Vegetables are protective foods and a natural source of minerals and antioxidants which helps in delaying ageing and prevention of new generation diseases. They are rich sources of vitamins, minerals and dietary fibre essential for functioning of human body. Diverse climatic conditions prevailing in different parts of India offer ideal situation for cultivation of a variety of vegetable crops ranging from tropical to extreme temperate conditions. India stands second, next to China, in area and production of vegetables in the world. Cultivation of high yielding varieties including F1 hybrids, adoption of improved technologies and by bringing more area under irrigation and intensive cultivation resulted in a quantum jump in production of vegetables in the country during the past two decades.

Vegetables are defined as edible herbaceous plants or parts of plants consumed as raw or after cooking and are rich in vitamins and minerals, low in calorific value and neutralize the acid substances produced during digestion of high energy foods. Olericulture is a branch of horticulture that deals with production, storage, processing and marketing of vegetables and has its origin when man started growing vegetables for human consumption. The term Olericulture comes from Latin words holus-holeris = any kind of culinary vegetable, pot herb, and cultura = to cultivate. Vegetable crops include a large number of plants, mostly annuals and a few perennials, grown for their edible leaves, stem, flower buds, flowers, fruits and roots. Vegetables are integral part of a balanced diet and are considered as “Protective foods” as their consumption prevent several diseases. They have a prominent role in combating malnutrition of animals and human beings.

Quite a large number of vegetable crops are grown in the country either on a commercial scale or limited to backyards of homesteads. A few crops have similarity while others have dissimilarity in their climatic and soil requirements, parts used, method of cultivation etc. While describing individual vegetables, there is possibility of repetition in many aspects. In order to avoid repetition, it is essential to classify or group them into different classes/groups. Different methods of classification followed in vegetables are described below: I. Botanical classification Botanical classification is based on taxonomical relationship among different vegetables. Plant kingdom is divided into four viz. Thallophyta, Bryophyta, Pteridophyta and Spermatophyta. All vegetables belong to Division Angiospermae of Spermatophyta. It is further divided and two classes viz., Monocotylydoneae and Dicotylydoneae.

Diverse soil and climatic conditions prevailing in different parts of the country offer scope for cultivation of a variety of crops in India. Around 250 crops either cultivated or grown under natural habitat are used for vegetable purpose. The crops and varieties vary in their soil and climatic requirements, cultivation practices, resistance to pests and diseases, quality etc. Considering the climatic conditions for growing vegetable crops and for evolving zone wise technologies and recommendations, the entire country is divided into eight agro- climatic zones under the All India Co-ordinated Research Project (Vegetable Crops) as given below: Table: Agro-climatic zones and states under each zone

Vegetables are grown on a limited scale in homesteads for family use and cultivated in an extensive scale for marketing. Depending on the purpose for which they are developed, vegetables gardens are classified into different types, viz., kitchen garden or nutrition garden, market garden, truck garden, garden for processing, garden for seed production and vegetable forcing or protected cultivation. 1. Kitchen garden or nutrition garden Kitchen garden or home garden or nutrition garden is primarily intended for continuous supply of fresh vegetables for family use. A number of vegetables are grown in available land for getting a variety of vegetables. Most of works are done by family members. Area of garden, lay out, crops selected etc. depend on availability and nature of land. In rural area, land will not be a limiting factor and scientifically laid out garden can be established. In urban areas, land is a limiting factor and very often crops are raised in limited available area or in terraces of buildings. Cultivation of crops in pots or in cement bags is also feasible in cities. The unique advantages of a kitchen garden or home garden are: (i) Supply fresh fruits and vegetables high in nutritive value

The family Solanaceae consists of 85 genera, which include both tuberiferous and non-tuberiferous ones. Brinjal (Solanum sp.), chilli (Capsicum sp.) and tomato (Lycopersicon sp.) are the major fruit vegetables under the family. In all genera, fruit is an indehiscent berry. A key for the identification of the above three genera are furnished below: A. Anthers connivant in a cone, longer than filaments B. Anthers dehisce by apical pores or short slits, leaves entire, lobed or pinnatifid - Solanum BB. Anthers dehisce introsely by longitudinal slits, the tips empty, leaves pinnatiset - Lycopersicon AA. Anthers not connivant in a cone, not larger than the filaments, dehisce by lateral slits - Capsicum

Crops belonging to family Cucurbitaceae are generally known as ‘Cucurbits’. It consists of a wide range of vegetables either used for salad purpose (cucumber) or for cooking (all gourds), pickling (West Indian gherkin) or as dessert fruit (muskmelon, water melon) or candied or preserved (ash gourd). As a group, cucurbits occupy the largest area in India and in other tropical countries. Its use is not primarily because of calories, minerals or vitamins since they are generally low to moderate in nutrients with a few exceptions like bitter gourd (rich in vitamin C- 96mg/100g), pumpkin (vitamin A 1600 IU/100g), Kakrol (high protein 3.1g/100g,), parwal and chow chow (calcium- 531 mg and 140 mg / 100 g respectively). From the nutritional point of view, cucurbit seeds are valued for their high oil and protein contents. Seed proteins of cucurbits are comparable to that of legumes and are richer in methionine. The family Cucurbitaceae comprises about 117 genera and 825 species in warmer parts. Chakravarthy (1982) estimated 36 genera and 100 species in India.

Okra is predominantly a crop of tropics and subtropics. It occupies fifth position, next to tomato, in area under vegetables in the country with a production of 33.24 lakh metric tonnes from an area of 3.47 lakh hectares (2001-02). The crop is cultivated for its young tender fruits, used in curry and soups after cooking. It is a good source of vitamins A and B, proteins and minerals. It is also an excellent source of iodine and is useful for the treatment of goitre. Fruit is useful against genito-urinary disorders, spermetorrhoea and chronic dysentery. Fruits are also dried or frozen for use during off-season. Dried fruit contain 13-22% edible oil and 20-24% protein and is used as refined edible oil. Dry fruit skin and fibres are used in manufacture of paper, card board and fibres. Root and stem are used for clearing cane juice for preparation of jaggary.

Peas and beans belonging to the family Fabaceae (Syn. Leguminosae) are delicious and preferred vegetables grown throughout the world. These include cool season vegetables like pea, French bean, lima bean, broad bean and tropical vegetables like cowpea, hyacinth bean, winged bean, jack bean, sword bean etc. These are integral components of sustainable agriculture due to their ability to fix atmospheric nitrogen and to improve soil properties. Legume vegetables are rich in protein and essential amino acids and have significant role in combating malnutrition among poor people and vegetarians. Common features of legume vegetables are summarized below: All legume vegetables are self-pollinated due to cleistogamous nature. Flowers are zygomorphic with papilionaceous corolla, mono-adelphous or di-adelphous stamens. All are direct sown crops and do not respond to transplanting. Since seed size is comparatively bigger and they are closely planted, a high seed rate is required for most of crops.

Vegetables belonging to the family Brassicaceae (Syn: Cruciferae) are known as Cole crops. These are the most widely grown vegetables in temperate and sub-tropical zones. The word ‘Cole’ comes from abbreviation of word ‘caulis’ meaning stem. Cole crops are a group of highly differentiated plants originated from a wild plant Brassica oleracea var. oleracea (=B. sylvestris L.) commonly known as “Wild cliff cabbage” or “colewort”, through mutation, human selection or adaptation. Cole crops include cabbage, cauliflower, knol khol, Brussels sprouts, Chinese cabbage, sprouting broccoli, kale etc. of which cabbage and cauliflower are the most popular and widely grown. Mediterranean region is the centre of origin of Cole crops. From there, it spread to Europe and other temperate and sub-tropical regions. Cabbage, knol khol and curly kale were the first known cultivated types. Cauliflower became widely known in the 18th century and Brussels sprouts in 19th century. In the thirties of 20th century, sprouting broccoli started cultivation particularly in the USA. Linnaeus in 1753 included all forms of Cole crops in one species, Brassica oleracea. Later the works of many, including Neuwhof (1969) resulted in putting them into different forms as given below: B. oleracea var. capitata L. - Cabbage

Bulb crops include onion, garlic, leek, shallot, welsh onion and chive- all belonging to the genus Allium. This genus was earlier included in the family Liliaceae due to its superior ovary. It was later shifted to Amaryllidaceae as flowers are bom in a bracted umbel on top of a scape. Being the typical genus in the family Amaryllidaceae, a new separate family status was given to all the specious under Allium as Alliaceae. The common features of bulb crops are: The stem is under ground and rudimentary. The edible portion, bulb is formed by fleshy leaf bases in onion, fleshy axillary buds within thin foliage in garlic, blanched stem and leaves in leek etc. All the bulb crops have a characteristic order due to presence of allyl - propyl - disulphide. All are cool season vegetables and are grown during winter months in plains.

Radish, turnip, carrot and beet root are the major root crops grown in the country. In addition, root crops like rutabaga, parsnip, salsify, chervil and celeriac are grown in a limited scale in different areas. Though the crops belong to different families, their cultural requirements are uniform. The common features of root crops like radish, turnip, carrot and beet root are: In all root crops, the tap root and a portion of hypocotyl develop into fleshy root. All root crops are cool season crops and are the best grown during winter in plains and spring-summer in hills of North India All crops, except beet root, exhibit two distinct groups, viz., tropical or Asiatic or annual types and temperate or European or biennial types. In beet root, tropical annual types are not available. Seeds of annual types are produced in plains. Biennial types require a chilling temperature, after attaining or completion of vegetative phase, for transforming to reproductive phase. Since this chilling temperature is available during winter at high altitudes, seed production of biennial types are practiced only in hills of North India. All root crops require well drained loose and friable soil without any clods for raising a good crop. Seeds are sown on ridges or on raised beds for proper development of roots.

Potato is fourth major food crop after rice, wheat and maize in the world. It produces the highest dry matter, well balanced protein and more calories/ unit area and time. Unlike other food crops, potato tubers contain vitamin-C (17 mg/100 g). It provides carbohydrates, minerals, fibre and a number of vitamin-B groups. Potato protein is comparable to that of milk and egg. Unlike European countries, in tropics and sub-tropics, the crop is of short duration and fits well in intensive cropping system. It can be grown in a wide range of climatic and soil conditions and tubers are available throughout the year. Tubers can be left un-harvested in the soil for some time and are also suitable for long distance transport and storage. Several products like chips, flakes, French-fries, finger chips, granule, disc, cubes and flour are made out of potato tubers Origin and distribution Potato is a native of tropical South America. Traditionally, it was adapted as a commercial food crop in temperate climate under long day conditions, mainly in Europe. It was introduced to India in 16th or 17th Century by Portuguese or the British. 

Tropical tuber crops are an important group of subsistence crops in tropical and subtropical zones. Carbohydrates synthesised and stored in the form of starch in underground tubers are used as food by millions in under-developed countries. It is also used as raw material by many industries. Cassava, sweet potato, Chinese potato, edible aroids like elephant foot yam, taro, tannia and yams like greater yam, lesser yam and white yam are major tuber crops grown in India. Tuber crops are mainly grown as rainfed with minimum cost of production. All are propagated through vegetative means and require fertile and well drained loose soil for proper root development. All roots crops require high dose of potassium for high productivity.Cassava is the most important starchy root crop grown in the tropics and is mainly cultivated in southern peninsular India. Introduced during seventeenth century by Portuguese, the crop played a significant role to overcome food shortage among the low income group of people in Kerala. Underground tuber is rich in starch and mainly consumed after cooking. Processed products like chips, sago and vermicelli made of tapioca are also popular in the country. Being easily digestible, it forms an important ingredient in poultry and cattle- feeds. It is also widely used for production of industrial alcohol, starch and glucose.

Leaf vegetables are rich sources of provitamin-A, vitamin-C and minerals like calcium, iron etc. They also provide roughage required in human diet. The Indian Council of Medical Research (1984) recommended a daily intake of 100 g and 40 g of leaf vegetables in the diet of woman and man, respectively. Amaranth, beet leaf, spinach, fenugreek, cabbage etc. are the major leaf vegetables grown in the country. In addition, a number of under-utilized annual crops are also grown as leaf vegetables in specific regions. Tender stems and leaves of a number of perennial crops are rich sources of vitamins and minerals and are used for cooking. The major annual leaf vegetables have a few features in common: Most of leaf vegetables are of short duration and the entire harvest is over within 80-90 days Leaf vegetables are cultivated by direct sowing and by transplanting. In direct sowing, seeds are sown as in nursery and harvested 30 days after. In transplanted method, 25-30 days old seedlings are transplanted at a closer spacing and harvesting is done by frequent clippings or cuttings.

Vegetables which are consumed raw without cooking are known as salad crops. In temperate regions, a large number of quick growing cool season crops like lettuce, celery, parsley, endive, chicory, chervil, cress, water cress etc. are consumed as raw. Only lettuce and celery are cultivated on a commercial scale in developed countries. Growing awareness on nutritional values of raw vegetables and also health consciousness of people resulted in increased consumption of salad vegetables in tropics too. Vegetables like onion, cucumber, tomato, carrot, radish, beet root, cabbage, capsicum, melon etc. are used as salads without cooking.  (Hindi: Salad) Fam.: Asteraceae (Compositae) Lettuce is the most popular salad crop of the world and the most important vegetable crop in temperate regions. The crop is grown mainly under protected structures in temperate countries. Tender leaves and heads are chopped and used as salad along with salt and vinegar.

Perennial vegetables live/survive in field for several years and go on yielding vegetables without much care and attention. They are usually planted on the side of kitchen garden without much interference with tillage operations of other annual crops. Tender leaves, shoots, fruits or tubers of a number of perennial crops are used for vegetable purpose in different agro-climatic conditions. They may be trees or shrubs as in bread fruit, jack fruit, drumstick, etc. or bushes as in colocasia or trailing plants as in yams, chow-chow and ivy gourd. Temperate perennial vegetables are asparagus, rhubarb, artichoke and seakale. All the above crops have tuberous roots, rhizomes or corm. Above-ground portion may dry up during winter and again sprout during spring. Tuber crops like cassava, elephant foot yam, Colocasia (taro), Dioscorea (greater yam, lesser yam) etc. grown under tropical conditions are also perennials. But for cultivation purpose, they are replanted every year and are treated as annuals.

Mushrooming population, subsiding agricultural resources; land and water, people’s concern towards quality of vegetable s/food and changing climate throws several challenges for vegetable production. Conventional management and crop improvement strategies alone can no longer sustain the nation’s as well as global demand. So there is an urgent need to adopt modern biotechnological methods which are multidisciplinary where a large number of tools and elements of conventional breeding technique, genetic engineering, molecular biology, molecular genetics, bioinformatics and biochemistry are utilized and integrated. Biotechnological tools provide three major aspects of genetic improvement viz, application of tissue culture, molecular breeding or marker assisted breeding and genetic engineering.

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