Plant Responses and Control of Water Balance PDF
Preview Plant Responses and Control of Water Balance
CONTRIBUTORS TO THIS VOLUME J. GALE JOHNSON PARKER D. HILLEL ALEXANDRA POLJAKOFF-MAYBER MERRILL R. KAUFMANN E. RAWITZ T. T. KOZLOWSKI GLENN W. TODD AVINOAM LlVNE YOASH VAADIA AUBREY W. NAYLOR FRANK G. VIETS, JR. WATER DEFICITS AND PLANT GROWTH EDITE D B Y T.T . KOZLOWSK I DEPARTMENT OF FORESTRY THE UNIVERSITY OF WISCONSIN MADISON, WISCONSIN VOLUME III Plant Responses and Control of Water Balance 1972 ACADEMIC PRESS New York and London COPYRIGHT © 1972, BY ACADEMIC PRESS, INC. ALL RIGHTS RESERVED NO PART OF THIS BOOK MAY BE REPRODUCED IN ANY FORM, BY PHOTOSTAT, MICROFILM, RETRIEVAL SYSTEM, OR ANY OTHER MEANS, WITHOUT WRITTEN PERMISSION FROM THE PUBLISHERS. ACADEMIC PRESS, INC. Ill Fifth Avenue, New York, New York 10003 United Kingdom Edition published by ACADEMIC PRESS, INC. (LONDON) LTD. 24/28 Oval Road, London NW1 LIBRARY OF CONGRESS CATALOG CARD NUMBER: 68-14658 PRINTED IN THE UNITED STATES OF AMERICA LIST OF CONTRIBUTORS Numbers in parentheses indicate the pages on which the authors' contributions begin. J. GALE (277), Department of Botany, The Hebrew University of Jeru salem, Jerusalem, Israel D. HILLEL (65, 307), The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot, Israel MERRILL R. KAUFMANN (91), Department of Plant Sciences, University of California, Riverside, California Τ. T. KOZLOWSKI (1), Department of Forestry, The University of Wiscon sin, Madison, Wisconsin AVINOAM LIVNE (255), The Negev Institute for Arid Zone Research, Beersheva, Israel AUBREY W. NAYLOR (241), Department of Botany, Duke University, Durham, North Carolina JOHNSON PARKER (125), Northeastern Forest Experiment Station, Forest Service, U. S. Department of Agriculture, Hamden, Connecticut ALEXANDRA POLJAKOFF-MAYBER (277), Department of Botany, The Hebrew University of Jerusalem, Jerusalem, Israel E. RAWITZ (307), The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot, Israel GLENN W. TODD (177), Department of Botany and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma YOASH VAADIA (255), Agricultural Research Organization, Volcani Cen ter, Bet-Dagan, Israel FRANK G. VIETS, JR. (217), Soil and Water Conservation Research Divi sion, Agricultural Research Service, U. S. Department of Agriculture, Fort Collins, Colorado ix PREFACE The very enthusiastic reception given to the preceding two volumes of this treatise was indicative of a rapidly expanding interest in the im portance of water to plants. There clearly is mounting concern throughout the world with diminishing water supplies and the need for water con servation to overcome impending deficiencies of food and fiber at a time when population is increasing at an alarming rate. For such reasons addi tional research on plant-water relations is needed and is proliferating rapidly along a broad front. These considerations provided the impetus for bringing up-to-date a number of topics involving water deficits in plants which were not covered in adequate depth or omitted in the first two volumes. This volume includes comprehensive and well-documented chapters on the influence of water deficits on shrinkage of plant tissues, seed germina tion, reproductive growth, and such internal plant responses as proto plasmic resistance to desiccation, enzymatic activity, nitrogen metabolism, hormonal relations, and mineral nutrition. The final two chapters deal with alleviation and control of water deficits in plants. The terminology of this volume follows that developed and used in Volumes I and II. The contributors to this volume were chosen for their demonstrated competence and scholarly productivity in the subject areas discussed. I owe each of these eminent scientists a debt of gratitude for his scholarly contribution. T. T. KOZLOWSKI xi CONTENTS OF OTHER VOLUMES VOLUME I. DEVELOPMENT, CONTROL, AND MEASUREMENT 1. Introduction Τ. T. KOZLOWSKI 2. Water Structure and Water in the Plant Body A. S. CRAFTS 3. Terminology in Plant and Soil Water Relations S. A. TAYLOR 4. Evaporation of Water from Plants and Soil C. B. TANNER 5. Availability and Measurement of Soil Water W. R. GARDNER 6. Plant Factors Influencing the Water Status of Plant Tissues I. R. COWAN and F. L. MILTHORPE 7. Drought-Resistance Mechanisms JOHNSON PARKER 8. Determination of Water Deficits in Plant Tissues H. D. BARRS AUTHOR INDEX—SUBJECT INDEX VOLUME II. PLANT WATER CONSUMPTION AND RESPONSE 1. Water Consumption by Agricultural Plants Μ. E. JENSEN xiii xiv Contents of Other Volumes 2. Water Consumption by Forests A. J. RUTTER 3. Water Deficits and Physiological Processes A. S. CRAFTS 4. Water Deficits and Growth of Herbaceous Plants C. T. GATES 5. Water Deficits and Growth of Trees R. ZAHNER 6. Water Deficits in Vascular Disease P. W. TALBOYS AUTHOR INDEX—SUBJECT INDEX CHAPTE R 1 SHRINKING AND SWELLING OF PLANT TISSUES Τ. T. Kozlowski DEPARTMENT OF FORESTRY, THE UNIVERSITY OF WISCONSIN, MADISON, WISCONSIN I. Introduction 1 II. Vegetative Tissues 2 A. Leaves 2 B. Stems 7 C. Roots 14 III. Reproductive Tissues 17 IV. Measurement of Shrinkage and Swelling 27 V. Biological Implications of Shrinkage and Swelling of Plants . 30 A. Wilting 31 B. Stomatal Aperture 33 C. Flow of Oleoresins and Latex 42 D. Dispersal of Spores, Pollen, and Seeds 45 E. Root Functions 53 F. Errors in Growth Measurements 54 G. Cracking and Splitting of Plants 55 References 57 I. INTRODUCTION Variations in size of plants during their development are the result of changes in hydration and temperature as well as the progressive accretion of growth. The size changes caused by recurrent shrinking and swelling, which are superimposed on growth of tissues, sometimes are small but at other times may greatly exceed those resulting from continuous growth of tissues through cell division and enlargement. During the growing season the reversible changes in size of plant tissues that are accounted for by changing levels of hydration are much greater than those caused by direct thermal effects. The latter are discussed by Wiegand (1906), Marvin (1949), Small and Monk (1959), Winget and Kozlowski (1964), and ι 2 Τ. Τ. Kozlowski McCracken and Kozlowski (1965). These thermal effects are beyond the scope of this chapter and will not be discussed further. This chapter will consider characteristics, causes, measurement, and significance of shrinking and swelling of vegetative and reproductive tissues of plants as a result of changes in cell turgor. Shrinkage and swelling of plant tissues reflect changes in the energy status of the water as well as in cell turgor. The turgor changes are con trolled by relative rates of absorption of water and transpiration and by internal redistribution of water in plants. During a period of soil drying, cell turgor decreases and plant tissues may shrink more or less progres sively during each day if atmospheric conditions are conducive to high transpiration throughout the drought. The rate of shrinkage during a rain less period may be slowed by atmospheric conditions (e.g., cloudy weather or high relative humidity) which decrease transpiration. Small amounts of expansion during each night are superimposed on the trend of net shrink age of tissues during a drought. However, as plants become severely de hydrated they are less likely to regain turgidity during the night, often resulting in permanent wilting of leaves. Diurnal contraction and expansion of plant tissues are related to higher transpiration than absorption of water during the day, and the reverse at night. During the day absorption of water through the roots lags behind transpiration because of resistance to water movement through the plant. The internal water deficits in plants which develop and decrease turgor during the day usually are reduced or eliminated during the night, when both absorption of water and transpiration are low, but absorption is some what greater of the two (Kozlowski, 1968b; Kramer, 1969). II. VEGETATIVE TISSUES Both seasonal and diurnal shrinkage of leaves, stems, and roots have been well documented for many different species of herbaceous and woody plants. A few examples will be given. A. LEAVES Several investigators have shown that leaf thickness is related to inter nal water balance. For example, simultaneous measurements by Meidner (1952) of leaf water content and leaf thickness of detached leaves of Zizyphus mucronata, Heteromorpha involucrata, Gymnospora buxifolia, and Xymalos monospora showed that these were highly correlated, pro vided that for each species the changes in thickness did not exceed those measured in the field. A 1% change in leaf moisture content was cor- 1. Shrinking and Swelling of Plant Tissues 3 related with a 4% change in leaf thickness in Zizyphus, a 4.5% change in Heteromorpha, a 7.5% change in Gymnospora, and a 7% change in Xymalos. However, these correlations ceased when leaf water content changes exceeded 3.3% in Zizyphus, 1.8% in Heteromorpha, 1.2% in Gymnospora, and 1.0% in Xymalos. Gardner and Ehlig (1965) found that changes in leaf thickness of herbaceous plants were related to turgor pressure but the amount of leaf shrinkage varied among species. As leaves of cotton (Gossypium hirsutum) were relatively rigid and well supported by veins they exhibited only modest shrinkage and wilting symptoms. By comparison, leaves of pepper {Capsicum fruitescens) underwent considerable change in thickness during drying and showed extreme wilting symptoms as turgor pressure ap proached zero. Brun (1965) related changes in leaf thickness of banana (Musa acuminata) to transpiration and stomatal opening. When leaves were excised or the petioles frozen, stomatal opening and transpiration in creased and leaf thickness decreased sharply. These changes in leaf thick ness suggested rapid development of internal water deficits. Leaf thickness did not decrease appreciably when the air above a leaf was saturated or when a leaf was cut under water. Raschke (1970a) measured separately the amount of shrinkage of the epidermis and the entire leaf of Zea mays in response to internal water stress. The time course of shrinkage of the whole leaf and epidermis was similar but the relative amplitudes of changes in thickness were greater for the epidermis. In one experiment, for example, thickness of the epidermis was reduced by 32% during drying whereas that of the entire leaf decreased by 18%. Parker (1952) described a number of internal changes in needles of Pinus strobus and P. nigra var. austriaca during progressive drying. As internal water deficits developed, cells of the chlorenchyma, endodermis, and transfusion tissue decreased in size (Fig. 1). In P. nigra var. austriaca the adaxial needle surface, and in P. strobus all three surfaces, were bent inward. The shape of cells inside the hypodermis was altered in a way that varied with location of the cells. Some chlorenchyma cells collapsed in their longest direction; others stretched when attached to the hypodermis at the needle corners. In the latter case the transfusion cells contracted but the corners of the needle did not bend inward. Hence, cells attached be tween these tissues were stretched. Cells of the endodermis became flattened whereas transfusion tracheids and transfusion parenchyma cells collapsed or were distorted. Xylem and phloem cells were altered little, if at all, during progressive drying of needles. Chaney and Kozlowski (1969c) showed that leaf shrinkage and ex pansion in English Morello cherry {Prunus cerasus grafted on Prunus
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