eChapters

10.1 INTRODUCTION

‘Tissue culture’ is commonly used as a blanket term to describe all types of plant cultures, viz., callus, cell, protoplast, anther, meristem, embryo and organ cultures (George, 1993). It relies on the phenomenon of cell totipotency. The different techniques of culturing plant tissues may offer certain advantages over traditional methods of propagation.

Growing plants in vitro in a controlled environment, with in-depth knowledge of the culture conditions and the nature of the plant material, ensures effective clonal propagation of genetically superior genotypes of economically important plants. Micropropagation has become an important part of the commercial propagation of many plants (George and Sherrington, 1983; and Zimmerman et al., 1986) because of its advantages as a multiplication system (Pierik, 1997 and Razdan, 2003). Several techniques for in vitro plant propagation have been devised, including the induction of axillary and adventitious shoots, the culture of isolated meristems and plant regeneration by organogenesis and/or somatic embryogenesis (Williams and Maheswaran, 1986; and Gautheret, 1985).

Tissue Culture is becoming as an alternative means to vegetative propagation of plants. In vitro growing plants are usually free from bacterial and fungal diseases. Virus eradication and maintenance of plants in virus free stage can also be rapidly achieved in cultures (Sharma, 2016).

Introduction

The horticulture sector has been a driving force in stimulating a healthy growth trend in Indian agriculture. This sector contributes around 28 per cent of the GDP from about 13.08 per cent of the area and 37 percent of the total exports of the agricultural commodities (Rather et al., 2013)  India is currently producing 257.2 million tonnes of horticulture produce from an area of 23 million ha. Over the last decade, the area under horticulture grew by about 3.8% per annum but production rose by 7.6% per annum. The higher growth rate in horticulture was brought about by improvement in productivity of horticulture crops, which increased by about 28% between 2001-02 and 2011-12. (Anonymous, 2012)

1. INTRODUCTION

Food processing involves the use of wide range of unit operations and technologies to transform the raw, bulky and perishable food into more shelf-stable, palatable and marketable food products. Food processing is one of the most effective solution to reduce the wastages, improves the quality and safety aspects of food products, increase the food availability and marketability. Fruits and vegetables are considered as an integral part of any dietary system as these are rich sources of vitamins, minerals and dietary fibres. India is the second largest producer of fruits and vegetables after Brazil and China which contributes 10 % of world fruit production and 14 % of world vegetable production. Fruits and vegetables are more prone to spoilage as compared to cereals due to their nature and composition. The spoilage can be occurr at the time of harvesting, handling transportation, storage, marketing and processing that results in lot of wastage in the form of seeds, pulps, peels etc. Efficient management of these wastes can help in preserving vital nutrients of fruits and vegetables, and bringing down the cost of production of processed foods, besides minimizing pollution hazards. In India, processing of fruits and vegetables is extremely low as compared to the developed countries.

Biotechnology can help in the bio-processing of fruits and vegetables for the production of novel products having better sensory and nutritional qualities, improved shelf life. Bio-processes involve the use of different micro-organisms and enzymes along with modern biotechnological techniques like genetic engineering.

9.1 INTRODUCTION

India is the second largest producer of fruit crops with annual production of 68.4 million metric tonnes from an area of 6.1million ha (Anon 2010). The national horticulture mission commenced in 2005 had fixed a target to double the horticultural production by 2011-12. According to the available production data of horticultural crops, it seems that we are very close to achieve our target. But, if the loss caused by biotic and abiotic stresses is accounted, a sound conclusion can be drawn that still there is a huge scope for productivity improvement in fruit crops.

Among biotic factors bacteria, fungi, nematodes, viruses and insect pests, diseases and other pests are widely recognized as the biggest threat to the sustainable production of fruit crops. Every fruit crop is infected with one or other pathogen/pest, which causes a significant reduction in yield. The disease alone both in field and storage accounts for 25-30 per cent losses (Rangaswami and Mahadevan 2002). Along with diseases, insect-pests also cause reduction in the yield. About 600 insect and mite pests have been reported in temperate fruits alone in India (Sharma and Singh 2006).

Beside biotic factors, abiotic factors (salt, drought, low and high temperature) also limit the potential yield of fruit crops. It is estimated that nearly 10 million ha is affected by salinity/alkalinity in India (Singh 2006). Moreover, fruit cultivars are also to be modified for yield and traits of consumers preference e.g. seedlessness in grapes and citrus.

Genetic improvement can be achieved by following the conventional breeding approaches, when the gene of interest is present in related cultivars/species and the crop is sexually crossable. But due to long juvenility and genetically prevalent problems like incompatibility, sterility in most of the fruit crops and apomixis in citrus, mango and apple, conventional techniques seem to have limited role in the improvement of fruit crops.

Various biotechnological approaches either alone or in combination with conventional breeding approaches can provide a direct solution for the genetic improvement of fruit crops.

Origin, History and Definition

The term biotechnology was coined by Karl Ereky, a Hungarain engineer, in 1919. The origin of biotechnology can be traced back to prehistoric time when armers and gardeners have been making use of hybridization and grafting among plants with a view to bring about an improvement in existing attributes. Using these approaches, several hundred varieties in ornamental plants were produced. Microorganisms were already used for processes like fermentation, formation of yoghurt and cheese from milk, vinegar from molasses, production of butanol and acetone from starch by Clostridium acetobutylicum or the production of antibiotics like penicillin from Penicillium notatum. Four defferent phases of biotechnological research were witnessed during the last century. In 1920, Chain Weizmann used Clostridium acetobutylicum to convert starch into butanol and acetone (during world war I, acetone was used as an essential component of explosives). Alexander Fleming in 1929 discovered penicillin from Penicillium notatum and wounded soldiers were given treatment using this antibiotic during world was II. In 1970s with the discovery of restriction enzymes, which led to the development of recombinant DNA, technology brought a revolution in the field of biology. The latest phase in the history of biotechnology is the study of structure and function of whole genome (DNA) and whole proteome (protein). This area of research is described as genomics and proteomics, respectively. Some more important activities in the field of biotechnology are given in Table1

In fact, biotechnology is the product of interaction between science of biology and technology. It is the technological exploitation and control of biological system. Biotechnology has wide range of its uses and accordingly Office of Technology Assessment described biotechnology as: (i) old biotechnology that includes fermentation, i.e. formation of vinegar from molasses and that of cheese and yoghurt from milk, production of antibiotics from certain fungi and process of baking and brewing and (ii) new biotechnology that includes the techniques of recombinant DNA and PCR polymerase chain reaction, cell culture and fusion and bioprocessing which became possible only through the researches in molecular biology. However, no efforts have been made to distinguish between old and new biotechnology. Keeping in view the importance of biotechnology, attempts have been made to define it. Following are some of the definitions of biotechnology, however, none of the definitions of biotechnology seems to be complete. The first definition seems to be comprehensive and wide.

11.14. Nanotechnology 11.14.1. Concept • Nanotechnology is science, engineering, and technology conducted at the nanoscale, which is about 1 to 100 nanometers. • Physicist Richard Feynman is considered as father of nanotechnology. The idea and concepts behind nanoscience and nanotechnology started with a talk entitled “There is Plenty of Room at the Bottom” by physicist Richard Feynman at an American Physical Society Meeting at the California Institute of Technology on December 29, 1959, long before the term nanotechnology was used. In his talk, Feynman described a process in which scientists would be able to manipulate and control individual atoms and molecules. Over a decade a later, in his explorations of ultra precision machining, Professor Norio Taniguchi coined the term nanotechnolog

It is difficult to define ‘stress’ precisely. In engineering and the physical sciences, it is usually defined as the force applied per unit area. But as far as in biology, stress it is usually described more loosely as any factor that disturbs normal functioning of an organism. Any environmental factor potentially unfavorable to plant is termed as stress.

The effect of stress on plant condition is called strain. Stress is the action, whereas strain is the reaction. Stress may be defined as external conditions that adversely affect growth, development and productivity. Stress may further classified as:

• Zero stress: This is the level of exposure of plants to environmental factors that leads to neither injury nor reduction in growth and yield of crops.
• Stress escape: Capacity of the plant to complete its life cycle during wet season before onset of stress.

2.1 Insect Pests

Insects are often a major obstacle to the successful production of cucurbits (York, 1992). They can severely reduce yield, injure or kill plants, spread diseases and adversely affect fruit quality. A number of insect pests, mites and nematodes have been found to infest cucurbitaceous vegetables but fortunately, in India, fruit flies and a few species of beetles are of economic importance; aphids and blister beetles though of regular occurrence, seldom cause severe damage.
 
Other insect pests reported to infest the cucurbitaceous vegetables are pumpkin caterpillar, Diaphania indica (Sounders), snake gourd semilooper, Plusia peponis Fab., white fly, Bemisia tabaci Genn., stink bugs, Apspongopus spp. and flea beetle, Phyllotreta spp. etc. These biotic pressures on the crops are increasing day by day due to round-the-year intensive cultivation of photo and thermo insensitive cultivars as well as indiscriminate use of toxic agro-chemicals in the present era of chemicalized agriculture.

Bitter gourd (Momordica charantia) is a widely grown vegetable variety in India. It is one of the important members of the family Cucurbitaceae. The seed production can be done throughout the year in tropical climate and during spring, summer and rainy season in subtropical climates. In Tamil Nadu September – October is suitable for seed production. In hills seed production can be done during summer season.

It is rich in iron and Vit –C and native of tropical Asia particularly eastern India and Southern China (Sheshadri 1986 Mini Raja et al., 1993).
 
Botany: Monoecious annual, staminate flowers small, yellow and borne on slender pedicel. Pistillate flowers solitary have small pedicel, flowers are yellow, leaves segmented pentamerous. Filaments 3, two are bilocular and one is unilocular. There are three short styles ended with three bilobed or divided stigmas.

Chromosome 2n=22: 6-centromere in middle, 3-submedian, 2-subterminal  (Vargheuse, 1973) 

Momordica dioica: 2n=28

Momordica cochincniensis: Sweet gourd of Assam

Germplasm

KAU-Vellanikara, IIHR-Bangalore, NDUAT-Faizabad, CSAUAT-VRS, Kalyanpur, BPUA&T-Pantnagar and IARI- New Delhi are the major sources of bitter gourd germplasm.

Bitter gourd (Momordica charantia L., 2n = 2x = 22, family Cucurbitaceae, monoecious, cross-pollinated but genetically behaving like self-pollinated crop), also known as balsam pear, bitter melon, bitter cucumber, and African cucumber is rich source of vitamin C and iron and credited with medicinal use in management of diabetes. Fruits are cooked with other vegetables, stuffed, stir-fried, or added in small quantities to beans and soups to provide a slightly bitter flavor. The bitterness of most cucurbits is mainly due to cucurbitacins. The bitterness of bitter gourd is due to the cucurbitacin-like alkaloid momordicine and triterpene glycosides (momordicoside K and L) as reviewed by Behera et al. (2010). Bitter gourd is grown on approximately 340,000 hectares across Asia, with India and China accounting for more than half the production. Estimated area of bitter gourd in India is about 80,000 ha with production reaching to 10,00,000 resulting into a productivity of 12 tons/ha. States accounting for major area of bitter gourd are Chhattisgarh, Telangana, Andhra Pradesh, Orissa, Madhya Pradesh, Uttar Pradesh, Bihar, Tamil Nadu, Haryana and Assam.

Bitter gourd (Momordica charantia L.) is one of the important commercial cucurbitaceous cash crops grown mainly by small holding farmers in Asia where it is cultivated on more than 340,000 ha annually (McCreight et al., 2013). Eastern Asia, possibly Eastern India, or Southern China is most likely the center of origin for bitter gourd (Walters and Decker-Walters 1988; Miniraj et al., 1993). It is also known as bitter melon, bitter cucumber, balsam pear, bitter apple, or bitter squash (Morton, 1967). Fruits are known for abundant source of vitamins and minerals. Delicious preparations are made from fruits after stuffing and frying. It is also consumed in the form of Juice, Tea and Pills. Bitter gourd fruit abounds in phytonutrients (Dhillon et al., 2017) and often used to manage type 2 diabetes as a folk medicine. Clinical studies confirmed that elevated fasting glucose levels in pre-diabetics can be reduced by supplementing the diet with bitter gourd fruits. (Amirthaveni et al., 2018; Krawinkel et al., 2018). Medicinal properties present in the bitter gourd fruits are used in the curing of diabetes, asthma, blood diseases and rheumatism.

The current seed market of bitter gourd in Asia values ≈ 16 million Euros. The bitter gourd seed market in India alone is 400 metric tonnes having value of 350-400 crores. 70 % area is under hybrids and 30 % is covered by open pollinated varieties.

Bitter gourd or Bitter melon, Momordica charantia L under the family Cucurbitaceae (Chromosome no. 2n = 2× = 22) is widely grown in India, Indonesia, Malaysia, Singapore, Thailand, China, Japan, East Africa, the Caribbean and South America for its edible fruit. Tender fruits are widely used as cooked vegetables in a number of ways. Bitter gourd is an excellent source of vitamin C, iron, magnesium, potassium, calcium and ß carotene. The fruits contain non-toxic glycoside momordicin, which gives it bitterness and also health benefits. It also contains an insulin-like compound called Polypeptide-p or p-insulin and steroidal compound “Charantin” having hypoglycemic property.
Origin, domestication and adaptation in India
Wild or semi-domesticated variants spread across Asia in prehistorical period, and it was probably domesticated in Southeast Asia. It has probably originated in eastern India or Indo-Burma area or southern China. Uncarbonized seed coat fragments have been tentatively identified from the spirit cave in northern Thailand however, there have been no archeological reports of bitter gourd remains in China (Marr et al, 2004).Population resequencing revealed the divergence between wild and South Asian cultivars about 6,000 years ago, followed by the separation of the Southeast Asian cultivars about 800 years ago, with the latter exhibiting more extreme trait divergence from wild progenitors and stronger signs of selection on fruit traits.

Anthracnose
Diagnostic Symptoms
• Pathogen attacks all aerial parts of plants and at any stage of their growth.
• Symptoms are circular, black, sunken spots with dark center and bright red orange margins on leaves and pods.
• In severe infections, the affected parts wither off.
• Seedlings get blighted due to infection soon after seed germination.
• Infected pods have discolored seeds (Fig.3).
Etiology
Scientific Classification
Kingdom : Fungi
Division : Eumycota
Sub- division : Deuteromycotina

Bleaching is essentially whitening or decolourizing. It is an important step in the processing of dry plants. It involves chemical processes that can change the ability of colour bodies to absorb light by changing their degree of saturation (Robson, 1967). This chemical action removes the discolouration occurring during the dehydration phase of preservation of plants. It allows the effective use of dyes for colouring. Bleaching agent is a material that lightens or whitens a substrate through chemical action. To reduce the processing costs, multistage bleaching is suggested. In this method, both oxidative and reductive bleaching chemicals are used.

Plant biodiversity, in particular, is arguably the single greatest resource that humankind has garnered from nature during our long cultural development. Nowhere is the value of biodiversity more evident than in our food supply. Roughly one third of all plant species have edible fruits, tubers, nuts, seeds, leaves, roots, or stems. The World Health Organization estimates that 3.5 billion people in developing countries rely on plant-based medicine for their primary health care, in which tuber crops also play a major role (Tuxill, 1999). There are 25 hot spots of biodiversity of which Western Ghats and Eastern Himalayan are the most important ones in India. About 7% of world flora and 6.5% of world fauna are in India. Indo-Burma region is one of the eight hottest hot spots of the world, and is the centre of origin of tuber crops like Dioscorea, Colocasia, Amorphophallus and Alocasia.

Onion is an economically significant bulb crop cultivated across diverse agroecological environments. Its cultivars vary considerably in bulb size, shape, colour, pungency, maturity, storage behaviour and photoperiod response. Understanding its vegetative and reproductive morphology, growth habit, physiology and taxonomic relationships is fundamental to crop improvement and germplasm conservation. This chapter examines the botanical features and taxonomic position of onion within the genus Allium. It explains relationships among cultivated types, landraces and allied species and discusses varietal classification according to climatic adaptation and consumer preference. Classical characterization and molecular taxonomy are considered important tools for developing productive, resilient and market-preferred onion cultivars.

Botany: Bottle gourds belonging to the family cucurbitaceae is an annual vine having white flowers and smooth, large, hard-shelled gourds. Brownish seeds are numerous in a whitish green pulp. Each seed is somewhat rectangular in shape with grooved notches near the attached end. Grown most often in warmer climates, this squash grows from 6 to 36 inches long and 3 to 12 inches in diameter.

Seeds leaves, flowers and young stems are all edible. Helpful in shedding extra calories. It contains higher concentrations of Dietary Fiber, Vitamin A, Vitamin C, Vitamin K, Vitamin B6, Folate, Potassium, Manganese, Protein, Vitamin E, Thiamin, Riboflavin, Pantothenic Acid, Calcium, Iron, Magnesium, Phosphorus and Selenium. A rich source of minerals and vitamins, bottle gourds contains many healing and medicinal properties. The cooked vegetable is not only easy to digest but also contains cooling, calming (or sedative), diuretic properties. It contains low calories also has iron, Vitamin C and B complex. Regular consumption of this vegetable provides relief to people suffering with digestive problems, diabetics and convalescents.

Bottle gourd (Lageneria siceraria) 2n=2x=22 is also known as white flowered gourd. Most important vegetable of ancient China.
 
Origin : According to De Candolle (1882) Bottle gourd has been found in wild form in South Africa and India. However, Cutler and Whitaker (1962) are of the view that probably it is indigenous to Tropical Africa on the basis of variability in seeds and fruits. This species appear to have been domesticated independently in Asia, Africa and the New world (Heiser, 1973).
 
Botany: It is monoecious, annual vine with soft pubescence. Leaves are cordate ovate to reniform-ovate, Flowers are white, solitary, open at night and has hairy ovary. Fruit shape is cylindrical, oval egg shaped, club shaped, round and other shapes also appeared.

Genetics of Important Traits

Bitterness: Single dominant gene (Path and Singh, 1950)

Fruit colour: Monogenically controlled (Kalloo, 1993)

Two major genes are involved for fruit shape (Path and Singh, 1950). Single gene for fruit colour involved (patchy v/s white) and reported by Path and Singh (1950). Monogenic recessive inheritance for andromonoecious sex form is reported by Singh et al. (1996). Hermaphrodite sex form is characterized by long corolla (3.5-4.5cm instead of 2.5-3.5cm in normal). In hermaphrodite condition fruits bears prominent blossom scar.  Long fruit conditioned by AA genotype and Round fruit is due to aa genotype where Partial dominance is reported (Kushwaha, 1996).

Bottle gourd (Lagenaria siceraria, 2n = 2x = 22, family Cucurbitaceae, monoecious, cross-pollinated but genetically behaving like self-pollinated crop), is grown primarily in India on large scale for consumption as cooked vegetables. Bottle gourd is considered to be one of the earliest species of plants to be domesticated by humans. Bottle gourds are regularly grown and consumed in various parts of the world, particularly Asia. Fruits of bottle gourds are harvested young and used as a vegetable. The mature, dried fruits have been used throughout the world for making storage jars and utensils and hence the name bottle gourd. Shoots and leaves are also cooked and eaten. Lately, bottle gourd juice is also becoming popular in India as a health drink. Other countries growing bottle gourd on limited scale are Sri Lanka, Indonesia, Malaysia, Thailand, Philippines, China, Hong Kong, Tropical Africa, Colombia and Brazil. After seed scooping, the hard rind is used as containers also. Seeds are used for oil extraction and oil is used as cooking oil.

During 2017-18, India produced 27 lakh tons (2.7 million tons) of bottle ground from 1.60 lakh ha (0.16 million ha) and this translated into a productivity of 17 tons/ ha (Horticulture Statistics at a Glance-2018, MAFW, 2018). Top six states producing bottle gourd on significant scale are Bihar, UP, Haryana, MP, Odisha, and Pujab, production being in the range of 135,000 to 650,000 tons.

Bottle gourd, Lagenaria siceraria under the family Cucurbitaceae (Chromosome No: 2n = 2× = 22) is commonly grown vegetable crop of India, Africa, Central America and other warmer regions of the world. Tender fruits are widely used as cooked vegetables in a number of ways. Bottle gourd is a good source of vitamin C and zinc that may offer several skin benefits. It also contains minerals like calcium, magnesium, iron, and zinc. Its dietary fibre enhances gastro-intestinal health and promotes bowel movements and prevents constipation.
Origin, domestication and adaptation in India
It is the only crop known to have been cultivated in pre-Columbian times in both the Old and New World. Bottle gourd is indigenous to the tropical Africa. It has
bihemispheric distribution in Africa, the old world and America, the new World. Its utilization by man is about 16,000 years in the Old World and 12,000 years in the New World. It was independently domesticated in the two hemispheres. It was one of the world’s first cultivated plants grown not primarily for food, but for the use of hardshelled fruit as containers. The apparent wild plant produces thinner-walled fruit that, when dried, would not endure the rigors of use on long journeys as a water container. Today’s bottle gourd may owe it’s tough, waterproof wall to selection pressures over its long history of domestication. The bottle gourd was theorized to have drifted across the Atlantic Ocean from Africa to South America.

Horticulture includes variety and diversity of crops. Thus, it can be divided into several branches depending upon the crops it deals with. Following are the branches of horticulture.

1. Pomology: The term pomology is a combination of two Latin words pome i.e. fruit and logos i.e. science. Recently it has been designated as ‘Fruit Science’. It deals with the study of fruit crops. It includes all aspects of fruit crops e.g. importance, uses, origin and distribution, area and production, soil and climate requirement, botany, nursery raising, cultivation practices, plant protection measures, stage and methods of harvesting, post-harvest handling, marketing, export, import, etc. e.g. mango, banana, citrus, grape, apple, peach, pomegranate, fig, etc.
2. Olericulture: The term olericulture is also derived from the Latin word. Cultivation of vegetable crops. Recently it has been designated as ‘Vegetable Science’. Vegetables are said to be herbaceous plants of which edible plant parts are used for consumption either cooked or salad. It may be stem, root, leaf, flower, etc. It also includes all aspects of vegetable crops e.g. importance, uses, origin and distribution, area and production, soil and climate requirement, botany, nursery raising, cultivation practices, plant protection measures, stage and method of harvesting, post-harvest handling, marketing, export, import, etc. e.g. tomato, brinjal, chilli, cucumber, red pumpkin, watermelon, cabbage, cauliflower, etc.
3. Ornamental Horticulture: It includes various groups of ornamental plants used to decorate in-door and out-door areas. Ornamental horticulture is the study of growing, arranging and tending decorative plants and flowers. It is further divided into.

Breadfruit (Artocarpus altilis) belongs to family Moraceae. The Latin name is derived from Greek words (artos = bread, karpos = fruit), and altilis meaning ‘fat’. Baked or roasted in a fire, the fruit has a starchy texture and fragrance, reminiscent of fresh baked food.

Breadfruit is an important staple crop and component of traditional agro-forestry systems in the Pacific for more than 3,000 years. This species originated in the South Pacific and spread throughout Oceania by intrepid islanders settling the numerous islands of Melanesia, Micronesia and Polynesia. Due to efforts of Captain Bligh and French voyagers, a few seedless varieties from Polynesia were introduced to the Caribbean in the late 1700s. These gradually spread to other tropical regions. Breadfruit is now grown in close to 90 countries.

Introduction

Global food productivity will have to rise significantly to satisfy an expanding world population. Increased vegetable production is one option towards the efficient conversion of natural resources into food stuffs. As a group, vegetables are a diverse range of herbaceous plants that do not belong to any particular botanical species, genus or family. Individual members may be at various stages of domestication. Vegetables are typically annual herbaceous species, whose plant parts (leaves, stems, flowers, fruits, roots or tubers) are consumed as fresh or as cooked product, and as an additional source of vitamins, minerals, fibre, phytochemicals, protein and/or calories. Health benefits are also claimed for some vegetable species, mainly due to antioxidant activity and capacity to scavenge free radicals.

Domesticated plants have been fundamentally altered from their wild relatives; these species have been moved into and adapted to new environments. They have become dependent on the farmer’s hand and they have been reshaped to meet human needs and wants. Modern crops are the results of thousands of years of these evolutionary processes. Like all biological evolution, crop evolution involves two fundamental process; the creation of diversity and selection (Harris and Hillman, 1989). Crop evolution is distinguished by two types of selection; one natural and another artificial or conscious. These evolutionary processes must continue in order for agriculture, a living and evolving system to remain viable.

In the hands of plant breeder’s sexual hybridization is a powerful tool for producing superior plants by combining characters distributed in different members of a species or different species of a genus. Genetic variability within the species has been efficiently utilized by breeders in their efforts to improve crops. However, the existing variability in a breeding population may not be sufficient for modern plant breeding purposes, and thus great efforts have been made to broaden the existing gene pool of crops through utilization of wild germplasm.

The current status of advances in fruit breeding is through the development of different scientific approaches augmented by ever-increasing knowledge and application of genetics, statistics and biotechnology. These innovative approaches very specific for a species in most of the cases, are the major tools of the fruit breeders to tackle the different objectives of fruit improvement programme at present Fruit improvement is a very slow process due to the long generation cycle varying from species to species, thereby reducing the chances of exploiting genetic recombination. Besides this factor, most of the fruit species are either highly heterozygous or polyploidy in nature. Due to this reason the asexual propagation of fruit plants is a conventional means while wide segregation occurs upon sexual reproduction. Such expectation is not unlikely because the types selected as commercial varieties are definitely to be vigorous ones, and a positive correlation exists between vigour and heterozygosity.

This discussion on breeding of fruit plants involves different aspect of the species concerned is so essential as well as fundamental that discussion of them must procede any consideration of breeding methods themselves. The plant species are grouped into two-self-pollinated and cross-pollinated. These two groups have emerged on the basis of pollination mechanism which plays significant role in the method of breeding application. To emphasize the difference in the reproductive systems of these two groups one should know the details about floral biology, mechanism of pollination control, reproduction by asexual and sexual means and self and cross-pollinated plants.

Introduction

Stress is any unfavorable condition for a plant’s normal growth and development. In the case of crop plants, such adverse conditions are caused by biological (biotic) and non-biological (abiotic) environmental factors. Abiotic stress is the negative impact of non-living factors on living plants in a specific environment. Usually, abiotic stress is unavoidable, and we can only go for its management.

The most basic stresses include:

• Extreme (high/low) temperatures

• Soil-chemical properties

• Water deficiency

• Excessive moisture

• Element toxicity or deficiency

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.

Vegetable crops are highly susceptible to biotic stresses incited by different diseasecausing micro-organisms (fungi, bacteria, phytoplasma, virus), insect pests, nematodes, arachnids and weeds. In contrast to abiotic stresses caused by the environmental factors such as drought, heat, soil salinity, alkalinity, etc., biotic stress-causing agents directly deprive their host of its nutrients leading to reduced plant vigour and, in extreme cases, death of the host plant. In vegetable crops, different biotic stresses are the major cause of pre- and post-harvest losses.
Indiscriminate use of chemicals for the control of diseases, insect pests and nematodes has several disadvantages particularly, increasing cost involved in chemical control, residual toxicity of the chemicals (fungicides, antibiotics, insecticides) in food chain and development of resistance against pathogens and insect pests to different chemicals. Management of diseases and insect pests involve the use of resistant varieties and integration of cultural and chemical control measures.

High temperature stress
Abiotic stresses either individually or in combination cause morphological, physiological, biochemical and molecular changes that adversely affect plant growth and ultimately yield. The major forms of abiotic stress plants are exposed to in nature are heat, drought, cold and salinity. Of these abiotic stresses, heat stress has an independent mode of action on the physiology and metabolism of plant cells. High temperatures above optimal have generally damaging effects on plant development which has led to the prediction that Global warming have a negative effect on plant growth. High temperature regimes may cause severe yield reduction leading to even famine. High temperature stress has wide range of effects on plant in terms of physiology, biochemistry and gene regulation pathways. The susceptibility to high temperatures in plants varies with the stage of plant development and genotype.
Mechanisms of heat tolerance
Heat tolerance is generally defined as the ability of the plant to grow and produce economic yield under high temperature conditions. Several plant physiological parameters and mechanisms that contribute to heat tolerance in the field include:

29.1 Introduction

An environmental factor that interferes with the complete expression of genotypic potential of a crop is called stress. The stresses may be biotic (pathogens, insect-pests, etc.) or abiotic. The main abiotic stresses are drought, mineral deficiency/toxicity and heat or cold. The losses due to abiotic stresses can be minimized by:

Crop management: The degree of stress can be reduced by suitable agronomic/soil management practices, e.g., irrigation to relieve drought stress, soil amendments to reduce salinity.

Development of resistant cultivars: This offers the cheapest, easiest to apply and most eco-friendly approach to reduce losses due to any stress.

Indirect breeding: Evaluation of materials under stress often helps in identification of a resistant line that may become an important commercial cultivar.

???????Direct breeding: It is deliberate breeding of materials for stress resistance. When a genetically variable material is grown under the stress environment, selection can be based on survival, yield and other traits contributing to stress resistance.

Plant abiotic stresses are external and nonliving factors that have harmful effects on plants. A non-living factor must exert influence on the normal range of environmental variation to adversely and significantly affect the plant performance or the physiology of the organism. Abiotic stresses are the most harmful factors affecting the growth and productivity of crops worldwide, resulting in a yield reduction ranging from 10% to 100%. They are most harmful when occurring together with other abiotic stresses and their effect in yield will only worsen with the climatic changes experienced now and expected to be more severe in the future.

28.1 Introduction

The stress that is caused by biological agents or factors such as diseases, insect-pests and parasitic weeds is called biotic stress. The term disease can be broken into two words: “dis” (means negative, reverse or opposite) and “ease” (means comfort, or freedom from pain or discomfort). Hence, plant disease can be defined as any harmful alteration from the normal functioning of physiological processes. Diseases may be bacterial, fungal or viral. A wide range of insects infests various crop plants. The extent of damage caused to crop plants by various organisms is usually in the order fungi > bacteria > viruses > nematodes = insects. But the relative importance of these organisms varies to a great deal in different crops. Breeding of cultivars resistant to diseases and/or insect-pests is the cheapest, safest and most dependable means of limiting the losses due to them. Resistant cultivars form an important component of integrated management of diseases and insect-pests.

28.2 Breeding for Resistance to Biotic Stresses-Diseases

Agrios (1970) has defined disease as: “Disease is a series of invisible and visible responses of plant cells and tissues to a pathogenic microorganism or an environmental factor that result in adverse changes in form, function or integrity of plant and may lead to partial impairment or death of the plant or its parts.” The organism causing disease is called pathogen, while the plant affected by the disease is called host.

The principles underlying breeding for resistance to diseases are much the same as for other characters, except for one important difference, i.e., the diseases caused by pathogens are the product of interaction between two genetic systems, that of the host and that of the parasite. Both systems are capable of variation and evolution and affect the interaction between host and pathogen. Here the breeder is required to deal with the heritable traits of both the host plant and the pathogens invading it.

Biotic stresses include diseases and insect pests which cause serious damage to the crop plants and ultimately yield loss. Biotic stresses can be listed as follows:

• Diseases caused by pathogens which include fungi, bacteria, and viruses
• Insects
• Nematodes
• Parasitic weeds

Another category of stresses are called as abiotic stresses which are caused by environmental factors as:

• Water stresses (water logging, drought)

Vegetables are considered protective foods and play an important role in human nutrition. These help to combat malnutrition and also diversify diets with variety of colours. The compounds imparting various colors to the vegetables are important antioxidants that also help to combat degenerative diseases like cancer. Over the years, vegetable sector has made an appreciable progress in terms of production and productivity and emerged as the better option to diversify agriculture, generate employment and enhance farmers’ incomes. The worldwide production of vegetables has doubled over the past quarter century and the value of global trade in vegetables now exceeds that of cereals.

Globally, India ranked second in vegetable production and contributed 15.8 and 14% to global vegetable area and production, respectively. The production of vegetables in India is estimated to be 212.91 million tonnes in the year 2022-23 compared to 209.14 million tonnes in the year 2021-22. India ranked first in production of okra in the world (73% of world production) and second in brinjal (27.55%), cabbage (13%) and tomato (11%). The major vegetable growing states in India are West Bengal (14.1%), Uttar Pradesh (11.4%), Bihar (9.3%), Madhya Pradesh (8.0%) and Gujarat (7.1%). Vegetables are especially important crops for farmers with small holdings because an appreciably higher income per hectare can be generated by growing vegetables than from conventional staple crops (Genova et al, 2006). However, vegetables are generally considered more vulnerable than staple crops to stressful environmental conditions including extremes of temperatures, drought, salinity, alkalinity, water logging, mineral nutrient excesses and deficiency (Chinnusamy et al, 2005). These environmental stresses are likely to be exacerbated by the prevalent climatic changes in many parts of the world.
Among environmental factors, soil salinity stress is one of the main factor reducing production and productivity of vegetables in arid and semi-arid regions where irrigation water has excessive salt and annual rainfall is low. In India, about 6.73 million ha of land (~2.1% area of the country) is salt affected, out of which 2.96 million ha is saline and 3.77 million ha is sodic (Arora & Sharma 2017). About 75% of salt-affected areas exist in four states, i.e., Gujarat, Maharashtra, West Bengal, and Rajasthan (Mandal et al., 2018).

INTRODUCTION

India has emerged as second highest producer of potato in the world, after China. The crop has been identified as the most important crop for ensuring food security for the developing countries, and a highly nutritious food providing more calories, vitamins and nutrients per unit area of cropped land than any other staple food. The crop has witnessed phenomenal increase over the seven decades of potato research in India. For a crop which was introduced in the country only in the early 17^th century, and was neither adapted, nor its staple food, the remarkable increase in potato production and productivity is an exceptional achievement of breeding this temperate introduction into the present day potato cultivars.

BREEDING REQUIREMENTS

The table potatoes introduced in India were adapted to long photoperiods of up to 14 hours and crop durations of 140-180 days allowing them to be cultivated only in the hilly regions of India. The unique and diverse agro-climatic condition of the country, comprising of contrasting conditions in the Indian plains, where potato could be grown in the winter months necessitated breeding efforts to develop the potato varieties suitable for the sub-tropical plains and the other potato growing regions. The winters in sub-tropical plains have short photoperiod (with about 10-11 hours sunshine) and the crop duration is limited to 90-100 days because of short and mild winter. Further constraints on photosynthetic activity due to early morning fog, posing a strong limitation on tuber bulking. This is followed immediately by a long hot summer period, which coincides with the post-harvest storage period of potato, creating challenging storage problems. The rapid degeneration of seed stocks, with concomitant decrease in yield due to accumulation of viral diseases and tuber storage and utilization in hot and humid climate thus needed to be addressed, in priority. Besides, these southern, north Bengal and Sikkim hills and the plateau offer agro climatic area specific problems related to the biotic and abiotic stresses prevalent in the regions. Moreover, the unique reproductive biology of the plant made it possible to flower only under the long day conditions of the hills, where hybridization was initiated at Kufri (Shimla), Himachal Pradesh. However, during the initial years, it was not possible to evaluate the breeding progenies in the warmer sub-tropical plains due to the quick degeneration of hill bred progenies and dormancy of hill potatoes.

Important breeding methods can be classified as follows:
    1.    Introduction
    2.    Selection
    a.    Mass selection: Done in self pollinated crops, cross pollinated crops and dioecious crops.
    b.    Individual plant selection: Done in self pollinated crops, cross pollinated crops (line breeding) without control of pollination, artificially self pollinated lines, dioecious plants and clonally propagated lines.
    3.    Hybridization
    a.    Crossing in self pollinated crops.
    b.    Single crosses, double crosses and synthesized varieties.
    c.    Varietal crosses.

———————— is a thornless and seedless selection from Kagzi lime.

A. Pramalini            B. Vikram

C. Chakradhar        D. Jai devi

1. Quantitative characters are governed by

a) Monogene

c) Recessive gene

b) Bi-gene

 d) Polygene

2. Monohybrids are derived by hybridizing two individuals which differ for

a) Single-character

c) Quadruple character

b) Double character

 d) Multiple character

Abstract

Plum breeding work has been in progress since 1991-92 and continued upto 1996- 97.  The hybrid seedlings thus obtained after one year of growth in nursery were planted in test rows for the selection of types that had improved quality and better shelf life. Cultivar Santa Rosa, the mainstay of plum industry in Himachal Pradesh though performing well from production and adaptation point of view but lacked in uniform fruit ripening, very acidic at seed and low shelf life or transportation ability. After detailed evaluation and characterization for various pomological traits, two-way hybridization in seven different cultivars belonging to Japanese and European plum were made. In test rows the hybrid seedlings were assessed for number of horticultural characters i.e. morphological, flower and fruit. On the basis of detailed analysis some promising types have been selected which are briefly described, however yield potential is being evaluated as most of  the seedling have started fruiting regularly only two to three years back.

Introduction

Cucurbits, belonging to the family Cucurbitaceae are among the most ancient cultivated plants. The term cucurbit was coined by Liberty Hyde Bailey for cultivated species of Cucurbitaceae. Other vernaculars applied to the family and several of its members are ‘gourd’, ‘melon’, ‘cucumber’, ‘squash’ and ‘pumpkin’. The Cucurbitaceae consists of two well defined sub families, eight tribes representing varying degrees of circumscriptive cohesiveness and about 118 genera and 825 species (Jeffrey, 1990). It is mostly tropical and sub tropical in distribution and only a few species occur in temperate regions. Some are semi desert or saprophytic in nature. The Indian sub continent is considered to be the centre of origin for a number of wild and cultivated crops. Chakravorty (1982) reported that 36 genera and 100 species of cucurbits are found in India. Cucurbits are cultivated in 8.5 m ha area in world giving a production of 17.9 mt. While in India a total of 4.5 mt cucurbits are produced from an area of 0.42 m ha area (FAO, 2004).

Cucurbitaceae is one of the most genetically diverse groups of plants in the plant kingdom. As a family and as individual crop, cucurbits epitomize adaptive differentiation and evolutionary divergence. Not only may cultivars within a crop vary significantly in their characteristics, but the same cultivar grown in distinct areas can have different needs in response to disparate local growing conditions. Cultures and ethnic groups may have different cultivar preference and horticultural practices, which also increase morphological diversity within a crop.

Cucurbits are of tremendous economic importance as food plants. They are extensively grown in mixed cropping of more than one kind in long and meandering river beds. Of various improvements approaches possible, breeding of superior pure lines and hybrid cultivars of cucurbits utilizing locally adopted land races are the most important methods which will have far reaching impact on increasing the production and productivity of cucurbits.

Introduction

Spices have played a very important role in shaping the history of human culture and civilization. Spices condiments and aromatic plants were the first articles traded by ancient people. These prompted the foreigners to the land of spices. Among spices, seed spices is a group well distributed over different agro-climatic regions in India covering major part in semi-arid to arid region largely in Rajasthan and Gujarat. The other states where one or more of seed spices grown are Haryana, Punjab, M.P., Bihar, U.P., West Bengal, Orissa, Tamil Nadu and Karnataka. The seed spices are grown in different parts of the world covering mainly Mediterranean region, South Europe and Asia. These crops were introduced to India from Mediterranean and Central Asian region, perhaps a long time ago. Today India enjoys the position of largest producer and exporter in the world for these crops. The country is bestowed with immensely rich land races diversity in seed spices crops. Much of the country’s agro-biodiversity is in the custody of farming community who followed age old farming systems. However the land races are being lost due to expansion of agriculture production in the frontier areas or replacement with the improved cultivars. Hence, scientific management of these valuable resources on different dimensions of activities in India viz. survey and collection, characterization, evaluation, documentation and conservation has assumed prime importance today. Out of the total 20 seed spices grown in India the ten are prominent. These important seed spices are divided into major and minor group of seed spices. The crops covered as major seed spices are coriander, cumin, fennel and fenugreek, whereas, ajowan, dill, nigella, celery and anise constitute minor group. The semi-arid to arid region is considerably rich in plant biodiversity of seed spices and it is required to conserve the natural wealth of these crops. The increasing loss of plant diversity owing to numerous natural and manmade causes calls for immediate efforts for its collection and safeguard.

Tomato varieties produced 50% in plastic house cover more than what they produce in open air (Diez et al., 1985). Nevertheless this production increase is not, by itself the reason for the use of protected cultivation which requires higher expenses. The key factor is the cost increase of final product obtained during off-season, which created an interesting margin in spite of high production costs. The effect of cost of seed in total cost is negligible, which permitted the use of hybrid seed. The new hybrids have brought about production increases which can be calculated to be over 50% more than what the greenhouse varieties produced with the cost of hybrid seed giving an effect on total production costs of only 6-7%. So that under these circumstances, production increase associated with hybrids is certainly very advantageous, apart form other benefits to be derived from hybrids.

The term genome refers to a complete set of DNA, including all of its genes. Each genome contains all of the information needed to build and maintain that organism. In the nucleus of each cell, the DNA molecule is packaged into thread like structures called chromosomes and each species has specific chromosome number. Most of the plants are diploid and they show in each one of its body cell, twice the number of haploid chromosomes (n) found in the gametes.
There are two main types of chromosomal variation that involve changes in the number. These are euploidy (in Greek “eu”means true or even and “ploid”means unit), which involves the variation of whole sets of chromosomes and aneuploidy(“aneu” means uneven), where a single chromosome within a set varies. This variation may be either increase or decrease in the chromosome number. The euploids include diploid (2n), triploid (3n), tetraploid (4n), hexaploid (6n) or even higher degree of polyploidy. Polyploidy, thus involves more than two genomes and is, therefore, a genometic mutation involving increase in the dose of whole genome. This condition of polyploidy is more common in angiosperms.

A few months back when Sharad Deshpande was talking about some processing tomatoes, I said that there is a lot of history behind processing tomatoes. He said then why don’t you speak on the subject and I said why not. So that is how this talk happened. First, I thought I will speak on breeding tomatoes as its history is even more interesting than what has happened later. I had heard a story when I went to USA for the first time in 1982. I was with Dr Charlie Rick, the father of tomato genetics, in his lab in USDA, UC, Davis, California. He talked about how the processing industry happened, who bred the types suitable for processing, how 80 percent of processing tomatoes of the USA came from California, where we are today and what could be done in this area.

In the changing Global scenario, food, nutrition, healthcare and livelihood security are the matter of great concern to human, social and economic development. The global community is increasingly looking towards finding means of sustainable nutrition for the growing population across all countries. The emphasis is on identifying lowresource strategies acceptable to the communities that do not put an unnecessary burden on the environment (FAO, 1993).
Nutritional security denotes the consumption and equitable access to adequate quantities of healthy, safe, affordable and nutritious food by every member of the family essential for optimal health and well-being. Concern for improvement of nutritional quality of vegetables has arisen in the context of providing nutritional security to our everincreasing population because poor nutrition is linked with increased risk of obesity, diabetes, and heart disease as well as broader impacts including higher health care costs and decreased productivity.
More than 1.0 billion people globally are hungry due to food insecurity problem and about 3.0 billion people are malnourished due to poor nutrition causing mainly micronutrient deficiency.

Reproduction by asexual means is common among higher plants. The best known means of asexual reproduction are by corms, bulbs, rhizomes, stolons, or other vegetative organs. Plants normally propagated in agricultural practice by these means or by budding or grafting include nearly all fruit and nut trees, strawberries, blackberries and raspberries, grapes, pineapples, almost all ornamental shrubs and trees and a few field crops such as sugar cane, potatoes, and sweet potatoes. Asexually or clonally propagated plants produce genetically identical progeny. Clones are identical copies of a genotype. Together, they are phenotypically homogeneous. However, individually, they are highly heterozygous and segregate widely upon sexual reproduction. This is not unexpected, because the types selected as commercial cultivars are likely to be vigorous ones, and a positive correlation exists between vigour and heterozygosity in most species.

2.1. Multiple Choice Questions

1. The process of bringing a wild species under human management is referred to as ????.
   1. Selection
   2. Rejection
   3. Domestication
   4. None of the above
2. ?????was perhaps the first man to use artificial hybridization to develop several new fruit varieties.
   1. Dawrin
   2. Knight
   3. Beal
   4. Mendel
3. Plant breeding aims to ???????
   1. Improve yield only
   2. Disease resistant only
   3. Insect resistance only

The brinjal, eggplant or aubergine (French name) has originated in the Indian sub-continent and China (Thomson and Kelly, 1957, Purewall, 1957 and Martin and Rhodes, 1979). Brinjal is an important vegetable crop of the Far East, Bangladesh, India, China and the Philippines. Brinjal belongs to the family Solanaceae and is known under the botanical name Solanum melongena L. (2n = 24). There are 3 main botanical varieties under the species melongena(Chowdhury, 1976). The round or egg-shaped cultivars are grouped under var. esculenturn, the long slender types are included under var. serpentintumand the dwarf brinjal plants are put under var. depressum.

1) Phomopsis fruit rot or Blight
Diagnostic Symptoms
• Plants are attacked at all stages of growth.
• On leaves, circular to irregular, clearly defined grayish brown spots having light centers appear. The diseased leaves become yellowish in colour and may drop off.
• Several black pycnidiacan be seen on older spots.
• Lesions on stem are dark brown, round to oval and have grayish centers where pycnidia develop.
• At the base of the stem, the fungus causes characteristic constrictions leading to canker development and toppling of plants.
• On fruits, small pale sunken spots appear which on enlargement cover entire fruit surface. These spots become watery leading to soft rot phase of the disease. A large number of dot like pycnidia also develop on such spots.
• Infection of fruit through calyx leads to development of dry rot and fruits appear black and mummified (Fig.1).