The biology of apples and pears (the biology of horticultural crops)

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Goes into some detail on the biology of apples and pears. Goof background material for students in horticulture, agriculture, botany, biology and other endeavors.


  • Biology of Apples and Pears is a comprehensive reference book on all aspects of pomology at the organ, tree and orchard level. It provides detailed information on propagation, root and shoot growth, rootstock effects, canopy development in relation to orchard design, owering, pollina- tion, fruit set, fruit growth, fruit quality factors and quality retention in store. It also deals with mineral nutrition, water relations and irrigation, diseases and pests, and biotechnology. The book emphasizes the scien- tic basis of modern tree and orchard management, and fruit storage. It describes key cultivar differences and their physiology and genetics, and environmental effects and cultivar environment interactions in tropical and subtropical as well as temperate zone conditions. It is writ- ten for fruit growers, extension workers, plant breeders, biotechnologists and storage and crop protection specialists as well as for researchers and students of pomology and horticulture. hasawealthofexperienceinthescienceoffruitgrowing. He held senior positions at East Malling Research Station and was chair- man of the Orchard and Plantation Systems (High Density Planting) working group of the International Society for Horticultural Science for many years. Recently he was in charge of the Horticultural Research Centre, Marondera, Zimbabwe. He has visited fruit growing areas and lectured to fruit growers and scientists in countries, spanning four continents. He has published extensively in the primary literature and has contributed to, edited or co-edited numerous volumes on various aspects of fruit trees and plantation systems.
  • BIOLOGY OF HORTICULTURAL CROPS Existing texts in horticultural science tend to cover a wide range of topics at a relatively supercial level, while more specic information on individual crop species is dispersed widely in the literature. To ad- dress this imbalance, the Biology of Horticultural Crops presents a series of concise texts, each devoted to discussing the biology of an impor- tant horticultural crop species in detail. Key topics such as evolution, morphology, anatomy, physiology and genetics are considered for each crop species, with the aim of increasing understanding and providing a sound scientic basis for improvements in commercial crop production. Volumes to be published in the series will cover the grapevine, citrus fruit, bananas, apples and pears, and stone fruit. The original concept for this series was the idea of Professor Michael Mullins, who identied the topics to be covered and acted as General Editor from until his untimely death in . Biology of the Grapevine, Michael G. Mullins, Alain Bouquet and Larry E. Williams Biology of Citrus, Pinhas Spiegel-Roy and Eliezer E. Goldschmidt
  • Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, So Paulo Cambridge University Press The Edinburgh Building, Cambridge , United Kingdom First published in print format ISBN-13 978-0-521-38018-8 hardback ISBN-13 978-0-511-06533-0 eBook (NetLibrary) Cambridge University Press 2003 2003 Information on this title: This book is in copyright. Subject to statutory exception and to the provision of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. ISBN-10 0-511-06533-7 eBook (NetLibrary) ISBN-10 0-521-38018-9 hardback Cambridge University Press has no responsibility for the persistence or accuracy of s for external or third-party internet websites referred to in this book, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate. Published in the United States by Cambridge University Press, New York
  • Contents Preface page xi Acknowledgements xii Introduction The special characteristics of apple and pear production: setting the scene for their scientic study Recommended reading References The growing of apples and pears The history of apple and pear growing Trade in fresh apples Trade in pears Apple and pear products Climatic conditions in major centres of production Recommended reading References Apples and pears and their relatives Taxonomy The place of cultivars in apple and pear production Apple scion cultivars Apple rootstocks Rootstock effects on scion performance Other characteristics of apple rootstocks Major apple rootstocks Pear scion cultivars v
  • vi Pear rootstocks References Apple and pear root systems: induction, development, structure and function Introduction Root initiation Root growth of the rooted cutting and during tree establishment Orchard tree root systems Functions of roots Special features of apple and pear seedling roots References The graft union, grafting and budding Introduction Formation of the graft union Union formation in T-budding and chip budding Incompatibility Double working Effects of temperature on grafting and budding Effects of height of budding or grafting on scion vigour and cropping Effects of interstocks on root and shoot growth and cropping References Mechanisms of rootstock and interstock effects on scion vigour Introduction Mechanisms of rootstock and interstock effects on vigour Conclusions and comments Recommended reading References The shoot system Introduction
  • vii Buds Bud dormancy Dormancy through correlative inhibition Seasonal bud dormancy Shoot extension growth Water shoot growth Secondary thickening References Leaves, canopies and light interception Leaf anatomy and morphology Leaf production and growth Leaf senescence and shed Individual tree and orchard leaf area Effects of light interception and of within-tree shade Shading by stems, fruits and leaves Canopy light interception and distribution References Photosynthesis, respiration, and carbohydrate transport, partitioning and storage Introduction Photosynthesis Respiration Net CO exchange by canopies Source-sink relationships and carbohydrate partitioning Net carbon exchange and orchard productivity References Flowers and fruits Juvenility Flowering Pollination Female ower fertility Fruit set
  • viii Fruit growth Fruit skin colour, russet and cracking References Eating quality and its retention Introduction Fruit sensory quality Changes during maturation and ripening Readiness for harvest Control of ripening and senescence Calcium and fruit eating-quality Calcium nutrition Other nutrients and fruit eating-quality Recommended reading References Mineral nutrition Introduction Nutrient requirements Symptoms of deciency or excess Nitrogen nutrition Phosphorus nutrition Potassium nutrition Calcium nutrition Magnesium nutrition Manganese nutrition Copper nutrition Boron nutrition Iron nutrition Zinc nutrition Effects of aluminium on nutrition Interactions between nutrients Orchard management and tree nutrition Recommended reading References
  • ix Water relations Introduction Soil water availability Evaporation and evapotranspiration Basic concepts in tree water relations Roots and tree water relations Stem water relations Leaf water relations Fruit water relations Integrated effects of water stress Irrigation Droughting Effects of ooding References Diseases, pests, and resistance to these Introduction Virus and MLO diseases Bacterial disease Fungal diseases Pests Replant problems References Biotechnology of apples and pears Propagation in vitro Genetic transformation Molecular markers References Cultivar Index General Index
  • Preface Biology of Apples and Pears is written for undergraduates and postgraduate students of horticultural science, for scientists from other disciplines who need a core reference book on these crops, and for fruit growers and technical advisers. There is already a vast amount of published work on apple and pear biology and production. However, much of this literature is difcult to interpret and apply in the context of rapid changes in areas of production hence environ- mental constraints and of cultivars with basic differences in physiology.This book addresses these issues directly by emphasising responses to environment, and cultural and storage technology at the cultivar level. Biology of Apples and Pears deals with the biology of their eating quality and its retention as well as of their tree growth and cropping. It also emphasises the factors underlying the dramatic change from orchards of large trees to modern high-density orchards of dwarfed trees, and also those underlying modern techniques of fruit tree irrigation and nutrition. Throughout the book the results of research on apple and pear biology are linked to the relevant current concepts in more basic seciences. The numer- ous references, therefore, cover both crop-specic and basic-science research papers and reviews. Given the breadth of coverage, from anatomy and histology through physio- logy to biotechnology and disease, pest and environmental stress resistance there must inevitably be questions of relative emphasis. The guiding principle followed has been to concentrate on those aspects of the biology currently most important to the production of apple and pear fruits through to the point of consumption. xi
  • Acknowledgements Special thanks are due to Horticultural Research International, East Malling for allowing access to their library after my retirement and to Mrs Sarah Loat, Librarian, for her help. C.J. Atkinson, E. Billings, P.S. Blake, D.L. Davies, N.A. Hipps, D.J. James, D.S. Johnson, J.D. Quinlan, J.R. Stow, K.R. Tobutt, R. Watkins, A.D. Webster and other previous colleagues gave generously of their time for discussion, but are not in any way responsible for any errors of weeknesses in their text. M. Blanke, R. Harrison-Murray, S.E. Horton, B.H. Howard, K. Hrotko, J.S. Kamboj, A.N. Lakso, H.A. Quamme, S. Sansavini and J. N. Wunsche were particularly helpful with respect to sourcing text gures and tables. The co-operation of the Japanese Academic Association for Copyright Clearance is gratefully acknowledged. Mrs Molly Kurwakumire typed the initial text and Mrs Barbara Jackson subsequent modications and correspondence. The continued support of Dr Maria Murphy and colleagues at Cambridge University Press is gratefully acknowledged and the book is dedicated to the scientists upon whose work it is based. xii
  • Introduction The special characteristics of apple and pear production: setting the scene for their scientic study Apples and pears are among the oldest of the worlds fruit crops, g- uring in both the Bible and the tales of Homer. They are by far the most important of the deciduous tree fruits, are widely grown in temper- ate and, increasingly, in tropical regions, and gure prominently in world trade. The fruits of apples and pears are primarily grown for the fresh fruit mar- ket, which is much more remunerative than that for processing. ORourke () noted that in the United States a thousand tons of apples qualifying for fresh sale would, on average, generate more than three times the revenue of a thousand tons sold for juice and that even within the fresh fruit cate- gory the most desirable fruits may sell for three or four times the price of the least desirable fruits. Moreover, apples and pears for fresh consumption, and also even in some processed forms, are marketed by cultivar name to a much greater extent than has been traditional for other fresh fruits and vegetables, and the different cultivars command different prices. The culture of apples and pears is, therefore, directed towards the production of fruits of named cultivars and to the production of fruits of high perceived qual- ity within each cultivar. In general the cultivars do not come true-to-type when grown from seed and the necessary uniformity is achieved by clonal propagation. Fruit avour, texture, size and colour are all characteristics of the cultivar but can be inuenced by tree nutrition and pruning and by fruit thinning. Market demand extends throughout the year although any one cultivar in a particular region has only a limited harvesting season, excepting some
  • relatively minor tropical production. To meet year-round demand the season of availability is extended in several ways. Growing a range of cultivars with different harvesting seasons, from early to late, in the same orchard or locality. This approach is declining in im- portance in the major areas of commercial production as demand focuses increasingly on a fairly limited number of cultivars. Growing the cultivars which are in greatest demand in areas with different seasons of production. Thus Golden Delicious apple is available through- out the year on English markets by combining northern hemisphere sources, apples from southern France being available earlier than from northern France or the Netherlands, and southern hemisphere sources such as South Africa. The use of long-term storage, which encompasses both the use of low tem- perature and controlled atmosphere stores to modify the ripening process and also the use of pre-harvest treatments to improve the intrinsic potential storage life of the fruits. Such treatments include those to modify chemical composition so as to maintain cell wall and membrane integrity, and also harvesting the fruits at an appropriate stage of maturity. The perennial nature of apple and pear trees and their characteristic pat- terns of owering and fruiting are also very important. If seedling fruit trees are planted at a spacing appropriate to their natural size at maturity the yield per unit area of orchard would be low for many years after planting. The trees at maturity would also be so large as to require ladders to prune and pick, making these operations slow and expensive, and would be too shaded in their lower parts to produce fruits of acceptable commercial quality there. Moreover it is difcult and expensive to ensure thorough application of pesticides throughout the canopies of large trees and to carry out effective pest and disease monitoring. A major thrust in orchard system develop...