Jameel M. Al-Khayri · Shri Mohan JainDennis V. Johnson Editors

Advances in Plant Breeding Strategies: Agronomic, Abiotic and Biotic Stress TraitsVolume 2

Advances in Plant Breeding Strategies: Agronomic, Abiotic and Biotic Stress Traits

Jameel M. Al-Khayri • Shri Mohan Jain Dennis V. Johnson Editors

Advances in Plant Breeding Strategies: Agronomic, Abiotic and Biotic Stress Traits Volume 2

ISBN 978-3-319-22517-3 ISBN 978-3-319-22518-0 (eBook) DOI 10.1007/978-3-319-22518-0

Library of Congress Control Number: 2016933868

Springer Cham Heidelberg New York Dordrecht London © Springer International Publishing Switzerland 2016 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifi cally the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfi lms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specifi c statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made.

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Editors Jameel M. Al-Khayri Department of Agricultural Biotechnology King Faisal University Al-Hassa , Saudi Arabia

Dennis V. Johnson Cincinnati , OH , USA

Shri Mohan Jain Department of Agricultural Sciences University of Helsinki Helsinki , Finland

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Pref ace

Thus far conventional plant breeding methods have been successfully used for sus-tainable food production worldwide. Human population is increasing at an alarming rate in developing countries, and food availability to feed the additional mouths could gradually become a serious problem. Moreover, agriculture production is being adversely affected as a result of environmental pollution, rapid industrializa-tion, water scarcity, erosion of fertile topsoil, limited possibility of expanding arable land, lack of improvement of local plant types, erosion of genetic diversity, and dependence on a relatively few crop species for the world’s food supply. According to FAO, 70 % more food must be produced over the next four decades to feed the projected 9 billion people by the year 2050. Only 30 plant species are used to meet 95 % of the world’s food requirements, which are considered as the major crops . The breeding programs of these crops have been very much dependent on the ready availability of genetic variation, either spontaneous or induced. Plant breeders and geneticists are under constant pressure to sustain and expand food production by using innovative breeding strategies and introducing minor crops which are well adapted to marginal lands and provide a source of nutrition as well as crops having abiotic and biotic stress tolerances. In traditional breeding, introgression of one or a few genes in a cultivar is carried out via backcrossing for several generations. Now, new innovative additional plant breeding tools, including molecular breeding and plant biotechnology, are available to plant breeders, which have a great potential to be used along with the conventional breeding methods for sustainable agriculture. With the development of new molecular tools such as genomics, molecular marker- assisted backcrossing has made possible rapid introgression of transgenes, reduc-tion of linkage drag, and manipulation of genetic variation for the development of improved cultivars. For example, molecular breeding has great potential to become a routine standard practice in the improvement of several crops. However, a multi-disciplinary approach of traditional plant breeding, plant biotechnology, and molec-ular biology would be strategically ideal for developing new improved crop varieties worldwide to feed the world. This book highlights the recent progress in the devel-opment of plant biotechnology, molecular tools, and their usage in plant breeding.

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The basic concept of this book is to examine the use of innovative methods aug-menting traditional plant breeding toward the development of new crop varieties, grown under different environmental conditions, to achieve sustainable food production.

This book consists of two volumes: Volume 1 subtitled Breeding, Biotechnology and Molecular Tools and Volume 2 subtitled Agronomic, Abiotic and Biotic Stress Traits . This volume contains 18 chapters highlighting breeding strategies for spe-cifi c plant traits including improved nutritional and pharmaceutical properties as well as enhanced tolerance to insects, diseases, drought, salinity, and temperature extremes expected under global climate change. Chapters addressing these topics are grouped into four parts: Part I Sustainability, Nutrition and Pharmaceuticals; Part II Forage and Tree Traits; Part III Abiotic Stress Tolerance; and Part IV Biotic Stress Resistance.

Each chapter begins with an introduction covering related backgrounds and pro-vides in-depth discussion of the subject supported with high-quality color photos, illustrations, and relevant data. The chapter concludes with prospects for future research directions and a comprehensive list of pertinent references to facilitate fur-ther reading.

The book is an excellent reference source for plant breeders and geneticists engaged in breeding programs involving biotechnology and molecular tools together with traditional breeding. It is suitable for both undergraduate and postgraduate students specializing in agriculture, biotechnology, and molecular breeding, as well as for agricultural companies.

Chapters were written by internationally reputable scientists and subjected to a review process to assure quality presentation and scientifi c accuracy. We greatly appreciate all chapter authors for their participation toward the success and quality of this book. We are proud of this diverse collaborative undertaking, especially since the two volumes represent the efforts of 105 scientists from 29 countries. We are also grateful to Springer for giving us an opportunity to compile this book.

Al-Hassa , Saudi Arabia Jameel M. Al-Khayri Helsinki , Finland Shri Mohan Jain Cincinnati , OH , USA Dennis V. Johnson

Preface

vii

Contents

Part I Sustainability, Nutrition and Pharmaceuticals

1 Sustainable Agriculture and Plant Breeding .......................................... 3 Dinesh Narayan Bharadwaj

2 Breeding Crop Plants for Improved Human Nutrition Through Biofortification: Progress and Prospects ................................. 35 Prakash I. Gangashetty , Babu N. Motagi , Ramachandra Pavan , and Mallikarjun B. Roodagi

3 Role of Genomics in Enhancing Nutrition Content of Cereals ............. 77 Mehanathan Muthamilarasan and Manoj Prasad

4 Molecular Farming Using Transgenic Approaches ................................ 97 Ramandeep Kaur Jhinjer , Leela Verma , Shabir Hussain Wani , and Satbir Singh Gosal

Part II Forage and Tree Traits

5 Forages: Ecology, Breeding Objectives and Procedures ....................... 149 Saeed Rauf , Dorota Sienkiewicz-Paderewska , Dariusz P. Malinowski , M. Mubashar Hussain , Imtiaz Akram Khan Niazi , and Maria Kausar

6 Breeding vis-à-vis Genomics of Tropical Tree Crops ............................. 203 Padmanabhan M. Priyadarshan

7 Coconut Breeding in India ....................................................................... 257 Raman V. Nair , B. A. Jerard , and Regi J. Thomas

Part III Abiotic Stress Tolerance

8 Molecular Breeding to Improve Plant Resistance to Abiotic Stresses...................................................................................... 283 Gundimeda J. N. Rao , Janga N. Reddy , Mukund Variar , and Anumalla Mahender

viii

9 Single Nucleotide Polymorphism (SNP) Marker for Abiotic Stress Tolerance in Crop Plants ............................................ 327 Ratan S. Telem , Shabir H. Wani , Naorem Brajendra Singh , Raghunath Sadhukhan , and Nirmal Mandal

10 Transgenic Approaches for Abiotic Stress Tolerance in Crop Plants ... 345 Shabir Hussain Wani , Saroj Kumar Sah , Mohammad Anwar Hossain , Vinay Kumar , and Sena M. Balachandran

11 Breeding Strategies to Enhance Drought Tolerance in Crops .............. 397 Saeed Rauf , Jameel M. Al-Khayri , Maria Zaharieva , Philippe Monneveux , and Farghama Khalil

12 Breeding Strategies for Enhanced Plant Tolerance to Heat Stress ....... 447 Viola Devasirvatham , Daniel K. Y. Tan , and Richard M. Trethowan

13 QTLs for Genetic Improvement Under Global Climate Changes ........ 471 Ramón Molina-Bravo and Alejandro Zamora-Meléndez

14 Genotype x Environment Interaction Implication: A Case Study of Durum Wheat Breeding in Iran .................................. 515 Reza Mohammadi and Ahmed Amri

Part IV Biotic Stress Resistance

15 Breeding Strategies for Improving Plant Resistance to Diseases .................................................................................................. 561 Thomas Miedaner

16 Breeding and Genetics of Resistance to Fusarium Wilt in Melon ............................................................................................. 601 Ali Oumouloud and José M. Álvarez

17 Viral, Fungal and Bacterial Disease Resistance in Transgenic Plants .................................................................................. 627 Vinod Saharan , Devendra Jain , Sunil Pareek , Ajay Pal , R. V. Kumaraswamy , Sarita Kumari Jakhar , and Manvendra Singh

18 Current Status of Bacillus thuringiensis: Insecticidal Crystal Proteins and Transgenic Crops .................................................. 657 Devendra Jain , Vinod Saharan , and Sunil Pareek

Index ................................................................................................................. 699

Contents

ix

Contributors

Jameel M. Al-Khayri Department of Agricultural Biotechnology, College of Agriculture and Food Sciences , King Faisal University , Al-Hassa , Saudi Arabia

José M. Álvarez Centro de Investigación y Tecnología Agroalimentaria de Aragón , Zaragoza , Spain

Ahmed Amri Genetic Resources Unit , International Center for Agricultural Research in the Dry Areas (ICARDA) , Rabat , Morocco

Sena M. Balachandran Biotechnology Section , ICAR-Indian Institute of Rice Research Rajendranagar , Hyderabad , India

Dinesh Narayan Bharadwaj Department of Genetics and Plant Breeding , C.S. Azad University of Agriculture and Technology , Kanpur , Uttar Pradesh , India

Viola Devasirvatham Department of Agriculture and Environment, Plant Breeding Institute , University of Sydney , Cobbitty , NSW , Australia

Prakash I. Gangashetty Research Program – Dry Land Cereals , International Crops Research Institute for Semi-Arid Tropics (ICRISAT), West and Central Africa (WCA), ICRISAT Sahelian Center , Niamey , Niger

Satbir Singh Gosal School of Agricultural Biotechnology , Punjab Agricultural University , Ludhiana , India

Mohammad Anwar Hossain Department of Genetics and Plant Breeding , Bangladesh Agricultural University , Mymensingh , Bangladesh

M. Mubashar Hussain Department of Plant Breeding and Genetics , University College of Agriculture, University of Sargodha , Sargodha , Pakistan

Devendra Jain Department of Molecular Biology and Biotechnology, Rajasthan College of Agriculture , Maharana Pratap University of Agriculture and Technology , Udaipur, Rajasthan , India

x

Sarita Kumari Jakhar Department of Molecular Biology and Biotechnology, Rajasthan College of Agriculture , Maharana Pratap University of Agriculture and Technology , Udaipur , Rajasthan , India

B. A. Jerard Central Plantation Crops Research Institute , Kasaragod , Kerala , India

Ramandeep Kaur Jhinjer School of Agricultural Biotechnology , Punjab Agricultural University , Ludhiana , India

Maria Kausar Department of Plant Breeding and Genetics , University College of Agriculture, University of Sargodha , Sargodha , Pakistan

Farghama Khalil Department of Plant Breeding and Genetics , University College of Agriculture, University of Sargodha , Sargodha , Pakistan

Vinay Kumar Department of Biotechnology , Modern College of Arts, Science and Commerce (University of Pune) , Pune , India

R. V. Kumaraswamy Department of Molecular Biology and Biotechnology, Rajasthan College of Agriculture , Maharana Pratap University of Agriculture and Technology , Udaipur , Rajasthan , India

Anumalla Mahender Division of Crop Improvement , Central Rice Research Institute , Cuttack , Odisha , India

Dariusz P. Malinowski Texas AgriLife Research , Texas A&M University , Vernon , TX , USA

Nirmal Mandal Department of Agricultural Biotechnology , BCKV , Mohanpur, Nadia , West Bengal , India

Thomas Miedaner State Plant Breeding Institute , Universitaet Hohenheim , Stuttgart , Germany

Reza Mohammadi Cereal Department , Dryland Agricultural Research Institute (DARI), AREEO , Kermanshah , Iran

Ramón Molina-Bravo School of Agrarian Sciences , National University of Costa Rica , Heredia , Costa Rica

Philippe Monneveux International Potato Center (CIP) , La Molina, Lima , Peru

Babu N. Motagi Grain Legumes Research Program , International Crops Research Institute for Semi-Arid Tropics (ICRISAT), West and Central Africa (WCA) , Tarauni , Kano , Nigeria

Mehanathan Muthamilarasan Department of Plant Molecular Genetics and Genomics , National Institute of Plant Genome Research , New Delhi , India

Raman V. Nair Central Plantation Crops Research Institute , Kasaragod , Kerala , India

Contributors

xi

Imtiaz Akram Khan Niazi Department of Plant Breeding and Genetics , University College of Agriculture, University of Sargodha , Sargodha , Pakistan

Ali Oumouloud Institut Agronomique et Vétérinaire Hassan II , Ait Melloul , Morocco

Ajay Pal Department of Biochemistry, College of Basic Sciences and Humanities , CCS Haryana Agricultural University , Hisar , Haryana , India

Sunil Pareek Department of Horticulture, Rajasthan College of Agriculture , Maharana Pratap University of Agriculture and Technology , Udaipur , Rajasthan , India

Ramachandra Pavan Department of Genetics and Plant Breeding , University of Agricultural Sciences , Bangalore , Karnataka , India

Manoj Prasad Department of Plant Molecular Genetics and Genomics , National Institute of Plant Genome Research , New Delhi , India

Padmanabhan M. Priyadarshan Central Experiment Station , Rubber Research Institute of India , Thompikandom , Kerala , India

Gundimeda J. N. Rao Division of Crop Improvement , Central Rice Research Institute , Cuttack , Odisha , India

Saeed Rauf Department of Plant Breeding and Genetics , University College of Agriculture, University of Sargodha , Sargodha , Pakistan

Janga N. Reddy Division of Crop Improvement , Central Rice Research Institute , Cuttack , Odisha , India

Mallikarjun B. Roodagi Department of Soil Science and Agricultural Chemistry , University of Agricultural Sciences , Dharwad , Karnataka , India

Raghunath Sadhukhan Department of Genetics and Plant Breeding , BCKV , Mohanpur, Nadia , West Bengal , India

Saroj Kumar Sah School of Agricultural Biotechnology , Punjab Agricultural University , Ludhiana , India

Vinod Saharan Department of Molecular Biology and Biotechnology, Rajasthan College of Agriculture , Maharana Pratap University of Agriculture and Technology , Udaipur , Rajasthan , India

Dorota Sienkiewicz-Paderewska Department of Agronomy , Warsaw University of Life Sciences , Warsaw , Poland

Manvendra Singh Department of Molecular Biology and Biotechnology, Rajasthan College of Agriculture , Maharana Pratap University of Agriculture and Technology , Udaipur , Rajasthan , India

Contributors

xii

Naorem Brajendra Singh Department of Plant Breeding and Genetics. COA , Central Agricultural University , Imphal , Manipur , India

Daniel K. Y. Tan Department of Agriculture and Environment, Plant Breeding Institute , University of Sydney , Cobbitty , NSW , Australia

Ratan S. Telem Farm Science Centre (KVK) , Kangpokpi , Manipur , India

Regi J. Thomas Central Plantation Crops Research Institute, Regional Station , Kayamkulam, Alappuzha , Kerala , India

Richard M. Trethowan Department of Agriculture and Environment, Plant Breeding Institute , University of Sydney , Cobbitty , NSW , Australia

Mukund Variar Central Rainfed Upland Rice Research Station , Hazaribagh , India

Leela Verma School of Agricultural Biotechnology , Punjab Agricultural University , Ludhiana , India

Shabir Hussain Wani Division of Plant Breeding and Genetics , SKUAST-K , Shalimar Srinagar , Kashmir , India

Maria Zaharieva National Agricultural University La Molina (UNALM) , Lima , Peru

Alejandro Zamora-Meléndez School of Agrarian Sciences , National University of Costa Rica , Heredia , Costa Rica

Contributors

Part I Sustainability, Nutrition and

Pharmaceuticals

3© Springer International Publishing Switzerland 2016 J.M. Al-Khayri et al. (eds.), Advances in Plant Breeding Strategies: Agronomic, Abiotic and Biotic Stress Traits, DOI 10.1007/978-3-319-22518-0_1

Chapter 1 Sustainable Agriculture and Plant Breeding

Dinesh Narayan Bharadwaj

Abstract World population is expected to increase from the current 6.7 billion to more than 10 billion people by the year 2050. This 45 % increase in the current world population will create demand for increased food and other raw materials. At present the supply of fossil fuel, fertilizers, water and chemicals such as insecti-cides, pesticides and fungicides are at their peak; but this situation will not remain linear in the future. Modern agriculture is essentially based on varieties bred for high performance under high-input systems which generally do not perform well under low-input conditions. Excessive uses of these inputs are posing serious threats to ecology, environment, soil health and ground water. Furthermore, the amount of arable land for crop cultivation is limited and decreasing due to urbanization, salini-zation, desertifi cation and environmental degradation. With respect to global warm-ing, yields of important food, feed and fi ber crops will decline. In addition to these environmental factors, abiotic and biotic stresses also cause losses to crop produc-tion. Thus, the challenge before agriculture scientists is to improve the genetic architecture of agricultural crops to perform well against threats and stresses; this will require diverse approaches to enhance the sustainability of agriculture farms. This proposed shift in plant breeding goals, from high energy input and high perfor-mance of agriculture, entails an improved rationalization between yield and energy coupled with high quality food as global resources. Sustainable crop production is a way of growing food in an ecologically and ethically responsible manner that does not harm the environment and sustains communities.

Keywords Biodiversity • Ecology • Environment • Global resources • Plant genetic resources • Scarcity • Sustainable agriculture • Renewal energy

D. N. Bharadwaj (*) Department of Genetics and Plant Breeding , C.S. Azad University of Agriculture and Technology , Lakhanpur Housing Society, 251 , Kanpur 208002 , Uttar Pradesh , India e-mail: bdn_csauk@rediffmail.com

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1.1 Introduction

Since the advance of human civilization, agriculture has continued to be the back-bone of the economy all over the globe, as most people depend upon the agriculture sector for food, feed, shelter and clothes. The current agriculture sector has suffi -cient production of food grains, oilseeds, pulses, fi ber and other commodities to feed the global population and provide raw materials for industrial use.

After World War II, the development of improved technology, new high-yielding varieties, mechanization, enhanced use of chemical and fertilizers led to maximiz-ing yields (Rosset et al. 2000 ), but this development adversely affected agroecology and labor demands in agriculture. Present agricultural industrialization to produce the food, fi ber and other commodities has signifi cantly reduced the risk of cost- input in both sectors. Owing to advanced technology and the Green Revolution during the past 50 years, agricultural production has nearly tripled. Modern agricul-ture is essentially based on plant varieties for high performance under a high-input system of fertilizer, water, pesticides and fossil fuels. Currently the use of these chemical inputs is at their peak because these varieties do not perform well under low input conditions. However, on one hand, the availability of these inputs will not continue forever and on the other hand, the situation is alarming because of the degradation of natural resources and ecosystems. The Green Revolution came at a high cost to the environment, public health and social welfare. High agricultural production also maximized the risk of depletion of topsoil, contamination of ground water, decrease in the number of family farms and ecological imbalances . The cur-rent farming system is dependent on fossil fuels and toxic inputs; ignorance of their hazards has proved to be a dead-end road. The increase in the population growth coupled with urbanization and industrialization has led to the decrease in per capita availability of land for cultivation, availability that continues to diminish day by day, as a result the global resources are in decline and human population is increasing.

As projected to 2050, world population will reach around >10 billion people (Dasgupta 1998 ), this increased population will create a huge demand for food and raw materials to provide basic human needs (Table 1.1 ). The most debatable topic of today is land degradation, environmental losses due to maximum use of harmful

Table 1.1 Trends in increase of population, food production, resource consumption and future demands

Resources

Years

1960 2000 2050

Population (billions) 3 6 9–10 Food production (mt) 1.8 × 109 3.5 × 109 6.5 × 109 Agricultural water (km 3 ) 1,500 7,130 12–13.500 N fertilizer use (Tg) 12 88 120 P fertilizer use (Tg) 11 40 55–60 Pesticide use (Tg, active ingredient) 1.0 3.7 10.1

D.N. Bharadwaj

5

agriculture inputs, which are steadily degrading soil fertility, contaminating ground water, exacerbating ecological imbalances , intensifying emission of harmful green-house gases and promoting a rise of atmospheric temperature. These changes began a key shift in the natural climate cycle and result in excessive rain, snowfall, drought, wind storms and other calamities affecting human society. Overall crop productivity is also declining due to soil degradation in the form of low nutrition, reduced water- holding capacity, toxicity, infestation and persistence of weeds. To overcome these socioeconomic problems, several countries have started a new movement known as sustainable agriculture which is now receiving increasing support and acceptance of intellectuals from various sectors of agriculture and industry. Sustainable agricul-ture has been gearing up with many environmental and social concerns and offers innovative and economically-viable opportunities for farmers, laborers, consumers, policymakers and industrialist in the entire societal food chain.

1.2 Conventional Plant Breeding

Conventional agricultural methods are heavily dependent on non-renewable energy (fossil fuel) resources. Plant breeding adapts the principles of genetics to improve the quality, diversity and high yield performance of crops with the objective of better-suited plants to human needs. Plant breeding is simply the process of crossing the best parent species, identifying and recovering the best performing progeny over the parents. The process of plant breeding involves three steps: germplasm collec-tions, identifi cation of superior phenotypes and their hybridization to develop improved cultivars (Fehr 1987 ; Stoskopf et al. 1993 ). Furthermore, the best plants are selected from the mixed population; they are then stabilized for several years. These newly-developed improved varieties with superior traits are then tested in different climates for their suitability, multiplied and distributed among farmers, but the process may take 12–15 years. In this regard the Veery variety of wheat is a good example of plant breeding for it was developed through 3,170 crosses involving 51 crop parents collected from 21 countries (Rajaram et al. 1996 ).

1.3 Sustainable Agriculture: Concepts and Principles

The manifold progress in the agricultural sector during the past half-century in crop and livestock productivity has been strongly driven by over exploitation of resources such as fertilizers, irrigation, agricultural machinery, pesticides and land use effi -ciency. It would be overly-optimistic to assume that these resources will also remain linear in future (Tilman 1999 ). The concerns of sustainability in agricultural system center on the need to develop technologies and practices that do not have adverse or harmful effects on the environment, food quality, productivity and services to farm-ers and their society. New approaches are required to integrate biological and

1 Sustainable Agriculture and Plant Breeding

6

ecological concerns into food production, minimize the use of non-renewable inputs that causes harm to the environment or to the human health (farmers and consum-ers), which can make productive use of the knowledge and skill of farmers to solve common agricultural and natural resource problems. Improving natural capital is a central theme of sustainable agriculture and can make the best use of available resources, genotypes of crops, animals and the balanced ecological conditions under which they are sustained (Cassman et al. 2002 ). Agricultural sustainability suggests a focus on genotype improvement through complete exploitation of modern bio-logical approaches, understanding the benefi ts of ecological and agronomic man-agement, manipulation and redesign. The ecological management of agro-ecosystems that addresses energy fl ows, nutrient cycling, population-regulating mechanisms and system resilience can lead to the redesign agriculture at a site specifi c magni-tude (Pretty 2008 ). Sustainable agriculture outcomes can be positive for food qual-ity, productivity, reduced chemicals use and carbon balances (Roberts and Lighthall 1993 ). Signifi cant challenges, however, remain to develop national and international policies to support the wider emergence of more sustainable forms of agricultural production across both developed and developing countries. The sustainable agri-culture development program recognizes use of limited natural resources, economic growth and encourages saving them for future use. It gives due consideration to long-term interests in preserving topsoil, biodiversity and rural communities, rather than short-term profi t interests. It is a site specifi c and dynamic process with a sys-tem-wide holistic approach in solving farm management problems (Fig. 1.1 ). Sustainable agriculture has three main goals: environmental health, economic prof-itability and socioeconomic equity.

Farmers localKnowledge Society

Pests

Farminputs Crop Sustainable

yield Biodiversity

Soil

Losses

Politicalsystem

Water qualityand

quantity

Economicsystem

Soil Biota

Fig. 1.1 Sustainable agriculture system

D.N. Bharadwaj

7

Sustainable agriculture is a model of social and economic organization based on an equitable and participatory vision of development which recognizes the environ-ment and natural resources as the foundation of economic activity. It applies farm-ing principles of ecology i.e. positive relationships between organisms and their environment. The term sustainable agriculture was fi rst coined by the Australian agricultural scientist McClymont ( 1975 ). According to him, it is an integrated sys-tem of plant and animal production practices having a local/site-specifi c application for long term sustainability and has objectives to:

(a) Satisfy human food, fi ber and shelter needs. (b) Enhance environmental quality and the natural resource. (c) Assure the most effi cient use of non-renewable natural resources with integra-

tion of natural biological cycles. (d) Strengthen the economic viability of farm operations. (e) Enhance the quality of life of the entire society.

The M.S. Swaminathan Research Foundation (MSSRF) Chennai, India has developed an Integrated Intensive Farming System (IIFS) which is also known as ecological farming or intensifi cation of natural resources. It involves agricultural intensifi cation , diversifi cation and value addition on a sustainable basis (Kesavan and Swaminathan 2008 ). This system is economically rewarding, intellectually challenging, energy effi cient and employment oriented. It is based on intensive use of natural resources, traditional knowledge and the skill of farmers to increase pro-ductivity; effi cient recycling of organic residues and a risk-minimizing integrated system. This system is self-reliant, transforming agriculture from chemical use to eco-farming, but its package is site or area specifi c (Fig. 1.2 ).

Achieving the goal of sustainable agriculture is the responsibility of all partici-pants in the system: farmers, laborers, researchers, retailers, consumers and policy-makers. Their cooperation and contribution will strengthen the sustainable agriculture system. Industrial agriculture consumes resources such as fossil fuel,

Fig. 1.2 Development of sustainability

1 Sustainable Agriculture and Plant Breeding

8

water, topsoil and contributes to degradation of natural resources such as air, water, soil and biodiversity. Therefore, judicious use of all natural and human resources is advocated and given prime importance for sustainable agriculture. The stewardship of land and natural resources involves maintenance and conservation of natural resources (Dobbs and Pretty 2004 ) for their long-term sustainability (Table 1.2 ). It is a way of producing food that is healthy to eat, does not harm the environment or animals, provides a fair wage to the farmer, and supports enhanced local community (Indicators for sustainable water resources development 2013 ). Sustainable agricul-ture includes the following objectives:

(a) Characterization, conservation, evaluation, and use of plant and microbial genetic resources of interest in the agro-alimentary sector.

(b) Use of genomic and proteomic tools to study heredity productiveness, adaptive-ness and quality traits in plant breeding programs. The new plant cultivars should enhance effi ciency, quality of products and growing sustainability.

(c) Interaction studies between soil, rootstocks, cultivar, auxiliary fauna, biological pest control and improvement of plant growth system.

1.3.1 Use of Decomposers for Sustainability

Sustainable agriculture should not deprive decomposers of biological waste. The living systems of the earth are capable of sequestering more greenhouse gasses than they release; there is need to learn and create sustainability to work with nature

Table 1.2 Difference between conventional and sustainable farming systems

No. Conventional farming system Sustainable farming system

1 Rely on technological innovation and skills

Rely on farmers knowledge and skill management

2 Management technology depends on high capital investment

Management technology depends on low capital investment

3 Large scale and big farms Small and medium scale farms 4 Monoculture or single crop cultivation

over many years Diversifi ed crop cultivation

5 Extensive use of fossil fuel fertilizers, insecticides and energy

Reduced use of fossil fuel, rely on alternate natural cycles of waste

6 Rely on mechanization and less labor Rely on human resources and more labor demand

7 Rely on commodity supply chain Rely on value addition and direct marketing

8 More transportation and high pollution Less transportation and low pollution 9 Livestock depends on concentrated

system Livestock depends on pasture based system

10 High pollution to atmosphere and natural resources

Less pollution to atmosphere and natural resources

D.N. Bharadwaj

9

rather than against it. Decomposers have enormous possibilities to produce a sig-nifi cant quantity of bio-energy while still allowing the decomposers to feed the plants. It is possible to become more effi cient than it is today and to return suffi cient agricultural organic wastes to the soil to be more benefi cial to the decomposers.

1.3.2 Sustainable Resource Management

The increasing demand for food creates uncertainty because one of our greatest challenges is to increase food production in a sustainable manner with judicious use of natural resources, without over-exploiting them within balanced ecosystems (Cassman et al. 2002 ), so that everyone can be fed adequately and nutritiously. Sustainable farming must have a continuous fl ow of biological energy by recycling of nutrients through crop and livestock residues to the soil as organic matter restores healthy and productive organic soils that minimize the use of non-renewable inputs that are harmful to the environment, as well as the health of farmers and consumers (Goulding et al. 2008 ). Ecological agro-ecosystem management addresses energy- fl ows, the nutrient cycle, population-regulating mechanisms and system resilience. Sustainable agriculture outcomes can be a positive force for food productivity, it reduces pesticide use and carbon balances but it has signifi cant challenges and needs the support of national and international policies of governance in developed and developing countries.

A better concept of resource management is centered on intensifi cation of natu-ral resources i.e. land, water, biodiversity (fl ora and fauna), technologies, genotypes and ecological management practices that minimize harm to the environment. The basic resources for agricultural development are prone to various forms of degrada-tion. Therefore, it is necessary to develop strategies for conservation and improve-ment of these natural resources without compromising their stability for future use. The sun, air, water and soil are the four most important natural resources, of these, water and soil quality are highly subject to human intervention and pollution. Crop productivity is dependent on availability of soil nutrients and water, but without replenishment land suffers nutrient depletion and ultimately leads to reduced yields (Goulding et al. 2008 ). The authentic agricultural sustainability initiatives arise from shifts in the use of inputs of agricultural production e.g. from chemical fertil-izers to nitrogen-fi xing legumes; from pesticides to emphasis on natural biological control and from ploughing to zero-tillage. Sustainability of agricultural and resource management can be achieved by the following steps:

(a) Recycling of crops and livestock waste as manure. (b) Growing legume crops to enhance bacterial symbioses to sequester atmospheric

nitrogen. (c) Enhance production of nitrogen fertilizer from natural gas. (d) Use of renewable energy from hydrogen (water), solar and windmills. (e) Use of genetically engineered (non-leguminous) crops to fi x atmospheric

nitrogen.

1 Sustainable Agriculture and Plant Breeding

10

Water Water is the principal natural resource, without which agriculture is not possible; in future it may be a major limiting factor if mismanaged. An effi cient use of water can establish high crop production . During the dry season groundwater is the only source to sustain the crops; therefore, it is necessary today to conserve ground water by adopting following practices:

(a) Recharge of ground water and its proper storage. (b) Selection of drought-tolerant crop species/varieties. (c) Using drip irrigation or sprinkler systems to encourage economic water

consumption. (d) Growing crops with effi cient or minimum water use.

The quality of water can be conserved to reduce or stop salinization and contami-nation of surface and ground water from pesticides, nitrates and selenium . Salinization of soil becomes a major problem if the water table is near the root zone of the crops (Morison et al. 2008 ). The growing of salt-tolerant crops and drip irri-gation can minimize the effects of salinization. Pesticide and nitrate contamination of water can be reduced by cultivating drought-tolerant forages, agroforestry and restoration of wildlife habitat on farms.

Wildlife Conservation of wildlife habitat on agricultural land can reduce soil ero-sion and sedimentation. The support of wildlife diversity will enhance natural eco-systems and agricultural pest management (Green et al. 2005 ).

Air Air pollution is mostly caused by smoke from the burning of agricultural waste, dust from tillage, harvest and transportation, spraying of insecticides, pesti-cide and emission of other harmful gasses like nitrous oxide from fertilizer. The burying of crops residue in the soil, planting wind breaks, cover crops and perennial grasses on open land can reduce air pollution.

Soil Healthy soil is one of the most important components of sustainability; it involves management of physical, chemical and biological properties to contain large quantity of organisms to maintain the soil ecosystem (Kibblewhite et al. 2008 ). Organic matter and compost are nutrients for benefi cial soil micro-organisms such as protozoa, bacteria, fungi and nematodes. Properly managed soil organisms per-form vital functions to grow healthy and more vigorous plants; therefore, they are less susceptible to pests. Regular additions of organic matter can increase soil fertil-ity by increasing soil nutrients and microbes. Soil erosion caused by heavy storms, wind and fl ooding are a severe threat to crop productivity. The following methods can enhance the soil fertility.

(a) Crop rotation and cover crops. Rotation of two or more crops in the same fi eld interrupts pest reproductive cycles, reducing the pest control practices and fer-tilizer requirements, as one crop provides nutrients for the subsequent crop (Huang et al. 2003 ). Planting of cover crops improves soil quality, prevents soil erosion, minimize weed growth and better economic gains (Sullivan 2011 ).

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(b) Natural sources of soil nutrients. Indian hemp ( Crotalaria juncea ) and cowpea ( Vigna unguiculata ) can improve micronutrient availability; increasing soil organic content, physical properties, aggregate porosity, bulk density, water retention capacity and the fi xing of atmospheric nitrogen (Sullivan 2004 ). Use of organic manures can improve soil health by reducing salinity, sodicity and alkalinity (Yadav et al. 2013 ). Use of forestry crops, ally crops, sericulture and wasteland reclamation also stops soil erosion. Agro-industrial waste, rice husk/bran, bagasse/press cake, cotton dust, oil cake, wastes from slaughter houses, waste from marine industry, crop residue, recycling of biomass, vermin-culture and vermin-composts, pro-fertilizers, i.e. Rhizobium and Azotobacter , are all examples. FYM (farm yard manure) viz. waste, excreta undigested protein, urea, Ca Mg, Fe, P. and slurry bleeding enhance soil fertility.

(c) No-till or low-till farming. No-till or low-till farming systems minimize distur-bance to the topsoil residue cover and increases the retention of water and nutri-ents in the soil, making more water available for crops by improving infi ltration and decreasing evaporation from the soil surface.

Farm Diversity Regional farm diversity can reduce the vulnerability of food pro-duction to climate change . Although monocultural farms are more advantageous in terms of effi ciency and management, they are more vulnerable to pests and diseases (Fraser et al. 2005 ). Diversifi ed farms are more resilient economically and ecologi-cally and also create more niches for benefi cial insects and is less risky to farmers. Annual cropping systems with crop rotation are more effective to suppress weeds, pathogens, insect pests, and to maintain stability of soil fertility and to promote soil moisture conservation.

Carbon Chain According to recent carbon footprint analyses, the entire chain of food production and consumption accounts for 20 % of global greenhouse gas emis-sions. Reducing these emissions and increasing the long-term storage of carbon in the soil are, therefore, essential measures to prevent climatic catastrophe (Lal 2008 ).

Sustainable Renewable Energy Sources Non-renewable energy sources will not be available indefi nitely and their decline can be catastrophic in the future. Sustainable agricultural systems should not rely heavily on non-renewable energy sources and these must be replaced in the future with renewable, economical and feasible energy sources (Boyle 1996 ). Sustainable sources are biofuels, hydrogen, wind power, hydropower, geothermal energy, ocean energy, solar energy and bio- energy. Bio-energy from agriculture waste may lead to conserving food crops. Forage crops have more potential as crops for renewable biological energy because they capture about two-thirds of the total solar energy used in agriculture; together with forestry it can be doubled again. The use of forage crops to produce more renewable energy has two advantages: (a) most forage crops require less nitrogen fertilizer and pesticides than maize and soybeans, meaning less reliance on fossil energy in minimizing pollution and (b) most forage crops are perennial and require no annual tillage and thus cause less soil erosion; soil also being a good storehouse of biological ene rgy.

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Current technologies used to produce ethanol and biodiesel hold more promise to realize the limited use of non-renewable energy source and can replace petroleum energy signifi cantly. Pyrolysis is another alternative for renewable energy source.

Pyrolysis This is another high-priority area of sustainable bio-energy and one of the most promising technologies of the day (Marker et al. 2012 ). Pyrolysis is a form of chemical decomposition of organic materials under high temperature in the absence of oxygen; this process has been extensively used in the chemical industry to produce charcoal, activated carbon and methanol from wood. The technology needs to be adapted more widely. Pyrolysis has several signifi cant advantages over current methods of producing ethanol and biodiesel from maize and soybeans, as follows:

(a) Low-cost technology of varied sizes available for individual farmers, more fea-sible and cost competitive which can used for a wide variety of feed stocks (e.g. forages, non-food crops, wood and various wastes).

(b) A variety of useful products are produced such as biogas, bio-oil, chemicals, bio-char and tars.

(c) Bio-oil can be further converted into ethanol, biodiesel and biogases. Biogases can be again used to fuel the pyrolysis process to produce ethanol or biodiesel.

(d) Pyrolysis is less water consuming and does not pollute the air. (e) Bio-char can be added back into croplands to promote soil fertility as organic

matter that maintains soil ecology by promoting relationships between organ-isms and roots of the plants, water, carbon dioxide and nitrogen in the atmosphere.

(f) Bio-energy crops used in pyrolysis may sequester more greenhouse gasses than are released, as part of carbon is retained in the soil by the plant roots.

Further it is possible to fi nd ways to generate signifi cant quantities of bio-energy from the fl ow of the earth’s biological pyramid and nutrient recycling processes within ecological limits of sustainability, without compromising the effi ciency and integrity. However, the truly renewable energy are solar energy and hydropower.

1.4 Strengthening of Natural Agro-Ecosystems

Agricultural sustainability emphasizes the potential benefi ts from improved geno-types of crops and livestock and their agro-ecological management. It includes genetically modifi ed organic crops; provided they improve biological and economic productivity for farmers and do not harm the environment, along with ecological conditions under which they are grown. Higher productivity output is a result of interaction between genotype and environment (GxE) (Khush et al. 1988 ). Agricultural sustainability focuses on both genotype improvements through modern biological approaches, as well as improved understanding of ecological and agro-nomic management, manipulation and redesign (Collard and Mackill 2008 ; Flint and Wooliams 2008 ; Thomson 2008 ).

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Mature ecosystems must be in a state of dynamic equilibrium that acts as a buffer against large shocks and stresses. The present agro-ecosystems have weak resil-ience for transitions towards sustainability that need to focus on structures and func-tions that may improve resilience (Folke 2006 ; Holling et al. 1998 ; Shennan 2008 ). Sustainable agro-ecosystems have to balance the plant properties towards the natu-ral ecosystem without reducing productivity. To improve natural agro-ecosystem, biological diversity needs to create increased natural control and regulatory mecha-nisms to manage biotic factors (pests and diseases) rather than to eliminate them from the ecosystem. The conversion of traditional to sustainable agro-ecosystem is a complex process requiring a site-specifi c approach to restore resource manage-ment which is contributed by a number of important factors, their interactions and interrelationships; these factors include:

(a) Integrated Pests Management (IPM). This technique uses natural/biological ecosystem resilience, diversity of pest, disease and weed control; chemical pes-ticides are used only as a last resort when other options are ineffective (Bale et al. 2008 ; Hassanali et al. 2008 ). To keep destructive insects under control IPM emphasizes crop rotation, intercropping and other methods to disrupt pest life cycles. The cultivation of resistant Bt ( Bacillus thuringiensis ) plant varieties is also recommended to control pests.

(b) Integrated Nutrient Management. This includes balancing biological nitrogen fi xation within farming systems and supplementing with inorganic and organic sources of nutrients to soil if needed (Goulding et al. 2008 ).

(c) Agroforestry. This approach includes planting multifunctional trees in agricul-tural systems and their collective management to develop as nearby forest resources.

(d) Aquaculture. This involves development of aquatic fauna such as fi sh, shrimp and other aquatic resources into irrigated rice fi elds and fi sh ponds which enhances the protein production in farming systems (Bunting 2007 ).

(e) Water Harvesting. Owing to better rainwater retention in dry land or degraded land areas, crops can be grown on small plots under irrigation to improve water harvesting (FAO 2013 ; Morison et al. 2008 ; Pretty 1995 ; Reij et al. 1996 ).

(f) Livestock Integration and Rotational Grazing. In farming systems this consists of keeping livestock viz. dairy cattle, pigs and poultry, including using zero- grazing, and cut and carry systems (Altieri 1995 ; Wilkins 2008 ) which can enhance farm sustainability. Rotational grazing and periodic shifting of animals to different areas, prevents soil erosion by maintaining suffi cient vegetative cover, it also saves on animal feed costs, distributes the manure and contributes to soil fertility. The implication and adoption of the abovementioned practices can make several favorable component changes in the farming system. The growing of hedge rows and alley crops encourages many pest predators and also act as wind breaks to reduce soil erosion. The rotation of legume crops helps to fi x atmospheric nitrogen and also acts as a barrier crop to prevent carry-over of pests and diseases. Grass contour strips slow surface-water run-off which encourages percolation to recharge the water table and can be used as fodder for

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livestock. Catch cropping prevents soil erosion and leaching during critical periods and is a source of green manure which may increase soil organic matter with water-retention capacity.

(g) On-farm Biological Processes. These processes include the rebuilding of depleted natural buffers of predator stock and wild host plants that increase the levels of nutrients, enhancing exploitation of micro-environments and positive interactions between them which promotes sustainable productive agro- ecosystems (Firbank et al. 2008 ; Kibblewhite et al. 2008 ; Wade et al. 2008 ).

(h) Effi cient use of Inputs. It has been observed that sustainable approaches are less toxic, less energy intensive and more productive and profi table to farmers. This maximizes reliance on natural renewable on-farm inputs which largely impacts on the environmental, social and economic strategy. Conversion of any conven-tional farming system to a sustainable system does not mean replacement of chemical inputs only, but it substitutes enhanced resource management and use of scientifi c knowledge of packages and practices on farms and in rural communities.

(i) Zero Waste Agriculture. This approach represents a step towards sustainable agriculture which optimizes the use of fi ve natural kingdoms, i.e. plants, ani-mals, bacteria, fungi and algae to produce biologically diverse food, energy and nutrients in a synergistic integrated cycle and profi t-making processes where the waste of one process becomes the feedstock for another.

(j) Urban Agriculture. World urbanization is increasing at a rapid rate which is reducing the amount of agricultural land and its production. But this urbaniza-tion can also be used for human welfare if urban agriculture becomes an impor-tant component for agricultural sustainability. Urban agriculture can include animal husbandry, aquaculture, agroforestry and horticulture. As production is close to the consumer, it can reduce transportation costs, pollution from storage and packaging cost. Urban agriculture will also help in the disposal of urban waste, create economic development and improve food security in poor com-munities (Butler and Moronek 2002 ).

(k) Participatory Plant Breeding . The Green Revolution has left millions of farmers in developing countries in an uncertain situation; most of them operate small farms under unstable and diffi cult growing conditions. Adoption of new plant varieties by these farmers has been hampered by their lack of fi nancial resources and existing policies of proprietary rights which have been implemented to pro-mote an industrialized model of agriculture. The participatory plant breeding technology and the involvement of farmers in new research on varieties can be a good option to insure their participation (Pixley et al. 2007 ). In many coun-tries farmers and scientists have begun participatory plant breeding which is the best way to breed for sustainable agriculture; a good example is the organic durum wheat program in France.

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1.5 Plant Breeding Methodology for Sustainable Agriculture

Classical plant breeding programs have been very successful in producing cultivars suitable for favorable environments, together with necessary excessive use of fertil-izer and chemicals for control of weeds, pests and diseases, which have increased agricultural production several fold. The current high-input agriculture system has more unfavorable environmental impacts and is causing increasing concern with crops. The contribution of plant breeding to sustainable agriculture is important and based on following objectives:

(a) Enrichment of the source material with landraces and cultivars, accompanied by appropriate breeding methods for yield enhancements.

(b) Screening of cultivars, breeding techniques and their genotypic profi ling. (c) Selection in segregating generations should be based on individual plant evalu-

ation and performance which can reduce genotype × environment (G×E) inter-action with increased heritability .

These abovementioned techniques and further selection criteria can maximize heritability gain and provide effi cient solution in resolving sustainable agricultural problems.

1.5.1 Sustainable Use of Plant Genetic Resources

Plant genetic resources remain a key component of global food security , and to assure future peace and prosperity. Plants are the major source for human suste-nance, directly for human food, clothing and shelter, and indirectly in processed commodities and as animal feed. Since ancient times, crop plants have been sub-jected to several evolutionary forces and human selection processes from their wild ancestors to the domesticated/cultivated forms of today. The genetic diversity expresses individual traits, representing variation in the molecular building blocks of DNA which are at the core of a crop’s ability to undergo continuous variations. The combination of current breeding technology and genetic diversity are of great potential to adapt crops according to the choices of farmers and consumers. Plant genetic resources in agriculture have undergone evolutionary processes of conser-vation, diversifi cation, adaptation, improvement and then seed production systems. As genetic resources, traditional varieties are conserved in gene banks; in this regard the fi rst gene bank was created in the 1930s. There are now around 1,400 gene banks functioning worldwide, maintaining more than 504 million accessions. In situ and ex situ conservation gene banks are also maintained by farmers but without conservation information/data this biodiversity resource is underutilized for breed-ing purpose (Cohen et al. 1991 ). Plant genetic resources are the backbone of agri-culture and play a positive and unique role in the development of new cultivars (Malik and Singh 2006 ). Plant breeding functions as a bridge between the

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conservation in gene banks and production of improved varieties and their distribution among farmers for cultivation. For sustainable use of genetic resources, FAO is playing a key role under the following two strategies: (a) appropriate poli-cies and strategies at the regional, national and international levels to create a favor-able environment for sustainable use of plant breeding and seed sectors and (b) capacity building, providing educational and training support in developing coun-tries through various institutions in plant breeding and the seed sectors.

1.5.2 Agriculture Biodiversity and Food Security

Agricultural biodiversity is the foundation of food security throughout the world; species biodiversity and farming systems provide valuable ecosystem functions for agricultural production (FAO 1996 ). The sustainable use of conservation and enhancement of agro-biodiversity is valuable for insuring food security because there are several serious threats to loss of agro-biodiversity; therefore there is a criti-cal need to rapidly adopt an agro-ecosystems approach to genetic resource conser-vation and integrated ecological pest and soil management.

1.5.3 Plant Genetic Resources

Diverse genetic resources provide an array of potentially useful traits to the plant breeder which are exhibited in landraces and wild varieties, for resistance to dis-eases, pests and environmental stresses (e.g. heat, drought, cold ) that are highly desirable in achieving improvements in crops (Brown et al. 1989 ). In this context, a good example is the rice grassy stunt virus disease that seriously damaged rice fi elds from Indonesia to India in the 1970s. About 6,273 varieties were tested for resis-tance to the virus ; ultimately an Indian variety was found suitable to breed success-ful resistant hybrid varieties which are still widely cultivated. Similarly, in other countries, rich biodiversity exists in crops such as cereals , fruits, vegetables, indus-trial crops, oil crops and forages, which can contribute signifi cantly to agricultural diversifi cation (Feehan et al. 2005 ). By recombining this genetic diversity, many new varieties have been developed by modern plant breeders with improved traits never before available to farmers .

1.5.4 Exploitation of Existing Germplasm

Only a scant 0.1 % of the world’s plant species are grown as crops and only a very small proportion of the total genetic variability is represented by commercial variet-ies. Exploitation of plant diversity can be used to achieve breeding objectives in

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major crops, to develop new crops, to meet emerging needs from existing crops, to ensure benefi t to the world’s population from breeding programs and to ensure the sustainability of crop production . Species that are rarely cultivated and genes from accessions and species related to existing crops, can be exploited to satisfy the need for improvement of agricultural production. Molecular and statistical methods have the potential to speed up introduction of novel germplasm, to allow quantitative assessment of diversity, characterization of desirable genes, tracking of chromo-somes, genes, or gene combinations through breeding programs, selection of rare recombination and direct gene transfer through transformation. Several underuti-lized plants have potential for improving agriculture in diversifi ed agro-ecological niches; these have great potential for exploitation as economic products for food, fodder, medicine, energy and industrial purposes (Bhag Mal and Joshi 1991 ).

1.5.5 Breeding for Abiotic Stresses

Agricultural sustainability depends on genotypic improvements and its environ-mental interaction through modern biological approaches and better understanding of ecological, agronomic management, manipulation and redesigning or remodel-ing of crops. As in the case of cereal crops, abiotic stress factors such as low nitro-gen, drought, salinity and aluminum toxicity causes large and widespread yield reductions; therefore, breeding for tolerance to these abiotic stresses is important (Bänziger et al. 1999 ). Drought severity and occurrence is predicted to increase with climate change and the area of irrigated land is subject to increased salinization and the cost of inorganic N is set to increase. Breeding for low N can be adopted while retaining the ability of the crop to respond at high N input. Breeding for drought and salinity tolerance together is a diffi cult and complex trait but this mechanism can be explored by marker-assisted selection (MAS) for component traits. MAS for drought tolerance in rice and pearl millet , and salinity tolerance in wheat, has evi-denced some encouraging results by the pyramiding of stable quantitative trait loci which is controlling the component traits. The understanding of processes and iden-tifi cation of responsible genes for genomic technologies has revealed great potential for breeding tolerance to drought and salinity stresses in wheat due to contributions from their wild relatives .

1.5.6 Wide Hybridization

Plant tissue culture techniques have successfully produced progenies in a number of useful crosses in distantly-related species. Several interspecifi c and intergeneric hybrids have been produced by crossing related species/genera that do not normally reproduce sexually; these crosses are referred to as wild crosses , as in the case of triticale which is a hybrid between wheat and rye, where the F 1 progeny was sterile

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due to an uneven number of chromosomes but by doubling of the chromosomes (with colchicine) during cell division which inhibited cytokinesis, a fertile line was produced by Rimpu in 1890 ( http://www.agriinfo.in/ ). This sterility in the F 1 hybrid may be due to pre- or post-fertilization incompatibility.

If fertilization occurs between two species or genera of wheat and rye (Fig. 1.3 ), the hybrid embryo may abort before maturation; if this happens the embryo can be rescued by an embryo rescue procedure and cultured to produce a whole plant. Using this technique an interspecifi c cross of Asian rice ( Oryza sativa ) and African rice ( O. glaberrima ) has produced a new rice for Africa. Hybrids can also be pro-duced by protoplast fusion techniques where protoplasts are fused together, usually in an electric fi eld and viable recombinants regenerated in culture media.

1.6 Organic Agriculture

The objective of sustainable agriculture is to encourage crop production with reduced use of non-renewable inputs such as nutrients, pesticides, water and other maintenance; this concept was formulated by Albert Howard, an English botanist and organic farming pioneer, in the 1940s. In recent years the use of natural resources, management of plant diseases, insects and pests, has begun to point the way for sustainable agricultural plants as invaluable resources. Careful plant selec-tion is the fi rst important step in developing a balanced and self-perpetuating farm-ing system. Plant survival with minimal maintenance is not the only issue in sustainability for there is a diffi culty with invasive exotic plants, displacing native plants and disrupting natural ecosystems. Sustainable agriculture mainly is a rejec-tion of the industrialized food production and gear-up to feed the ever-growing global human population. Organic agriculture seems to be the best approach for sustainable agriculture because it is a rapidly growing sector that focuses on

Fig. 1.3 Wide hybridization between, wheat and rye produced triticale grain

D.N. Bharadwaj