Preface Vegetables are important constituents of our healthy diet and provide more profits to the growers. Crop improvement is the most satisfying method of increasing the productivity of any crop. With the experience of teaching vegetable breeding to graduate and post graduate students for more than fifteen years and involvement in developing few varieties of vegetable crops and serving as Professor and Head of the Department of Vegetable Science, idea of bringing out a book was conceived and started compiling notes during all these years. Listing of references is not exhaustive to avoid bulkiness of the book where information is presented in very comprehensive manner. Production and consumption of vegetables has expanded greatly. Improved varieties have had a main role in the increase in yield and quality of vegetable crops. The diversity of vegetable crops is appalling and greatly contributed to increased production and consumption of vegetables world over. For improvement of crops information on origin, distribution and evolution of crop and its related species is very essential. Information on genetics and genetic resources is prerequisite to choose the appropriate breeding  strategies to fulfill the objectives. Objectives of breeding vary with region and also purpose for which the product is used i.e., for fresh market, for processing or dual purpose and how the crop is grown i.e., under protection, open field cultivation or kitchen garden etc. Depending on the objectives and genetic resources, breeding methods or procedures can be adopted and it will results in useful varieties or hybrids. Information on breeding of vegetables crops is covered in very abridged form. More number of crops covered in this book by appending and updating information on genetics, genetic resources, breeding methods/procedures and varieties developed in each of the 26 vegetable crops wherever information is available. Origin and evolution, genetic resources, genetics of fruits, breeding methods and varieties/hybrids developed is the sequence followed in presenting the information on each of the crops.

Tomato is relatively recent addition to the world’s vegetable crops. Now became one of the most important vegetable crops and is popular & widely consumed. It is being grown extensively in USA, China, India, France, Israel and Netherland.   It is used in fresh and processed form. Among the vegetables maximum attempts have been made to improve this crop because of its short duration, easy cultivation and large number of seeds per fruit and this has made it an ideal crop for many research works. An exclusive Tomato Genetics Co-operative located in University of California, USA, published genetic information on the crop and maintains a large number of     collections which have already been thoroughly catalogued.   Origin and Distribution: Native of Peru in South America and spread to North America by migrating birds. Largest number of wild tomato forms is present in Mexico. Spanish Priests introduced it to Europe in around 1550. In Europe it is known as Poma amoris = Amorous apple (Love apple). Wild relatives found in narrow elongated mountainous regions of Andes in Peru, Ecuador and Bolivia and Galapagos islands. Domestication and cultivation of tomato appears to have first occurred outside its centre or origin. Domestication of tomato was first done by Mexican people i.e. Red Indians, which is considered as secondary center of origin. Now cultivated tomato is common in Peru but recently added to their diet.

India is the primary centre of origin of brinjal. Decandolle (1904) reported it as native of Asia. In Europe it is not known earlier (before 17th early). According to N.I Vavilov, the egg plant originated in Indo–Burma region and china and spread to South Europe, china and Japan. Vavilov (1951) suggested China a centre of origin of brinjal. Crop is restricted mainly to South and South-East Asia, Southern Europe, China and Japan. Wild brinjal types are available in Southern Coastal area of Africa. Botany Solanum melongena’ L. var. esculentum - round or egg shape  var. serpentinum – long, slender type  var. depressum – dwarf brinjal plant  It is often cross pollinated crop due to heteromorphic flower structure (heterostyle)

‘Chili’ (European literature) word derived from ‘Chile’ which means any pepper in Mexico and Central America. Peppers are an important constituent of many foods adding flavor, colour, vit.C and pungency and therefore indispensable to the world food industries. China, Mexico, Japan, Turkey, Indonesia, Pakistan and India are major producers.   Origin:  The cultivated chilli is of South American origin. Authorities generally agreed that capsicum originated in the new world (America) tropics and sub tropics. Pepper pods are there from 2000 year old burials in Peru. Decandolle concluded no capsicum was indigenous to the old world (Europe), peppers unknown in Europe until 16th century. Chilli was introduced into Spain by Columbus on his return trip in 1493 and cultivation spread from Mediterranean region to England by 1548 and to central Europe by close of 16th century. Portuguese carried capsicum from Brazil to India prior to 1885 and cultivation was reported in china during late 1700’s. All capsicum species have 2n = 24. Polyploids with 2n = 36, 48 and  aneuploid 2n = 25 reported

If there is scarcity of food, potato can come to the rescue because of its virtue of high yielding (40-50 t/ha) and is a staple food. It produces more calories per unit area and per unit time than any other major food crops. Potato which is the staple food of Europeans and Americans belong to the highlands of Andean mountainous regions of Peru and Bolivia where it has been cultivated since 6000 years.   Origin: Peru, Bolivia. Many wild species occur at Mexico and Central America. Potato was introduced to Europe in 16th century by Spaniards (Salaman, 1966) and in early 17th century to India most probably by Portuguese. There are some suggestions based on linguistic and botanical evidences that potato might have been introduced in India directly from South America across the Pacific Ocean. Earlier potatoes were grown in hilly areas of North and South since British settlers brought the varieties continuously from UK and these were bred for long day temperate conditions of Europe. But in India potatoes are grown in short day-subtropical plains. The seed stocks used to degenerate due to accumulation of viruses and loose their yield potentiality. Seed potatoes were mainly imported from Europe i.e. U.K., Italy and Netherlands and Burma till the beginning of Second World War and the imports gradually reduced.

Okra has higher average nutritive value (ANV) of 3.21 which is higher than tomato, egg plant and most of the cucurbits except bitter gourd (Grubban, 1977). Its roasted seeds are substitute for coffee. It is one of the export potential crop where it accounts to 60 per cent of fresh vegetables (excluding potato, onion and garlic) exported from India. Importing countries are Middle East, Western Europe and USA. Origin and Distribution : It belongs to the genus Abelmoschus established by Medikus, 1787, however de Candolle (1824), treated it as section of Hibiscus.   In 1924 Hochreuntiner reinstated the genus Abelmoschus of Medikus stating that calyx, corolla and stamen fused together at the base and fall as one piece after anthesis (deciduous) where as in case of hibiscus these are persistent. Though the genus is of Asiatic origin, the origin of cultigen Abelmoschus  esculentus is variable like India (Master, 1875) Ethiopia {de Candolle (1883) and Vavilov (1957)}, Western Africa (Chevalier, 1940 and Mardorct, 1947) and Tropical Asia (Grubban, 1997) and probably its might have entered India at the end of 19th century. Cultivated okra is of old world origin. It arose as a cultigen in the Abyssinian region (Ethiopia). Wild species are indigenous to Africa.  Three wild species Abelmoschus tuberculatus, A. moschatus and A. ficulneus are native to India. Introduced to Mediterranean region to Europe and Asia. But during Columbian period it was introduced to America.  It still turnout to be polyphyletic (many places) in origin. A. tuberculatus (Indian origin) and an unknown species cross resulted into A. esculentus.

Cucumber Cucumber (Cucumis sativus) is a warm season vegetable used as salad and for pickling purpose has little or no frost tolerance.  Growth and development favoured  by temperature above 200C.  Cucumber cultivars generally classified as pickling or slicing types. In India often cucumbers (Cucumis sativus) are confused with melons (Cucumis melo ) as morphologically some variants of these species overlap, but they are not cross compatible. Kakri of North India are different from kakri of South India and Maharashtra. In Maharastra and South India cucumbers are referred as kakri but, in North India Kakri means Long melon i.e. Cucumis melo Var. utilissima.

Melons (Cucumis melo) are annuals with climbing, creeping or trailing vines of length up to three meters. The desert types quench thirst and add to the nutrient content of main diet. The non-desert types are used as vegetables. Muskmelon (Cucumis melo., 2n=2x=24) encompasses the netted, salmon -flesh cantaloupe, the smooth – skinned green fleshed ‘Honey Dew’, the wrinkled, white – fleshed, ‘Golden Beauty’ and several other dessert melons in USA. Origin: Not known with certainty but, 40 or more wild species of Cucumis are found to occur in the tropics and subtropics of Africa. Wild species of Cucumis occur in Africa and it is likely that it originated in African continent. It does not appear to have been known to the ancient Egyptians, not to the Greeks and seemed to have reached Europe towards the decline of Roman Empire. Although melon was introduced into Asia at a comparatively later date there are undoubtedly well developed secondary centers of origin of C. melo in India, China and then Southern USSR. In India Oriental pickling melon (C. melo var conomon) and snap melon (C. melo var momordica) are unique and have considerable variability in Western Ghats of India. They are popular desert and preserving melons cultivated in Warm humid tropical condition of South India. It is also considered that China as primary center of origin and Indo-Burma as secondary center of origin. It has been introduced to Europe and from Europe to the USA by the early travelers. At present muskmelon is being cultivated throughout the world under tropical and subtropical climatic conditions. Polymorphism in leaf, flower, fruit shape and colour (Kirkbride, 1993), allowed the classification of horticulturally important melons into seven groups.

Water melon is tender to frost and most of cultivars require relatively long growing season. Plant growth and fruit development are fallowed by higher temperature and abundant sunlight. Atmospheric humidity greatly regulates fruit and foliage diseases. Taxonomy and Origin: Ealier it was classified as Citrullus Vulgaris Schrod. But in 1963 Thieret called attention to the correct name, C. lanatus (Thumb) Mansf. Africa is centre of origin of the genus. In 1857 David Living Stone, the famous missionary explorer found both bitter and sweet melons grown together in Africa and native people used them as source of water. Cultivation is prehistoric as there are pictures made in ancient Egypt. Early cultivation occurred in Mediterranean area and as far as India also and It was brought to USA by European colonist as early as 1629.

Ridge gourd or Ribbed gourd (Luffa acutangula Rox b. L) and Sponge gourd or Smooth gourd (Luffa cylindrica) have diploid chromosome number  2n=2x=26. Luffa has old world origin in Subtropical Asian region including India (Kalloo, 1993). These two species are inter-crossable. F1 plants generally, intermediate between the parents and showed various irregularities like, univalants, rings and chains of 4 chromosomes, chromatids bridges and fragments at metaphase and thus the species are not easily crossable and the F1 plants appear to be of not much practical value. The genus is monoecious annual vine, tendrils are branched, flowers are yellow, anthers are free and pistil has three placentas with many ovules and stigma are three and bilobate. Fruits oblong or cylindrical and rind becomes dry on maturity.

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.

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).

Squashes and Pumpkin (Cucurbita, spp, 2n = 2x = 40) are the words quite often used interchangeably. However, the term squash is more commonly used for C. pepo which is consumed as an immature fruit. The term pumpkin is normally applied to the edible fruit of any species of Cucurbita utilized when ripe as a table vegetable or in pies.   Origin:  The genus Cucurbita is native to America.  The center of diversity is the tropics near the Mexico- Gauatamla border. The archaeology evidences indicate that these were widely cultivated in South Western United States, Mexico, and northern South America in Pre-Colombian times i.e. prior to 1492 A.D. C. pepo : Summer squash : Some varieties belong to winter squash, pumpkin and marrows. It has bushy habit, peduncle hard, sharply angular, grooved, leaves broad, triangular in outline, usually with deep lobes little or no expansion of peduncle at fruit attachment. In North America it is commonly found. C. mixta : Squash, cymlins, cushaws: It is used as summer and winter squash, leaves shallowly lobed, hard corky peduncle. This is also commonly found in North America.

Keys to Genera Flowers zygomorphic, stamens definite, corolla papillonacious, petals imbricate: 1I, 1O, 3 IO Group I:    Herbs or shrubs, leaves imparipinnate, leaf lets entire, pods usually dehiscent, or if indehiscent usually small, a few seeded. Cyamopsis Group II:    Herbs low or climbing, leaves paripinnate, leaflets ending in a tendril or bristle, style bearded, pods dehiscent. Sub group 1: Staminal tube oblique at mouth, pod compressed. Vicia Sub group 2: Staminal tube truncate (cutting off) at mouth, pods torpid.  Pisum Group III:     Climbing or prostrate and rarely erect Sub group 1: style bearded, stamen diadelphous Sub-sub group: stigma terminal: Dolichos Sub-sub group: Stigma oblique: Keel spiral : Phaseolus Keel not spiral: Vigna Sub group 2: Style not bearded, stamen monodelphous: Canavalia Group IV:    Trees or shrubs, some times climbing, pods indehiscent: Psophocarpus Garden Pea It is cool season crop cultivated throughout the world. It is extensively grown in temperate zone and is restricted to cooler altitudes in tropics and winter season in sub tropics. It is rich source of proteins (25.6%), amino acids and sugars. It goes well with other vegetables in vegetable dish.

Among beans, the most popular bean is French bean and it has wider distribution and larger gene pool. Various names are associated with cultivars viz., Snap bean, salad bean and green bean and all these names associated are with beans of vegetable types. The names haricot bean, dry bean and navy bean are applicable to pulse types. String bean, dwarf bean and pole bean applicable to growth forms. It is known as Rajmah in Hindi, Tingalawari in Kannada and Fras bean in Punjabi. Cultivars preferred for Canning, frozen and freeze-dried are having round pods. Fresh market cultivars are flat or oval shaped. Yellow pod cultivars are also grown. Generally fresh market cultivar yields higher in temperate region than in tropical region. Beans are said to be antidiabetic and good for bladder burns, cardiac, carminative, diuretic. Origin and Distribution: Phaseolus vulgaris was domesticated in Central America about 7000 years ago and it is also thought to be domesticated in Brazil and Northern Islands and was introduced to Europe in 16th century. Vavilov (1951) reported that Phaseolus vulgaris originated in South Mexico and Central American centre of origin. The first cultivar has been selected in Peru. From Peru it spread to Europe and to Asia. Wild species P. aboriginus in North West Argentina is considered as the wild progenitor of French bean. Based on growth habit, crop can be classified into pole type, semi pole type and bush type. Former varieties are more string types. American origin of P. vulgaris is questioned by De Candolle (1584). Southern part of Mexico and Central America are considered to be primary centre of origin. While secondary centre lies in Peru-Bolivian-Ecuador of South American continent. In Europe, French bean spread rapidly in 16th and 17th centuries and reached England by 1594. From Europe, it was introduced to India during 17th century (Simmonds, 1976).

Southern pea / black eyed pea are the other names associate with cowpea. It is grown for vegetable and also as pulse crop and varieties are specific for use. Classification of Cowpea 1.    Vigna unguiculata (L.) Walp. Cv. Sesquipedalis: yard long bean or asparagus bean: Possess long pods and used as vegetable.  2.    Vigna unguiculata (L.) Walp. Cv. Cylindrica: dual purpose, i.e. vegetable and pulse  3.    Vigna unguiculata (L.) Walp cv. Radiata: Pulse type.   More emphasis is given for pulse types for crop improvement. Less attention is given to vegetable types. Pole and bush types are available in vegetable type. Cowpea improvement is from vine to bushy habit with low fiber content and low glucosides and increased protein content. Origin and Distribution: Cowpea is in cultivation from ancient times in the tropics of old world. Country of origin is uncertain. In India, it has been known from the vedic times. Vavilov (1939) considered India as the primary centre of origin. But it is now generally agreed that Africa is centre of origin since wild forms are found in Africa and in Asia wild forms are absent (Smartt, 1990). Faris (1965) concluded that, cowpea arose from domestication of wild form Vigna unguiculata ssp dekindtiana in West Africa. But domestication is actually happened in Ethiopia and dissemination was West wards Africa, East ward across the Indian Ocean. It has spread from Africa to Asia and Europe through Egypt. Introduced to West Indies in 16th century by Spaniards and was taken to USA around 1700. Now cowpea is widely distributed throughout the tropics and subtropics.

Dolichos bean is known as Lablab bean, hyacinth bean or sem. Grown as field crop in MP, Maharashtra, AP and TN. Genus Dolichus is renamed as Lablab (Syn. D. lablab, D. purpureus, Lablab niger, L. bvulgaris) and Lablab purpureus name is widely accepted. Dolichos lablab L. (synonyms Lablab purpureus (L.) Sweet.) is leguminous pod vegetable grown in tropics and few temperate countries. Lablab niger var. lablab is synonym to Dolichos lablab var. typicus where long axis of seed is parallel to suture and is vegetable type. Lablab niger var. lignosus synonym to Dolichos lablab var. lignosus where long axis of seed is perpendicular to suture and is pulse type.

Onion Onion is very popular vegetable crop grown worldwide. Consumption is in the form of fresh, frozen, and dehydrated bulbs and green bunching onion. Origin of Allium cepa is still somewhat mystery. Vavilov (1951) suggested that the onion originated in the area of Pakistan. Others have suggested Pakistan, Iran & the mountain areas to the north (Jone& Mann, 1963). One fact is certain that the onion has been around in its present edible form for thousands of years. Onion recorded in tombs as early as 3200 B.C. It was mentioned as a food in the bible and in the Koran with reference thought to be around 1500 B.C. In addition to being a food considered by people, plant is having certain healing power. Some early drawing indicates that onions were used in spiritual offerings.

Cabbage Cabbage is an important crop in USA, Northern European countries, Russia, Japan & Australia and its breeding occurs here, but Holland and Japan are the major breeding countries. It is also being cultivated in India and crop improvement work is taken up in India also. Origin and General Botany: Historical evidence indicates that modern hard head cabbage cultivars descended from wild non headed Brassica originated in the Eastern Mediterranean and in Asia Minor. The Celts and Late Romans are responsible for spread cabbage throughout Europe. Latin name Brassica derived from Celtic word “bresic” meaning cabbage. Over a period hard headed evolved in Northern Europe and loose headed and heat resistant types evolved in South Europe. Cabbage was first introduced to America in 1541 by French explorer Jacques Cartier (planted seeds in Canada) and earlier colonist introduced the crop in to India also. Round headed types-are evolved earlier than flat (evolved in 17th or 18th century).  Broccoli, Cauliflower, Brussels Sprout, Collards, Kale, and Kohlrabi are all readily intercrossed members of this species.

Cauliflower follows cabbage in importance with regard to area and production in the world. However in India Cauliflower is more widely grown than cabbage. This crop grows at a latitude 11°N to 60°N with average temperature ranging from 5- 8°C to 25-28°C. It can stand to the temperature as low as -10°C and as high as 40°C for a few days. Italy and India are the major countries growing CF on large scale. Important cauliflower growing states in India are UP, Karnataka, West Bengal, Punjab and Bihar. It is commonly grown in Northern Himalayas and Niligiri hills in south. Origin and Distribution: Cauliflower is thought to have been domesticated in the Mediterranean region since, the greater range of variability in the wild types of B.oleracea is found there (Nieuwhof, 1969). Wild Cole warts are still found in wild state in sea cost of England and Denmark and in the North West France and various localities from Greece to Great Britain. The Cole crops, including cauliflower and cabbage have descended from a common Kale like ancestor, the wild cabbage (B.olearcea var. sylvestris L.) which is still found in western and southern Europe and North Africa (i.e, sea coasts of England and Denmark and in North West France and various localities from Greece to Great Britain). Cyprus and area around Mediterranean courts are considered to be the primary centers of origin for Cauliflower. It is also reported that cauliflower is originated from a related species. B.cretica. As per Bosewell (1949), it originated in the islands of Cyprus from where it moved to other areas like Syria, Turkey, Egypt, Italy, Spain and North Western Europe. Cornish types originated in England fallowed by temperate types originated in Germany and Netherlands in 18th century. The present Indian tropical cauliflowers developed as a result of intercrossing between European and Cornish type. In India tropical types with resistance to high temp and high rainfall conditions have been developed. Tropical types are grown in Indian plains from May to September, followed by temperate types known as snowball cauliflower.

Amaranthus is one of the main genera of large and taxonomically diverse group of leafy vegetables. Amaranthus is the cheapest dark green leafy vegetable because of low production costs and high yield. It is often described as poor man’s vegetable. Origin and Distribution: The main vegetable type Amaranthus tricolor L. originated in South or South East Asia, particularly in India. Budhist monks and Muslim invaders took the crop to neighboring countries. Another vegetable type A. dubius shows diversity in Central America, Indonesia, India and in Africa. A lividus is a popular leafy vegetable in Southern and Central Europe. Amaranthus included 50 to 60 species.

Carrot (Daucus carota L.) is a cool season root vegetable and temperature is the important factor affecting root shape and colour, besides soil type and moisture content of soil. It provides an excellent source of vitamin A and fiber in the diet. The genus Daucus, which include carrot, has many wild forms that grow mostly in the Mediterranean region and South West Asia. Representatives are found in Africa, Australia, & North America. For Daucus carrot L. it is generally agreed that Afghanistan is the primary center of genetic diversity and therefore the primary source for dissemination. Asia Minor, Afghanistan, North West India, Iran and Turkey are the centers of origin of carrot. Banga (1957& 1963) has provided evidence that the purple (anthocyanin) carrot together with a yellow variant spread from Afghanistan to Mediterranean area as early as 10th and 11th century. It is known in Western Europe in 14th and 15th century, China in 14th century and Japan in 17th century. The European carrot (Carotene carrot) derived from the Asiatic (anthocyonin containing) form of carrot (tropical carrot).  Afghanistan is the centre of diversity of the purple coloured carrot (anthocyanin). Integration of Asiatic and European carrots has given the present day forms. The yellow coloured (carotene rich) forms were also thought as mutants of anthocyanin carrots. The yellow mutants were traced in Asia Minor in 10 and 11th centuries, Spain in 12th century, North Western Europe in 14th century and England by 15th century.  The crop was introduced to China during 14th century and to Japan during 17th century. D. carota and D. sativus are only cultivated species of the genera with Chromosome No. 2n = 18. All forms have same chromosome number. 

It is a popular root crop having wide range of adaptability, grown in Japan, Koria, China, India and other European countries. Origin and Distribution: Radish was an important food in Egypt during 2000 BC.  Fossils study reveals that, it was a food as early as 2700 BC. It spread to China during 500 BC and to Japan during AD 700. Variability of crop decreased from Europe to China and from there to Japan. Recent study indicates that East of Mediterranean, most probably China was the centre of origin of the crop. This means Europe and Asia are the probable places of origin.

Beta vulgaris 2n = 2x=18 is an important vegetable crop in Eastern and Central Europe and it belongs to family Chenopodiaceae. It is of lesser importance in Western Europe and USA where it is known as garden beet. The swollen roots are consumed as vegetable and salad. The other types which are non-horticultural forms are known as sugar beet, mangold and fodder beet. Origin: Leaf beet is the earliest domesticated form. It is believed to be originated from Beta maritima known as sea beet which is indigenous to Southern Europe.  Botany: Biennial producing enlarged hypocotyl (roots) and rossette of leaves in first year and flowers and seeds in second year.

Turnip is the root vegetable cultivated in cooler season or temperate regions of the globe. Brassica rapa L 2n = 2x = 20 is formerly known as B. campastris subsp rapifera. Swede (B. napus var. napobrassica) is directly related to turnip. Origin: It is originated in cooler part of Europe, presumably from biennial oilseed forms. It was known to Greeks and Romans at beginning of Christian era. It was introduced to Britain from France by Romans and into North America by the early European settlers in the 17th century.

Sweet potato Ipomea batatas(L). Lam. is an asexually propagated vegetable. It is grown in most of the tropical and subtropical region of the earth. In USA production extended to temperate regions. Vines as well as roots are eaten or fed to live stock. It is the source of industrial starch and potential source of the alcohol. Among the major tuber crops cultivated in India sweet potato rank third after potato and cassava in area and production. Origin: Available evidence suggests South Mexico through Central America and Northern South America as the probable center of origin. It is perennial but handled as annual. Its hardiness and drought tolerance are well recognized. Family: Convolvulaceae, Chromosome number: 2n=90 It is the only known natural hexaploid morning glory. Most of the wild species are diploid (2n=30). Hybridization is restricted with in species because of its hexaploidy nature. Extensive variability with in species is observed. Tuber is the fleshy subterranean stem or shoot but in sweet potato tuber is a root, and hence it cannot be a tuber (common error). It is a perennial, and the storage root is capable of continued enlargement and does not mature in the sense of reaching some final size or stage of development. From the stand point of function, the root system consists of absorbing roots and fleshy storage roots.

Cassava (Syn: Tapioca) Manihot esculenta (Crantz) (2n = 2x = 36) (Hindi : Mravuli) is perennial shrub cultivated in tropics for its starchy tuberous roots. It is one of important tuber crops cultivated in tropics because of its high carbohydrate yield per unit land and labour and its adaptation to poor soil and water stress and its tolerance to dominant pest and diseases. Cassava contains cyanide, the toxic principle which limits food and feed value. In cassava the glycoside linamarin and lotaustralin are converted to hydrocyanic acid, a potent toxin, when come in contact with linamerase, an enzyme that is released from rupture of cells. Tuber peel contain significantly higher amount of glycosides than the pulp. It can be removed by cooking in water for about 5 minutes.

Selected References Abdul, N. M., Joseph, J. K. and Karuppaiyan, R., 2004. Evaluation of okra germplasm for fruit yield, quality and field resistance to yellow vein mosaic virus. Indian J. Plant Genet. Resour., 17:241–244. Alegbejo, M., Ogunlana, M. and Banwo, O., 2008. Short communication. Survey for incidence of Okra mosaic virus in northern Nigeria and evidence for its transmission by beetles. Span J. Agric. Res., 6:408- 411. Ali, M., Hossain, M. Z., Sarker, N. C., 2000. Inheritance of yellow vein mosaic virus (YVMV) tolerance in a cultivar of okra (Abelmoschus esculentus (L.) Moench). Euphytica. 111:205–209. Ali, S., Khan, M. A., Habib, A., Rasheed, S. and Iftikhar, Y., 2005. Correlation of environmental conditions with okra yellow vein mosaic virus and Bemisia tabaci population density. Int J. Agric. Biol., 7:142–144. Allard R. W., 1960. Principles of Plant Breeding by Publishers: John, Wiley and Sons, Inc.  Anonymous, 1990. Report on international workshop on okra genetic resources; 1990 October 8–12; National Bureau for Plant Genetic Resources, New Delhi, India. Rome (Italy): IBPGR. Aparna, J., Srivastava, K. and Singh, P. K., 2012. Screening of Okra Genotypes to Disease Reactions of Yellow Vein Mosaic Virus under Natural Conditions VEGETOS., 25 (1): 326-328.     Basset, M.J. (Ed.). 1986. Breeding Vegetable Crops. AVI Publ. Bhattacharya, M.K., Nandpuri, K.S. and Singh, S., 1979. Genetic divergence in tomato. Acta Horticulturae, 93:289-300. Bose, T.K., Kabir, J., Maity, T.K., Parthasarathy, V.A. & Som, M.G., 2003. Vegetable Crops. Vols. I-III. Naya Udyog.