eChapters

Introduction

Cell and tissue culture techniques are becoming increasingly popular as alternative means of plant vegetative propagation. Plant tissue culture involves asexual methods of propagation and its primary goal is crop improvement. The success of many in vitro selection and genetic manipulation techniques in higher plants depends on the success of in vitro plant regeneration. Crop breeding and rDNA technology require the widespread use of reliable true to type propagation and better regeneration methods. Plant regeneration can be grouped in to different categories of enhanced release of axillary bud proliferation, organogenesis and embryogenesis. The oldest practical application of tissue culture techniques is the propagation of disease free plants from meristem tip culture. Meristem tip consisting of dome and one or two subjacent leaf primordial with a size up to 0.25 mm are aseptically cultured in appropriate nutrition media. The resulting plants are disease free because the pathogen is not generally present in the meristematic cells.

The aim of germplasm conservation is to ensure the availability of useful germplasm at any time. Breeding programs rely heavily on locally adapted ancient plant varieties and their wild relatives as sources of germplasm. Further, the continuing search for high yielding varieties of crop plants with resistance to pathogens and pests warrants the availability and maintenance of large collections of germplasm. In species which are propagated through seeds, it is economical to preserve the seeds. These seeds are dried to water content of 5 - 8% and then stored at a temperature of -18° C or lower and low humidity. In case of vegetatively propagated species, preservation of germplasm heavily taxes manpower and land resources. As in vitro techniques are becoming more important in crop improvement through the use of somatic cell genetics, the material produced in vitro will have to be conserved in vitro. The in vitro system is extremely suitable for storage of plant material, since in principle it can be stored on a small scale, disease free and under conditions that limit growth. Germplasm storage in vitro is crucial for the future development and safety of agriculture.

Introduction

Okra, Abelmoschus esculentus (L.) Moench, is annual herb grown in tropical and subtropical parts of world for green tender immature fruits and consumed as cooked mostly fresh but sometimes sun dried or frozen also used as vegetable. Some parts of plant and roots are used for medicinal as well as purification of sugarcane juice. Green fruit contains vitamins, calcium whereas seeds possess 13-22 per cent edible oil and 20-24 per cent edible protein. India is leading producer of okra and exporting fresh as well as processed fruits to other countries and also ranked first in area (0.48 million ha.), production (3.5m tones) and productivity (9.8 t/ha) during 2005 against the world area (0.78 million ha.), production (4.99 m tones) and productivity (6.4t/ha).

Introduction

Genetic resources are the building blocks for new varieties. The Indian gene centre is floristically extremely rich. Most of the tropical and sub-tropical fruits believed to have originated from Hindustan and Indo Malaya-Region. Hindustani gene centre possess a rich diversity of 152 crop plants distributed in different agro-ecological regions of India (Arora, 1985). The Indian sub-continent is one of the centers of origin and diversity of vegetables crops. Around 80 species of major and minor vegetables occur in wild forms (Choudhury, 1967, Seshadri 1987). Among the 118 genera belonging to the Cucurbitaceae family Cucurbita, Cucumis, Citrullus and Lagenaria genera are of great importance. There is tremendous genetic diversity within the family, genera and even within species level. The adaptation range varies from tropical and subtropical regions to extreme arid desert and in temperate regions from Tarai belts to higher altitudes. Extreme germplasm collections are maintained at different centers of the world which represents valuable resources for breeding even in wild form, primitive cultivars, landraces/ folk varieties/ farmer’s selection in a much localized pockets. Now we have very good strains for highly nutritive value, multiple disease resistant and extended shelf lives from our local material through intensive breeding.

Indigenous plant germplasm are adapted component of plant biodiversity. Such adapted components are more valuable resources either as a cultivar or as a parental line in hybridization programme. It might be also a putative material for biotechnological treatment for tolerance to biotic, abiotic factors or nutritional and quality components. Indigenous germplasm can be basically of two types, one which has been domesticated and subjected to human intervention, the other one may be called wild plants or wild relatives and still in the process of evolution without the human intervention. Biochemically the cucurbits are characterized by bitter principles, called cucurbitacins. Great variety of cucurbits contains bitter principle in portion of the plant at some stage of development. Cucurbitacins are tetracyclic triterpenes having extensive oxidation level. Bitter principals found in roots differ from those in fruits. Seedlings specially radicals contains cucurbitacins which are considered primary. The pollen also carries bitter principles and hence when bitter pollen fertilized non-bitter ovule the resulting fruit will be bitter known as metaxenia effect. Cucurbits are consumed in various forms i.e. salad (cucumber, gherkins, longmelon), sweet (ash gourd, pointed gourd), pickles (gherkins), deserts (melons) and culinary purpose. Some of them (e.g. bitter gourd) are well known for their unique medicinal properties. In recent years, abortifacient proteins with ribosome-inhibiting properties have been isolated from several cucurbit species, which include momorcharin (from Momordica charantia), luffaculin (from Luffa operculata), trichosanthin (from Trichosanthes kirilowif) and beta-trichosanthin (from Trichosanthes cucumeroides). Among these, Trichosanthin is of particular interest because its ribosome-inhibiting properties have been found to be effective in inhibiting the replication of human immunodeficiency virus (HIV), indicating its potential as a therapeutic agent for AIDS. In cucurbits three conditions are found (i) fruit and vegetative parts bitter (ii) fruit not bitter but vegetative parts bitter (iii) bitterness absent in both vegetative parts and fruits. Hence some kind of co-evolutionary relationship between cucurbits found and they are very helpful during evaluation of germplasm.

Introduction

The North-eastern region comprises of eight states viz. Assam, Arunachal Pradesh, Meghalaya, Manipur, Mizoram, Nagaland, Tripura and Sikkim lying between 21.5^o N - 29.5^o N latitudes and 85.5 ^o E - 97.3 ^o E longitudes. It has a total geographical area of 262180 Km² which is nearly 8 % of the total geographical area of the country. In the whole of NE region, about 35 % area is plain and the remaining 65 % area is under hills. Whereas in Assam plains account for 84.44 % of its total geographical area and the remaining 15.56 % area is under hills. Net sown area is highest in Assam (34.12 %) followed by Tripura (23.48 %), however, Arunachal Pradesh has lowest net sown area in the region. Cropping intensity is highest in Tripura (173 %) followed by Manipur (152.1 %), Mizoram (136.36 %) and Assam (123.59 %). About 0.5 million hectare area is under shifting cultivation in the NE region. Out of 4.4 million hectare net sown area, roughly 1.4 million hectare lies in hilly sub region and at least 1.3 million hectare suffer from serious soil erosion problem.

The diverse agro climatic conditions, varied soil type and abundance of rainfall offers immense scope for cultivation of different types of horticultural crops, including fruits, vegetables, flowers, plantation crops, tuber and rhizomatous crops and crops of medicinal and aromatic importance. The region has rich diversity of different vegetable crops and both indigenous tropical vegetables and temperate vegetables are grown to a considerable extent. The major vegetables grown in the region are brinjal, cabbage, cauliflower, okra, onion, pea, potato, tomato, knol-khol, radish, carrot, French bean and different cucurbitaceous crops. Tuber and rhizomatous crops like tapioca (cassava), sweet potato, Dioscorea, colocasia, ginger and turmeric grow abundantly in the region.

Introduction

Leafy vegetables belong to an important group of vegetables and are highly nutritious due to their richness in Vitamin A (Carotene), Vitamin C, Folic acid, Riboflavin, Thiamine and minerals like Iron, Calcium and Phosphorus etc. Appreciable quantity of proteins is also found in these crops. They also provide a variety of phyto-nutrients including beta-carotene, lutein and zeaxanthin, which protect cells from damage, age-related problems, among many other effects. Dark green leaves even contain small amounts of Omega-3 fat. They are available at cheaper rate in the market as compared to other vegetables. They provide roughage and have an important place in the balanced diet. It is recommended that a daily intake of 100 g and 40 g of leafy vegetables in the diet of woman and man respectively. India is the 2^nd largest producer of leafy vegetables in the world after China, accounted for about 10% of the world production (Singh et al., 2006) but, the production levels of these leafy vegetables are very low because of lack of availability of high yielding varieties. Leafy vegetables are those crops from which leaves and associated parts are harvested for use as vegetable. The leaves of about 700 different kinds of plants belonging to125 families are consumed in the form of vegetables. The major leafy vegetables grown in the country are amaranth, spinach beet (desi palak), spinach and fenugreek. In addition to this a number of under-utilized annual crops are also grown as leafy vegetables in specific regions. Leafy vegetables are usually grown in kitchen and market gardens. Tender stems and leaves of a number of perennial crops are rich sources of vitamins and minerals and are used for cooking. Though leafy vegetables have high nitrate and oxalate levels, but adverse nutritional effects are not to be feared with a consumption level of 100-200 g per day. The commonly grown major leafy vegetables and their wild relatives are listed below

Introduction

Cowpea, {Vigna unguiculata (L.) Walp.} is an important food legume in the semi-arid tropics covering Asia, Africa, Southern Europe and Central and South America (Henriet et al., 1997; Mortimer et al., 1997; Van Ek et al., 1997). It is a drought tolerant and warm weather crop. Therefore, well adapted to the drier regions of the tropics where other food legumes do not perform as well. It fixes atmospheric nitrogen and grows well even in the poor soils with more than 85% sand and with less than 0.2% organic matter and low levels of phosphorus (Kolawale et al., 2000 and Sanginga et al., 2000). Also, it is shade tolerant and therefore, compatible as an intercrop with maize, millet, sorghum, sugarcane and cotton as well as with several plantation crops (Singh and Emechebe, 1998). Coupled with these attributes, its quick growth and rapid ground cover checks soils erosion and in situ decay of its roots and nitrogen rich residues improves soil fertility and structure which together have made cowpea an important component of cropping system in the dry savannas of the sub-Saharan Africa (Carsky et al., 2001 and Mortimer et al., 1997).

Cowpea is cultivated in about 14 million ha world wide with about 5 million tons annual production. However, a substantial part of the cowpea production comes only from few countries. Nigeria is the largest producer and consumer of cowpea with about 5 million ha area and about 3 million tons production annually. Niger Republic is the next largest producer with 3 million ha and over 1 million ton production. Northeast Brazil grows about 1.5 million ha of cowpea with about 500.000 tons production. In the southern USA about 40,000 ha of cowpea is grown with an estimated 45,000 tons annual production of dry cowpea seed and a large amount of frozen green cowpeas. Even though exact statistics are not available, India is the largest cowpea producer in Asia and together with Sri Lanka, Pakistan, Nepal, Bangladesh, Thailand, Indonesia and other far eastern countries, there may be over 1.5 million hectares under cowpea in Asia.

Introduction

‘Cole crops’ is a general term used to describe several vegetables in the Brassicaceae family. It is an important and highly diversified group of vegetable crops grown worldwide that belongs to Brassica oleracea (Monteiro and Lunn, 1998) and includes particularly six Brassica crops (cabbage, cauliflower, Brussels sprouts, broccoli, kale and knol kohl). All of these crops can trace their history to a common ancestry of wild cabbage originating in the Mediterranean and Asia Minor regions. Cole crops are one of the oldest cultivated plant groups in the world. They are cultivated in Europe since very ancient time from where they have spread to other parts of the world (Nieuwhof, 1969). All the cole crops (except few cauliflower, broccoli and cabbage types) require chilling temperatures for about two months to transform from vegetative phase into reproductive phase. However, the period of chilling requirement differs according to the kind of crop and varieties. Cole crops are also commonly called as European or biennial vegetables due to their cool temperatures requirements and two season requirement to complete their life cycle.

Major Resources of Cole Crop Germplasm

Germplasm is any form of the hereditary material from an organism. Genetic resources encompass all the various forms of germplasm that are available for collection, storage and use. The genetic diversity of crops, represented by traditional local cultivars and wild relatives has been disappearing rapidly during recent decades. Initial concern was noted by H.V. Harlan in the 1930s (Harlan and Martini, 1936) but by the 1960s, modern plant breeding and land-use changes accelerated loss and stimulated the realization that genetic resources in regions of diversity were being lost at an alarming rate. To conserve the genetic variation within the cole group, a comprehensive base collection of the cultivated forms of Brassica oleracea has been established at the vegetable gene bank of Horticulture Research International (HRI), Wellesbourne, (U.K.). Gene banks have also been established at Instiuut de veredeling van Tuinbouwgewssen, Wageningen, the Netherlands and the Instituto del Germoplasm, Bari, Italy (Van der Meer et al., 1984) for conservation of genetic resources. The International Board for Plant Genetic Resources (IBPGR) has recognized HRI as an international centre for conservation of Brassica oleracea (Innes, 1975). Large number of collections of cole crops is also available with the United States Department of Agriculture, Plant Introduction Service. In India, National Bureau of Plant Genetic Resources (NBPGR), New Delhi has been assigned the duty of conserving the germplasm of all crops, including vegetables. Germplasm of all the cole crops is being maintained at the Indian Agricultural Research Institute, New Delhi (tropical types) and its regional station at Katrain (temperate types). Other major institutes maintaining germplasm of cole crops include Punjab Agriculture University, Ludhiana, G. B. Pant University of Agriculture & Technology, Pantnagar, Indian Institute of Vegetable Research, Varanasi, Dr. Y.S. Parmar University of Horticulture and Forestry, Solan and SKUAS&T, Srinagar.

Introduction

Cucumber is one of the most popular vegetable of cucurbitacae family and grown worldwide for its freshly harvested fruits. Fruit yield in cucumber is suppressed due to its fruiting habit. Fruits developing from the first pollinated flower inhibit the development of subsequent fruits. This phenomenon is broadly known as crown fruit dominance or first fruit inhibition. Therefore, in mechanical once over harvest of seeded cucumber, only one to two fruits per plant are developed. Fruit set inhibition is less in seedless cucumber when compared to its seeded counter part. Parthenocarpy is the development of fruit without fertilization. This phenomenon was first studied in cucumber byNoll (1902) who introduced the term parthenocarpy. In parthenocarpic lines, a larger proportion of photosynthates could be diverted to fruit tissue instead of producing seeds. Partheonocarpic habit has become indispensable to greenhouse cucumber production because it alleviates the need for bees. Individual plants in the greenhouse produce many fruits simultaneously, with many fold higher yield in comparison to field grown crop.

Greenhouse or parthenocarpic cucumber production is very popular in many areas of the world. The fruits of parthenocarpic cucumber are mild in flavour, seedless and have thin edible skin that requires no peeling. Fruits are generally 10-14 inches in length and 200 g in weight. The parthenocarpic varieties require no pollination for fruit setting. If pollination occurs, the fruit will form seeds, shape of fruit will be destroyed and develop bitter taste. It is therefore essential to prevent bees and other pollinators entering the green houses. Cucumber cultivars are selected for commercial use based on quality and yield characteristics. An important quality factor is the shape of the cucumber referred to as the length to diameter (L/D) ratio. This becomes important to meet specifications of the number of whole cucumber units per container. The cool marine environment causes the L/D ratio of many cultivars to be undesirably long and therefore many of the useful cultivars for other production regions have been eliminate. The presently available parthenocarpic cucumber cultivars have been bred and developed in Europe under similar climatic conditions and produce fruit with desirable L/D ratios. The parthenocarpic cultivars have potential for improvement of both the L/D ratios and fruit interior quality.

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

Tomato is one of the most important vegetable crops which is grown throughout the world. It is a rich source of minerals, vitamins and antioxidants and considered as a protective food. It is used in several forms ranging from raw to processed one and is widely used as one of the food ingredient. Its popularity is due to its versatility and the variety it lends to the human diet. Tomato leads all other vegetables in terms of total global production except potato which is often classified as starchy staple. India stands fourth in terms of global tomato production after China, USA and Turkey. The total production of tomato in India during 2007-08 was 10.26 million tones which accounted for 8.9 % of total vegetable production. Though concrete historical records of its first introduction into the country from its primary centre of diversity in South America do not exist, tomato is presumed to have been brought here during the second half of the 18^th century through Far Eastern countries. It is believed that tomato was introduced in India during British period in the year 1828 by Royal Agri -Horticultural Society, Calcutta. The story of tomato transformation from an exotic fruit to a popular dietary item and a major item of commerce all over the world is one of the most fascinating events in the saga of crop domestication. As recently as 1900, tomato was avoided in the belief that it was poisonous because of its known relation to the nightshades and other toxic members of the nightshade family. The tomatine is a predominant alkaloid mainly present in foliage and green fruits. However, at the stage of ripening, tomatine is degraded into an inert compound which is not toxic.

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.

Introduction

Germplasm identification as a part of a philosophy of consumer protection extends through the entire seed trade and allied industries, from plant breeders to food consumers. Increasingly, countries are introducing schemes for Plant Breeders (or germplasm) Rights. These reward breeders financially for their efforts and offer protection for their germplasm, but in turn require that new germplasm are distinct from others and also uniform and stable in the expression of their characteristics. Since, the genetic variations in plants and plant populations are of considerable interest to have desirable traits to develop a commercial variety. Biochemical and molecular biology based data and its analysis for information regarding selection have been realized of utmost importance.

Introduction

The Indian gene centre has rich diversity in vegetable crops. This diversity includes crops native to India like eggplant, parval, ridge gourd, sponge gourd, Colocasia sp., elephant yam and for centre of diversity for other vegetable crops i.e., Okra, Cucumber, Chayote, Chilli, Cucurbita etc. Rich diversity also occurs in introduced crops such as tomato, french bean, cowpea, leafy brassica, amaranth, yam and in cucurbits, bottle gourd, bitter gourd, coccinea, ash gourd, snake gourd and in bulbous crop like onion and garlic.

Genetic Resources of Vegetable Crops in India

Their diversity and conservation about 400 species constitute the global diversity in vegetable crops. This diversity is mainly distributed in seven-eight geographical regions, which represent the centres of origin and diversity as well. Among these, the regions possessing maximum diversity are the tropical American, Tropical Asian and the Mediterranean (q.v.) regions. In the tropical Asian region, both India and China hold maximum diversity.

Phenotypic Diversity

Phenotypic diversity measures the portion of genetic diversity which is expressed phenotypically. So it varies with the character under study and the genetic background and the environment in which it is measured. The measures of genetic diversity based on variance of quantitative traits may be unreliable indicators of diversity in a population at the level of individual gene. But diversity at the molecular level (isozymes, RFLPs) may be a reasonable estimate of phenotypic diversity. The degree of differentiation is related to several biological attributes such as breeding system, mode of pollination and seed dispersal, life history, geographical range, successional stages, etc. The outbreeding populations are much less differentiated whereas the selfers or apomictic are strongly differentiated. Populations of outbreeders contain different alleles especially the rare alleles which contribute little to the diversity. Inbreeders should have greater interpopulations diversity and less intrapopulation diversity than the comparable outbreeders. Further, inbreeders are more prone to show an even distribution of their genetic diversity among populations and this makes their optimum sampling more difficult and any evidence of the geographic pattern of this diversity levels would greatly improve sampling efficiency but geographical and environmental factors rarely explain more than 50% variation.

Plant genetic resources are the most valuable and essential basic raw material to meet the current and future need of crop improvement programme. A wider genetic base assume the priority in plant breeding research aimed as developing new varieties for increased crop production. PGR for food and agriculture are a reservoir of genetic adoptability, which act as buffer against environmental changes and economical challenges. The erosion of these resources results in a severe threat to the world long term food securities. The fundamental objective of the genetic resource conservation is the maintenance of genetic diversity within each of the species. In general PGR include all species which contribute to people by providing food, medicine, feed, fiber etc. PGR is our heritage which needs conservation for prosperity.

Genetic resources management is a complex process starting from the identification of a target gene pool for conservation to the use of genetic resources. Many of these activities not only generate but also require geo-referenced data (Spatial data). Analysis of these data can lead to a greater understanding of the eco-geographic representation of existing collections, increasing the efficiency of conserving and managing genetic resources and broadening our understanding of the distribution of genetic diversity. Genetic resource databases could potentially serve as an information resource to a broader scientific community, providing relatively independent global data sets to meet the unique needs of researcher. GIS can merge genetic diversity information with other georeferenced data such as population density, climate, topography and soils, adding value to genetic resources. GIS analysis can help develop conservation strategies, monitor genetic diversity, select potential collecting sites, design in situ reserves and enhance genetic resources use. Currently, GIS use is constrained by limited georeferenced information.

Introduction

Eggplant or aubergine {Solanum melongena L. Solanaceae), is indigenous to a vast area stretching from northeast India and Burma, to Northern Thailand, Laos, Viet nam and Southwest China and wild plants can still be found in these locations. There is a wealth of eggplant common names. Eggplant is a major fruit vegetable with world production exceeding 31 million tonnes (Mt). Leading producers are China (17 Mt) and India (8 Mt), Egypt (1 Mt), Turkey (0.9 Mt), Japan and Italy (0.4 Mt). Eggplant is particularly favoured in Asia where it has been cultivated for millennia, and in India it is considered King of Vegetables. Brinjal, native to India, shares 31 % area (5.1 × 10⁵ ha) and 28% production (82 × 10⁵ t) of the world (Anon., 2003). It contributes 9% of the total vegetable production in the country. Three states/provinces viz. Orissa (1.41 × 10⁵ ha), West Bengal (1.29 × 10⁵ ha) and Bihar (0.72 × 10⁵ ha) cover 67% of total brinjal area in India (Anon., 2006). It is widely adaptive and highly productive (17.78 t/ha) crop of tropical and sub-tropical regions. It is comparable with tomato for nutritional values like vitamin C, iron and fiber, thereby, can play an important role in combating malnutrition in under-nourished regions (Singh et al., 2001). However, genetic improvement, production technology, post harvest handling and plant protection measures are important for increasing the production, productivity and consumption of brinjal.

Introduction

Indian subcontinent is one of the twelve mega diversity centres for cultivated plants and their wild relatives. More than 15000 species of flowering plants are indigenous to this region, which include 160 species of economic importance, 320 species of wild ancestral forms and approximately 800 species of ethnobotanical origin. Global diversity in vegetable crops is estimated around 400, of which 80 originated in India. These indigenous vegetables have immense potential in meeting the vegetable requirement of the country. They are rich in nutritional value especially in proteins, minerals and vitamins. Many of these vegetables have medicinal uses. Most of them are not used to their potential and their popularisation is needed in meeting the vegetable requirement of the country in coming days.

Ash gourd (Benincasa hispida Cong.)

Ash gourd also known as Wax gourd (Benincasa hispida Cong.) belonging to family Cucurbitaceae, is cultivated for its immature and mature fruits used as vegetable and in confectionery and ayurvedic medicines. A small fruited medicinal ash gourd is also grown in Kerala which is good for people suffering from nervousness. In areas where winter is mild, the crop can be grown throughout the year. The released varieties are KAU Local, Indu, Co.1, Co.2, APAU Shakthi, Karikumbala, Boodikumbala and IVAG -502. In addition, MAH-1 and MAH-2 are F1 hybrids released from private sector. The crop is raised by sowing seeds in pits at a spacing of 2.5 × 2.0 m in Tamil Nadu, 3.4 × 1.8-2.5 m in West Bengal and 4.5 × 2.0 m in Kerala. The seeds can also be sown in channels at a spacing of 2 × 0.5m. The crop is trailed on branches and twigs spread on the ground. The fruits are harvested at immature or fully ripe stage depending on demand. Immature fruits can be harvested 21 days after anthesis. Mature fruits for storage, long distance transport and seed extraction are harvested after full development of waxy coating on fruit surface. The average yield are 30-35 t/ha.

Introduction

Peas (Pisum sativum L., 2n = 2x =14) are consumed as fresh vegetables or dry seeds throughout the world. In India, peas are grown as winter vegetable in plains and as summer vegetable in the hills. As field pea, it occupies about 0.45 m ha area in India, accounting for only about 2% of the total pulse area. About 90% of its area and production is limited to Uttar Pradesh alone. The area under vegetable peas is on increase. The acreage of vegetable pea in India is 2.72 lakhs ha with a productivity of 9.9 tons/ha. Pea is a rich source of protein (7.2% in green pea & 20 % in dry pea) and minerals (0.8%).

The geographical region comprising of Central Asia, the Near East, Abyssinia and the Mediterranean is considered as centre of origin based on genetic diversity. According to Blixt (1970), the Mediterranean is the primary center of diversity with secondary centers in Ethiopia and the Near East.

Garden pea, seeds have been observed in archeological excavations of Mohan Jodaro and Harappa, there are distinct hot weather tolerant and round-seeded varieties which carry high resistance to fusarium wilt and powdery mildew (Erysiphe polygoni). These varieties have a different use as a pulse crop for meeting protein requirements of common people. These are considered as intermediate stages of domestication of the present day vegetable (garden) pea, which is sweet and wrinkled-seeded. In fact, the quick spread of Arkel variety, an introduction from England in seventies, has displaced some of the native round-seeded varieties like Asauji, Hara Bonia, Hoshiarpuri, Kaparkheda, Kalanagni, Lucknow Bonia etc. there is need to conserve these valuable germplasm, before they are swept away by genetic erosion.

Introduction

Radish (Raphanus sativus L., 2n=2x=18) is a root cum leafy vegetable suitable for sub tropical and temperate climate. Radish probably originated in Europe and Asia. It has been under extensive cultivation in Egypt since long. It was introduced to England and France in the beginning of 16^th century. In 1806, it was introduced to America. Radish does not exist in wild stack. It is believed to have originated from R. raphanistrum which is widely distributed as weed in Europe. Radish is primarily a winter crop but with the development and release of new varieties, it can be grown all the year round. The new varieties can withstand heat and does not bolt in spring. Radish is a favourite crop because of its quick growth and availability in 4-7 weeks.

Its fleshy roots are modified roots, developed from both the primary root and hypocotyl. The leaves and roots are consumed both as salad and cooked. The radish root is a good appetizer; its different preparations are useful in curing liver and gall bladder problems. Roots are also used in treating urinary complaints and piles. The juice of fresh leaves is useful as diuretic and laxative. Pungency in radish is due to volatile isothiocyanates while pink colour is due to pigment anthocyanin.

Radish is a good source of vitamin C containing 15-40 mg per 100g of edible portion. Roots also contain proteins, fat, minerals, fibre and carbohydrates, besides trace elements like aluminium, barium, lithium, manganese, silicon, titanium, fluorine and iodine. Pink skinned radish is generally richer in vitamin C than the white skinned type. Radish contains glucose as the major sugar and also contains fructose and sucrose in smaller quantities. Pectin and pentosans are also reported to be present. The leaves are good source of extraction of protein on a commercial scale and seeds are potential source for non-drying fatty oil suitable for soap making, illuminating and for the edible purposes.

Introduction

Turnip is an important root crop which is very popular particularly in northern India. It is a cool season crop mainly grown as a fall or winter crop in the hills and winter crop in the plains. Turnip (Brassica rapa L. syn. Brassica compestris var. rapa) belong to family Brassicaceae. It has a chromosome number of 2n=2x=20. Two main centers of origin have been indicated. The Mediterranean area is considered to be the primary centre of origin of European type/temperate types. While Eastern Afghanistan with adjoining areas of Pakistan is considered to be another primary centre with Asia Minor, Transcaucasus and Iran as secondary centre. The parents of cultivated turnip are found in the wild form in Russia, Siberia and Scandnavia. It was cultivated by the ancients and ranked next to grapes and cereals in Italy. It was introduced in England probably in 1590 and United States in 1606 (Yawalkar, 1980). Turnips are now cultivated throughout the world.

Turnips are botanically biennial herbs, but are cultivated as annual root crops for both animal and human consumption. The turnip root contains 41.6% moisture, 6.2 g carbohydrates, 0.5 g protein, 0.2 g fat, 0.04 mg thiamin, 0.04 mg riboflavin, 43 mg ascorbic acid, 30 mg Ca, 40 mg P and 0.4 mg Fe per 100 g of edible portion. The turnip green contains 15,669 IU vitamin A per 100 g (Aykroyd, 1963). Turnip is grown for its enlarged root as well as for its foliage. Extra seedlings from thinning are often used as greens. The fresh roots are consumed in salads or cooked as vegetable or used in pickles. The young leaves contain high amount of ascorbic acid and iron, rank second in vitamin A content and are cooked as greens.

The fleshy thickened underground portion of turnip is actually the hypocotyl. The colour and shape of this underground portion vary with the cultivars and the roots are flat globular to top-shaped and long. The colour of under ground portion may be white or yellow, while that of above ground portion may be red, purple, white, yellow or green. A distinct tap root and secondary roots arise from the lower part of the swollen hypocotyl. Thickening begins in the central part of the hypocotyle, followed by the upper and lower parts. Normally, the roots attain edible maturity in 40-80 days depending on cultivar and climatic conditions.

Introduction

Carrot (Daucus carota L., 2n=2x=18) is a cool-season root vegetable grown all over the world in temperate as well as sub-tropical climates. In India, it is cultivated over an area of 24,000 hectares with an annual production of 3,50,000 metric tones with a productivity much lower (14.58 t/ha) than the world average (22.17 t/ha) as per FAO, 2004. Carrots are used for human consumption as well as for animal feed. Carrot can thus be used for augmenting fresh fodder supply to milch animals during the lean winter in Kashmir (Hussan and Ahmed, 1999). Carrot has a significant place as an ingredient in soups and sauces and in dietary composition and also as a salad. A sweet preparation called Gajar Halwa is very famous dish in North India. Besides canning, it is also used in preparation of pickles. It is also exported in the form of fresh roots to the countries like Kuwait and Sharjah. Carrot is a rich source of á and â- carotene. The total carotenoid content in the edible portion of carrot roots ranges from 6.00 to 54.80 mg/100g. The yellow and orange coloured roots contain relatively more carotenoid. Carrot roots contain protein, fat, carbohydrate, minerals (especially Ca, Mg, Na, K, Cu, S etc.) besides vitamin A, B₁, B₂, nicotinic acid and vitamin C. In carrot roots, sucrose is the most abundant with endogenous sugar contents 10 times than those of glucose and fructose.

Asia minor, Afghanistan, North West India, Iran and Turkey are the centers of origin of carrot. As per Encyclopedia Britannica, carrots have originated from Afghanistan, Punjab and Kashmir with secondary centers in Ethiopia and North America. The European carotene carrot (syn. Western carotene carrot, temperate carrot) has been derived from the Asiatic anthocyanin containing forms of carrot (syn. Eastern anthocyanin carrot, tropical carrot). Afghanistan is the centre of diversity of the purple coloured carrot (anthocyanin carrot) and as such this country is suggested as the primary centre for origin. Integration between the Asiatic and European carrots has given the present day forms which are fleshy, smoother, less forked and better coloured.

Punjab and Kashmir are also considered as primary centre of origin with secondary centers in Ethopia and North America. It is still found in its wild form in Himachal Pradesh and Kashmir valley where wild animals especially brown bear feed on its roots. People still eat the wild carrots in some parts of Kashmir (Yawalkar, 1980). In north India highly coloured types of carrots are found which are not available in Europe. The colour of carrot ranges from absolute colourless to light lemon, light orange, orange and deep orange, light purple, deep purple and almost black. It is also an indication of this region being a primary centre of origin of carrot.

Introduction

The traditional approach to transferring genes from wild to cultivated species is based on interspecific hybridization followed by selection of hybrids that combine the trait with the cultivated genetic background. This breeding strategy is achieved by various backcross generations in which the selected hybrids at each generation are crossed back to the cultivated genotype with the aim of reducing the wild genome and its undesirable traits. The use of molecular markers has allowed this breeding approach to be greatly improved, since these markers directly reveal genetic variability through DNA analysis (Staub et al. 1996), and therefore their detection is not influenced by environmental effects. Since the development of numerous molecular markers for plant genometatic analysis, the possibility to select the genotype instead of the phenotype has been closely examined, leading to the concept of molecular marker-assisted selection (MAS; Paterson et al. 1991). The basic concept of MAS for crop improvement has been well discussed by Collard et al. (2005) which is most appropriate for this chapter. The most widely used markers suitable for MAS are RFLP, RAPD, AFLP, and SSR. Their common origin is point mutation or chromosome rearrangements that were accumulated during the evolution of the species without negatively influencing their survival and reproduction. The choice of the most suitable markers for MAS can differ and depends on the labor required for their detection, possibility of revealing single or multiple loci, dominant or co dominant nature and costs.

Introduction

Chilli is one of the most important spice and condiment of daily use in all most all the Indian houses. The fresh and dry fruits are the rich source of Vitamin A (292 IU) and Vitamin C (111 mg/100g). Its pungency not only improves the taste of the different preparations but also improve their storability. The colour of the fruits is due to the presence of the pigment capsanthin and pungency and acridity is due to the presence of alkaloid oleoresins knows as capsaicin (C₁₈ H₂₇ O₃ N). The capsaicin has a very good medicinal importance and also having importance for the pharmaceuticals industries for preparation of the different types of the drugs, because of the presence of the antioxidants like Vitamin A, C and P (Rutin). The green and red sweet pepper, bell pepper, Pimiento (heart shape) and cherry pepper are used in the fresh market processing industries for stuffing pickling and dehydrated processed meat. It is used as green as well as dry powder, pickles, salad and for industry to prepare the medicines for external and internal uses.

Introduction

Potato is a wonder crop that can be grown under diverse range of agro-climatic conditions. Short duration; high yield per unit area and time and wide flexibility in planting and harvesting time are important virtues of potato that enable its inclusion in intensive cropping systems.

Potato is not an Indian crop but is a native of high Andean region of South America. It was introduced in India perhaps in 16^th or early 17^th century by either the Portuguese traders or the British missionaries. The present day cultivated potatoes (tetraploid, 2n=4x=48) in most of the world represent Solanum tuberosum spp. tuberosum and S. tuberosum spp. andigena, although it’s numerous diploid (2n=2x=24) relatives are still under cultivation in and around its primary and secondary centers of origin in South America (Pandey and Sarkar, 2005). The great Irish famine in the 19^th century, caused by late blight disease, nearly wiped out all the earliest potato introductions in the Europe and dramatically changed the potato cultivation and production scenario in rest of the world.

Unlike in European Countries 80% of the potato is grown in India under short day conditions as a short duration crop i.e. 70-90 days. The tubers are exposed to high temperatures during planting (September-October) and harvesting (February-May). The crop is irrigated and suffers mid day water stress. The potato varieties introduced from Europe were unsuitable for growing under the above conditions. Systematic potato research in India spanned over the last half-a-century of the 20^th century in the past millennium. The Central Potato Research Institute (CPRI), which was established in 1949, has bean mainly responsible for tremendous growth of potato production in the country. The indigenous technological advances made it possible to extend potato cultivation in almost all part of the country. Now in India, compared to the production, area and yield of potato in 1949-50, the increase over the same period was 1513%, 559% and 270% respectively (Naik and Thakur, 2007). According to the FAO, potato production worldwide stands at 329 million tones and covers more then 19 million ha.

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.

Introduction

In 1990, the magnitude of fungal diversity, that is, the actual number of species worldwide, was estimated conservatively to be at least 1.5 million. Of the 1.5 million estimated fungi, it has been estimated that 14,000 species produce fruiting bodies of sufficient size and suitable structure to be considered macro-fungi which can be called mushrooms. Of these, about 50 % or 7,000 species are considered to possess varying degrees of edibility and more than 3,000 species from 31 genera are regarded as prime edible mushrooms. To date, only 200 of them are experimentally grown, 100 economically cultivated, approximately 60 commercially cultivated and about 10 have reached an industrial scale of production in many countries (Hawksworth, 2001). Of the 14,000 species of mushrooms in the world, around 700 have known for medicinal properties. Thus, mushrooms have vast prospects as sources of medicines. The early herbalists were more interested in the medicinal properties of mushrooms than in their basic value as a source of food. Humankind has constantly searched for new substances that can improve biological functions and thereby make people fitter and healthier. About 3.5 billion people worldwide, all over half of the world populations rely on plant-based medicines and dietary supplements for their primary health care. Of the plant materials involved in medicines or health tonics, quite a few are fungi. The practice of using fungi as herbal medicines can be traced in different early records of the ‘materia medica’. The earliest book on medicinal materials the “Shen Nongs Herbal” recorded the medicinal effects of several fungi such as Ganoderma lucidum, Poria cocos, Tremella fuciformis, Polyporus umbillatus and other unidentified fungi. The most famous of all work on the traditional medicines “Pen Ts’ao Kang Mu” which was compiled by Li Shi-Zhen of the Ming Dynasty recorded the medicinal fungi totaling more than twenty species, including Ganoderma lucidum, Poria cocos, Polyporus umbellatus, Lentinula edodes, Termitomyces albuminosus, Auricularia auricula, Pleurotus ostreatus, Armillaria mellea etc. A very unique insect-infecting fungus, Cordyceps sinensis, was for the first time taken as a medicinal fungus in the book “Essentials of Materia Medica”. There have been new discoveries and developments in the field of medicinal fungi, which have greatly enriched the treasure house of our traditional medical and medicinal sciences. As a result of large number of scientific studies on medicinal mushrooms in the past three decades, the traditional uses of many mushrooms have been confirmed and new wider uses found. Some traditionally important and leading medicinal fungi in the Oriental medicines are presented below

Milk is a product of biological origin and is a suitable vehicle to accommodate any additive without apparent changes in its look. The quality of milk and its products depends upon quality of raw milk used in their manufacture, processing and handling conditions. It is therefore, necessary to check quality of raw milk to assess its suitability for processing, through various quick tests called “Platform Tests”

Raw milk quality assessment

(A) At collection center: - Milk from various suppliers is generally collected at dairy factory or privately owned collection centers located in marked area of milk sheds. The quantum of supply may vary from 2 – 100 Liters. As each supplier has to be paid in relation to quantity and quality of his produce, it is important to draw samples and ascertain its quality by performing quick tests for the purpose of acceptance or rejection.

Sampling procedures - The sampling procedure differs according to the nature of material and the purpose for which the sample is required. The sample collected for chemical analysis should be representative of the entire batch. Thorough mixing with proper instrument is essential to ensure representative sample. Samples for chemical analysis are to be delivered the same day for testing. If un-avoided, add small amount of preservative (Formaldehyde) to prevent deterioration and bear label to the effect.

Sample from single container – The procedure involved is thorough mixing of contents. If it is small container the contents should be poured from one vessel to another with swirling. In case of can the contents should be mixed with the help of plunger which should be moved up and down and sideways for about 10-15 times. The sample is then drawn with the help of dipper from different levels and collected in clean and dry sample bottles.

Laboratory Tests

Sampling procedures

Samples from number of containers- As soon as the cans are received at the reception dock, remove the lid, mix contents of each can with a plunger and draw equal quantities from each container and mix together. Draw approximately 80 – 100 ml of sample for testing. If the cans are of same diameter, Alternatively, milk from different containers are first poured into a vat and then the sample is drawn by thorough mixing as above..

Samples from storage tank – Before drawing sample from storage tank, switch on the mechanical agitator and allow the contents to mix for 15-20 minutes. Discard first 1.0 L of milk. Transfer 250-500 ml of the mixed milk from the outlet valve into a sample bottle.

Samples from rail / road tankers- Open the lid of the tanker and insert a big plunger through the main hole and move it forward, downward and backward bring the plunger to the surface at each stroke. Continue mixing for 15-20 minutes. Draw proportionate quantities of sample with the help of suitable dipper from different levels. Draw 250-500 ml of well-mixed sample into the sample bottle. The total volume of individual composite sample should not be less than 150 ml.

In the last decade or so, the problem of determining the microbial content and their activities in dairy products has been under close scrutiny. The dairy industries still adopt the dye reduction test because it is cheap, simple and satisfactory. However, other new techniques have been introduced along with some modifications in traditional tests. The microbiological quality must be maintained. To assess the bacterial content and their activities in dairy products, various methods are available for the microbiological testing of milk. The specific tests should be chosen as per the application and other factors like cost etc. On the basis of public health and economic consideration it is necessary to test microbiological quality of milk at a number of points along the chain from producer to consumer which includes - raw milk supply, bulk milk arriving at processors premises, monitoring bulk milk during storage prior to processing and monitoring the procession & the quality control of finished products. The techniques for estimating bacterial numbers in raw material are divided into two categories.

A. Estimation of Calcium

Requirements : Pottasium permanganate solution (0.1N) – Dissolve by heating 33g of potassium permanganate in 1000ml distilled water and allow to stand in coloured bottle for several days. Filter contents through 6mm thick film of asbestos mat on Gooch crucible.

Asbestos mat – Digest asbestos with dilute hydrochloric acid(1:3) for 2-3 days, wash free from acid and digest with 10% sodium hydroxide for few days, wash free from alkali. Digest with dilute Nitric acid(1:3) for several hours and wash. Shake with water into fine pulp and digest with 0.1N potassium permanganate solution that has been acidified with dilute sulphuric acid (1:3), for 1 hour and wash. Use this pulp for layering 6mm film on Gooch crucible.

Dilute hydrochloric acid (1:4), Ammonium hydroxide solution (1:1), Saturated ammonium oxalate solution, Diluted sulphuric acid (1:4)

India has emerged as the largest producer of milk in the World. This has boosted the confidence of producers, planners, dairy entrepreneurs and scientist alike. India has poised to play a major role in global dairy market in coming decade. The rapid growth of science and technology has positive impact on our life style and with strong trend of urbanization several demographic changes are likely to occur. There going to be ever increasing demand on the role of milk and milk products for human health. Accordingly, the demand for higher standards of milk products in terms of hygiene and safety of dairy products is to be followed. The competitiveness for the export of milk products among different dairy industry has increased in recent times due to GATT agreement. The biggest challenge before Indian dairy industry is the quality and safety of milk products indented for human consumption. Legal standards are made to have control over quality of food offered for sale and to safe guard the consumer form health hazards. It is therefore, imperative to determine different parameters that define product quality and safety. The purpose is to ensure production and distribution of products within well defined and accepted standards. This chapter deals with various parameters of product testing in order to maintain requisite prescribed standards.

The growing chemicalization of milk presents a great challenge to the dairy industry. A number of chemical compounds get entry into milk, intentionally or un-intentionally, through their direct or indirect usage for crop, animal; or dairy husbandry practices, as environmental contamination. Several of these contaminants may be naturally present on grazing grass or use as pesticides for green fodder or they may get entry through use of compounded animal feeds. These eventually get excreted into milk as residues and pose problems to food safety. The risk of health hazards arises from veterinary drugs, residual pesticides, heavy metals, detergents and micotoxins etc. It is therefore, become necessary to detect these contaminants in order to make food safe for human consumption.

Detection of Aflatoxin M 1 in Milk

Material requirements : Glass column(30 cm x 1 cm), Silica gel (63-200 µg particle size), volumetric flasks, beakers, micro pipette, HPLC equipment fitted with C 18 column(25 cm x 4.6 mm) and fluorescence detector.

Reagents: Sodium chloride solution (400g in 1000ml water), acetonitrile/water mixture (25:75), sodium sulphsate, chloroform, toluene/acetic acid mixture (9:1), acetonitrile/diethyle ether/hexane mixture (1:3:6), chloroform/acetone mixture (8:2), n-hexane and aflatoxin standard ampule.

Preparation of stock solution : Transfer contents from 2.5ml or 0.5ml ampoule, quantitatively, to 25ml or 50ml volumetric flask respectively. Rinse ampoule with small quantities of chloroform and collect rinsing into flask. Makeup the volume with chloroform, mix well and store at 5º C or below. These solutions will contain 1 µg per ml aflatoxin M1.

Working solution : Transfer 0.5ml of stock solution to a 10ml conical flask. Evaporate contents to dryness using inert gas. Dissolve residue in 10ml of acetonitrile/water mixture. Prepare series of dilutions containing 0.0025, 0.005, 0.01 and 0.025 µg/ml aflatoxin. Similarly treat 5ml of stock solution to give a concentration of 0.5 µg/ml.

Over the past several years, there has been significant change in consumer perception on quality and food safety. Consumers are demanding healthy, nutritious and cost-effective products processed under controlled hygienic conditions. Food safety concern, in recent years, has become dominant and important. The requirement of food safety and quality assurance has never been so demanding as it is now. Globally food safety is being addressed independent of food quality. In anticipation of consumer demands on food safety, food sanitary standards at national and international levels are under constant review. Several inter governmental agencies / organizations are engaged in work related to quality assurance and food safety. Amongst these World Health Organization (WHO) and Codex Alimentarius Commission (CAC) play the major role in protecting public health and defining standards of quality and safety aspects of foods for regional and or world wide usage.

Regulatory Institutions

The quality environment in the Indian food processing sector revolves around compulsory legislation which specify minimum standard and certification system. Legal standards are generally made to have control over the quality of foods offered for sale and to safeguard the consumer from health hazards posed by practice of adulteration. There are basically three types of Indian standards namely

Frequency Distribution: A tabular presentation of the data in which the fre- quencies of values of a variable are given along with them is called a frequen- cy distribution. Two types of frequency distribution are available

1. Discrete Frequency Distribution or Ungrouped Frequency Distribution
2. Continuous Frequency Distribution or Grouped Frequency Distribution

Objective (a): Prepare a discrete frequency distribution from the following sentence in English: “Today there is hardly a phase of Endeavour which does not find statistical devices at least occasionally useful.”

Theory: This problem relates to discrete frequency distribution i. e. a frequency distribution which is formed by distinct values of a discrete or continuous variable.

The important convincing appealing and easily understood method of presenting the statistical data is the use of diagrams and graphs. Diagram makes the comparison of the data but graphs makes the relationship among the data.

Objective: Aggregated figures for merchandise export in India for eight years are as follows

Pie charts are useful to compare different parts of a whole amount. They are often used to present financial information. E.g. A farmer’s expenditure on farm can be shown to be the sum of its parts including different expense cate- gories such as cultivation, irrigation, sowing, harvesting, and general running costs (i.e. rent, electricity, fuel etc).

A pie chart is a circular chart in which the circle is divided into sectors. Each sector visually represents an item in a data set to match the amount of the item as a percentage or fraction of the total data set.

Measures of Central Tendency

The term ‘Mean” or ‘average’ is something, we have been familiar with from a very early age when we start analyzing our marks on report card. We add together all of our test results and then divide it by the sum of the total number of marks there are. We often call it the average. However, statistically it’s the Mean!

The Median is the ‘middle value’. When the totals of the list are odd, the me- dian is the middle entry in the list after sorting the list into increasing order. When the totals of the list are even, the median is equal to the sum of the two middle (after sorting the list into increasing order) numbers divided by two. Thus, remember to line up values, the middle number is the median!

The Mode in a list of numbers refers to the list of numbers that occur most frequently. A trick to remember this one is to remember that mode starts with the same first two letters that most does. Most frequently - Mode.

Objective: The distribution of age of males at the time of marriage was as follows

Paratition Value

Median is calculated for dividing the series into two equal parts. If the series is divided into four, eight, ten or hundred parts then the measures are called Quartile, Octile, Decile and Percentile respectively denoted by Q_(1,2,3), O_(1,2..7), D_(1,2…9) and P_(1,2…99).

A relative measure of dispersion based on the quartile deviation is called the coefficient of quartile deviation. It is defined as

MEAN DEVIATION

The mean deviation is the first measure of dispersion that we will use that ac- tually uses each data value in its computation. It is the mean of the distances between each value and the mean. It gives us an idea of how spread out from the center the set of values is.

The mean deviation is based on all the observations, a property which is not possessed by the range and the quartile deviation. The formula of the mean de- viation gives a mathematical impression that is a better way of measuring the variation in the data. Any suitable average among the mean, median or mode can be used in its calculation but the value of the mean deviation is minimum if the deviations are taken from the median.

COEFFICIENT OF THE MEAN DEVIATION

A relative measure of dispersion based on the mean deviation is called the coefficient of the mean deviation or the coefficient of dispersion. It is defined as the ratio of the mean deviation to the average used in the calculation of the mean deviation.

STANDARD DEVIATION AND THEIR COEFFICIENT

The standard deviation is a measure of the spread of scores within a set of data. Usually, we are interested in the standard deviation of a population. However, as we are often presented with data from a sample only, we can estimate the population standard deviation from a sample standard deviation. These two standard deviations - sample and population standard deviations - are calculat- ed differently. In statistics, we are usually presented with having to calculate sample standard deviations.

FOR GROUPED DATA

Objective: The following data shows the marks of students and their frequencies find the standard deviation and its coefficient.

COEFFICIENT OF VARIATION:

The most important of all the relative measure of dispersion is the coefficient of variation. This word is variation not variance. There is no such thing as coefficient of variance. The coefficient of variation( C.V.) is defined

FOR GROUPED DATA

Objective: Data regarding lives of two new models of refrigerators collected in a recent survey are

MOMENTS

The term moment in mechanics refers to the measure of a force with reference to its tendency to produce rotation. The strength of this tendency is depen- dent upon the amount of the force and the distance from the origin at which the force is applied. If on both the sides of the origin the force are equal than there will be a balance, at a balanced position the positive product equals the negative product.

Moment is used in Statistics in a quite analogous sense. The class frequencies are looked upon as the forces and the deviations of the different values from the mean are taken as the distances. In other words, moment is the mean of the first, second, third, fourth, etc. powers of deviations of the different values from the arithmetic mean. The first moment about the mean is always zero and second moment about the mean is variance.

If the moment calculated from arithmetic mean are called central moments and denoted by μ with a subscript which indicate the order of the moment. Moments are the mean values of powers of the deviations in any frequency distribution taken about three points

SKEWNESS

Skewness means lack of symmetry. Skewness denotes the tendency of a distri- bution to depart from symmetry. A frequency distribution is said to be skewed if the frequencies decrease with markedly greater rapidity on one side of the central maximum than on the other side. This characteristic of a frequency distribution is known as skewness and the measures of asymmetry are usually called measures of skewness.

The main object of measuring skewness is to know the direction of the varia- tion from an average and to compare the frequency distribution and the shape of their curves.

There are two types of skewness

(i) Positive Skewness (ii) Negative Skewness

KURTOSIS

Kurtosis refers to the extent to which unimodal frequency curve is peaked. Kurtosis is a measure that refers to the peakedness of the top of the curve. Kurtosis gives the degree of flatness in the region about the mode of a frequency distribution.

Types of Kurtosis

There are three categories of kurtosis that can be displayed by a set of data. All measures of kurtosis are compared against a standard normal distribution, or bell curve.

The first category of kurtosis is a mesokurtic distribution. This type of kurtosis is the most similar to a standard normal distribution in that it also resembles a bell curve. However, a graph that is mesokurtic has fatter tails than a standard normal distribution and has a slightly lower peak. This type of kurtosis is considered normally distributed but is not a standard normal distribution.

The second category is a leptokurtic distribution. Any distribution that is leptokurtic displays greater kurtosis than a mesokurtic distribution. Characteristic of this type of distribution is one with extremely thick tails and a very thin and tall peak. The prefix of “lepto-” means “skinny,” making the shape of a leptokurtic distribution easier to remember. T-distributions are leptokurtic.

The final type of distribution is a platykurtic distribution. These types of distributions have slender tails and a peak that’s smaller than a mesokurtic distribution. The prefix of “platy-” means “broad,” and it is meant to describe a short and broad-looking peak. Uniform distributions are platykurtic.

CORRELATION

In case of bivariate or multivariate normal distributions, we may be interested in discovering and measuring the magnitude and direction of the relationship between two or more variables. For this purpose we use correlation. The sys- tematic interrelationship between the variables is termed as correlation. When only two variables are involved the correlation is known as simple correlation. If more than two variables are involved the correlation is known as multiple correlation. An increase in one variable may cause an increase in the other variable, or a decrease in one variable may cause a decrease in the other vari- able, then they are said to be positively correlated. If a decrease in one variable causes an increase in the other variable or vise versa, the variables are said to be negatively correlated.