OTHER TITLES IN THIS SERIES 1. Plant Modification for More Efficient Water Use by J.F. Stone (Editor) 1975 χ + 320 pp. 2. Tree Ecology and Preservation by A. Bernatzky 1978 viii + 358 pp. 3. Cycling of Mineral Nutrients in Agricultural Ecosystems by M.J. Frissel (Editor) 1978 viii + 356 pp. 4. Interactions Between Non-Pathogenic Soil Microorganisms and Plants by Y.R. Dommergues and S.V. Krupa (Editors) 1978 xii + 476 pp. 5. Ecology of Root Pathogens by S.V. Krupa and Y.R. Dommergues (Editors) 1979 χ + 282 pp. 6. Soil Disinfestation by D. Mulder (Editor) 1979 xiv + 368 pp. 7. Management of Semi-arid Ecosystems by B.H. Walker (Editor) 1979 χ + 398 pp. 8. Management and Analysis of Biological Populations by B.S.Goh 1980 χ + 288 pp. 9. Comparison of Forest Water and Energy Exchange Models by S. Halldin (Editor) 1979 xi + 258 pp. 10. Alternative Methods of Agriculture by R. Boeringa (Editor) 1980 vi + 200 pp. 11. Wetlands of Bottomland Hardwood Forest by J.R. Clark and J. Benforado (Editors) 1981 xviii + 402 pp. 12. Plant Production and Management under Drought Conditions by J.F. Stone and W.O. Willis (Editors) 1983 vii + 390 pp. 13. Evapotranspiration from Plant Communities by M.L. Sharma (Editor) 1984 vii + 344 pp. 14. Forest Amelioration by O. Riedl and D. Zachar 1984 viii + 624 pp. 15. Floodplain Forest Ecosystem by M. Penka, M. Vyskot, E. Klimo and F. Vasicek Part I. Before Water Management Measures 1985 xii + 468 pp. Part II. After Water Management Measures in preparation 16. The Origin and Domestication of Cultivated Plants by C. Barigozzi (Editor) 1986 vi + 218 pp. 17. Soil Microbial Associations by V. Vancura and F. Kunc (Editors) 1987 in preparation 18. Tree Crop Physiology by M.R. Sethuraj and A.S. Raghavendra (Editors) 1987 xii + 361 pp. DEVELOPMENTS IN AGRICULTURAL AND MANAGED - FOREST ECOLOGY 18 tree crop physiology Edited by M.R.SETHURAJ Rubber Research Institute of India, Kottayam 686 009, Kerala, India and A.S. RAGHAVENDRA School of Life Sciences, University of Hyderabad, Hyderabad 500 134, India ELSEVIER Amsterdam — Oxford — New York — Tokyo 1987 ELSEVIER SCIENCE PUBLISHERS B.V. Sara Burgerhartstraat 25 P.O. Box 211, 1000 AE Amsterdam, The Netherlands Distributors for the United States and Canada: ELSEVIER SCIENCE PUBLISHING COMPANY INC. 52, Vanderbilt Avenue New York, N.Y. 10017, U.S.A. ISBN 0-444-42841-0 (Vol. 18) ISBN 0-444-41515-7 (Series) © Elsevier Science Publishers B.V., 1987 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or other- wise, without the prior written permission of the publisher, Elsevier Science Publishers B.V./Science & Technology Division, P.O. Box 330, 1000 AH Amsterdam, The Netherlands. Special regulations for readers in the USA — This publication has been registered with the Copyright Clearance Center Inc. (CCC), Salem, Massachusetts. Information can be obtained from the CCC about conditons under which photocopies of parts of this publication may be made in the USA. All other copyright questions, including photocopying outside of the USA, should be referred to the publisher. Printed in The Netherlands ν PREFACE Tree crops pose methodological problems for the physiologists, mainly because of their large size, variable canopy architecture and the perennial nature. Measurements made on a single leaf or group of leaves, representing one or different strata are used to describe the physiology of the whole tree canopy. Often the estimates of tree biomass are only derived from the measurements of stem-girth and tree-height. The relevance of such data to the actual situation on tree is, of course, limited. Nevertheless, the practical problems involved in making realistic measurement of any physiological parameter at whole-tree level are to be admitted. Therefore, a logical compromise is sought between practical limitations and the required accuracy. Some of the tree crops are vegetatively propagated and the stock-scion interaction interferes with the desired homogeneity of plant material during experimental observations. Many tree crops are cross pollinated and the degree of genetic differences among the population introduces high variability in the research data. Even when genetically uniform materials are vegeta- tively propagated, the heterogeneity of soils, because of the large area required for experimentation, vitiates results in spite of the best statistical designs. The fluctuations in light climate and other micrometeorological parameters within a canopy make the attempts to measure photosynthesis at canopy level, quite laborious. The obstacles on the path of research in tree physiology created several g'aps in our knowledge. The substantial amount of loss in biomass due to respiration has not been accurately esti- mated in tropical tree crops. Similarly, trees could not easily be subjected to the classical growth analysis or assimilate partioning (including harvest index estimates) because of their forbidding volume, strong periodicity in growth and marked remoteness of sink from source (in terms of space VI as well as time). These methodological problems have been tackled to certain extent by individual scientists by adopting innovative modifications in the methodologies to suit the peculiar situations posed by the tree crops. Many mathematical principles have been tried and attempts for modelling, based on representative data, have met with some measure of success. The scientists who assembled at an international symposium "TREE- PHYSINDIA-82", held at Rubber Research Institute of India, Kottayam discussed the special problems encountered by tree physiologists. The plenary session of this symposium recommended that a publication be brought out to present information on methodology adopted for various physiological studies in tree crops. We made an attempt to present a spectrum of research efforts directed to understand the trees. The present book therefore contains reviews on general physiology as well as detailed information on certain selected tree crops. The contributed articles in the first part, would provide an insight into different approaches to study the physiology of tree crops, with an emphasis on principles of methodology. The chapters of the second part, offer case-histories of physiological investigations on selected economically important tropical tree crops. Considering the diverse subjects covered, and the wide variation in the emphasis given to different physiological aspects among the crops, uniformity of presentation could not be adhered to. We would be glad, if this publication forms a source of knowledge and stimulates further work in the difficult and challenging field of tree physiology. M.R. SETHURAJ January, 1987 A.S. RAGHAVENDRA VII ACKNOWLEDGEMENTS This book is the result of a recommendation from the plenary session of "TREEPHYSINDIA-82", an international symposium held at Rubber Re- search institute of India, Kottayam. The editors wish to express their thanks to the organisers of the symposium for entrusting this task to them. We wish to acknowledge the permission granted by the Chairman, Rubber Board and specially thank him for encouragement. One of the editors (Dr. A.S. Raghavendra) has .since then moved to the University of Hyderabad. We are grateful to Professor Bh. Krishnamurthy, Vice-Chancellor and Professor K. Subba Rao, Dean of Life Sciences, University of Hyderabad for their support and encouragement. We wish to thank all the authors who have contributed articles in response to our request. The secretarial assistance of Shri R. Babu is ack- nowledged. The help of Ms. D. Sudha Sundari and Ms. T. Vani in proof reading and in the preparation of subject index is gratefully appreciated. We thank Mr. Anil S. Raina of Instant Business Forms for doing a commen- dable job in typing this manuscript. We thank Drs. Jan 3.M. Velterop and Elsevier Science Publishers for an active association in this venture. M.R. SETHURAJ A.S. RAGHAVENDRA XI CONTRIBUTORS The figures in parentheses refer to the number of contributed chapter. M.C. ANDERSON (4), Commonwealth Scientific and Industrial Research Organisation, Division of Water and Land Resources, P.O. Box 1666, Canberra A.C.T. 2601, Australia. D. BALASIMHA (13), Central Plantation Crops Research Institute, Regional Station, Vittal 574 243, Karnataka, India. D.N. BARUA (11), Adviser, Tocklai Experimental Station, Jorhat 785 008, Assam, India. E.F. BRUENIG (7), Chair for World Forestry, University of Hamburg and Institute for World Forestry and Ecology, Hamburg, West Germany. J. CATSKY (2), Institute of Experimental Botany, Czechoslovak Academy of Sciences, Flemingovo n.2, CS-16 0 00 Praha 6, Czechoslovakia. R.H.V. CORLEY (8), Unifield T.C. Limited,Unit 1, St. Martins Ways, Industrial Estate, Cambridge Road, Bedford MK42 OLG, England, U.K. F.E. ECKARDT (1), Institute of Plant Ecology, University of Copenhagen, Oster Farimagsgade 2D, 1353 Copenhagen, Denmark. N.G. HEGDE (15), The Bharatiya Agro-Industries Foundation, 'Kamdhenu', Senapati Bapat Road, Pune 411 016, India. T. KIRA (6), Lake Biwa Research Institute, Otsu, Shiga 520, Japan. H. MULLERSTAEL (7), Institute for World Forestry and Ecology, Federal Research Centre for Forestry and Forest Products, Hamburg, West Germany. C.A. PRIESTLEY (5), East Mailing Research Station, Maidstone, Kent ME19 6B3, England, U.K. A.S. RAGHAVENDRA (10), School of Life Sciences, University of Hyderabad, Hyderabad 500 134, India. V. RAJAGOPAL (9), Central Plantation Crops Research Station, Kudlu, Kasaragod 670 124, Kerala, India. A. RAMADASAN (9), National Research Centre for Spices, Post Box No.1701, Marikunnu, Calicut 673 012, Kerala, India. P.K. RAMAIAH (12), Central Coffee Research Institute, Coffee Research Station 577 117, Karnataka, India. Z. SESTAK (2,3), Institute of Experimental Botany, Czechoslovak Academy of Sciences, Flemingovo n.2, CS-16 0 00 Praha 6, Czechoslovakia. XII M.R. SETHURA3 (10), Rubber Research Institute of India, Rubber Board, Kottayam 686 009, Kerala, India. R.N. SINGH (14), Shyama Sadan, Nand Nagar Colony, I.T.I. Road, Varanasi 411 016, India. G.R. SQUIRE (8), Unifield T.C. Limited, Unit 1, St. Martins Ways, Industrial Estate, Cambridge Road, Bedford MK 42 OLG, England, U.K. D. VENKATARAMANAN (12), Central Coffee Research Institute, Coffee Research Station 577 117, Karnataka, India. 3. ZIMA (3), Institute of Experimental Botany, Czechoslovak Academy of Sciences, Flemingovo n.2, CS- 160 00 Praha 6, Czechoslovakia. 3 CHAPTER 1 THE CONTROLLED-ENVIRONMENT PLANT-CHAMBER TECHNIQUE FOR C0 -EXCHANGE MEASUREMENTS IN TREE AND FOREST RESEARCH 2 F.E. ECKARDT Institute of Plant Ecology, University of Copenhagen, Oster Farimagsgade 2 D, 1353 Copenhagen, Denmark ABSTRACT CO^-exchange is an extremely sensitive indicator of the physiological behaviour of trees, in relation to the environment, complementary to the much slower tree ring growth. Among the different methods, employed to study CO^-exchange, the controlled-environment plant-chamber technique permits to establish a link between laboratory research and micrometeorologi- cal observations. This approach implies a thorough understanding of the metabolism of the O^-exchange as well as of the interaction between the plant and its environment at different levels of integration in the eco- system. These matters are considered along with the problem of chosing the right experimental material. Various control systems employed in plant chambers are described. Finally, the discussion focusses on deduction of plant behaviour from chamber data, through a detailed study of not only various environmental parameters, but also of the architecture of the entire tree stand. INTRODUCTION The complex physiological response of an individual tree to various environmental factors depend, not only on the plant taxon involved, physical and biological interactions within the ecosystem of a given climate and geology, but also on the time and space horizons. Hence it is important to select the biological and environmental variables at different levels of in- tegration in the ecosystem, and to study these processes, for each species. The first approach to such research is to establish a carbon budget 6 of the system. It implies the simultaneous study of CC^-exchange and growth combined with some modeling. From the budget, it is possible to know the amount of atmospheric carbon absorbed by the above ground biomass and the extent of carbon returned to the atmosphere from soil surface. The carbon budget will also reveal the quantity of the carbon transferred to the roots (Fig. 1). Fig. 1. Carbon budget data for Salix glauca stand during a full growing season. The carbon in carbon dioxide taken up from (+) or given off (-) to the atmosphere is given on the left. On the right is shown how the carbon taken up is used for the growth and development of leaves and shoots (-), or is translocated to the roots (+). CC^-exchange is measured at leaf or branch level and related to various weather conditions. Although often combined with growth analysis, CO^-exchange measurements per se, represent a considerable interest since they link and predict plant response to specific environmental changes. Such measurements thus, can partly substitute long-term forest research programmes (Mooney et al., 1980; Golley, 1983). PLANT METABOLISM CO^-exchange Under optimal water conditions and normal CO£ concentration of the air, photosynthesis increases proportionally with photon flux density at low densities but levels off at higher densities. Similarly, under optimal