Breeding Plantation Tree Crops: Temperate Species S. Mohan Jain l P.M. Priyadarshan Editors Breeding Plantation Tree Crops: Temperate Species 13 Editors S. Mohan Jain P.M. Priyadarshan Helsinki University Rubber Research Institute of India Helsinki, Finland Regional Station [email protected] Agartala, India [email protected] ISBN: 978-0-387-71202-4 e-ISBN: 978-0-387-71203-1 DOI 10.1007/978-0-387-71203-1 Library of Congress Control Number: 2008937489 # Springer ScienceþBusiness Media, LLC 2009 All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer ScienceþBusiness Media, LLC, 233 Spring Street, New York, NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. Printed on acid-free paper springer.com Preface Tree species are indispensably supportive to human life. Due to their long life cycle and environmental sensitivity, breeding trees to suit day-to-day human needs is a formidable challenge. Whether they are edible as apple, cocoa, mango, citrus, litchi, pear, dates, and coconut or industrially essential as rubber or beverages like coffee and tea, improving yield under optimal, suboptimal, and marginal areas calls for a unified effort from scientists around the world. While the uniqueness of coconut as ‘kalpavriksha’ (Sanskrit-meaning tree of life) makes its presence in every continent from Far East to South America, tree crops like cocoa, oil palm, rubber, apple, peach, grapes, and walnut prove their environmental sensitivity toward tropical, subtropical, and temperate climates. Desert climate is quintessential for date palm. Thus, from soft drinks to breweries to beverages to oil to tyres, the value addition offers a spectrum of products to human kind, enriched with nutritional, environmental, financial, social, and trade-related attributes. Taxonomically, tree crops never confine to few families, but spread over a cross-section of genera, an attribute so unique that contributes immensely to biodiversity even while cultivated on commercial scale. Many of these species encourage other flora to nurture in their vicinity, thus ensuring their integrity toward preserving biodiversity. While wheat, rice, maize, barley, soybean, cassava, and banana make up the major food staples, many fruit-yielding tree species contribute toward nutritional enrichment in human life. The edible part of these species is the source of several nutrients that make additives for the daily human diet, for example, vitamins, sugars, aromas, and flavor compounds, and raw material for food-processing industries. Tree crops face an array of agronomic and horticultural problems in terms of propagation, yield, appearance, quality, diseases and pest control, abiotic stresses, and poor shelf life. Shrinkage of cultivable land and growing demand has enforced these crops to be grown under marginal conditions that call for concerted efforts from breeders to improve these crops substantially. Concerted efforts have not been incurred to bring out the compilation of research done on tree crops grown under both traditional and nontraditional environments. Even if available, they v vi Preface are scattered and also lack comprehensive treatment and wholesomeness. The task of improving yield in tree crops is foremost in the acumen of global agricultural research, and the advancements made in this arena are immense both at conventional and molecular means. This two-volume series on Breeding Plantation Tree Crops dealing both tropical and temperate species separately is a sincere effort toward compiling the research available worldwide and bring them to the reference of scientists, researchers, teachers, students, policy makers, and even planters. It is worthwhile to note that in the forthcoming years, tree crops are to be given much importance on par with annual crops due to carbon trading and nutritional upgradation of the daily diet. Since tropical species are more diverse, the first volume on tropical species contains 16 chapters on fruits and nuts (banana, mango, guava, papaya, grape, date palm, litchi, avocado, and cashew), oil crops (coconut, oil palm, and olive), industrial crops (rubber), and beverages (coffee, tea, and cocoa). The second volume contains temperate fruit species including apple, apricot, almond, citrus, pear, plum, raspberry, and walnut. The chapters were authored by crop-specific experts worldwide. We appreciate the untiring efforts rendered by the authors in ensuring the inclusion of latest advancements and their cooperation in revising their manuscripts timely. A few reviewers spared their precious time in improving the quality manuscripts. We are immensely thankful to them for their valuable help. Finally, we thank Springer for bringing out this series to the readers. Helsinki, Finland S. Mohan Jain Agartala, India P.M. Priyadarshan Contents Almond (Prunus dulcis) Breeding................................ 1 Thomas M. Gradziel Breeding Apple (Malus  Domestica Borkh)....................... 33 S. Pereira-Lorenzo, A.M. Ramos-Cabrer, and M. Fischer Apricot Breeding ............................................ 83 Hanne´l Ham Citrus Breeding ............................................. 105 Fred G. Gmitter, Jaya R. Soneji, and Madhugiri Nageswara Rao Pear Breeding .............................................. 135 Manfred Fischer Plum Breeding .............................................. 161 Walter Hartmann and Michael Neumu¨ller Raspberry Breeding .......................................... 233 Julie Graham and Nikki Jennings Breeding Walnuts (Juglans Regia) ............................... 249 Gale McGranahan and Chuck Leslie Index ..................................................... 275 vii Contributors Manfred Fischer BAZ Quedlinburg, Institut fu¨ r Obstzu¨ chtung Dresden-Pillnitz; IPK Gatersleben, Genbank Obst Dresden-Pillnitz (former affiliation), Sobrigener,¨ Str. 15, D - 01326 Dresden, Germany, [email protected] Fred G. Gmitter Institute of Food and Agricultural Sciences, Citrus Research and Education Center, University of Florida, 700 Experiment Station Road, Lake Alfred FL 33850, USA, [email protected] Thomas M. Gradziel Department of Plant Sciences, University of California, Davis, California, [email protected] Julie Graham Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK Hanne´ l Ham ARC Infruitec-Nietvoorbij, Private Bag X5026, Stellenbosch 7599, South Africa Walter Hartmann Institute of Special Crop Cultivation and Crop Physiology, University of Hohenheim, Emil-Wolff-Straße 25, 70599 Stuttgart, Germany, [email protected] Nikki Jennings Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK Chuck Leslie Department of Plant Sciences, Mail stop 2, One Shields Ave., University of California, Davis, CA 95616, USA ix x Contributors Gale Mcgranahan Department of Plant Sciences, Mail stop 2, One Shields Ave., University of California, Davis, CA 95616, USA, [email protected] Michael Neumu¨ ller Technical University of Munich, Center of Life and Food Sciences Weihenstephan, Unit of Fruit Science, Alte Akademie 16, 85354 Freising, [email protected] S. Pereira-Lorenzo Escola Polite´ cnica Superior, Departamento Produccion´ Vegetal, Universidad de Santiago de Compostela, Campus de Lugo, 27002, [email protected] A.M. Ramos-Cabrer Escola Polite´ cnica Superior, Departamento Produccion´ Vegetal, Universidad de Santiago de Compostela, Campus de Lugo, 27002 Madhugiri Nageswara Rao Institute of Food and Agricultural Sciences, Citrus Research and Education Center, University of Florida, 700 Experiment Station Road, Lake Alfred FL 33850, USA Jaya R. Soneji Institute of Food and Agricultural Sciences, Citrus Research and Education Center, University of Florida, 700 Experiment Station Road, Lake Alfred FL 33850, USA Almond (Prunus dulcis) Breeding Thomas M. Gradziel 1 Introduction An adaptation to harsh climates combined with an ability to develop a deep and extensive root system has allowed cultivated and wild almond to exploit a wide variety of ecological niches in its ancestral range in central Asia extending from the Takla Makan desert in western China to the Mediterranean (Kester et al. 1991; Ladizinsky 1999). Almond is also well adapted to mild winter and dry, hot summer conditions due to its low chilling requirement for early bloom, rapid early shoot growth, and high tolerance to summer heat and drought. It is the earliest temperate tree crop to bloom, which limits production to areas relatively free from spring frosts. Because almond is self-sterile, it requires cross-pollination that further acts to promote genetic variability and, therefore, adaptability to new environments. Commercial production is often limited by the need for cross-pollination in orchard systems, particularly in areas where spring storms can reduce both flowering duration and activity of required insect pollinators. A high suscept- ibility to fungal and bacterial diseases of the blossoms, leaves, branches, and fruits also reduces production