eChapters

10.1 Introduction

Leek is a non-bulb forming tetraploid plant of onion family. It belongs to monocotyledons group like onion and garlic, and has white narrow bulbs with broad leaves and etiolated pseudostem formed by the leaf sheaths. Except large size it looks like green onion. Its cultivation is not commercial in India and grown only in kitchen garden. Recently, its cultivation has been noticed in temperate regions of north India and the Niligiri hills of South India. Leek is cultivated for blanched stems and leaves. It is a hardy biennial plant, consumed as salad and used in flavouring the soups. It has flattened leaf blades rather than the radial, and it is bigger than onion. As compared to onion, it has milder and more delicate flavour. 

9.1 Introduction

Garlic (Allium sativum L.) is one of the important bulb crops grown and used as a spice or condiment throughout India. It is derived from two words gar meaning spear and lic meaning herb. It is also important foreign exchange earner for the country. Garlic has higher nutritive value than other bulb crops. It is rich in proteins, phosphorous, potassium, calcium, magnesium and carbohydrates. Healthy garlic bulbs contain allicin, a colourless, odourless and water-soluble amino acid. On crushing the garlic bulbs, the enzyme allinase breaks down into allin to produce allicin of which the principal ingredient is odoriferous diallyl disulfide. Garlic contains about 0.1% volatile oil. 

6.1 Introduction

It is an important vegetable in European countries. It got its name from the capital city of Belgium since it has been grown around Brussels for hundreds of years. From Belgium it has been introduced to England (1810). Some parts of Long Island in New York are also well known for Brussels Sprout production. In India, it is widely grown in Kodai kanal and Nilgiris hills of Tamil Nadu and Maharashtra. Exact statistics regarding area, production and productivity are not available. It is a cool, moisture loving and frost resistant biennial, with axillary buds produced in the leaf axils during the first year of growth and a seed head is produced in the second year of growth. Edible part is swollen axillary bud (sprouts or buttons or mini cabbage). 

8.1 Introduction

Common onion, Allium cepa L., is a vegetable that is the most widely cultivated species of the genus Allium. It has been cultivated for more than 5000 years. However, its wild species do not exist. Allium is a Greek word. Onion is native of Central Asia. According to Vavilov onion originated in Pakistan, however, others opined it to have domesticated in the mountainous regions of Central Asia comprising Turkmenistan, Uzbekistan, Tajikistan, Afghanistan, Pakistan and north Iran. Jones and Mann proposed the area comprising Pakistan and Iran or South East Asia as the centre of origin. Onion is very important in cookery. 

7.1 Introduction

Chinese cabbage appears to be native of China. It is known to have arisen from a cross between Pak choi (Brassica rapa var. chinensis, non-heading Chinese cabbage) from south China and turnip (Brassica rapa var. rapifera) from north China when they were grown together in the city of Young-chou. Artificial crosses between these species have proved this hypothesis. Its chromosome number 2n=20 distinguishes it from cole crops. It is not a member of cole group but regarded as very closely allied crop due to similarity in breeding systems, cultivation practices, season of growing and other features besides being like a member of Brassica vegetables. In general Pe-tsai cabbage, i.e., heading type (B. rapa subsp. pekinensis or B. pekinensis) and pak-choi cabbage, i.e., leafy type (B. rapa subsp. 

5.1 Introduction

Sprouting broccoli is believed to be the first to be originated from wild cabbage (Brassica oleracea var. sylvestris) or wild cliff cabbage which is found growing wild in southern Europe and along the eastern Mediterranean Sea. It is also known by several other names such as Calabrese or Italian Green because it was cultivated first in Italy by the ancient Romans and spread to other countries only from sixteenth century onwards. In India, it was introduced during the second half of the 20th century. The word broccoli is derived from the Latin word Brachium meaning an arm or branch. Broccoli contains higher amount of protein, vitamin A and C and appreciable quantities of thiamine, riboflavin, niacin, calcium and iron. 

Common Name: Ganth gobhi or kadam

4.1 Introduction

Knol khol or kohlrabi is not very widely grown in our country except in Kashmir, West Bengal and some of the South Indian states. Kohlrabi is a herbaceous biennial grown for its edible stem. The edible part in kohlrabi is the tuber formed by the thickening of stem tissue above the cotyledons, i.e., swollen stem called knob or tuber. 

3.1 Introduction

Cauliflower is a cruciferous vegetable that is naturally high in fibre and B-vitamins. It is said that the cauliflower has originated around the Mediterranean Sea. Ancestor of cauliflower is Brassica cretica which has been descended from the wild cliff cabbage, Brassica oleracea var. sylvestris, a native of coastal region of Europe and Africa. Cauliflower is cultivated worldwide in different climatic conditions ranging from temperate to tropics during most of the cropping seasons and is available round the year. Curd is the economic part of cauliflower and is an intermediate stage between vegetative and reproductive stage. It was introduced in India during the Mughal period. In 1822 a botanist Dr Jemson, In-charge of Company Bagh, Saharanpur, U.P introduced it in India from Kew Garden London. 

2.1 Introduction

Cabbage is consumed in the raw state as well as in cooked. The word cabbage has been derived from the French word Cobache, meaning head which is best described as single large terminal bud comprised of tightly overlapped numerous leaves attached to an unbranched short stem. It is known for its rich source of vitamin A and C. It is an effective curative against scurvy disease. Cabbage leaves are low in calories (24 %), fat (0.2 %) and carbohydrates (5.4 %). It is a good source of protein (1.3 %). Cabbage is an excellent source of minerals such as calcium, iron, magnesium, sodium, potassium and phosphorus. It contains good amount of ascorbic acid. Cabbage is used mainly as a vegetable and nice pickle (sauerkraut) is prepared from it. It is also used as salads. Cabbage is well known for its medicinal properties. 

1.1 Introduction

Horticulture is defined as “The science and art of growing vegetables, fruits, flowers, ornamental plants and landscaping of gardens and surroundings in small and commercial gardens”. The Latin word “horticulture” comprises two parts: “hortus” (which means “garden”) and “cultura” (which means “cultivation”). In other words, horticulture is the nurturing of gardens. Pomology, olericulture, floriculture, and landscaping are the main aspects of horticulture. Horticulture is becoming more and more important since it produces greater output per unit of land and provides humans with nourishing food, improving their quality of life and enhancing the visual beauty of nature. Regarding the worth of the goods, one of the main branches of horticulture is vegetable growing.

Technically speaking, every component of a vegetable is edible. However, the phrase is typically used to refer to edible plants that include reserves of food in the form of roots, tubers, bulbs, stems, petioles, leaves, buds, flowers, fruits, and seeds that can be consumed either cooked or raw. Growing vegetables is crucial not only for supplying food that is protective but also for serving as a substantial auxiliary food that contributes more significantly to food consumption. They are vital parts of a balanced diet since they are nutrient-rich.

Plant breeding or crop plant improvement is one of the oldest accomplishments of man. It began when he domesticated plants by growing them under controlled conditions and selecting those types that suited to his food requirements, about 10,000 years ago. As settlements improved, men could find time to innovate agricultural practices and to have better selections. Thus, domestication of plants and animals marked one of the most important phases in man’s progress from a nomadic and highly individualistic life to the organized and cooperative society. All our food crops as we know them now are the direct results of this primitive agriculture. This early phase of plant breeding was haphazard and slow based on selection of desirable types from the availability variability and it largely remained an art and not a science until Mendel’s laws were rediscovered in 1900 and applied to plant breeding at the beginning of 19^th century. 

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.

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)

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.

Any organism with other than two basic sets of chromosomes, that is, monoploid, triploid, tetraploid, and various aneuploids is termed as polyploid. There are several economically important crops which are natural polyploids emphasizing the economic importance of polyploids in agriculture. These are:

Triploid-Banana

Autotetraploid-Alfalfa, potato, coffee, peanut or groundnut Autohexaploid- Sweet potato

Amphidiploid/allopolyploid-Wheat, cotton, oats, Brassica species (B. carinata- Ethiopian mustard, B. juncea-Indian mustard, B. napus--rapeseed), sugarcane

Man-made commercially successful allopolyploid- Triticale

Mutation is defined as a sudden heritable change in gene or in chromosome structure. The process of hereditary change is termed mutation and the individuals affected by the change are called mutants. Besides recombinations, mutations are the cause of genetic variation from which every breeding activity proceeds. By means of mutations, the multiplicity of the types of a population is not only increased by one genotype, but also by large number of further new genotypes due to possibility of subsequent recombinations of mutant with the existing genotypes.

Recurrent selection is a method of breeding applicable to cross-pollinated crops, designed to concentrate favourable genes scattered among a number of individuals by selecting in each generation among the progeny produced by mating inter se of the selected individuals (or their selfed progeny) of the previous generation. The concept of recurrent selection grew out of need to increase the number of superior genotypes that could be obtained from breeding stock of corn. This could have been possible by increasing the frequency of superior genes in the gene pool and by increasing the chances for genetic recombination to occur. The original idea behind recurrent selection was proposed first by Hayes and Gerber in 1919 and independently by East and Jones in 1920. Jenkins (1940) was the first to describe the method in detail and Hull (1945) proposed the name ‘recurrent selection’. Each cycle of recurrent selection requires:

Composites defined as advanced generation populations maintained by random mating in the material constituted through mixing of equal quantity of seeds of crosses showing less inbreeding depression in F2 over F1. The components of composites inbreds, open-pollinated populations, locally available open-pollinated cultivars, hybrids, advanced generation lines, improved populations. Mixing the seeds of several phenotypically outstanding lines produces a composite variety and encouraging open pollination to produce crosses in all combinations among, the mixed lines. The lines used to produce a composite variety are rarely or not tested for combining ability with each other like as done in case of synthetics where the combining ability of the component lines is invariably tested for GCA. Composite are commercial varieties and are maintained by open - pollination in isolation. While mixing the seeds of various genotypes, care should be taken that the component lines are similar in maturity height, seed size, colour, etc. so that the composite maintained through random mating in isolation manifests a reasonable degree of phenotypic uniformity. The variety is maintained by open pollination. Farmers can use their own seed for 3 to 4 years.

A variety produced by crossing inter se a number of genotypes selected for good general combining ability in all hybrid combinations with subsequent maintenance of the variety by open-pollination. Synthetics development is common in cross- pollinated crops in the early phases of breeding. The synthetic method of breeding is suitable for improving cross-fertilized crops. It is widely used to breed forage species. Successful synthetic cultivars have been bred for corn, sugar beets, and other species like cauliflower in India. The suitability of forage species for this method of breeding stems from several biological factors. Forages have perfect flowers, making it difficult to produce hybrid seed for commercial use. The use of male sterility may facilitate controlled cross-pollination, which is difficult to achieve in most forage species. To test individual plants for use in producing the commercial seed, it is essential to obtain sufficient seed from these plants. The amount of seed obtained from single plants of these species is often inadequate for a progeny test. Furthermore, forage species often exhibit self-incompatibility, a condition that inhibits the production of selfed seed. Synthetic cultivars are also used as gene pools in breeding progeny. Synthetic cultivars are advantageous in agricultural production systems where farmers routinely save seed for planting. One of the well-known and widely used synthetic has been the Iowa stiff- stalk synthetic (BSSS) of maize.

The term hybrid or hybrid variety is used to designate F1 populations that are used for commercial plantings. Such F1 populations are obtained by crossing clones, open-pollinated varieties, and inbred lines that are genetically dissimilar. Historically the first attempts to make practical use of fortunate mating system of maize came late in the nineteenth century by W. J. Beal in Michigan, stimulated by Darwin’s work on inbreeding and outcrossing. Beal suggested use of F1 varietal crosses to exploit heterosis for commercial crop. The hybrid seed was to be produced by detasseling alternate rows. It was George Harrison Shull (1909) who first suggested a pure line method of corn breeding based on inbred lines obtained by continued self-fertilization and the use of F1 hybrids between these inbred lines for the production of commercial crop. His proposal was to make use of single crosses (hybrids between two inbred lines) based on the superior performance of the hybrids in various combinations between the inbred lines.