of potash, of the chlorosis. Further, from the growth data pre- and some ammonium phosphate. Sulfur-index readsented, one can conclude that even when chlorosis is ings there are 0.113, 0.116, 0.113, 0.156, 0.060, and not sufficiently evident to identify the cause, there is 0.080. An observation made by several people at still a loss of dry-matter production if the S-index Naalehu was that in one field observation test, the level is not at or somewhat above normal. blocks that received S had little or no tasseling, while It is not uncommon to find cane fields in Hawaii the check blocks and the field had relatively many showing an off-color that suggests a N deficiency, tassels. At Wailuku where the S levels have been very and yet N fertilizer will not remedy the situation. A low, blossoming in the past has been extremely sheath analysis invariably will then show a S index heavy. considerably below 0.200 percent. At Naalehu, for There are several ways in which S deficiencies can example, readings in such off-color areas will be be corrected. If the soils are neutral in pH, sulfate of 0.073 , 0.097, 0.094, 0.073 , 0.081, and 0.098. Yet ammonia and sulfate of potash may be used until the areas only a mile or two away will show dark green S readings get above the required level. If the soils are fields with S readings such as 0.264, 0.304, 0.298, acid and require phosphate as well as sulfur, single 0.243, 0.218, 0.286, 0.399, and 0.400. Reasons for superphosphate, which contains gypsum in addition such variations would include the composition of the to Ca phosphate, is a good device. Gypsum can be lava flows from which the particular soil was derived. used alone if phosphate fertilizer is not required. On the northeast shore of the Island of Hawaii are Flowers of S also may be used, but to become availplantations that often experience smogs originating able as a plant nutrient, it needs to be worked into the from an active volcano, and at these places the S- soil. Often pure S is the cheapest form since freight index readings can be 0.247, 0.246, 0.289, 0.301, charges per unit of S are lowest for it. If a cane plant 0.354, and 0.450. growing on a particular soil is low in Mg as well as S, On the Island of Maui, the plantation at Wailuku commercial epsom salts or Sul-po-mag may be used. has very low S-index readings, due, in part, to the

CHAPTER 11

Calcium (Ca)

IMPORTANCE OF Ca TO CROPS According to Miller (1938), Bamford (1931) credited an article published in Germany by Salm-Horstmar as the first reference demonstrating the essentiality of Ca to plant growth. The precise importance of Ca and its compounds, as pointed out by Jones and Lunt (1967), is related to roles within the plant, which include membrane integrity and the maintenance of the protoplasmic structure of meristems, ovules, and mitochondria. As Ca pectate, it is a part of cell walls, and some claim it to be cementing material holding cells together. It is also involved in certain enzyme activities. It serves as a ready means of eliminating excesses of organic acids through precipitation. Probably its greatest impact on crop production, however, relates to its influence on the composition of the soil solution. Where Ca is very deficient, agricultural soils become progressively more extreme in pH, resulting in high fixation of P and excessive accumulations of such potentially toxic solutes as Al, Fe++, Mn, and Ni. Calcium is also important in counteracting Mg toxicity. In alkaline and saline soils, gypsum (CaS0 4 ) is effective in counteracting Na toxicity. SELECTION OF A Ca INDEX TISSUE In an experiment at Waipio, Hawaii, in 1939-1940, Ca data were found to be at or slightly above the

critical level of 0.200 (Table 11-1). In contrast is a similar set of data for an unirrigated crop at Kailua in the uplands. This particular crop was, by standards later established, definitely deficient in Ca (Table 11-2).

As with the other nutrients, each tissue has its own particular range of Ca. Calcium levels for each tissue were arrived at in the 1939-1940 study by averaging 17 separate collections (Table 11-3). From these data, it seems fairly clear that Ca in the blades is rather firmly located and continues to accumulate as the leaf ages; dead blades are generally much higher in their Ca levels than the old living blades, suggesting very little or no recycling of the element within these organs. The relationships shown for the sheath tissues as well as the stem tissues, however, suggest that part of the Ca in them is mobile, since the Ca content of the early cane samples is higher than that of the later samples. In Table 11-4 are given the averages for the various general tissue organs as appear in Table 11-3, but in this comparison all four plant crops are reported separately, as well as their corresponding ratoons (indicated by R in the headings). Here, the elongating cane was combined with the meristematic material, and, hence, these two designations are called "young stems." No Ca was applied to these crops. Plot A may be compared with the Waipio data for Plot B in Table 11-1 and 11-3 for

375

CALCIUM TABLE 11-1.

1

CALCIUM CONTENT OF SUGARCANE PARTS (percentage of dry weight) — 'H31-1389 , WAIPIO PLOT B

Year: Plant part Meri stem Spindle cluster Young blades Old blades Young sheaths Old sheaths Elongating cane Green leaf cane Top internodes 16th 3 internodes 15th 3 internodes 14th 3 internodes 13th 3 internodes 12th 3 internodes 11th 3 internodes 10th 3 internodes 9th 3 internodes 8th 3 internodes 7th 3 internodes 6th 3 internodes 5th 3 internodes 4th 3 internodes 3rd 3 internodes 2nd 3 internodes 1st 3 internodes Weighted average: a

1939

Date: 2/13 Age (mos.): 3-5 .41 .21 .36 .56 .22 .29 .22 . 10

whole plant

.33

4/20 5.8 .37 .17 .22 .23 .17 .18 .23 .050 .070

-16

6/26 7.9 .42 .16 .16 .18 .17 .16 .25 .060 .035

1940

9/1 10.1 .42 .17 .24 .20 .18 • 17 .24 .090 .042

10/27 12.0 .42 .18 .30 .44 .18 .19 .22 .086 .058

12/26 13-9 .40 .14 .22 .26 .14 .13 .23 .067 .053

3/9 16.3

5/17 18.6

7/26 21.0

.35 .16 .18 .16 .12 .08 .22 .066 .056

.31 .15 -19 .27 .17 .12 .22 .078 .071 .055 .058 .060 .054 .070 .066 .070 .062 .049 .058 .057 .055 .052 .052

.18 .15 .22 .27 .08 .08 .14 .067 .047 .056 .074 .091 .097 .089 .077 .098 .108 .097 .081 .064 .067 .063 .058 .053 .048

.07

.08

.040 .042

.037 .037 .033 .032 .034

.052 .046 .041 .032 .033 .025 .030

.057 .046 .039 .051 .041 .030 .031

.067 .061 .058 .057 .052 .048 .042 .040 .039 .040

.10

.09

.10

.07

.06

A blank space means the indicated plant part was not present.

the land involved was the very same. It is striking that the mature cane in the one case contained 0.055 percent Ca and in the other 0.054. Differences in the other tissue organs do occur, but by and large the similarities are greater. It should be remembered that a new variety was involved, growing over a 5-year period following the 5-year period of the first set. The other comparison—that is, between plant and corresponding ratoon—is also very good. It should be easy indeed to use plant composition to ascertain with precision the availability of Ca to the crop. To accomplish this, it would simplify the procedures were it possible to use a particular tissue organ as the Ca index tissue. In Table 11-5 are listed the various correlations between each possible index tissue and the various work organs. With data such as those reported in Tables 11-1 and 11-2 and with knowledge of the weights of the various plant parts at each collection,

it is possible to obtain weighted Ca averages for the whole plant, the greentop as well as for the mature cane, or any other combinations of plant parts. All of the correlations shown are highly significant, statistically, but for the most part their coefficients of determination are low. In Table 11-6 is a similar analysis but for the 'H32-8560' plants grown at Waipio. Here the spindle cluster is also included as possible index tissue. In general, the correlations shown in Table 11-5 are much better than those in Table 11-6, and the reason is that there was a broader range of levels than for the Waipio 'H32-8560'. The meristem as a work tissue is most important, but for Ca as an index tissue it is only fair. The spindle cluster, although it is attached to the stem tip is very poor as a Ca index tissue for any of the plant parts, including the meristem. Of the remaining tissue organs, the young sheaths are superior to all in their sensitivity to the meristem Ca and about

CHAPTER

376

TABLE 11-2.

CALCIUM CONTENT OF SUGARCANE PARTS (percentage of dry weight)--'H31-1389', KAILUA PLOT B

Year:

Plant part Meristematic tissue Spindle cluster Young blades Old blades Young sheaths Old sheaths Elongating cane Green leaf cane Top internodes 15th 3 internodes 14th 3 internodes 13th 3 internodes 12th 3 internodes 11th 3 internodes 10th 3 internodes 9th 3 internodes 8th 3 internodes 7th 3 internodes 6th 3 internodes 5th 3 internodes 4th 3 internodes 3rd 3 internodes 2nd 3 internodes 1st 3 internodes

Weighted average: a

1939

Date: 2/15 Age (mos.): 3.6 30 .18 .26 .41 .14 . 11 .30 . 100

whole plant

.25

"1/21 5.8 -31 .13 .19 .22 .18 .17 .20 .120

6/27 8.0 .25 .11 .18 .23 .11 .12 .17 .050 .033

1940

9/2 10.2 .20 .07 .17 .16 .09 . 10 .13 .054 .028

.054

.036 .043

.033 .031 .042 .040

.17

.10

.07

10/29 12.0 -29 .13 .25 .29 .13 .10 .23 .037 • 031

Meristematic tissue Old blades Young blades Elongating cane Young sheaths Spindle cluster Old sheaths Green leaf cane Mature cane

Waipio (W)

Ka ÎIua (K)

.383 .279 .238 .230 .166 .164 .154 .077 .054

.264 .241 .199 .176 .128 • 125 .102 .061 .036

5/18 18.7 .34 .14 .22 .26 . 12 . 11 .17 .053 .030

.11 . 12 .18 .24 .10 .09 .08 .041 .042 .034 .036 .031 .035 .042 .046 .054 .038 .037 .038 .036 .039 .035 .034 .043

.06

.020 .024 .028 .028 .024 .030 .029

.032 .023 .028 .026 .031 .034 .027 .030

.08

.06

.05

.06

100 69 86 84 77 77 76 66 79 68

7/27 21.0

.23 .11 .17 .23 .11 .05 .10 .060 .031

.032 .025 .036 .041 .054 .071

COMPARISON OF CHARACTERISTIC Ca LEVELS (percentage of dry weight) BY TISSUE TYPE FOR 'H31-1389' GROWN AT WAIPIO AND AT KAILUA

Plant part

.25 .11 .19 .23 .13 .06 .14 .043 .022

3/9 16.3

.040 .042 .036 .035 .036 .039 .034 .036 .042 .055 .049

A blank space means the indicated plant part was not present.

TABLE 11-3.

12/27 14.0

11

CALCIUM TABLE 11-4.

377 CALCIUM LEVEL (percentage of dry weight) OF SEVERAL PLANT PARTS FOR FOUR PLANT CROPS AND FOUR RATOON C R O P S — 1 H 3 2 - 8 5 6 0 ' , WAIPIO

Plot Plant part Old blades Young stems Young blades Old sheaths Young sheaths Spindle cluster Green leaf cane Hature cane a

a

A

RA

.405 .346 .269 .190 .186 .144 .124 .055

.396 .373 .250 .186 .185 .142 .117 .049

B

RB

C

RC

D

RD

.366 .318 .241 .166 .165 .132 .111 .045

.353 .355 .255 .175 .174 .139 .127 .051

.452 .378 .283 .195 .195 .146 .131 .052

.401 .369 .249 .189 .182 .143 .125 .052

.428 .389 .275 .186 .189 .142 .131 .055

.388 .363 .250 .196 .176 .143 .117 .049

R indicates a ratoon crop.

TABLE 11-5.

CORRELATIONS 3 BETWEEN THE Ca LEVELS OF CERTAIN POSSIBLE INDEX TISSUES AND THOSE OF THE "WORK" T I S S U E S — 1 H 3 1 -1389 1

"Work" tissue Possible index tissue

Meristem

Merlstem Young blades Old blades Young sheaths Old sheaths

1.00 .452 .494 .795 .612

Whole plant

Green top

Mature cane

v 2

.458 .614 .739 .555 .657

.632 .785 .867 .816 .734

.450 .388 .508 .394 .516

1.8117 1.3481 1.7999 1.7611 1.6112

a All the correlations are statistical1 ly significant at or above the 1 percent level. b n « 238.

TABLE 11-6.

CORRELATIONS BETWEEN THE Ca LEVELS OF CERTAIN POSSIBLE INDEX TISSUES AND THOSE OF THE "WORK" TlSSUES—'H32-8560' a

"Work" tissue Possible index tissue

Meristem

Whole plant

Meristem Spindle cluster Young blades Old blades Young sheaths Old sheaths

1.000** .213* .257** .151 .537** .331**

-.166 .234** .224** .430** .184* .243**

a

n = 142.

Green top

Mature cane

.548** .556** . 765** .707** .734** .752**

-.119 .202* .195* .379** .122 .345**

CHAPTER 11

378

TABLE 11-7. CORRELATIONS BETWEEN THE Ca LEVELS OF CERTAIN POSSIBLE INDEX TIS1SUES AN D THOSE OF THE "WORK" TISSUES OF PLANTS GROWN IN A SAND CULTURE DEFICIENCY SERIES-- H53-26313 Possible index tissue "Work" tissue

Green leaf cane—top Meri stem All green blades Green leaf cane--bottom Old cane Elongating cane Roots Dead leaves Spindle cluster Ir

Young sheaths

Meristem

.8932** .9539** 1.0000** .8723** .8626** .8593** .9206** .9651** .7592** .8391** .8661** .8224** .1345 n.s. .4284 n.s. .6942** .7701** .8228** .8143** 5.7760

6.2776

Young blades—middle

.9457** .9041** .9133** .9298** .8550** .4714* .3869 n.s. .8281** .8115** 5.8576

Elongating cane

.8387** .8663** .8510** .8659** •9527** 1.0000** .4265 n.s. .7704** .6620** 6.0492

Old sheaths

Dead blades—middle

.8639** .6957** .7387** .8295** .5711* .6181* .0001 n.s. .6029** .8418**

.8471** .8209** .8801** .7841** .8622** .7599** .5694* .9594** .6656**

4.2416

5.7894

18.

equal to the others in relation to the greentop. They are poor in their correlations with the Ca of the mature cane, and, because of this, they are poor also for the whole plant. Actually, no one of the possible index tissues is of much value for estimating the Ca level of the mature cane. If critical work is desired in this connection, undoubtedly the use of a particular internode of the stem itself would be the solution. One reason for the generally low r's is the narrow range of Ca levels. To illustrate this point, analytical data from a Ca-deflciency series in sand culture were assembled for a Ca index selection (Table 11-7). In this table, the r's are very high because of the broad ranges of Ca treatment levels. As so often happens, if the data cover a very wide range of specific treatments, almost any tissue could be used as the index. In this case, the meristem as well as the elongating cane give the best summations, but due in part, at least, to the perfect r given each one when correlated with itself. None of the possible indexes correlate significantly with the roots. Although the r's shown in Table 11-7 are not from the same series, the actual Ca levels of the various tissues from another sand culture series, as well as the r, R1, and F values between each tissue Ca and treatment, are shown in Table 11-8, with culture nos. 3, 5, and 7 omitted. Also shown at the bottom of the table are the dry weight/plant yields of the cane tops with

culture no. 8 having the top yield. By far the best indexes in this series are the dead tissues—dead sheaths and dead blades. Although the young sheaths are satisfactory, they are exceeded by the old sheaths, old blades—top, and young cane. It is rather striking that the young leaves give very weak correlations with treatment. The very low level (0.02 percent) for the young sheaths probably represents the ultimate critical level below which the cell cannot survive. Where Ca is supplied as neutral salts, it has a mild effect on the absorption of other elements. As will be seen later, when Ca is supplied as the silicate or carbonate, Mn, Zn, Fe, Al, and so on, uptakes are markedly reduced. In Table 11-8 Zn, K, Mg, and P are all mildly affected by the neutral salts, and all these interactions are negative. Also of considerable importance, the data in Table 11-8 show that where minor elements are provided in normal amounts, the Ca level of the young sheaths associated with best growth (culture no. 8) is 0.11 percent of the dry weight. On the Ca-index basis (percentage of sugar-free dry weight) the index becomes 0.12, a value that would be much too low on very acid soils where freckling is common but quite adequate on soils with a more nearly neutral pH, as has been noted in many fields on Low Humic Latosols. For later general work, the young sheaths are used

379

CALCIUM TABLE 11-8.

CALCIUM LEVELS (percentage of dry weight) OF THE VARIOUS PLANT PARTS AS CORRELATED WITH SANO-CULTURE TREATMENT LEVELS, SOME INTERACTIONS, AND STATISTICAL DATA

Ca treatment level Plant part Meristem Splngle cluster Young b l a d e s — b o t t o m Young b l a d e s — m i d d l e Young blades--top Old b l a d e s — b o t t o m Old b l a d e s — m i d d l e Old b l a d e s — t o p Dead b l a d e s — b o t t o m Dead b l a d e s — m i d d l e Dead blades--top Young sheaths Old sheaths Dead sheaths Elongating cane Green leaf c a n e — t o p Old cane K — y o u n g sheaths (t O.W.) P — y o u n g sheaths (Z D.W.) P — o l d cane (% D.W.) M g — y o u n g sheaths (% D.W.) Z n — y o u n g sheaths (ppm) Dry weight/plant top (g) a Treatment levels: 12 > 15.035 g.

0 .05 .03 .03 .05 .14 -

.09 -

.02 -

.02 -

6.16 .781 -

.022 123 4

2 .05 .11 .09 .16 .31 • 17 .30 .41 23 .38 .62 .05 .06 .14 .07 .03 .02 2.83 .171 .153 .12 44 131

If .06 .08 .07 .13 .22 .10 .18 .40 .34 .52 .76 .05 .07 .17 .05 .08 .04 1.85 .119 .081 .06 22 289

6 .11 .08 .08 .15 .23 .14 .22 .41 .43 .62 .92 .06 .11 .24 .10 .13 .06 1.65 .115 .088 .05 20 2^9

Statistics 10

12

r

R2

.18 . 12 • 13 .20 32 .21 .37 .63 .68 .99 1.20 .11 .14 .39 .21 .18 .09 1.64 .128 .103 .05 25

.29 .15 .18 .28 .51 .32 .55 .95 • 93 1.26 1.75 .15 .17 .49 .27

.853** .665* .675* .538 .640 .820** .854** . 892** .977** .970** .953** .859** .963** .990** .789** .966** .858** -.680 -.565 -.543 -.678 -.625

• 731 .456 .487 .355 .569 .770 .757 .844 • 989 .972 .930 .791 .929 .994 .762 .937 .738 .848 .711 .680 .828 .838

.800**

.906

8 .29 .11 .17 .11 .27 .18 .29 .57 .54 • 73 1.02 .11 .11 .33 .17 .15 .08 1.70 .128 .088 .06 22 295

257

-

.08 1.99 .165 .100 .07 34 272

10.87** 3.35 3.80 2.20 5.28* 10.07** 10.87** 16.21** 323.30** 121.23** 46.59** 15.17** 39.18** 603.09** 11.21** 52.19** 9.85** 22.36** 9.86** 7.43* 19.26** 20.62** 38.38**

2 - 1.367 g added Ca/culture; 4 - 4.101 g; 6 - 6.835 g; 8 - 9.567 g; 10 = 12.301 g;

as the Ca index tissue. Its better correlations with the representing a very heavy crop well provided with meristem and its satisfactory correlations with the natural Ca, and the latter suffering a probable defigreentop are part of the reason for this selection. ciency, although still representing a heavy crop of Other reasons include the exact precision with which cane for the area. Figures 11-1 and 11-2 are patterned they can be removed from the plant, and, because after figures used earlier to determine the total they are partially enclosed by other sheaths and are in amount of N absorbed by the same two crops (see a vertical position on the plant, they are, except in Chapter 7). very rare situations, quite clean and free of insects and fungi and for the most part are always present. Cain Cane Tops To further improve its predictive value, the Ca index The estimates of accumulated growth were made usis defined as the Ca level of the young sheaths (from ing growth measurements and leaf counts made at leaves +3, +4, +5, and +6 reported as percentage of approximately monthly periods. The vertical elongathe sugar-free dry weight. tion and the circumferences of the internodes were used to estimate the volume of stem produced month Ca ACCUMULATION BY GROWING by month. At harvest, the yield of cane per acre was SUGARCANE PLANTS obtained, and this then was prorated back over the Of interest are not only the total amounts of Ca re- growing time. To estimate the amounts of Ca in the quired by a cane crop but also the accumulation of cane, the whole above-ground part of the plant and Ca by the crop as it grows. Chosen to illustrate these the accumulating trash were used. Of considerable things are Plots C at Waipio and Kailua—the former importance here is knowledge of the amount of Ca

CHAPTER 11

380

oU J 12.04** q q

Pol % cane Plant (20) Plant (131) F i r s t ratoon (20) F i r s t ratoon ( I 3 D

12.75 9.62 12.53 11.20

12.43 10.37 12.63 10.90

12.37 9.95 11.76 10.47

11.43 8.55 11.82 10.32

(li) (li) (li)

12.12 9.60 10.45 9.67

(q) (q)

8.27j°7.42 14.56*-

Tons pol/acre Plant Plant Fi r s t Fi r s t

(20) (131) ratoon (20) ratoon ( 1 3 0

10.47 10.00 9.10 9.57

12.29 11.66 9.68 10.12

12.67 11.20 9.87 9.08

I4.91f0 5-79 (P Co,¡) 6 . 3 0 * H n.s.

392 TABLE 11-19.

CHAPTER

I I

CALCIUM INDEXES, SOIL Ca, AND Mn INDEXES OF THE FIELD CROPS PRECEDING INSTALLATION OF THE FIVE LOW-ELEVATION EXPERIMENTS

Ca index reading Field

1

H i l o 54 Onomea 4 Pepeekeo 2 Hakalau 20 Hakalau 131

.182 .187 .190 .135 .235

2 .193 .130 . 142 .180 .265

3 • 193 .098 .150 .142 .185

Mn index r e a d i n g S o i l Ca (lb./acre-foot)

1

2

3

810 220 1,030 105 320

76 308 63 96 286

80 265 63 85 212

69 248 76 127 278

these experiments were started, the soil Ca level considered adequate was 100 ppm, or about ISO lb/acrefoot for this Hydrol Humic Latosol. Quite obviously, there isn't much relationship, for the Hilo plant crop gave a significant cane increase in the plant crop with 810 lb. Ca/acre-foot; the ratoon crop failed to show a response; there was no gain for sugar. The Onomea test in an area with 220 lb. Ca/acre-foot in the plant crop and 106 lb. in the ratoons gave a yield increase in both the plant and first ratoon crops but a weak sugar gain only for the plant crop. The Pepeekeo test with 1,030 lb. Ca/acre-foot gave no increase, either in plant or ratoon. The Hakalau test in Field 20 with 105 lb. soil Ca gave good responses in both cane and sugar, while Field 131 with 320 lb. soil Ca also showed a cane response in both the plant and first ratoon crops but a sugar response only in the plant crop. After these experiments were harvested, the soil Ca level required was raised by the soil analysts to 400 lb/acre-foot. Somewhat later it was raised again to 1,200! Later in this chapter it will be shown that this amount would cause losses of yield in some areas. The influence of the coral on cane quality and TPA is also shown in Table 11-18. In every case where there is a significant effect of coral on pol percent cane, it is negative—the largest drop being about 1.32 percentage points. This is related, in part at least, to a somewhat increased moisture level of the cane. In most of the cases where there was a significant drop in quality there was a cane yield increase, and so this effect of the coral was not reflected in the sugar yield. Even in the Pepeekeo 2 trial where there

was about an 8 percent drop in quality, the nonsignificant gain of 4.2 tons cane prevented a drop in the sugar yield. Thus, it can be said that, although coral stone worsens quality in this Hilo coast area, sugar yield drops have not been observed because even the highest amounts (11 tons/acre) tended to improve the cane yields. The Ca-index readings for the crops just prior to the start of the experiments are shown in Table 11-19 along with the soil Ca and Mn-index readings of the sheaths. Although the Mn readings had been taken on a routine basis as part of a Brewer plantation survey, their significance was not recognized until after the first round of these experiments was completed. It was then realized that Mn readings in excess of ISO ppm indicate toxicities involving not only the Mn of the tops but also the A1 and Mn of the roots. (Later this view was modified to include ferrous iron.) Using the Ca-index readings of the crops just before the experiments were started (and in view of the response in yield obtained in Experiment 97 at Pepeekeo where the coral stone increased yields considerably in excess of that expected just on the basis of Ca, the nutrient), the responses should now be examined on the basis of the effects of the ground coral on the various plant indexes. In Table 11-20, the Ca-index readings are shown for each plant crop and at least one ratoon. Usually in these experiments, the plant and first ratoon crops were harvested, and, of course, both of these were crop logged on a plot-by-plot basis. Then the second ratoon crop, although usually not harvested, was

393

CALCIUM TABLE 1 1 - 2 0 .

CALCIUM INDEX READINGS FOR TWO OR T H R E E CROPS WITH CORAL STONE A P P L I C A T I O N S IN EACH O F T H E F I V E L O W - E L E V A T I O N E X P E R I M E N T S (568 l b . CaO from p h o s p h a t e o r gypsum a l s o a p p l i e d in a l l p l o t s )

M e a n a crop c y c l e H I l o 54 Plant F i r s t ratoon Second r a t o o n Onomea 4 Plant F i r s t ratoon Second r a t o o n

Coral stone/acre 0

TABLE 1 1 - 2 1 .

Tons c o r a l Field

(tons)

2.0

5.5

11.0

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