eChapters

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:

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.

Among abiotic stresses, low and high temperature stress is very critical for determining the agricultural production. Plants exhibit a maximum rate of growth and development at an optimum temperature or over a diurnal range of temperatures (Fitter and Hay, 1981). When ambient temperature deviates from optimal, physiological, biochemical, metabolic and molecular changes occur within plants. This is an effort of plants to maximize growth and developmental processes and to maintain cellular homeostasis during such adverse conditions. Under increasingly stressful conditions, plants experience progressively more abnormal, impaired or dysfunctional cellular and whole-plant processes until the cardinal temperatures for survival are reached (Fitter and Hay, 1981). At the extremes of the natural temperature range of a plant, the degree of physiological, cellular, metabolic and molecular dysfunction becomes so severe that it leads to death.

Growth constraints and stress result in significant crop losses and therefore the mechanisms underlying endurance and adaptation to these changes have long been the focus of intense research (Bray 2004). Kültz (2005) elaborated two types of responses to a particular kind of stress:

A

Abnormal seedling: Abnormal seedlings are those seedlings which do not show the capacity for continued development in to normal plants when grown in good quality soil under favourable conditions of water supply, temperature and light.

Abortion: Loss of reproductive structures (e.g. a flower or an ovule) during development or arrest of development of any organ so that it remains imperfect or fails to reach maturity.

Absolute humidity: The amount of water vapour present in a given volume of atmosphere, usually expressed in g water per kg dry air, or g water per cubic meter air.

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.

6.1 Introduction

Plant breeding is the indispensible component of elevating production and productivity of spices by evolving high yielding and/or with good quality type. Thereby, the practice of identification and selection of desirable traits and introgression of those characters in a single plant is being done since the beginning of organized agricultural activities by humankind. The act of plant breeding was reshaped and got a momentum with a scientific basis after the discovery and rather rediscovery of Mendel’s laws. Worldwide, humankind could enjoy the direct benefits of methodical plant breeding during green revolution. Manipulation of genetic architecture for creating variation in the population and successive selection is the basic of all kinds of crop breeding. But the process of creation of variability and selection differs from crop to crop depending on their mode of reproduction. It is comparatively easier to get a new homogeneous population in self pollinating plants. Therefore, segregating generations are handled differently in these two categories of self and cross pollinated crops.

7.1 Plant Tissue Culture

Spices have great socio-economic impact in moden food habit of human but loss of resources day by day due to various reasons (industrialization, high population pressure) make the access of these valuable spices limited to people. Low production is general phenomena of common spices due to lack of high yielding varieties. Hence there is a need to improve the propagation method to meet the gap between demand and supply. Conventional vegatative propagation method is common approach for propagation but low multiplication rate, seasonal dependency and susceptible to abiotic stresses and diseases are major problems to achieve the optimum productivity. To overcome these drawbacks scientists have chosen the plant tissue culture technique (a modern approach of biotechnology which deals with the propagation the valuable/endangered plants under laboratory condition). Details about this technique and its role on spices are given below.

Plant Tissue Culture: Basic Components and Objectives

The technique of growing of a whole plant cell, tissue or organ under an aseptic condition in suitable synthetic medium is termed as plant tissue culture (Thorpe, 2007). De-differentiation and re-differentiation are two essential fundamental processes which help in the physio-morphological development of the plant.

3.1 Introduction
Since the dawn of humanity, the expansion of invention and technological innovation has made it possible to make a variety of goods to meet its needs. To get a competitive edge in the market, the manufacture of a product has three main goals, viz. efficient product planning, efficient manufacturing, and effective cost control.
These can be achieved through a random thinking, if the designer is fortunate to have the best design of a product of interest, which satisfies the needs of its customers. But it will rarely happen. Design thinking maximizes the possibility of happening of the best design in the journey of design a product in shorter possible time.
Design thinking, an emerging field in this direction, tries to create a product by utilizing the following steps.
i. Empathize
ii. Define
iii. Ideate
iv. Prototype
v. Test
3.2 Definition of Design Thinking
A design methodology called “Design Thinking” offers a problem-based approach to problem solving. By understanding the human needs which changes quickly, re-framing the issue in human-centric ways, generating a lot of ideas during brainstorming sessions, and taking a hands-on approach during prototyping and testing, design thinking is incredibly helpful in handling complicated challenges that are ill-defined or unknown. Anyone can use the Design Thinking approach to tackle complex problems that arise in our society, such as those in our businesses, governments, and other spheres of influence, if they have an understanding of these five steps of the process.

India is a major exporter of vegetables with 10th position in the world. In the past, the Dexport of Indian vegetables was restricted to potatoes and fresh onions, however, now, the Government of India finds great opportunities for expanding exports of several vegetables including lettuce, fresh peppers, tomatoes, squashes, gherkins, etc. Under World Trade Organization (WTO) regime, the development of stronger seed industry and improved production technology will give India a competitive edge in global market. New opportunities and challenges are emerging every day in the dynamic and global vegetable-based industries. However, such opportunities can be harnessed only if assured quality, in terms of organic farming and reduced pesticide residues, is maintained (Shanmugasundaram, 2004).

Heterosis

The superiority of F₁ hybrid over both its parents in terms of yield or some other characters or heterosis is increased vigours, growth, yield or function of a hybrid over the parents, resulting from crossing of genetically diverse organisms. The term heterosis was first coined by Shull in 1914. Generally heterosis manifested as an increase in vigour, size, growth, yield or some other characteristics. But in some cases, hybrid may be inferior to the weaker parent this is also regarded as heterosis.

Most of us consider weeds to be the troublesome, competitive, aggressive, undesirable, unsightly elements of the plant world. We hate weeds since desirable plants cultivated by us are deprived of food, water, sunlight and space by these plants. They can easily colonize an area and thrive even under non-ideal conditions of growth and may affect human welfare adversely. It is perhaps due to this that the saying, when weeds win all the people lose, has come into existence.

The terminology committee of the Weed Society of America gives the simple definition of weed as a plant growing where it is not desired. King (1974) in his book Weeds of the World observed that ‘‘a plant classed as a weed in one region where it has few, if any, uses may when growing in another region, possess some very valuable uses, or in few cases may actually be cultivated’’. For instance, Bermuda grass (Cynodon dactylon) is a highly troublesome weed in crop fields, but in village pastures, it is a much sought for forage grass. Quack grass (Agropyron repens) is a very good soil binding grass on erodable non-crop lands but it is a serious weed when it infests crop fields and orchards. Campbell (1923) considered weeds as ‘honest, independent competitors for food materials in the struggle for existence’. He pointed out that the term, weed has developed in the minds of people not according to specific qualities or by a definite concept in the mind of man, but by human caprice, e.g., corn is a cultivated crop, hence, desirable plant in a corn field. However, if a corn plant grows in a Soya bean field, it is considered a weed by the Soyabean farmer. Sometimes, two persons may differ about the weedy nature of a plant at the same place and time, e.g., water hyacinth (Eichhornia crassipes) is a weed for fisherman but it is a plant of aesthetic value for a city dweller.

Thus, a corollary to the above definitions of weed is that weeds are those plants, which grow out of their place, interfere with the utilization of natural resources, prolific, persistent, resistant, competitive, harmful and even poisonous in nature and can grow under adverse conditions.

The importance of vegetables in human nutrition is now well known all over the world. Vegetables are rich and comparatively cheaper source of minerals and vitamins. Their consumption in sufficient quantities provides taste and palatability, increases appetite and provides fair amount of fibre. Besides, they provide many specific chemical substances, which are essential for growth, reproduction and for the maintenance of good health and also beneficial in protecting against some degenerative diseases (Prior and Cao, 2000; David, 2005; Elison and Levin, 2006).

Apart from their nutritive value, vegetables probably do more than any other groups of food to add colour, texture and flavour to our daily diet. Majority of the population in India is vegetarian, and thus, vegetables form an essential item of food for both the rich and the poor people. National Nutrition Monitoring Bureau (1997) surveys indicated that the daily intake of most foodstuffs in Indian households, except for cereals and millets, is much below the recommended dietary allowances (RDA). The diets provided negligible amount of protective foods. It was found that consumption of green leafy vegetables (< 10 g) and other vegetables (70-80 g) per day, which are rich source of micronutrients, are woefully inadequate. However, as per the RDA, an adult man should consume 200 g roots and tubers, 100 g green leafy vegetables and 100 g other vegetables (Table 1) in a day. In addition, fresh fruits (100 g) as available in different seasons should be consumed regularly for the prevention of chronic diseases (NIN, 1998).

Introduction

Seed certification is a legally approved system for quality control of seed multiplication and production. Seed certification procedures are designed to ensure physical and genetic purity, freedom from other crop seeds, objectionable and other weed seeds and designated diseases with good germinability of the foundation and certified seed. Seed certification is done by the State Seed Certification Agency of the concerned state (SSCA) notified under section 8 of the Seeds Act, 1966 or by National Seed Corporation (NSC), where State Seed Certification Agency does not exist. The General Seed Certification Standards are applicable to all crops, which are eligible for certification, while field and seed standards are applicable to individual crop, constituted as the minimum seed certification standards. The word ‘seed’ or ‘seeds’ as used in these standards also includes all the propagating materials. Seeds or propagating material, which does not meet the standards of seed certification prescribed in the Indian Minimum Seeds Certification Standards, 2013 (Gunasekaran and Trivedi, 2013), are not certified by the Seed Certification Agency. The general seed and field standards for various crops are given at the end of this chapter.

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.

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).

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.

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.

Many materials can be applied to the soil as source of plant nutrients but the term fertilizer is often used to refer to relatively soluble nutrient sources with a high analysis or concentration. Commercially available fertilizers supply essential elements in a variety of chemical forms but many are relatively simple inorganic salts. Advantages of commercial fertilizers are their high water solubility, immediate availability to the plants, high concentration and low price per unit of nutrient, and the uniformity and accuracy with which specific amounts of available nutrients can be applied. Since they are relatively homogeneous compounds of fixed and known composition, it is fairly easy to calculate precise application rates and attain relatively consistent performance. This is in contrast to organic nutrient sources, which are a much greater challenge to manage because of their variable composition, variable nutrient availability and patterns of nutrient release that are greatly affected by temperature, moisture and other conditions that alter biological activity.

The solubility of commercial fertilizers can sometimes be a problem since soluble nutrients may move out of farm fields when applied in excess or large rains occur soon after fertilizer application. Soluble nutrients can be lost by leaching on well-drained soils and through tile outlets or in runoff on poorly drained soils. Denitrification can cause large losses of nitrate-N from water-saturated soils in wet springs.

Increasing soil cation exchange capacity by increasing organic matter reduces the movement and loss of some nutrients, although not nitrate-N (an anion). Management practices that synchronize nutrient availability with crop demand and uptake also minimize losses. Both application timing and the amount of fertilizer applied are important. Splitting fertilizer application into several small applications rather than a single large one is especially important to limit nitrogen leaching on well-drained sandy soils. Split nitrogen applications can also reduce nitrogen losses in runoff or from denitrification on poorly drained soils. Excess nutrient applications can be eliminated or at least significantly reduced by soil testing on a regular basis, setting realistic yield goals and fertilizing accordingly, accounting for all nutrient sources such as legumes, manure and other amendments and using plant analysis as a monitoring tool for the fertilizer program.

Seed Production Technology

1.    Paddy
2.    Sorghum
3.    Bajra        
4.    Maize              
5.    Blackgram    
6.    Soyabean                
7.    Cowpea             
8.    Redgram 
9.    Groundnut
10.    Sunflower
11.    Castor       
12.    Gingelly
13.    Tomato
14.    Brinjal
15.    Chilli
16.    Bhendi

Seed is the basic input of agriculture, and its importance has now well recognized in the food supply chain since the warranty for production could be succeeded only based on the availability of seed. Seed becomes the quality seed, on possession of specific characters, viz. germination, vigour, purity and health status, hence, seed production becomes the specified scientific technology with the foreseeing of quality and storability in addition to productivity. From time immemorial, seeds are being imposed with some management techniques for improvement in seed quality and thereby the productivity. These seed management techniques are known as seed treatments. Generally, seed treatment is the application of biological, chemical agents and physical techniques to the seed in order to obtain the benefit of plant protection, production and invigouration. Basically, seed treatments are intended to improve the quality of seeds since nothing can substitute poor quality seed, no matter how lavishly other inputs are spent on the crop established from such seeds. Even for a resource poor farmer, high quality seed would be a great advantage because it ensures the best utility of all inputs in addition to the augmentation of yield increase by 15 to 20%.

In general, seed treatment could broadly be classified into physical and physiological treatment. Physical treatment is external seed treatment, while physiological is impregnation of needy substances into the seed through various seed management techniques. Some of the germination augmenting physiological seed treatments are seed fortification, seed hardening, seed priming, dry permeation and pre-germination. In addition, some of the seeds are imposed with special treatments such as dormancy breaking treatment such as soaking in water, mechanical scarification, acid scarification, bio-scarification, scorching, warm stratification, cold stratification and electrical seed treatment. The common physical seed treatments are seed pelleting, seed coating/film coating and seed colouring. Seeds are also imposed with some other physical treatments that can act on the physiology of the seed such as irradiation, magnetic and electrical seed treatment. In addition, irrespective of seed, seeds are given with protective treatment when they are taken for storage, which are commonly termed as pesticide seed treatment. Seeds are also given with corrective treatment at their initiation reduction with seed quality characters during storage, which are termed as mid storage correction.