eChapters

3.1. INTRODUCTION

Heterosis is the superiority of the F1s over the parental forms. The term heterosis was first used by Shull (1910) to describe the interpretation of increased vigour, size, fruitfulness, speed of development, resistance to diseases and insect pests or some other characteristics manifested by out-breeding organisms as compared to corresponding inbreds. Exploitation of heterosis is gaining momentum due to increased yield, quality, uniformity, better desirable traits and management of biotic stresses. The future of most of the economic crops will be for hybrids for sustainable development of higher economic returns to the farmers. Sustainable increase in area under hybrid crops is witnessed by its popularity and adoption by the farmers.

4.1. INTRODUCTION

Rice (Oryza sativa) is the major food crop in the world. Nearly 40% of the world population consumes rice as the major staple food. Most of the people, who depend on rice as primary food, live in the less developed countries.  Archeological evidence on rice in India dates back to 1500-1000 B.C. Since the dawn of civilization, rice has served humans as a life-giving cereal in the humid regions of Asia and, to a lesser extent, in West Africa. Introduction of rice into Europe and the America has led to its increased use in human diets. There are 42 rice producing countries throughout the world but China and India are major rice production centers. Rice is grown in wide range of agro-climatic conditions ranging from mountainous (Jammu) lands to low land delta areas (Sundarban), spanning an area from 53° latitude north to 35° south of the world but about 90% of the crop is grown and consumed in Asia. Rice provides fully 60% of the food intake in Southeast Asia and about 35% in East Asia and South Asia. The highest level of per capita rice consumption (130-180 kg per year, 55-80% of total caloric source) takes place in Bangladesh, Cambodia, Indonesia, Laos, Myanmar (Burma), Thailand, and Vietnam (Kenneth and Kriemhild, 2000). In many cultures of the world rice is the central part of people’s life and culture. Rice is an excellent food and is an excellent source of carbohydrates and energy.

5.1. INTRODUCTION
     
Rice is an important provider of nourishment for the world’s population. Indian scented rice, ‘Basmati’ has dominated the domestic and international market for aroma. Aromatic rice is an important commodity worldwide and command premium price over non-scented varieties. Most of the trade in aromatic rice is from India, Pakistan and Thailand. Bulk of aromatic rice from India and Pakistan consist of Basmati, while Thailand is the supplier of Jasmine rice. The Indian subcontinent has the Natural Gift of basmati rice that has been accepted as the best scented, long and slender grain in the world markets and gets high price. In addition to Basmati, many local landraces are grown traditionally, which excel in aroma, grain quality and cooking quality. Most of these genotypes are short bold to medium bold grain and hence not traded in the international market. However, in the domestic market its demand is greater than the Basmati rice. These are mainly used for special preparation, such as Khir in Bengal.

6.1. INTRODUCTION

After introduction of TN-1 (Taichung Native-1), Jaya, IR8 and other high yielding rice varieties during sixties and seventies, the productivity increased drastically and remained at plateau since last three decades. With no possibility to extend land area for rice cultivation in Asia, there is some scope for production advantages in rice through further expansion of high yielding varieties coverage in Pakistan, Thailand and India, expansion of area under irrigation in Bangladesh, Cambodia, India, Myanmar, the Philippines, Thailand and Vietnam, or expansion of boro rice in Bangladesh, India and Myanmar. Thus, utilization of heterosis has become one of the main methods for increasing yield. Hybrid is one of the viable and proven technologies to improve rice productivity. China is the first successful country to produce hybrid rice in appreciable quantity. This technology not only helped China to increase the rice productivity, but also to save land for crop diversification. The 'National Food Security Mission' has been launched envisaging increase of annual rice production by 10 million tons by 2011-'12. Here, hybrid rice may play important role to achieve the assigned target.

7.1. INTRODUCTION

The cultivation of wheat (Triticum spp.) reaches far back into history. Wheat was one of the first domesticated food crops and for 8000 years has been the basic staple food of the major civilizations of Europe, West Asia and North Africa. Today, wheat is grown on more land area than any other commercial crop and continues to be the most important food grain source for humans. Its production leads all crops, including rice, maize and potatoes.

Wheat is special in several ways. It is grown on more than 240 million ha, larger than for any other crop, and world trade is greater than for all other crops combined. The raised bread loaf is possible because the wheat kernel contains gluten, an elastic form of protein that traps minute bubbles of carbon dioxide when fermentation occurs in leavened dough, causing the dough to rise (Hanson et al., 1982). It is the best of the cereal foods and provides more nourishment for humans than any other food source. Wheat is a major diet component because of the wheat plant’s agronomic adaptability, ease of grain storage and ease of converting grain into flour for making edible, palatable, interesting and satisfying foods.

8.1. INTRODUCTION

Exploitation of heterosis through development of hybrid wheat is one of the most attractive options to increase wheat productivity. The efforts on developments of hybrid wheat started in early fifties (Kihara, 1951; Fukasawa, 1953) through cytoplasmic male sterility system (Livers and Heyne, 1968). Later, in seventies, research works from public as well as private sectors have shifted their efforts to the use of gametocide (chemically hybridizing agent-CHA), and a number of gametocides were tested in eighties. In wheat, heterosis is especially interesting for grain yield and for the resistance of plants to both parasites and climate risks (Rousset, 1986). With this advantage in mind, the first phase of hybrid wheat development started in the United States in 1975. Chronological events of wheat hybrid development have been given in Table 8.1. Subsequently, a number of hybrid wheat has been released in countries such as Argentina, France, and United States (Pickett, 1993).

9.1. INTRODUCTION

Maize (Zea mays L. ssp. mays 2n = 20), known as corn in some countries is an important cereal crop of the world. The scientific name from Greek word ‘Zea’ for a kind of grain and West Indian word ‘malnis’ for corn. Maize was domesticated in Mesoamerica and hence formed the Mesoamerican people’s identity and later it spread throughout American continent. Maize is widely cultivated throughout the world and a greater weight of maize is produced each year than any other cereal grain. USA produces almost half of the world’s harvest (42.5%) and other top producing countries include China, Brazil, Mexico, Argentina, India and France. During the year 2007, worldwide maize productivity was around 4970 kg per ha. Maize is the only cereal that can be harvested and used at various stages of plant development. The crop can be cultivated on a wide area from 580 N to 400 S from below sea level to altitudes higher than 3000 m and in areas with 250 mm to more than 5000 mm of rainfall per year (Shaw, 1988, Dowswell et al., 1996).

10.1. INTRODUCTION

The development of hybrid breeding methodology in maize and its successful application to exploit heterosis is considered as significant achievement of plant breeding in the present century. 
Even though Beal (1880) suggested for commercial cultivation of F1 varietal hybrids. It was Shull (1909) on the basis of his experiment gave pure line method of corn breeding, which laid foundation for present day hybrid breeding. Pure line methods of maize breeding involve three steps. 
    
·    Large scale inbreeding to obtain many homozygous/nearly homozygous inbred lines. 
    
·    Testing the selected inbred lines in all possible crosses.
    
·    Practical utilization of inbred lines in seed production of single cross hybrids.

11.1. INTRODUCTION

Sorghum [Sorghum bicolor (L.) Moench] is the fifth most important cereal crop and is the dietary staple of more than 500 million people in over 90 countries, primarily in the developing world. It is grown on 47 m ha in 104 countries in Africa, Asia, Oceania, and the Americas. Among those, USA, Nigeria, India, Mexico, Sudan, China, and Argentina are the major sorghum producers globally. Sorghum grain is mostly used directly for food (55%), and is consumed in the form of porridges (thick or thin) and flat breads; however sorghum is also an important feed grain (33%), especially in Australia and the Americas. Stover (crop residue after grain harvest) is an important fodder source to both milch and draft animals in mixed crop-livestock systems. Sorghum is also a good source of green fodder due to its quick growth and high yield and quality of biomass. Of late, sorghum with sugar-rich juicy stalks (called sweet sorghum) is emerging as an important biofuel crop. Thus sorghum is a unique crop with multiple uses as food, feed, fodder, fuel and fiber. Sorghum is generally grown in rainy season (spring) but in India it is grown in both rainy and postrainy seasons. The postrainy season sorghum grain is prized for its food value (Reddy et al., 2009).

12.1. INTRODUCTION

Sorghum [Sorghum bicolor (L.) Moench] is an important food/feed/fodder crop in more than 90 countries across the world and it is one of the cheapest sources of energy and micronutrients (Reddy et al., 2009; Ashok Kumar et al., 2011). Considerable efforts have been made to improve sorghum productivity through genetic enhancement and crop production and protection research all over the globe. Sorghum being an often cross-pollinated crop with cross pollination up to 2-15% depending on genotype and environment (House 1985), initially, pure-lines were the target products although phenomenon of heterosis was demonstrated in sorghum as early as in 1927 (Conner and Karper, 1927). Predominant self-pollinating nature of sorghum with tiny florets with single seed per emasculation and pollination prevented commercial exploitation of heterosis for commercial sorghum production. However, the discovery of a stable and heritable cytoplasmic-nuclear male-sterility (CMS) mechanism (Stephens and Holland, 1954), enabling large-scale, economic hybrid seed production gave a fillip to the exploitation of heterosis since early 1960s. The first commercial sorghum hybrid CSH 1 was released in 1964 in India. Using CMS mechanism, large number of commercial hybrids have been developed and released/marketed for commercial cultivation in all sorghum growing regions with strong Indian National Agricultural Research Systems (NARS).

13.1. INTRODUCTION

Pearl millet crop has a wide adaptability to local environments. It is hardy and can be grown in areas which are very hot and dry and on soils too poor for sorghum. Pearl millet is considered more efficient in utilization of soil moisture and has a higher level of heat tolerance than even sorghum and maize. It is adapted to warm and dry climate but most of the area under the crop is in drought- prone areas of the world. In these areas, pearl millet is usually grown with limited inputs, sparse rainfall, low soil fertility, and also face disease and pest problems, with correspondingly poor yields.
 
The low average yields are primarily a result of the hot, dry conditions where pearl millet is mostly grown, rather than pearl millet plant’s capability. Pearl millet hybrids grown under better conditions yield 3000 to 4000 kg/ha compared to 300 to 800 kg/ha when moisture and soil fertility become limiting factors. A majority of the subsistence farmers who typically cultivate this crop are unable to take advantage of high yield potential because they have limited options for improving their management practices. Pearl millet production can be increased through growing varieties/hybrids with improved tolerance to drought, diseases and responding to higher rates of fertilizer applications.

14.1. INTRODUCTION

Barley (Hordeum vulgare L. emend. Bowden) is one the most important ancient crops and played very important role in the development of agriculture and human civilization. It has also played crucial role in the progress of science of agriculture, physiology, genetics, plant breeding and malting and brewing science. It is the fourth most cereal crop after rice, wheat and maize in acreages and production in the world.  It is grown and used all around the world in many countries and has fed livestock, poultry and people since ancient time.  Barley was domesticated about 10,000 years ago in the Fertile Crescent of the Near East. Fertile Crescent is considered the first of at least seven primary centres of agriculture origin in the world (Smith, 1998; Baik and Ulrich, 2008). Barley is best known around the world as a feed grain and a premier grains for malting and brewing. When most people think of composition of beer, they only think of barley over other cereals. Although utilization of barley for food is relatively low as compared to other cereals today, throughout its history barley has remained an important and major food source poor people living in Western and Eastern Asia and Northern and Eastern Himalayan region nation like Tibet, Nepal and in Northern and Eastern Africa (Newman and Newman, 2006, 2008). Moreover, there has been resurgence of interest and use of barley as food primarily in the developed world due to an increasing emphasis on incorporating the diversity in consumption of whole grain in people’s diets due to its health benefits.

15.1. INTRODUCTION

Finger millet Eleusine indica (L.) is an Old World cereal grass commonly known as ‘finger millet’, is one of the staple food crop especially in India and Africa, which is widely grown in the arid regions of Asia and Africa and important minor millet grown in India.  Eleusine, the generic name, is obtained after the “Eleusine” the Greek Goddess of cereals and the common name finger millet is derived from the finger like branching of the panicle. It is also know by Goosegrass, Yardgrass, Wiregrass, Silver Crabgrass, Crowfoot Grass. It is commonly known as Finger millet in English, Kelvaragu in Tamil, Nachani in Marathi etc. Some Indian varieties of finger millet are Kempu ragi, Ragalli shivalli, Pichakaddi etc.  This crop is one among the hardiest crops which can with stand severe drought conditions and can also grow well under scanty rainfall condition. However with good irrigation facilities the yield of finger millet matches with crops like rice. Finger millet seeds remain free of pests and insects for a long duration extending up to 50 years hence serving as a food reserve in case of tough situations like famine.

16.1. INTRODUCTION

Millets are a large part of the basic diet for farm households in the world's poorest people in the poorest countries. The production of millets on average for the 5 years have been given in Table 16.1. Top consuming countries are India, Nigeria, Niger and China. However, just because a country is a top global consumer does not mean that millet is a significant source of calories for them. India and China are rank as the 1st and 4th consumers of millet, but due to their population size they rank 11th and 38th in per-capita consumption, accordingly.

Millet particularly the finger millet) is an excellent dietary source of calcium, iron, manganese, and methionine-  an amino acid lacking in the diets of hundred of millions of the poor who live on starchy foods such as cassava, plantain, polished rice, and maize meal. Millet use is diverse, including in cereals (including porridge and kasha), soups, breads and stuffings, fermented beverages, and baby food.

17.1. INTRODUCTION

Yam bean is one of the adaptable, low-maintenance, and nutritious food crop grown in moderate soil. It has many synonyms, in India it is known as Mishrikand (Hindi), Keshar or Ram-kaseru or Shankalu (Bengali). The root crops produced by legumes have long recognized as important and the FAO (1979) has recommended them as a source of human nutrition. The tuber is rich in starch (15-20%), 3-4% sugar, and have considerable amount of protein (2-3%). The harvested crop keeps well for months under ambient temperature. Kale (2006) observed relatively high iron contents in storage roots (up to 130 mg/kg of storage root dry matter). It can also be used for alcohol production.

The crop is very hardy, resistant to common insect pests and diseases. Most important is that the crop is not grazed neither by goats nor cows. The crop grows well in hot-humid environment and requires long, warm frost-free growing season. A moist, light textural soil is preferred for production of tuberous roots. As a legume crop, it can be grown without nitrogen fertilizer. Under good growing condition its root nodules habour symbiotic colonies of nitrogen-fixing bacteria- Rhizobium spp. (Nielsen et al., 1998b). A season crop of yam beans can release as much as 53 tons of usable nitrogen per acre into the soil. Mycorrhyzae also associated with the crop, thus facilitating phosphorus uptake. Thus, yam bean is highly suited to the needs of small farmers, and from both an ecological and a socioeconomic perspective

18.1. INTRODUCTION

Plant genetic resources (PGRs) are the foundation for the development of a food and nutritionally secured society. Food is the foremost important to sustain life and livelihood followed by shelter and cloth. Thus, the slogan of 3Fs may be modified as, “Food, Frame (shelter) and Fibre (cloth)”. All these 3Fs we can get from PGRs. There must be balance between demands and resources. Gradually the demand for basic needs increasing. So, we have to improve the PGRs to cope with the increasing demands. PGRs are the foundation for the development of these 3Fs. India is a country rich in crop biodiversity and genetic resources. The status of Germplasm accessions in the National Gene Bank is being presented in Table 18.1.

Plant breeding/genetic improvement aims at altering plant genotypes in a way that they suit human needs for food, feed and industrial raw products and support sustainable plant production. In that sense, plant breeding may be regarded as the evolution of plant type by the will of mankind. Plant breeding/genetic improvement is important because an improved cultivar is the most-economic and least laborious input for farmers.

Plant breeding is one of the early accomplishments of humankind. Many of the cultivated plants are the result of slow and involuntary improvement from wild progenitors by human being over centuries. In fact, the process of domestication of wild plants is one of the most fascinating chapters in the history of humankind. Concept of plant breeding came in the being through domestication as it involved selection of the most desirable types. Among the ancient domesticates, some of the vegetable crops are front-runners, like peas, radish, muskmelon, watermelon, etc. Other present day popular vegetable crops were domesticated later in the Neolithic times. Some species including certain vegetables are still undergoing the domestication process. However, for all practical purposes, the breeders have given up domestication of wild relatives of the cultivated species. Today, breeders often incorporate important characters, like resistance to biotic stresses, adaptability to environments, etc. to the cultivated forms from their wild relatives.

Selection from the available variations is the oldest and the most effective breeding procedure. However, genetic recombination at present forms the basis of modern plant breeding approach. In this respect, Josef Kolreuter’s extensive crossing experiments between 1755 and 1806 were essentially the first attempts to scientifically-reconstruct naturally occurring species and types by combining their characters. Any way, no matter what method is adopted in the breeding approach, it inevitably involves selection, which is the most difficult part of overall breeding process.

The industrial revolution in Western Europe and concomitant flourish of capitalism and increasing commercial agricultural production stimulated breeding activities as a profitable venture of capitalistic economy. Throughout the 19th century, thousands of large and small seed companies were developed in Germany, England and the United States out of this impetus.

Dietary constitution of Indian people is mostly cereal based. However, the cereals supply chiefly carbohydrates. Therefore, there is deficiency of protein, minerals and vitamins, especially vitamin A, riboflavin, vitamin C, etc. in the diet. The dieticians advocate the intake of 125 g leafy vegetables, 75 g other vegetables and 100 g root and tuber vegetables (total 300 g) everyday because vegetables provide all the nutrient components like carbohydrates, protein, fat, minerals, vitamins and water along with roughages, which are the essential constituents of a balanced diet.

India has attained food security by increased cereal production due to green revolution. In case of vegetables, although there has been increase in production from 15 million tonnes during 1950 to 94 million tonnes in 2005 but still more vegetables are needed to meet the minimum requirement of at least 250 g per day per capita. There has also been increasing demand for fresh export and for processing industries. Moreover, there is a pressure for increasing vegetable supply caused by constantly increasing population in a world of limited acres.

Addition of new agricultural land is of course not possible. In this situation, plant breeding can be expected to contribute substantially to greater vegetable productivity. This can be accomplished not only by the breeding of basically higher yielding varieties but also by the development of varieties that help to stabilize production through resistance to various biotic and abiotic stresses.

Vegetables are cheaper source of carbohydrates, proteins, minerals, vitamins and dietary fibers, and hence, assume a place of very great importance in the diet of individuals. All kinds of vegetable are grown almost universally. India occupies the prime position in the production of vegetable crops and is the second largest producer of vegetables in the world. The area and production of vegetables in India have been increasing during the post-green revolution period, and the country is heading towards another revolution in the form of Golden Revolution. However, there is an utmost requirement for genetic improvement of vegetable crops in terms of productivity, qualitative characters and resistance to biotic and abiotic stresses. For any genetic improvement programme, the presence of genetic variation is pre-requisite and mutation is the ultimate source of this heritable variation.

Mutation technique that holds promise of generating a much wider desirable variability than classical breeding has been refined. Out of 2275 mutant varieties worldwide in all crops, as many as 66 mutants are in vegetables. In terms of percentage, China, India, USSR, The Netherlands, The United States of America and Japan account for 26.8, 11.5, 9.3, 7.8, 5.7 and 5.3%, respectively of mutagen varieties in all crops. Such varieties are 3% in case of vegetables. After mutation treatment by a mutagen to a specific plant, DNA alterations (deletion, duplication, inversion, translocation, or transposition of larger DNA fragments, or simple basic pair changes) occur and lead to the DNA sequence change. Hence, new characteristics of that plant are established. In fact, induced mutations supply us with many new plant lines, which may be used as primary materials for crop breeding. Hence, mutation breeding seems to be an effective and ultimate option to improve vegetable crops in the shortest possible time. A large number of new promising varieties in different crops, including vegetables, have successfully been developed worldwide using various mutagens (Chopra, 2005).

Vegetables have always been looked upon as an essential part of diet and are necessary for human health and well-being. Vegetables supply many kinds of nutrients, e.g., carbohydrates, proteins, minerals, vitamins, fibers, phytochemicals, etc. and also add flavour, colour and crispness to foodstuffs. For developing modern day vegetables, breeders have utilized an understanding of genetic principles and applied them for the improvement of these crops. They often make crosses (hybridization) between a crop plant and a related or wild species (a wide cross) enabling valuable genes to be used for genetic improvement of the crops. Over the last few decades, molecular breeding is supplementing plant breeder’s efforts for accelerated genetic enhancement bringing about a revolution in this area. This approach demands efficient procedures for the routine introduction of foreign DNA into plant genomes and utilizing them for the production of novel types of vegetable. In this chapter, attempts have been made to review most of the available molecular breeding techniques, which can routinely be employed in various aspects of vegetable improvement.

Cultivars are developed by selecting for desired traits or by removing undesirable traits that are controlled by genes (the blueprint for all characteristics in living organisms) from existing varieties or breeding lines. The plant species, varieties and clones are identified or selected by their physical features since olden times. However, these traits would change with respect to environmental and climatic conditions. The biochemical parameters like enzymes, proteins, alkaloids, etc. are also likely to change due to the stages of development of plant tissue. Successful selection strategies are dependent on the breeder’s ability to distinguish genetic effects from environmental effects on a visible or measurable trait. Therefore, the scientists resorted to use ‘genetic marker’, i.e., any stable and inheritable variation that can be measured or detected by a suitable method and can be used subsequently to detect the presence of a specific genotype or phenotype, which otherwise is very difficult to detect. Presently, the breeders and scientists all over the world are pursuing mostly DNA or molecular markers.

Hybrid vigour is used as a synonymous of heterosis. In 1910, the term heterosis was first used by Shull who defined this phenomenon as the stimulus of heterozygous, and in his word, it has been the “interpretation of increased vigour, size, fruitfulness, speed of development, resistance to insect-pests and diseases or to the climatic rigors of any kind manifested by the out breeding organism as compared with corresponding inbreds as a specific result of the unlikeliness in the constitution of uniting parental gametes”. This definition is often interpreted as not implying a genetic basis for heterosis, because the definition basically describes the phenotypes that result from the crossing of two different inbred lines. Generally, heterosis is manifested as an increase in vigour, size, growth rate, yield, or some other characteristics but in some cases, the hybrid may be inferior to the weaker parent. This also represents as heterosis (average heterosis), and if heterosis is estimated over the superior parent, such an estimate is sometimes referred to as heterobeltiosis, hence, authors feel “heterosis refers a biological phenomenon in which the F₁ population obtained by crossing of the two genetically dissimilar gametes or individual shows increased or decreased vigour over better parent or over the mid-parental value. Earlier, Power (1944)also suggested that the term heterosis should be used only when the hybrid is either superior or inferior to both the parents. Other situation should be regarded as partial or complete dominance. It can be easily explained with the help of Table 5.1.

Diseases of plants are produced by a variety of organisms from plant and animal kingdoms viz., fungi, bacteria, viruses, nematodes and insects. The diseases reduce total biomass (dry matter) production and consequently yield of the crop by general stunting, damage to the leaf tissues, fruits and seeds or by killing the plants. The degree of damage would depend upon the intensity of infection but both need not be proportional. One serious effect of disease is the disappearance from cultivation of otherwise excellent but susceptible varieties.

Vegetable crops have been found to be highly susceptible to biotic stresses from the disease causing microorganisms and insects-pests. The ability of pathogen and insect-pests to attack and proliferate in the host plant is highly specific. There are wide differences in the host plants in response to the attack by pathogens and insects. Although control of the diseases and insects by the use of chemicals is possible to certain extent but indiscriminate use of fungicides or insecticides over the crop has several disadvantages. Besides increasing cost involved in chemical control, residual toxicity of the chemicals such as fungicides, antibiotics and insecticides in food chain and development of resistance against pathogens and insect-pests to different chemicals are serious problems.

Genetic improvement of host plants conferring resistance to diseases and insect-pests is considered to be the best approach in the management of diseases and insect-pests, and this is more particularly true in case of vegetable crops. Indiscriminate use of chemicals in the vegetable sector has led to health hazard. This has resulted in switching towards organic vegetables. However, cost of production of organic vegetables naturally will not permit the common people to consume these products. Therefore, the best option is to induce resistance in the host varieties. The resistant varieties could in turn be an important component in the organic vegetable farming, thereby reducing cost of production to certain extent.

Concern for improvement of nutritional quality of vegetables has arisen in the context of providing nutritional security to our ever-increasing population. Nutritional security denotes the consumption and physiological use of adequate quantities of safe and nutritious food by every member of the family and encompasses the process of equitable distribution among members of household and communities (Nandi and Bhattacharjee, 2002). This would entail the need to ensure a varied food intake, comprising all the essential macro-and micronutrients (protein, carbohydrates, minerals and vitamins), plant pigments (lycopene, beta-carotene, anthocianin, lutein, capsanthin, zeaxanthin, etc.) and other functional phytochemicals (secondary metabolites, like flavonoids, isothiocyanates, glucosinolates, etc.) through a diversified diet. In this regard, production and consumption of vegetables that are the valuable source of micronutrients, beneficial phytonutrients and highly functional phytochemicals hold the key in assuring nutritional security.

Implication of vegetables in diet has been well conceived among the high-income group in the world since human health in recent years has assumed an unprecedently important status. Increased interests in nutrition, fitness and beauty have exaggerated concerns over diet and human health. A new diet-health paradigm is evolving which places more emphasis on the positive aspects of diet. Foods have now assumed the status of functional foods, which should be capable of providing additional physiological benefits, such as preventing or delaying the onset of chronic diseases as well as meeting basic nutritional requirements so with high-income elasticity, the demand for vegetables and perception of diversified diet have been growing steadily, hence, both access and consumption of vegetables have been increasing in the urban and peri-urban population groups. However, meeting the requirements for macro- and micronutrients for most of the population groups in households and communities of South Asia, Latin America and African countries seems far off because of meager presence of vegetables in the diet. In south Asia where meat intake is low, ascorbic acid emerges as one of the most important enhancers of iron absorption. This is attributed to the fact that foods containing vegetables may provide an optimal mix of minerals, vitamins, antioxidants, dietary fibers and other non-nutrients bioactive compounds.

India is contributing about 10% of the world’s vegetables, and in terms of production, the country stands second after China. The existing area under vegetable cultivation in India is around 6.89 million hectare with a production of about 96.54 million tonnes. There will be a demand of 151-193 million tonnes of vegetables in India by 2030 (Dhaliwal et al., 2006). There are extensive crop losses in vegetable crops due to increased insect infestations. Since vegetables are grown round the year, there is carry over of insect-pests across the seasons and also from sowing until harvesting. Vegetables also invite more pest problems because of their cultivation under high fertility conditions leading to high plant succulence. High yielding varieties and hybrids are further more prone to the attack of insect-pests. Insect infestation affects the quality and market value of vegetables adversely and it is estimated that 30-40% of the total production is lost due to the attack of pests (Lal et al., 2004). A large number of pesticides are being used repeatedly to manage the insect-pests in India. Indiscriminate use of pesticides has led to many problems like toxic residues in edible parts of the vegetables, adverse effects on non-target organisms and beneficial insects, resurgence of secondary pests and development of resistance in major pests to pesticides and also environmental pollution. Therefore, latest approach has been to minimize the use of highly toxic insecticides by integrating different strategies of pest control like use of biological control agents, pesticides of plant origin, insect resistant varieties and other cultural practices. In this chapter, efforts have been made to highlight the distribution, host range, identifying characters, biology and nature of damage of important insect-pests of vegetables and also the methods of their management crop or pest wise.

Introduction

Agricultural soils harbour a rich variety of nematode fauna, where they coexist with a myriad of other microorganisms. It has been estimated that one cubic meter soil of highly fertile field may contain as many as 3×10¹⁴ bacterial cells (300 g), 5×10⁸ protozoa (39 g), 1×10⁷ nematodes (12 g) and fungi (400 g), besides other organisms. The nemic fauna comprises of free-living (saprophagous and microbivorous), predatory forms and plant parasites (phytophagous). In addition, certain animal and insect parasitic forms may spend a part of their life cycle in soil. Plant parasitic nematodes (PPNs) exist in poly-specific communities and attack all types of plants- cultivated or wild. They possess a needle-like stylet or spear at their anterior end, which is used to puncture the plant cells and ingest the cell contents. Majority of PPNs dwell in soil and draw their nutrition from plant roots. Only a few forms attack the above ground plant parts such as stem, leaves, inflorescence and seeds. PPNs may be ectoparasites (feed from outside and do not enter plant tissues) or endoparasites (enter inside the plant tissues). The endoparasites spend a part of their life cycle in soil or may come out into the soil to re-infect the other roots. These may be further categorized into migratory or sedentary types. The migratory forms keep on moving, feeding and laying eggs that are scattered in soil or plant tissues. The sedentary nematodes are more harmful and a particular stage of their life cycle infects the plant and establishes a feeding site by modifying plant tissues by their enzymatic secretions. The females of sedentary nematodes usually attain swollen shapes upon maturity and lay hundreds of eggs in clusters.

Plant parasitic nematodes are ubiquitous, and so far, more than 1800 species have been recorded. They are obligate parasites and must feed upon plant hosts, thus, debilitating the plants to some extent. The extent of direct damage by the nematodes to plants depends on several factors viz., nematode density in soil, nature of parasitism (ectoparasite or endoparasite), host susceptibility, cropping pattern, edaphic factors (mainly soil texture and moisture) and ambient climatic conditions (like temperature and relative humidity). Nematodes, by themselves, rarely kill the plants to ensure their own survival. Nematodes also inflict considerable indirect damage to crops by interacting with other plant pathogens (fungi, bacteria and viruses) to cause disease complexes in which nematodes act as incitants, aggravators, or vectors.

Vegetables being good source of carbohydrates, proteins, minerals, vitamins and dietary fibers constitute important component of human diet. These are the cheapest source of natural protective food and increase the palatability. India is the second largest producer of vegetables next to China. Diseases are inherent component of agro-ecosystem, which must be dealt with continuous and knowledgeable basis. Diseases in the standing crop from the seedling stage until harvest and spoilage caused by microorganisms during transit, storage and marketing are major constraints in increasing production and availability of vegetables. At different stages of vegetable production, disease management requires several approaches, and it is more successful, if it is integrated into crop production system. Since vegetables are mostly grown year after year in the same fields especially near towns and cities, therefore, concerted efforts are required to manage the diseases. More than 300 diseases have been reported to occur on vegetable crops and it is beyond the scope of this chapter to discuss all the diseases. However, brief description of etiology, diagnostic symptoms and management practices being adopted are presented here for the economically important fungal and bacterial diseases of vegetable crops.

Plant viruses, like all other viruses, are obligate intracellular parasites that do not have the molecular machinery to replicate without the host. The plant viruses are defined as viruses pathogenic to higher plants. The discovery of plant viruses causing disease is accredited to Beijerinck who determined in 1898 that the plant sap obtained from tobacco leaves with the mosaic disease remained infectious even after passing through a filter. This was in contrast to bacteria, which were retained by the filter. Beijerinck referred to the infectious filtrate as a contagium vivum fluidum, thus, he used modern term virus.

Viruses occasionally cause significant problems in vegetable crops. However, the prevalence and severity of viral diseases differ from year to year. Aphids spread many of the viral diseases observed in vegetables. There are two types of viral transmission by aphids, i.e., persistent and non-persistent transmission. It is important to understand the difference between these two because persistent and non-persistent viruses differ both in their uptake and behaviour within the insect vector, consiquently, tactics used to limit their and spread vary considerably. In persistent transmission, the aphid usually carries the virus for life. Uptake of virus requires extended feeding and after an incubation period of several hours or days, the virus replicates and circulates within the insect. Because of the time required for feeding before acquisition by an insect vector, the spread of persistent virus is favoured by colonizing aphid species that spend time in the crop. Controlling the aphid vectors with insecticides can reduce the spread of persistent plant virus significantly. In contrast, aphids can acquire non-persistent viruses (NPV) within a few seconds after sampling an infected plant. Winged migratory aphids can move quickly from infected plants onto healthy ones, transmitting the virus in the process. Aphids rapidly lose the virus particles from their mouthparts, which are cleaned when they feed on the next available plant and are unable to transmit disease to additional plants. Because of the speed in which aphids acquire and transmit non-persistent viruses, insecticides are not usually effective in controlling their spread. One of the most common viruses found in many vegetable crops is cucumber mosaic virus (CMV). This is transmitted by several aphid species in a non-persistent manner. There are several strains of CMV that can infect over 775 different plant species in 85 families including snap bean, peppers, tomato, lettuce, tobacco and sugar beets. Symptoms vary depending upon the plant species infected but range may be from yellow-green mottling on leaves and fruits to severe stunting of plants. The viral diseases affecting different vegetable crops are being discussed below:

Post-harvest deterioration primarily means the loss of commodity after harvest. It is one of the serious problems for producers, distributors and consumers. Post-harvest deterioration of perishables is the spoilage of fruits and vegetables after harvesting. Perishables are the feed commodities with moisture content between 50 and 90%. Fruits with the size of 5 g to 5 kg or more, high to very high rate of respiration, high generation of heat, soft texture, easily damageable nature and shorter shelf life are more prone to the microbial damage. The post-harvest losses are caused either by pathological, physiological and mechanical means or combination of all these. These perishables because of having minerals, vitamins, and photochemicals (essentially required for the human health) become victim to the several biotic and abiotic factors easily. Once these fruits are detached from the plant are deprived of essential ingredients as hormones, nutrients, water and other requisites. These biotic and abiotic factors apart from rendering the produce unfit for human consumption reduce the aesthetic value, substantial decrease in food value and also organoleptic quality of the vegetables. The fleshy produce are prone to the exogenous agencies such as fungi, bacteria, etc. as well as other endogenous factors such as respiration, senescence, etc. which may lead to poor quality of the produce and also affect market quality. These perishables continue to respire and may carry out various biochemical activities, leading to ripening subsequently to senescence and making them more susceptible to microbial damage. In addition, tropical conditions prevailing in India, which are characterized by high temperature conditions, are optimal for fungal and bacterial infections. In India, the post-harvest losses of fresh fruits and vegetables are estimated to be about 30%. The post-harvest losses have been recorded are 5-20% at farmer’s field due to pre-harvest infection and sorting, 15-20% due to faulty packaging, 30-40% during transportation and 30-40% during marketing.

Key Facts
    
·    The United Nations Framework Convention on Climate Change (UNFCCC) defines ‘climate change’ as a ‘Change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over the comparable time periods’.
    
·    The main green house gases (GHGs) that have caused the global climate change or global warming are carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O).
    
·    CO₂ is the principal anthropogenic GHG that affects the earth’s radiative balance. It is the reference gas against which other GHGs are measured and therefore has a Global Warming Potential (GWP) of 1. CH₄ and N₂O have a GWP of 21 and 310 respectively.
    
·    CO₂ is responsible for most of the enhanced green house effect of more than 50%, CH₄ for about 10-15% and N₂O for about 8%.
    
·    The global atmospheric concentrations of CO₂, CH₄ and N₂O have increased since 1750. While CO₂ increased from a pre-industrial value of 280 ppm to 379 ppm in 2005, CH₄ increased from 715 ppb to 1774 ppb and N₂O increased from 270 ppb to 319 ppb during the same period.

Key facts

Agriculture
    
·    Agriculture production (plant growth) is highly dependent on climate since crop growth is influenced by solar radiation, temperature and precipitation and sensitive to climate variability and weather extremes (droughts, floods, severe storms).
    
·    Climate change is projected to have an effect on local agriculture and the net result could be harmful (e.g. frequent droughts, salinization of agriculture land due to sea level rise) or beneficial, (e.g. enhance CO₂ and higher yield, longer growing season, increased precipitation) or mixed.
    
·    Climate change or a doubling of GHGs (2 x CO₂) is projected to cause both gains and losses of agriculture land.
    
·    Each crop has a specific temperature range at which vegetative and reproductive growth will proceed at the optimal rate and exposures to extreme temperatures during these phases can impact growth and yield. Higher temperatures during the reproductive stage of development can affect pollen viability, fertilization and grain or fruit formation. 
    
·    Warming generally allow plants to grow faster that are below their optimum temperature, however for cereal crops faster growth means there is less time for the grain itself to grow and mature, reducing yields. 
    
·    Night-time temperatures are rising faster than daytime temperatures and are expected to continue rise in the future. According to International Rice Research Institute (IRRI), Philippines, the rise of night time temperature decreases rice yield by 10% for each 1°C increase in growing-season night time temperature in the dry season.

Key Facts
        
Agricultural food
    
·    There are multiple pathways through which climate-related factors may impact food contamination and food safety, food quality, foodborne diseases including changes in temperature and precipitation patterns, increased frequency and intensity of extreme weather events, ocean warming and acidification and changes in the transport pathways of complex contaminants.
    
·    All or most foodborne pathogens and their associated diseases are linked to changing environmental conditions, the notable of which are campylobacteriosis, salmonellosis and vibriosis.
    
·    An estimated 30% of reported cases of salmonellosis across much of continental Europe have been attributed to warm temperatures, especially when they exceed a threshold of 6°C above average. Likewise both in Australia and Canada a positive correlation was found between increasing temperature and incidence of salmonellosis.
    
·    Zoonosis such as Rift Valley Fever (RVF), West Nile Fever, tick-borne diseases and non-zoonotic animal diseases such as Blue tongue, African horse sickness, African swine fever are examples of animal diseases whose distribution is expected to be strongly influenced by climate change and variability.
    
·    Mycotoxin is a toxic secondary metabolite produced by filamentous fungi, commonly known as moulds and may contaminate agricultural commodities (food) by growing on them both before and after harvest, whenever the humidity and temperature are permissive. The most prominent mycotoxins are aflatoxins, deoxynivalenol, zearalenone, ochratoxin-A, fumonisin, and patulin.
    
·    The humans ingestion of mycotoxins occur through consumption of the mycotoxin contaminated plant-based foods, such as grains, maize, barley, rice, coffee, nuts and their residues, and metabolites in animal-derived foods, for example aflatoxin M1 (AFM1) in milk and meat products. In addition, mycotoxins may occur in beer and wine.

Key facts
    
·    The Food and Agriculture Organization (FAO) defines food security as a ’situation that exists when all people, at all times, have physical, social and economic access to sufficient, safe and nutritious food that meets their dietary needs and food preferences for an active and healthy life’. There are four dimensions of food security: Food Availability (availability of sufficient food for all people at all times, i.e. production); Food Accessibility (physical and economic access to food at all times, i.e. affordability), Food Utilization (access to food that is nutritious, safe and produced in environmentally sustainable ways, i.e. nutrients in food and food safety); and Food Stability (reliability of adequate food supply).
    
·    Agriculture is important for food security since it provides food for the people and is the primary source of livelihood for 36% of the world’s total workforce. In the heavily populated countries such as Asia and the Pacific, about 40% to 50%, and in sub-Saharan Africa, about two-thirds of the working population make their living from agriculture.
    
·    Agriculture, livestock and fisheries production are all sensitive to climate and are affected by its changes. Climate change will increase hunger and malnutrition, emergence of new pests and diseases and will threaten fishing and aquaculture industries.

Key facts
        
Agriculture and livestock
    
·    The Intergovernmental Panel on Climate Change (IPCC) defines adaptation as ‘adjustment in natural or human systems in response to actual or expected climatic stimuli or their effects, which moderates harm or exploits beneficial opportunities’. The adaptation can be considered as tackling the effects of climate change, whereas mitigation is tackling the cause of climate change such as reducing the sources or enhancing the sinks of greenhouse gases. There could be different types of adaptation such as autonomous (spontaneous) and planned adaptation (policy decision).
    
·    Autonomous adaptation includes altering varieties and/or species those are more appropriate to the altered thermal regime or with increased resistance to heat shock and drought; altering the timing or location of cropping activities; altering fertilizer rates to maintain grain or fruit quality consistent with the climate and altering amounts and timing of irrigation and other water management practices; diversifying income by integrating other farming activities such as livestock raising, integrated agriculture and aquaculture/fish farming; development and use of varieties and species resistant to pests and diseases, wider use of technologies to ‘harvest’ water, conserve soil moisture (e.g. crop residue retention) and to use water more effectively in areas where rainfall is projected to decrease and using seasonal climate forecasting to reduce production risk.

Climate Change has emerged as one of the most serious environmental concerns of recent times. The most imminent climatic change is increase in atmospheric temperature due to increased levels of greenhouse gases such as carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O) and hydrochlorofluoro carbons (HCFCs). Because of increasing concentrations of the greenhouse gases in atmosphere, there is much concern about future changes in the climate system viz., Atmosphere, Lithosphere, Biosphere, Hydrosphere and Cryosphere. Direct or indirect effects on the society linked sectors like water, forestry, agriculture, animal agriculture, fisheries, land and marine biodiversity and health due to climate change/variability are many-fold and economic impact of climate change is enormous. The recurrent drought and desertification threaten seriously the livelihood of over 1.2 billion people who depend on land for most of their needs.

Natural disasters are of meteorological or hydrometeorological origin. Disasters such as earthquakes and tsunamis are occasional, but rainfall-related hazards, flood or drought, are very frequent and thus call for proper monitoring of large-scale rainfall variation, and better manage- ment and planning to combat the problem(s). Variation in rainfall is very large spatially and temporally compared to any other atmospheric parameter, such as pressure or temperature. The large temporal variability in the Indian rainfall has produced frequent flood/drought and periods of above/below normal rainfall for several centuries past. Areas of high rainfall and runoff are flooded in the summer monsoon season whereas others face water stress and drought conditions. The influence of global warming on rainfall variations over India is reported in numerous observational (Singh et al., 1991, 1992) and modelling studies (Lal, 1994). 

Food security is one of the most important issues during this century under the projected climate change scenario. The world is facing severe food crisis due to weather vagaries as a part of global warming and climate change. Many countries are under severe food crisis during the crisis of weather abnormalities since 75 per cent of world’s population is dependent on agricultural activities for their livelihood. Therefore, there is an urgent need to produce more and more foodgrains at the global as well as national levels to meet the food requirement of growing population under the projected climate change scenario. There has been a major decline in world rice production since late 2007 due to various reasons including global warming and climate change in top rice producing countries. 

The Intergovernmental Panel on Climate Change (IPCC) in its fifth assessment report (AR5) stated that warming of the climate system is unequivocal and is more pronounced since the 1950s. The atmosphere and oceans warmed, the amounts of snow and ice have diminished, and rise in sea level is noticed. Each of the last three decades has been successively warmer at the earth’s surface than any preceding decade since 1850 and the globally averaged combined land and ocean surface temperature data show a warming of 0.85°C over the period 1880 to 2012. The recent years viz., 2015, 2016 and 2017 were the hottest years on record. The warming trend in India since 1961 has indicated an increase of 0.9°C, which is likely to impact many crops, negatively impacting food production. There are already evidences of negative impacts on yields of wheat and paddy in northern India due to increased temperature, water stress, and reduction in number of rainy days. Coastal agriculture has the onus of providing livelihood to nearly 20 % of Indian population. The water logging and coastal salinity are the major factors affecting the agricultural output from the regions.

Climate risk management in the semi-arid tropics (SAT) is one of the major challenges to achieving food security and development in India and large parts of sub-Saharan Africa and also in the case of Australia. Climate-induced production risk associated with the current season-to-season variability of rainfall is a major barrier in making rainfed agriculture sustainable and viable farm business. Since season outcomes are uncertain, even with the best climate information, farmers have limited flexibility in applying management with confidence. In fact in risky environments, farmers most often respond by adapting a risk averse strategy and are reluctant to invest in even risk reducing measures (Leathers and Quiggin 1991). In the SAT agro-ecologies, there are a limited range of enterprise or crop options to consider which may be further restricted by cultural traditions, food preferences or market opportunities.While there are fundamental differences between large scale commercial farms in Australia compared to the predominantly smallholder resource poor farms found in India, when it comes to climate risk management in the SAT, there are many commonalities. The purpose of this paper is therefore to (i) establish a framework for managing climate variability and transforming farming systems to be more resilient and sustainable for future climates; and (ii) provide some case study examples from climate risk management in low rainfall cropping system in Australia and consider how they may be applied in smallholder systems of the SAT.

The State of Kerala has witnessed an unprecedented and unusual flood which devastated the entire State during August 2018 after the notorious 1924 flood, popularly known as the flood of 1099. Heavy rainfall from 14 to18 August 2018 led to flash floods across the State. This was aggravated by the dam opening and subsequent water level in the downstream of the rivers. 33 dams were opened across the State. This has caused the river water to flow into the inland areas. Rivers overflowed and inundated the river side villages and towns. It was reported that the water levels at many places were of the order of 20 feet. Landslides were the major threat that claimed many human lives. A chain of mud slip/land slide events took place during the heavy rainfall period at the time of flood across the mid and high lands of the State, which are ecologically sensitive areas. Even before the heavy rainfall events started on 14th August, 2018 there were major rainfall events on August 8thand 9th. On 9thAugust 2018, Nilambur (Malappuram District) recorded extremely heavy rainfall of 400 mm which is a record rainfall in 24 hours as far as the State is concerned.

Tamil Nadu has unique physiography with western and eastern Ghats on the west and northwest, Bay of Bengal in the east and Indian Ocean to the south. Tamil Nadu has high dependence on natural resources and hence faces the threat of climate change and its impacts. Available evidence shows that there is high probability of increase in the frequency and intensity of climate related natural hazards (Stephen, 2012). Out of 13 million hectares of geographical area, about 7 million hectares of land is under cultivation. Of this 55 per cent is irrigated and rest is under rain fed / dry lands. In Tamil Nadu, ground water has been harnessed fully and dry land productivity is found oscillating with ruling variability in seasonal monsoon rain and hence agricultural productivity is always under stake.

The State of Karnataka is located between 11.50° to 18.50° N latitudes and 74.25° to 78.50° E longitudes and covers an area of 19.1 m ha which accounts for 5.8 percent of the total geographical area (TGA) of the country. Out of the total 19.1 m Ha in Karnataka the net cultivated area (2010-11) was 10.5 M Ha, net irrigated area 3.49 m Ha and net rainfed cultivated area 7.01 m ha. Karnataka has the largest area under rain-fed agriculture (Fig. 8.1). Nearly 55% of total food grain production and 74% of oilseeds production come from rainfed agriculture in Karnataka. Therefore rain-fed agriculture plays an important role in total food grain production in the state. Further the rain-fed agriculture has substantial untapped potential, which can be brought to use by increasing the crop yields in the dry land areas through the adoption of proper dry-land production technologies. The climate of the state is determined mainly by the geographical location with respect to the Sea, monsoon winds and physiography.

The extreme weather events of the present day and the expected future climate scenarios at global and regional scales have been attributed to the changes in the atmospheric chemical composition and the massive amounts of greenhouse gases (GHGs) emitted by humans since the industrial revolution, bringing about the global warming and resulting in Climate Change. Further, the natural disasters like flash floods are attributed to the highly conspicuous human interventions with nature – the earth and its atmosphere. The parody of the situation is that, while the GHGs sourcing countries are mainly the developed ones, the sink of the result are the agrarian-dominated and eco-sensitive economies of the tropics. Invariably, tropical regions are to be affected the most, because, on the one hand the general circulation of the atmosphere directly and naturally causes divergence of the polluted air from extra tropical regions towards tropics, while on the other, the industrialization within the tropical regions too would affect the local atmosphere. Karnataka State, being located well within the tropics, can be truly impacted by the climate change caused by anthropogenic sources and it is demarcated into 10 agroclimatic zones (Fig. 9.1) based on crops, soils and climate. Climate experts have warned that Karnataka is likely to be more vulnerable to climate change than other states in India.

The State of Andhra Pradesh in the present form came into being on June 2, 2014 as a result of the Andhra Pradesh Reorganization Act. The state has 13 districts out of which nine are along the coast of Bay of Bengal and four are land locked in the southern part. A part of Khammam district, which is now in the Telangana state, was also added to the East and West Godavari districts of the State of Andhra Pradesh. The existing data for these two districts do not include this part and this fact is to be borne in mind. The state has a geographical area of 1.602 lakh km2 with a population of 49.83 million. The state in the current form is more agrarian compared to the undivided state as about 62 per cent of population depends on agriculture as a source of livelihood. Yet, the contribution of agriculture to the state’s gross domestic product is only 17 per cent. Though the state is known as ‘rice bowl of India’, not all is well with agriculture in the state. Some parts, especially the coastal districts, are prone to incidence of cyclones and floods while some other districts, Rayalaseema districts, are chronically drought-prone. 

Evidence is fast accumulating that the problem of climate change is of a scale not previously encountered by human societies. The scale and scope of climate change challenges to food and water security are unprecedented. World food supply is already facing significant pressures. Even without climate change, ensuring sufficient food for all in the 21st century would be difficult enough. Climate influences food security through many channels. Climate change will increase the severity and frequency of cyclones, flooding and drought. It will intensify rainfall variability, increasing water stress, weeds, pests, and erosion and reducing soil fertility. Above certain temperature ranges, crops develop more rapidly, resulting in lower overall grain production, even moderate increases in temperature can decrease yields in major food crops. Population growth, urbanisation, higher per capita calorie intake, and increasing consumption of meat combine to put more pressure on exiting water recourses.

Importance of rice in Konkan area is characterized by heavy rains of 100 mm per week or so over an extended period and contributes 42.9 % of total rice production in the Maharashtra State. Rice is the only suitable crop that can be grown under puddled soil conditions, i.e. with standing water over bunded fields. Tansplanting method of rice is commonly followed by most of the farmers in this region. Puddled rice is said to be of assistance in mitigating the effects of floods. The problem of weeds is minimal in puddled rice culture. Thus, rice serves as a livelihood crop for millions of small, and marginal farmers in Konkan who can afford only low-cost technologies. Even though the crop is robust and versatile, it has faced drawbacks in terms of low yield and reduction in acreage. In Konkan region of Maharshtra, there are two agro climatic zones viz., North Konkan coastal zone comprising three districts viz., Thane, Raigad and Greater Mumbai and South Konkan Coastal Zone comprising two districts viz., Ratnagiri and Sindhudurg. Ratnagiri district receives the highest rainfall of > 3500 mm while Thane district receives the lowest rainfall (2000-2500 mm) in this region. Sindhudurg and Raigad districts receives 3000-3500 and 2500-3000 mm rainfall, respectively.

In order to achieve maximum and sustainable crop production from available farm resources, it is essential to have proper knowledge of the agro-climatic resources of the location/region. Therefore, a thorough understanding of the climatic conditions would help in determining the suitable agricultural management practices for taking advantage of the favorable weather conditions and avoiding or minimizing risks due to adverse weather conditions. better planning of cropping pattern, developing irrigation and drainage plans for an area (Chaudhary et al. 2015). Hence, trends of temperature and rainfall are studied in this section with possible impact studies on rice production for Chhattisgarh state. Challenges of rainfed rice production can be understood through trend studies of key weather variables. Analysis of rainfall in the context of rainfed rice production in Chhattisgarh state has been carried out. Analysis has been done at Department of Agrometeorology under All India Co-ordinated Research Project (Raipur) to characterize the key weather parameters statistics.

The Inter-governmental Panel on Climate Change  has confirmed that change in climate system is gradually leaving a strong impact. Observations undoubtedly show that there is increasein global temperatures, wide spread melting of snow and ice, and rising global mean sea level. Global climate has shown warming of 0.89 [0.69 to 1.08] °C over the period 1901–2012 which is mainly attributed to anthropogenic activities. Scientific findings indicate that warming is more pronounced than expected and the impact would be particularly severe in the tropical areas, which mainly consist of developing countries, including India (Shukla, 2016). Thus, climate change is a great challenge which is continuously being faced by the sustainable economic growth of the India. Climate sensitive sectors like agriculture, forestry, hydrology oriented sectors faces major threat due to projected changes in climate. India Meteorological Department (IMD) in 2012 reportedincreasing temperature trends during last 112 years and increase in heavy rainfall events and decrease in low and medium rainfall events over India.

India, as a developing country has reasons to be concerned about the adverse impact of climate change on its economy. A large part of its population depends on climate sensitive sectors for livelihoods which makes it highly vulnerable to climate change. Climate change can have serious impact on its crops, forests, coastal regions, etc. which can in turn affect the achievement of its important national development goals. The issue of climate change cannot however be taken up without linking it to developmental needs such as poverty, health, energy access and education. Traditionally climate change experts have focused on mitigation measures, adaptation measures have also been acknowledged of late as effective and equitable means to deal with climate change impacts. Most of the mitigation measures are high in terms of technology and capital. Therefore, while developed economies choose to mitigate climate change by making heavy investments, developing economies choose to adapt (Monika and Hooda, 2018). There is increasing recognition that the world’s current progress on reducing greenhouse gas emissions is not occurring rapidly enough to avoid impacts from climate change in the coming century. Because of this, the world is “committed” to a certain level of global warming and therefore,

Climate change is one of the most important global environmental challenges facing humanity and as per the instrumental records, the earth’s climate system has demonstrably changed on both global and regional scales since the preindustrial era. Further evidence shows that most of the warming (of 0.1°C per decade) observed over the last 50 years, is attributable to human activities. The levels of greenhouse gases namely carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) have increased markedly as a result of human activities. The CO₂ concentration in atmosphere is now more than 400 ppm and the decadal increase is from 0.86 ppm per year to 1.99 ppm per year (Table 16.1) which is the highest ever. The Intergovernmental Panel on Climate Change (IPCC, 2007) projects that the global mean temperature may increase between 1.4 and 5.8 oC by 2100. This warming of the earth-atmosphere system is expected to have severe impacts on the global hydrological system, ecosystems, sea level, crop production and related processes. Agriculture sector is the most vulnerable entity in light of the global warming and its impacts.

The Jammu and Kashmir State lies in the extreme North of the Himalayas and constitutes about 67.5 per cent of the North West Himalayan region. The State is predominantly a mountainous state with all the major Himalayan ranges and trans-Himalayas adequately represented. The State of Jammu and Kashmir located in the north Western corner of India, extends between 32o-17' and of 37o-50' North parallels of latitude and 73o-26' and 80o-30' East of meridians of longitudes and 81o East of Greenwich. The State on the basis of physiography may be divided into three main regions (i) outer Himalayas which comprise of Jammu province (ii) lesser Himalayas which comprises of Kashmir Valley and (iii) inner Himalayas which comprise of Ladakh province. Jammu, Kashmir and Ladakh regions have distinct agro climatic characteristics. Jammu region has two different climatic zones depending primarily on altitude. Lower hills & plains bear subtropical climate with hot dry summer lasting from April to July. The summer monsoon commences around first fortnight of July and fading away in early September.