eBook Chapters

Eswaran (2007) made genetic analysis of six parents and their 30 hybrids of Okra with the method of analysis proposed by Hayman (1954b). He estimated the various genetic parameters viz., _D?, _F?, H?₁, H?² and Ê as well as the various genetic ratio. The results are presented in Tables 69 and 70.

The estimates of _D? were significant for seven out of ten characters studied. This indicated that the component of variation due to additive genetic variance was important for days to seedling emergence, number of first fruiting node, height of first fruiting node, plant height, days to first picking, number of fruits per plant and fruit weight. These characters could be improved by resorting to simple selection. The estimates of H? ₁and H? ₂were positive and significant for almost all the characters studied. It indicated that there were unequal frequency of alleles i.e., u ¹ v at all the loci, in this context, ‘u’ refers to the frequency of alleles which increase the mean expression of the character and are situated at loci which exhibited dominance. On the other hand, ‘v’ corresponds to the frequency of alleles at loci that decreases the expression of the character. Further proof for the unequal distribution of the alleles over loci was obtained

Among the different biometrical methods available, triple test cross analysis is one of the most efficient designs currently available for investigating the genetic structure of populations. It provides a test of epistasis and in its absence it gives independent and equally precise estimates of additive and dominance genetic components (Mather and Jinks, 1982).

11.1. Statistical analysis

Triple test cross

Jinks and Perkins (1970) method was applied to detect epistasis and estimate additive and dominance components of genetic variance.

Abstract

Genetic analysis of yield and yield components in tomato (Lycopersicon esculentum Mill.) was worked out by using half diallel mating design. The good general combiners observed were Solan Vajr, FT-5 and UHF-265 for plant height; UHF-107 and UHF-260 for days to first picking; Solan Vajr for number of fruits per cluster; FT-5, EC-191536 and UHF-120 for average fruit weight; Solan Vajr, UHF-265 and FT-5 for harvest duration and FT-5 and Solan Vajr for marketable yield per plant. The best three specific combiners for marketable yield per plant were EC-191536 x Solan Vajr, BL-342-1 x FT-5 and UHF-107 x EC-191536. Hayman’s approach revealed non-allelic interaction in the expression of number of fruits per cluster, number of fruits per plant and marketable yield per plant. Preponderance of non-additive gene action was observed with dominance towards tallness, delayed first picking, more fruits per cluster, longer harvest duration and higher marketable yield, while involvement of complimentary epistasis was indicated in the inheritance of average fruit weight and number of fruits per plant.

ABSTRACT

Though the genetic control of sex determination is being explored in several animal systems, no much information is available on the genetic basis for sex specificities in dioecious or sexually polymorphic plant species. Date palm is a unique member of the family Palmaceae which exhibits dioecy. Here we report the sex-specific variation in the genomic DNA of male and female date palms as revealed from an extensive study conducted with palms representing different date palm growing regions of the Kingdom of Saudi Arabia. The genomic DNA content in females was less than 60 per cent compared to those of the male genotypes. Polymerase chain reactions carried out to amplify different segments of the alcohol dehydrogenase (AdhA) gene from the date palm genomic DNA yielded two DNA fragments each in the female genotypes where as the same primers amplified a single fragment in male plants. Genomic Southern analysis of Eco R1 restriction digests showed RFLP between the male and female genotypes with the male plants showing a single hybridization signal of approximately 14 kb size and the females showing six additional bands of varying molecular weights. The results of our investigations reveal the potential of molecular biology in differentiating the sex in date palm at DNA level. Further research is needed to develop DNA markers that will help to unequivocally identify the sex of dioecious plants at the seedling stage.

Plant breeding is essentially a technology. Any technology will stand the test of time if it is based on sound concepts. In the case of plant breeding, the concepts are provided by the science of genetics.

Plant productivity in its broad sense requires consideration of not only yield but also of a number of its direct and indirect components. For example in groundnut, besides pod yield, shelling percentage, 100-kernel weight and oil content are components relevant to defining productivity. A number of physiological (like biomass, leaf area, specific leaf weight), morphological (like days to flowering, number of branches, number of mature seeds), nitrogen-fixing, (where relevant, for example, number of nodules, nodule mass, nitrogenase activity) and such other characters influence yield directly or indirectly.

Yield and most yield contributing characters are quantitative in nature. A quantitative character is one which shows continuous variation. In contrast, qualitative characters like flower colour and seed coat colour show, in general, discrete variation and are controlled by fewer genes with major effects. A quantitative trait, however, is governed by many genes. The range of values of a quantitative character is described by a continuous distribution, usually assumed to be a normal distribution. The distribution is specified by the two parameters: mean and variance.

Biochemical reactions are mediated by enzymes and all enzymes are proteins. Proteins are polymers of subunits (monomers) called amino acids which are often termed as ‘residues’. Each amino acid has an amino group (NH ) at one end and a carboxyl group (COOH) at the opposite end. 20 different kinds of amino acids occur naturally in proteins. Each enzyme consists of a certain number of amino acids in a precisely ordered sequence. The blueprint for making proteins is coded in the nucleotide sequence of DNA. The number of nucleotides which code for an amino acid is termed a codon. There are 20 common amino acids but only four different nucleotides. Obviously a singlet code (one nucleotide coding for one amino acid) could code only for four amino acids. A coding sequence of two nucleotides for one amino acid or a doublet code would produce 4₂ = 16 possible coding combinations or codons and this arrangement is not sufficient to take care of 20 amino acids. A codon size of three nucleotides for one amino acid or triplet code seems more likely as it produces 4₃ = 64 possible codons as illustrated in Table 43.1 (Strickberger, 1968).

11.1 Introduction

In chapter 10, we have discussed the different types of variation, namely, genetic, environmental and genotype × environment interaction variations. We have also learnt how to estimate the phenotypic variance and its components including genotypic (also called genetic), environmental and g × e interaction variances from trial data. Now in this chapter, we shall discuss on the genetic components of polygenic (quantitative) variation and its implications on breeding strategies.

11.2 Genetic Components of Polygenic Variation

In this chapter whenever we call genetic variation, we mean polygenic (quantitative) variation, and we know that variation is usually measured in term of variance. However, variation, variability and variance are almost used synonymously. The genetic variance has been classified into different components by various workers. Fisher (1918) divided genetic variance into three components: additive, dominance and epistatic (interaction) variances. Wright (1935) classified genetic variance into two components: additive variance and non-additive variance (dominance and epistatic variances). Mather (1949) classified genetic variance into two components: heritable fixable variance (additive variance and additive × additive epistatic variance) and heritable non-fixable variance (dominance variance, and additive × dominance and dominance × dominance epistatic variances). Later, Hayman and Mather further divided the epistatic variance into three categories: additive × additive, additive × dominance and dominance × dominance.

Abstract

Most of the sorghum accessions are landraces, and much of the cultivated area of sorghum is under local land races. The local land races are highly adapted to specific environmental conditions and are useful sources of genetic variation. Under the present investigation one hundred and two local land races of sorghum collected from different geographical origins were evaluated during kharif 2010 and kharif 2011 in order to assess the genetic diversity. The analysis of variances showed highly significant differences among the accessions for all the characters studied.

ABSTRACT

India is the largest producer of banana, contributing to 17.3 per cent of the global production. In Kerala, it is the leading fruit crop, being cultivated in an area of 99,412 ha with an annual production of 7,31,650 tonnes. Biodiversity in the cultivars of banana, which consist of triploids, is complex especially in Nendran. Nendran belonging to Musa AAB plantain subgroup is the leading banana cultivar of the Kerala. in Kerala, several landraces are available, cultivated in different parts, known in different local names. Twelve Nendran ecotypes of banana belonging to AAB genomic group were collected from Banana Research Station, Kannara, Banana Nursery Farm, Palode and Instructional Farm, College of Agriculture, Vellayani to ana lyse genetic divergence using RAPD marker and morphological traits. Out of the forty one decamer primers screened for RAPD analysis, 34 could produce amplification. Twenty five primers showed high level of polymorphism. Finally, six of the most promising primers viz., OPA-01, OPA-03, OPA-13, OPB-04, OPB-10 and OPB-12 were used for RAPD analysis. Statistical analysis for the morphological traits and RAPD marker were conducted using the software programme NTSYS pc version 2.02e. The matrix average taxonomical distances (similarity coefficient) among the ecotypes ranged from 0.59 to 1.00 in RAPD profiles and morphological profiles (dissimilarity coefficient) ranged from 2.82 to 11.21. In the dendrogram (RAPD profiles), Koonoor Ethan showed the maximum genetic divergence. Quintal banana and Zanzibar came under a single clusters at a distance of 0.79 and clustered together at a distance of 0.82. Both the ecotypes showed next higher genetic divergence among the Nendran ecotypes. In the case of morphological traits, the same trend could be observed. Koonoor Ethan showed the maximum genetic divergence at a distance of 11.21 and Quintal banana showed next higher genetic divergence at a distance of 9.11. Koonoor Ethan, Quintal banana and Zanzibar were distinct ecotypes among the Nendran ecotypes of Kerala

Abstract

The genetic divergence among 249 germplasm lines of maize was assessed by D2statistics based on nine parameters at Agricultural Research Station, Karimnagar. The germplasm lines were grouped into eleven clusters. Clusters I and II were the largest clusters with 73 and 79 genotypes, respectively. The highest inter cluster distance was observed between cluster X and XI followed by cluster V and XI indicating more variability in the genetic makeup of inbreds included in these clusters. Cluster V showed highest mean values for grain yield/plant and ear length. Cluster XI had the lowest mean values for plant height and ear height and these two characters showed maximum contribution towards total divergence among different characters. Based on inter cluster distances, inter crossing among the genotypes belonging to cluster V, IX, X and XI has the chance of getting high yielding hybrids with higher heterosis.

Genetic architecture of a population is the result of prolonged natural selection. The populations which exist in diverse environments might have been strongly diversified genetically. So, it is necessary to understand the extent and rates of genetic divergence existing between the diversified forms or types. Genetic diversity may be available in improved germplasm or it may exist only in genetically inferior stocks.

Genetic divergence among the parents is important in self pollinated crops because a cross involving genetically diverse parents is likely to produce high heterozygous as well as heterotic effect. In such a cross, more variability could be expected in the segregating generations due to the accumulation of the genes of both the parents. Genetic divergence, as one of the criteria of selection of parents is considered in plant breeding as early as 1962 (Murthy et al., 1962; Timothy, 1963). Later, Joshi and Dhawan (1966), Murthy and Arunachalam (1966), Arunachalam et al. (1984) and Lefort-Buson (1987) also stated that for exploiting heterosis as a means of increasing production, it is necessary to have parents of maximum divergence. The more diverse the parents, more is the chance of pronounced heterotic effects and increased spectrum of variability in the segregating generations.

The availability of statistical tools to quantitatively measure the genetic divergence between two or more populations and the relative contribution of individual characters to the total divergence have permitted to trace the evolutionary patterns in some crops such as rice and tobacco and in choosing the parents for hybridization in crop plants (Rao, 1958; Blackith, 1960; Morishima and Oka, 1960; Murthy et al., 1962). Among the several statistical methods developed for measuring the divergence between the populations, multivariate analysis (D² statistic) developed by Mahalanobis in 1936, has been found to be a potent tool. Mahalanbobis’s D² statistic is an effective tool in quantifying the degree of divergence at genetic level and provides a quantitative measure of the association between geographic and genetic diversity based on generalized distance. It is now known that the estimates of genetic divergence are also influenced by environments and seasons. Therefore, if the divergence analysis is conducted in a number of seasons and parents are selected on the basis of consistent divergence over the seasons, the problem of influence of seasons on divergence analysis can be largely overcome.

Abstract

Genetic diversity of thirty two rice genotypes from different states of India was evaluated through Mahalanobis’s D2statistic under integrated fertilizer management for fourteen yield and quality characters. The genotypes were grouped in to seven different clusters. Cluster I had nine genotypes. Three genotypes each were included in cluster II, cluster IV and cluster VII, whereas six and seven genotypes in cluster III and cluster V, respectively while the cluster VI had only one genotype. The results revealed that the geographic diversity might not always be related to genetic diversity. Kernel length after cooking, days to maturity and kernel breadth contributed maximum towards divergence indicating their importance in choice of parents for the hybridization programme.

Date palm (Phoenix dactylifera L. Family-Palmaceae) also known as Khajoor or Kharek is an ancient important fruit tree of semi-arid and arid regions of the world. It grows well under poor desertic soils due to its hardy plant characteristics and deep root system. It is also one of the most suitable fruit trees, which can be easily grown under saline conditions. Date palm grows as much as one feet per year, and as high as 80-100 feet under favorable environment. It is well known fact for date palm that its feet in the water and its head in sun. It requires dry hot climate for growth and development of fruits. In arid region, crop production is risky preposition, where date palm cultivation contributes in achieving food security, high nutritive value food, crop diversification, desertification control, income generation and foreign exchange earnings. It can be grown at such places, where adequate irrigation facility is available; besides, other climatic requirements (Chandra et al, 1992, Singh et al, 2007). The date tree has religious significance. The fruits are used during holy month of Ramzan by Muslim peoples. As Saudi Arabia is principal producer of date palm in the world, the palm tree is incorporated in the national emblem of Saudi Arabia to represent vitality and growth

In recent years, we are just experiencing a surplus production in cereals and oil seeds leading to self-sufficiency through green revolution and yellow revolution. However, shortage in the production of vegetables has drawn the attention for increasing the cultivation of vegetables to provide food and nutrition security.

Vegetables are being cultivated over an area of 49 million hectares with the production potential of 487 million tonnes in the world. This accounts for 2.85 per cent of total cropped area in the world. India is the second largest producer of vegetables next to China, sharing nearly 12 per cent of the total world output (Joshi and Shukla, 1997). Vegetables occupy nearly 8.02 million hectares with the production potential of 133.10 million tonnes in the year 2009 in India (Anonymous, 2009).

Bhendi (Abelmoschus esculentus (L.) Moench) is an important member of family malvaceae and commonly known as okra or ladyfinger in India. It is one of the most ancient and traditional vegetable crops grown in tropical and subtropical regions of the world (Martin and Ruberte, 1978). Bhendi is originated from tropical Africa with 2n = 8x = 72 or 130 or 144 chromosomes and is an allopolyploidy in nature (Joshi and Hardas, 1956; Suresh Babu, 1987). Martin (1982) reported that it behaves as a diploid. Under the genus Abelmoschus, there are 30 species in the old world and four in the new world (Joshi et al., 1974). Out of them, Abelmoschus esculentus, is the only species known to be cultivated. Bhendi is being raised in India in an area of 0.44 million hectares with an average production of 4.52 mt with the productivity of 10.27 t/ha (Anonymous, 2009).

Introduction

India is the largest producer of pulses in the world, both in quantity and variety. But, presently, India is one of the largest importer of pulses. India imported pulse grains upto a tune of approximately 4000 crore rupees during 2006-07. It accounts for about 20 per cent of the total import bill during 2006-07. This is because of the green revolution (quantum jump in cereal production) accompanied with changes in the infrastructures and incentives including input supplies and price support systems in favour of major cereals. It altered the traditional cropping pattern against pulses with decades of emphasis on research as well as production in superior cereals coupled with a near total neglect of the rainfed areas, pulses were driven out of not only the irrigated areas, but also the rainfed farming and were relegated to the marginal lands. Further more, the weak infrastructural support for input supply, credit and marketing in the rainfed areas, the traditional home of pulses, also adversely affected the prospects for pulses. A vicious circle of low input use and low output thus got built in. Lack of processing and marketing facilities in pulses also contributed its share to the woes of pulse growers. The increasing shortage of pulses, resulted in the need for more and more import which, in turn has dampened the speed of rejuvenation of pulses sub-sector of agriculture sector.

The net per capita availability of pulses has fallen from 60.7 (1950-51) to 33.4 g (1991-92). On the contrary, the daily per capita availability of cereals has registered an increase from 334.2 (1950-51) to 443 g (1991-92). It leads to increase in the pulses/cereal ratio from 0.18 to 0.08 g i.e., by 55 per cent. This is despite the increases of 24.36 per cent in area; 61.71 per cent in production and 29.93 per cent in production. It is significant to note that almost all these increases had taken place during 1950-51 to 1960-61. The area, production and yield of pulses have either stagnated or declined since then. This stagnation of pulse production and productivity should be viewed seriously not only from the point of security and quality of food for our people, especially the poor and the rural population, but also from the soaring import bill, imbalance and distribution in the cropping pattern and resource allocation among various sub-sectors of agriculture.

The Coconut palm is a monotypic species of the family Arecaceae, under the tribe Cocoideae. It is considered as an important commercial crop in more than 18 countries in the world. The palm provides food, drink, shelter and also supplies raw materials for a large number of industries. Every part of the palm is utilized for some economic purpose or another. Hence, it is referred to as ‘Tree of Wealth” or the “Tree of Life” (Satyabalan, 1993). It is native of South East Asia. Genetic diversity has become one of the keywords of scientists who are concerned about the sustainable management of different tree crops. Genetic diversity plays an important role in tree breeding, because hybrids between populations of diverse origin, generally display a greater heterosis than between closely related parents (Zobel and Talbert, 1986). The present study was formulated to identify divergent parents for future breeding programme.

Two hundred and fifty genotypes of coconut cultivar Chawghat green dwarf, distributed in the two districts of Kerala viz., Kottayam and Pathanamthitta were evaluated for nut yield per plant during June-July, 2000. Seventy five genotypes, which had single tree nut yield of more than population mean ± 2 SE were selected as per the method outlined by Ledig (1974). These 75 genotypes were observed for 10 nut and endosperm characters in two seasons (years), during June-July 2000 and 2001.

Each tree was considered as a single genotype. Thirty nuts from a single tree were collected and divided into three replications (Chauhan and Kanwar, 2001; Thirugnanakumar, 2006a, b). Observations were recorded on 10 nut and endosperm characters viz.,1) oil content (%), cold percolation method; (Kartha and Sethi, 1957), 2) weight of unhusked nut (g), 3) weight of husked nut (g), 4) diameter (polar) of the husked nut (cm), 5) diameter (equatorial) of the husked nut (cm), 6) thickness of husk (cm), 7) husk: nut ratio, 8) thickness of meat (mm), 9) weight of kernel (g) and 10) weight of copra (g). The mean values so obtained were subjected to statistical analyses, in Randomized Block Design, as suggested by Chauhan and Kanwar (2001) and Thirugnanakumar et al.(2006a, b). The D² estimates were made following Mahalanobis (1936), as described by Rao (1952). Clusters were prepared following Tocher (Rao, 1952).

Gamboge tree Garcinia gummi-gutta (L.), is a member of the Clusiaceae family. It is a botanical cousin of Garcinia indica Choisy. It is a cross pollinated crop. It is called as Kodumpuli in Kerala. It is native of Tropical Asia. It thrives best in the ever green forests of Konkan, stretching from southward to the Kerala coast and Western Ghats upto 1800 m min the Nilgiris (CSIR, 1956). In Kerala, majority of the populations occur naturally in the central districts of Kerala, of different altitudes ranging from sea level to 200 m.

It is one of the potential under-exploited fruit crops. Now, it is gaining momentum for its commercial, industrial and medicinal importance. The dried rind is sold in the market at the rate of Rs. 200 per kg (Muthulakshmi et al.,1999). It is used as a food preservative, spicy source with astringent taste. It is meant for its good flavour, taste and keeping quality. The fruits are too acidic and cannot to eaten raw. The dried rind has unique use in fish curries for imparting its delicate flavour (Sarah, 1998). Dried rind can also be used for polishing gold, silver and coagulating rubber latex. Hydroxy citric acid (HCA) is a very rare natural components being extracted from the rind and is marketed in the name of ‘citrin’ and ‘citrimax’. It has high export value and fetches considerable foreign exchange. In foreign countries, it is used as a herbal medicine against cardiac diseases and for weight management through blocking fat synthesis. The derivatives of acid are potent metabolic regulators of obesity. The unique acid, lowers the blood lipids such as cholesterol and triglycerides by triggering the fatty acid oxidation in the liver through thermogenesis.

Introduction

The nature and magnitude of genetic variability present in the genetic stock afford the plant breeder, information to formulate a purposeful breeding programme for crop improvement. The association and the influence of yield components with yield, their heritability and genetic advance would characterise the various steps in the breeding programme in achieving the aim of the breeder. Studies on these lines in various crops have hastened the realization of crop improvement in general.

India grows a variety of pulse crop which probably no other country in the world grows. These are multiple utility, energy high crops as they provide protein for human consumption, green nutritious fodder and enrich soil fertility through biological nitrogen fixation. Vigna radiata (L.) Wilczek, commonly known as greengram or mungbean, is the most widely distributed of the six cultivated Asiatic Vigna species.

The current breeding approaches to yield improvement in greengram are based on the recognition that this crop have lost a large part of their genetic variability in the process of adaptation to stress environment. This variability must now be regenerated.

The foremost need for this purpose is the collection of germplasm from different parts of the world and the organisation of a very intensive hybridization programme, using diverse genetic stocks as parental lines. Selection of parents for hybridization based merely on geographic diversity can no more be a suitable criterion. The importance of genetic diversity has long been appreciated by crop specialists. Such an analysis will eventually help to choose desirable parents for hybridization and evolve superior genotypes.

Jack bearing the largest edible fruit in the world, is a tropical evergreen tree belonging to the family Moraceae. Previously, it was known as Artocarpus integrifolia.It is an indigenous fruit crop, probably originated in Western Ghats of India (Santapau, 1966) and is widely cultivated in South Asia, East Indies and other warm areas of both the hemispheres. Jack tree is commonly grown in Burma, Malaysia and Brazil. It is hardly recognized as a commercial fruit crop in India even though it is widely distributed in Southern states viz,. Kerala, Tamil Nadu, Karnataka and Andra Pradesh. It is also cultivated in other states like Assam, Bihar, Orissa, Maharashtra and West Bengal. It is an invariable component of Kerala’s homesteads and also grown as a shade crop in coffee, arecanut and cardamom plantations. It is also grown as a standard crop in pepper plantations. The crop has got a rare distinction of being used as the staple food of Kerala tribals and also in some African countries like Uganda.

The mango is one of the choicest fruit crops of tropical and sub-tropical regions of the world. Its popularity and importance can easily be realized by the fact that it is referred as ‘King of fruits’ in the tropical world. India ranks first, both in area (2.51 million hectares) and production (15.02 million tonnes) of mango and it contributes to 42.1 per cent of world’s mango production. Presently, India is home to more than 1000 mango cultivars differing in taste, aroma, size, fibre content and pulp characteristics.

Though more than 1000 mango cultivars are reported, only 25-30 are of commercial importance. Most of the important cultivars are not amendable to hi-tech cultivation practices and do not meet the requirements of modern horticultural production systems like precocity in bearing, dwarfing, regularity in bearing with high yield, resistant to diseases, pests, physiological disorders and good keeping quality. Hence, breeding attempts to develop an ideal mango variety would be dwarf, regular bearer with medium size fruits (250-300g). Additionally, it should be highly tolerant to various fungal and bacterial diseases. A variety suitable for pickling is also gaining the attention of the breeders. An ideal pickling type should have high acidity, high fibre, good texture and characteristic raw mango flavour.

The first and foremost step in developing an ideotype is to explore the vast diversity and systematic characterization for utilization in the breeding programme.

Considering the importance of conserving the available gene pool, systematic exploration works are being carried out by National Institute like Indian Institutes of Horticultural Research (IIHR, Bangalore), National Bureau of Plant Genetic Resources (NBPGR, New Delhi) and others to collect and conserve the germplasm in Field Gene Banks. Recently, in addition to the traditional germplasm conservation methods, cryopreservation is also gaining importance especially in the conservation of nuclear gene (pollen parent) diversity for future breeding.

Utilizing the conserved germplasm in the breeding programme requires precise information on the genetic relationships within such germplasm. Information on the genetic distance among the germplasm accessions will also help to avoid the duplicates, widen the genetic base of the core collections and ultimately help in preserving the valuable diversity.

Pomegranate is one of the popular fruit crops of tropical and sub tropical in India and enjoys high reputation for its dietetic and medicinal properties. The fruit is native of Iran and is extensively cultivated in Mediterranean countries like Spain, Morocco, Egypt, Iran, Afghanistan. It is also grown to a lesser extent in Myanmar, China, Japan, India and U.S.A.

The area under pomegranate cultivation has increased several folds in the recent past after the introduction of soft seeded varieties. Out of 30,000 hectares under this crop in India, Maharashtra state alone grows over eighty per cent of area with an average production of 8000 kg ha^-1 (Mote et al.,1992). The export of pomegranate fruits was 1790.3 tonnes in 1991-92 valued at rupees 215.3 lakhs which was more than two fold over the previous year’s export earnings (Chadha, 1994). The utility of the crop is gaining importance and at present new orchards of pomegranate are being planted on large acreage. Because of its versatile adaptability, hard nature, low maintenance cost, steady and high yields, fine table and therapeutic values, better keeping quality and very good export potential, there is greater scope for extending its area and increasing the production especially in the hot and semi arid regions of India.

In pomegranate, market preference is for the attractiveness of the fruit which are exhibited through better size, colour with bold and deep coloured arils besides possessing high juice-content. However consumers prefers the softness of the arils with low acidity. While, there are number of cultivated types available with these desirable characters, there are hardly cultivar having a combination of all or atleast a majority of them. Pomegranate improvement work, therefore has to be oriented towards the production of soft seeded type with other desirable characters (Phadnis, 1974).

Rice (2n = 24) is an annual grass (family: Graminae) with terminal panicles bearing the grains. It originated in Asia between the fourth and fifth millennia B.C. A substantial portion of the people in south and Southeast Asia and the southern part of China are depending on rice as staple food (Chang, 1976). Rice is planted in the most diverse environmental conditions of any major food crop, from sea level to around 3000 m altitude and from 30°S to 49°N. Temperature and day lengths are therefore quite diverse in the rice growing areas. Rice is also grown under water regimes ranging from dry land to deepwater fields where water may reach 5 m depth. The wide geographical distribution of rice and its early history of cultivation have resulted in the development of a great diversity of varietal types (Vergara, 1985).

Rice has been used as food by man for over 10,000 years and has fed a great number of people for a longer period than has any other crop. “Rice is life” for almost four billion people of the world contributing over 20 per cent of the total caloric intake of human population (Chaudhary and Tran, 2001). Rice is cultivated in 113 countries and on all continents except Antarctica and it is the staple food for 17 countries in Asia and the pacific, eight countries in Africa, seven countries, in Latin America and the Caribbean and one in the near east (IRC, 2003).

Globally rice is grown in around 155 million ha occupying one tenth of arable land, with an annual production of 579 million tonnes of rough rice (Iiyas Ahmed, 2003). The average productivity of 3.89 t ha^-1 of rice provides a per capita. Consumption of 100 to 240 kg per year across the globe. Over 90 per cent of the world’s rice is produced and consumed in Asia and more than half of it from India and China exploiting maximum arable land. More than two billion people obtain their 80 per cent calorie from rice and its derived products from 90 per cent of world’s rice area (FAO, 1999). Rice based on production systems and their associated post harvest operations employ nearly a billion people in rural areas in developing countries (IRC, 2003).

In recent years, we are just experiencing marginal surplus production in cereals leading to self-sufficiency through green revolution. However, the shortage of production in edible oils has drawn the attention for the increased cultivation of oil seeds, and increased productivity per unit area to provide sustainable food and nutrition security (Swaminathan, 1989).

The importance of oil seeds cannot be over emphasized in the Indian economy. Oilseed occupied nearly 19 million hectares, next only to food grains, in 1986-1987. Yet, the domestic production in the country has lagged far behind the increasing demand for edible oils, necessitating a massive import of edible oils which lead to the drain of the valuable foreign exchange. The total import bill on edible oil has increased from 1.41 per cent in 1970-71 to 3.05 per cent in 1986-87. Even then, the annual per capita availability of edible oils registered only a nominal increased from 3.5 kg to 5.9 kg during the same period, against the nutritional norm of 14 kg (Suresh Pal, 1989). Due to the concerted efforts made through the ‘Technology Mission on Oilseeds’, oil seeds production reached a peak of 178.9 lakh tonnes during 1988-’89 in India (GOI, 1990a). This is an impressive achievement in Indian Agriculture, to reduce the bill on the import of edible oils from 4.11 per cent (1987-’88) to 2.58 per cent (1988-’89) (Gill, 1990). Further efforts in increasing oilseeds production definitely will go a long way in drastically reducing the present import bill.

Among the oilseed crop, sesame (Sesamum indicum L.), “The Queen of Oil Seeds”, is one of the important ancient and traditional crops occupying third position in terms of acreage on the oilseeds map of the country. It is commonly known as Gingelly, Til, Benniseed and Simsim. It is an important source of edible oil for the nutritional refugees of most part of the world, especially for India. The oil is rich in oleic and linoleic acid. In addition, it serves as a good source of proteins, vitamins and minerals (Nagaraj, 1990). Its high keeping quality deserves special mention.

ABSTRACT

The investigation aimed at to examine the diversity among nineteen wild and cultivated germplasms of the genus Vigna namely, V. trichuriensis, V. hainiana, V. radiata, V. aconitifolia, V. minima, V. sinensis, V. radiata var. sublobata, V. radiata var.setulosa, V. umbellata, and allopolyploid of BR3x T9 at DNA level follwing Random Amplified Polymorphic DNA (RAPD) technique. Ten random decamer primers were used in amplification reactions, five of that were reproducible and clear. The five primers constituted 55 bands of, which 9 are polymorphic. The similarity index based on 0 and 1 matrix of banding was calculated and dendrogram following UPGMA was constructed. The germplasms formed altogether 4 clusters on the basis of 0.375 linkage distance. The first and second cluster consisted of single genotype of V. hainiana. and V. minima respectively. The third cluster comprised wild and cultivated types of V. sinensis. The 4th cluster on the otherhand, consisted of genotypes belonging to V. radiata, V. radiata var. sublobata, V. mungo, V. radiata var. setulosa, V. trichuriensis and allopolyploid of BR3 and T9. The wild forms of different species were found to exist in the same cluster as their cultivated form. The three mungbean genotypes namely B105 (V. radiata), B1 (V. radiata) and BR3 (V. radiata )are crossable within themselves and they belonged to the cluster -IV.The intercluster cross between different clusters would like to generate new genotypes with wide variability. Based on limited range of accessions tasted in the present investigation, the approach holds promise for the classification of Vigna germplasm, identification of Vigna and marker assisted breeding in Vigna.

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

Diversity connotes multiplicity of variety. In a given ecosystem, diversity refers to presence of number of different species of ?ora and fauna that have ecological niches in agreement with the environment. Scaling up, there exists diversity between different ecosystems. All life forms of ?ora and fauna on earth contains genetic material, that is the repository of an immense amount of genetic information in the form of traits, characteristics, etc. Focusing on the species level, genetic diversity refers to genetic variation that is observed in a population. Thus, genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. This provides in built latitude to the nature and/or the livestock breeders (including farmers) to manoeuvre/ manipulate so as evolve an improved population of desired qualities and traits. Further, genetic diversity is essential because the presence of adequate and appropriate genes in a population will make the species tide over adversaries owing to climate change and other emerging threats like new disease outbreaks. The ‘desired’ divergent gene pool provides the inherent resilient mechanism that equip the species to cope with likely challenging situation.

Over the years, with human interventions, the genetic diversity has been interfered with to meet specific needs; mostly with respect to garnering higher production and productivity. In the process, the diversity has been compromised for achieving the unitary goal. In certain cases, geographical barriers and other bio-physical constraints have also led to loss of diversity within a population. Studies on impact of climate change especially the effect of rise in environmental temperature on milk production of dairy animals indicate that global warming will negatively impact milk production. During 2020, the annual loss in milk production of cattle and buffaloes due to thermal stress will be around 3.2 million tonnes of milk costing more than Rs 5000 Crore at current price. Similarly, there would be prevalence of many emerging diseases including those with zoonotic implications owing to change in climatic conditions. Thus, the present day society is confronted with an imminent development dilemma of ecology vs. economics more specifically genetic diversity vs. higher production. It has led to volume of debates and discussions on the livestock development agenda to be pursued. The apparently con?icting interests has also generated antipathy amongst two schools of development.

Ralstonia solanacearum is a phytopathogenic bacterium belong ing to the b subdivision of the Proteobacteria (Yabuuchi et al., 1995) having a wide geographical distribution ranging from tropical, subtropical and warm temperate regions (Liu et al., 2009). It has broad host range and infects around 54 plant families and 450 plant species (Hayward, 1991; Wicker et al., 2007). 

Early attempts to study the diversity present in the R. solanacearum species complex resulted in separate race and biovar systems. R. solanacearum has been phenotypically classified into 5 races based on the host range at the plant species level and into five biovars based on the metabolic profiles related to the ability to reduce three disaccharides and three hexose alcohols (Wicker et al., 2007).

Vegetables are of short duration, have higher productivity and give more return per unit area, besides giving nutritious food to human being and can be fitted in different farming systems. They also play a major role in balancing human diet, thereby helping in alleviating hunger, poverty and malnutrition. Because of the public awareness for the significance of vegetable consumption, the demand of vegetables in the global market has increased immensely. Thus, vegetable farming is becoming profitable venture globally, opening avenues of self employment and revenue generation (Anon., 2009). At global level, India holds second position, next only to China in vegetables production with a share of about 14%. The present annual vegetables production of country is about 175 million tons from an area about 10.3 million ha with a productivity of 17.1 t/ha. India grows largest number of vegetables in the world, as having a spectrum of wide range of agro-climatic situations, ranging from dry temperate to humid tropics between the altitudes from sea level to snow line.

The Indian hot arid region is one of the most important arid ecosystems of the world in terms of biodiversity it possesses. This arid region spreads over 31.7 mha, occupies major part of north western India including Rajasthan, Gujarat, Punjab and Haryana, which together contribute 73% of arid region. High temperature, wind velocity, low humidity, low and erratic rainfall and high potential evapotranspiration are important characteristics of this region which narrowed down the choice for vegetables, besides permit their low productivity.

Dairy buffalo production has been a tradition in Asian region and some other parts of the world where fresh  buffalo milk, dahi (cultured sour milk), ghee (butter oil) and yoghurt are very popular. In Italy, the dairy buffalo industry is flourishing; thanks to the popularity of buffalo mozzarella cheese. Because of the market for Mozzarella, buffalo farming is a profitable enterprise and is carried out in an organized manner with modern equipment.

Development of sophisticated procedures for the isolation, manipulation and expression of genetic materials is a field called genetic engineering. Genetic engineering has applications in both basic and applied research. In basic research, genetic engineering techniques are used to study the mechanisms of gene replication and expression in prokaryotes, eukaryotes and viruses. For applied research, genetic engineering used for development of microbial cultures capable of producing valuable products such as human insulins, growth hormones, interferons, vaccines, enzymes etc. The commercial application of genetic engineering is sometimes referred as Biotechnology. In broad sense, Biotechnology refers the use of living organisms to carry out defined chemical processes for industrial application.

The process of isolation, purification and replication of specific DNA fragment is called molecular cloning or gene cloning. Molecular cloning is the base of most of the genetic engineering procedures. The purpose of molecular cloning is to isolate large quantity of specific genes in pure form. Thus molecular cloning is very important in genetic engineering and can be divided into several steps depends on the purpose. The steps are as follows:

Introduction

One of the main environmental problems is the improper disposal of agricultural waste, which has a negative impact on ecosystems when it is carelessly dumped into the environment. According to the majority of publications, burning, dumping, or storing the untreated and unused agro-industrial waste in a landfill are the methods used for disposal (Neh, 2020). Untreated trash increases the amount of greenhouse gases released into the atmosphere, which in turn aggravates climate change in a number of ways. This has detrimental consequences on the climate in addition to releasing more unwanted gaseous byproducts (Toop et al., 2017). As a result, substantial interventions are needed to use agro-waste sustainably. This can be achieved through the development of bioproducts with added value and sustainable energy technologies. Increased garbage output worldwide has put more stress on the environment, causing harm to soil, air, and water resources (Rao and Rathod, 2018). These effects jeopardize population health and the long-term sustainability of ecosystems. According to Zeidabadi et al. (2018), the agriculture sector produces between 21 and 37 percent of greenhouse emissions. A sustainable development paradigm that advocates for significant changes to traditional agricultural production techniques and waste management has emerged in response to this new reality. According to Torres-león et al. (2018), agro-wastes contain high amounts of complex carbohydrates, proteins, fibers, polyphenolic components, bioactive substances, etc. Organic compound wastes can be used as a raw material for a variety of agricultural, food, and pharmaceutical products, even if they are hazardous to the environment (Uzodinma et al., 2007). Because of their high nutrient content, agro-residues are not seen as trash; rather, they are exploited as a source material for new goods. The cost-effectiveness of conversion procedures for the development of bioproducts can be increased by using efficient pre-treatment technologies for agro-waste biomass, as well as by utilizing its biochemical properties and sophisticated conversion processes (Yusuf, 2017). The bioconversion of agricultural waste into enzymes and other bioactive compounds for the pharmaceutical industry, vermicompost, organic fertilizers, and biofuels for the agriculture sector, as well as nutraceuticals and food products, is greatly aided by microbial biotechnology and nanotechnology (Beltrán-Ramírez et al., 2019: Samborska et al., 2019). In the food and healthcare sectors, nanotechnology is being studied more and more because of its numerous potential uses. As previously indicated, the increased bioavailability and quantities of bioactive compounds significantly improve the potential for targeted delivery of bioactive compounds to particular tissues or organs. Nano-structured materials’ distinctive qualities and vast surface area make them potentially revolutionary for the food industry. Although the potential advantages of nanotechnology for society at large have been well acknowledged, food science has only lately started to investigate its uses (Del Rio Osorio et al., 2021).

Preternatural development of recombinant DNA technology has established genetic engineering in animals the most important field in application of biology for human benefit, from production of genetically modified animals to providing crucial technologies to medical science sector. On the basis of the nature of the target tissues, genetic engineering may target single cell line, particular tissue sectors or the organism as a whole. The purpose of transformation may be basic research involving elucidation of gene function, study effect of directed mutations, examination of physiological and developmental processes in animals or may be target oriented, such as production of proteins or metabolites in large quantities in a cell line, incorporating rDNA in the germline cells, gene therapy, use of rDNA in disease diagnostics, or production of transgenic animals for specific purposes.

Since floricultural and ornamental crops are grown for aesthetic purpose and are non-edible there is likely to be less concern in bio safety issues compared to other food crops. Hence there is considerable potential for developing transgenics in ornamental crops. Advances in transgenic technology provide new opportunities for manipulation of the genome. These will have significant impact on expanding and diversifying the gene pool of crop plants, introducing specific genes and shortening the time required for the production of new varieties or hybrids. Molecular breeding is beneficial to increase the production and quality by creating plants with enhanced resistance to diseases, insects or viruses and increased tolerance to environmental stresses like salinity, temperature or drought. Through this technique genes for shelf life, flower colour and architecture may be directly transferred to develop new varieties that are tailor made to customer preferences. Bioluminescent orchids and blue roses are the significant outcomes of the genetic transformation studies in ornamentals (Swarnapiria, 2009).

Since floricultural and ornamental crops are grown for aesthetic purpose and are non-edible there is likely to be less concern in bio safety issues compared to other food crops. Hence there is considerable potential for developing transgenics in ornamental crops. Advances in transgenic technology provide new opportunities for manipulation of the genome. These will have significant impact on expanding and diversifying the gene pool of crop plants, introducing specific genes and shortening the time required for the production of new varieties or hybrids. Molecular breeding is beneficial to increase the production and quality by creating plants with enhanced resistance to diseases, insects or viruses and increased tolerance to environmental stresses like salinity, temperature or drought. Through this technique genes for shelf life, flower colour and architecture may be directly transferred to develop new varieties that are tailor made to customer preferences. Bioluminescent orchids and blue roses are the significant outcomes of the genetic transformation studies in ornamentals (Swarnapiria, 2009).

GENETIC ENGINEERING VS. TRADITIONAL BREEDING

Breeding with transgenic plants is only justified when genetic variation within the primary and secondary gene pools of a species is too small or gene transfer by conventional techniques is difficult and time-consuming. There are a number of different means for increasing or even creating new genetic variation, like species hybridization, mutation induction and protoplast fusion, which have been frequently used to breed new varieties. It is worth mentioning that neither plant cultivation nor commercialization of commodities has any legal requirements and a public discussion about these plants is also lacking. Therefore, a breeder must carefully assess the different constraints of transgenic breeding before starting a breeding program which are the legal aspects and acceptance by farmers, consumers and stakeholders (Jung, 2010).

INTRODUCTION

While the world has been changing during the last few years both politically and economically in unexpected and remarkable way, food security remains an unfulfilled dream of billions of people. With the world population crossing six billion marks, the demand for food grains is increasing at an alarming rate. Increasing population, on the other hand, has led to decrease in cropping area. In order to meet the global food demand we have to increase the productivity. Insects have always been a major cause of yield-loss in agriculture. They account for 20-30% of crop-loss. Several approaches e.g. physical, chemical and biological have been used with varying degree of success to reduce such losses.
 
The insect pest management is one of the most important yield destabilizing factors in almost all the crops. While for some insects, genetic sources of resistance are available in the respective plant germplasm, for many others germplasm is almost devoid of effective resistance genes. It is because of this factor that conventional breeding strategies have not been successful in breeding insect pest’s resistant varieties. The only means available at present for managing the insect is extensive application of insecticides and pesticides. Excessive usage of the pesticides causes, on one hand, environmental pollution and on the other, it forces the insects to develop resistance against these chemicals. Application of the pesticides also imposes additional economic burden on the farmers.

The polymerase chain reaction (PCR) is a rapid way of amplifying (duplicating) specific DNA sequences

Method was devised by Kary Mullis of Cetus Corporation, Emeryville He recieved a $20,000 bonus and later a Nobel Prize

DNA heated to high temperature is not destroyed; separates into single strands, but reforms helix when cooled

PCR Method:

DNA to be amplified is put into solution containing:

Advances in molecular biology have sharpened the tools of the breeders, and brighten the prospects of confidence to serve the humanity. The application of biotechnology to field crop has already led to the field testing of genetically modified crop plants. Genetically engineered Rice, Maize, Soybean, Cotton, Oilseeds like Rape seed, Sugar Beet and Alfalfa cultivars are expected to be commercialized in the late of 20^th century. Genes from varied organisms may be expected to boost the performance of crops especially with regard to their resistance to biotic and abiotic stresses

Genetic engineering involves isolation of DNA fragments within a cell recombining them outside. The basic technique is quite simple. Two DNA molecules are isolated and cut into fragments by one or more specialized enzymes, the fragments joined together in a desired combination, then restored to a cell from replication and reproduction. This method also referred to as recombinant DNA technology. Genetic engineering developed in the mid 1970 when it becomes possible to cut DNA and to transfer particular pieces of DNA containing specific bits of information, from one type of organism into other.

Introduction

It refers to all activities designed to identify materials that cannot be used directly in breeding programmes, and further to transfer these traits to an intermediate set of materials that breeders can use further in producing new varieties for farmers. It is a bridge between Genetic Resources and Crop Improvement. That is collaboration between germplasm curator and plant breeder.

Crosses between adapted and exotic materials, where different proportions of introgression are obtained and evaluated, have been denominated as semi exotic materials. That should be readily used in regular breeding programme for cultivar development.

Objectives of pre-breeding 8-10 Years • Improved germplasm and associated genetic knowledge that enhance resistance expression and diversity.

• Reduce genetic uniformity in crops through the use of a wider pool of genetic material to increase yield, resistance to pests and diseases, and other quality traits.

• Identification of desirable traits/genes and their subsequent transfer into a suitable set of parents for further selection.

• Improved parental stocks which can be readily utilized within breeding programs and improved selection methodologies.

• Identify potentially useful genes in a well-organized and documented gene bank Designing strategies that lead to development of an improved germplasm that are ready to use in varietal development.

ABSTRACT

Of the several PCR techniques developed during the last two decades, random amplified polymorphic DNA (RAPD) offers a simple and economical means of genotype characterization. The information obtained through RAPD characterization is extensively used for the identification of genotypes, screening of duplicates, assessing genetic diversity and monitoring the genetic stability of conserved germplasm. The present study is a report on the DNA fingerprinting of P. nigrum and P. longum cultivars. Fourteen land races and three advanced cultivars of P. nigrum and eleven land races and one advanced cultivar of P.longum were used in the present study. Forty decamer primers from Operon Tech were screened using two representative genomic DNA samples of black pepper. Of these, 10 primers that yielded clear and dominant band patterns were selected for the final analysis of the 29 accessions. These generated 119 amplification products. The total number of markers per primer varied with respect to both P. nigrum and P. longum. Cultivar specific single bands were obtained for a few land races and accessions of both the Piper species.

Introduction

Agricultural biodiversity must be an integrated part of climate change adaptation and mitigation efforts. Climate change adaptation, biodiversity conservation and poverty alleviation should complement each other (FAO, 2007, 2008). Climate affects vectors, pathogens, hosts and host-pathogen interactions from the level of cellular defence to that of the habitat. Hoberg et al. (2008) provide an overview of predicted responses of complex host-pathogen systems to climate change. Climate change may affect the spatial distribution of disease outbreaks, and their timing and intensity (Epstein 2001). Outbreaks of African horse sickness, peste des petits ruminants, Rift Valley fever, bluetongue virus, facial eczema and anthrax are triggered by specific weather conditions and changes in seasonal rainfall profiles.

Dairy farmers are faced with a number of fundamental inquiries. The first inquires as to what dairy animal he needs to keep. Is the breed with the best production performance the one that has adapted to the local environment the most? What animal is the best, asks the second? Is it the one with a showwinning conformation or the one with a strong ancestry? Is the ideal dairy cow one that produces the most milk, has the best feet, legs, and udder support, or combines the performance of these characteristics in the best possible way?

Buffaloes have been classified in two main categories namely riverine and swamp buffaloes depending upon variation in their habitat and genome structure. River buffaloes are generally large in size mostly with curled horns and are mainly found in India, Pakistan and some of the west Asian countries, prefer to enter clear water and have 50 (2n) numbers of chromosomes and are primarily used for milk production and also used for meat production and draught power. Swamp buffaloes are stocky animals with marshy land habitats and have 48 (2n) numbers of chromosomes. They were primarily developed for draught power in paddy fields and haulage and are also used for meat and milk production. Swamp buffaloes are mostly found in south East Asian countries and few animals are also available in north eastern states of India.

Cocoa (Theobroma cacao L.) represented as ‘Food of Gods’ is considered as an important beverage crop next to Tea and Coffee. The economic produce of cocoa is the bean, when it is fermented and dried, become the source for chocolate. Cocoa is native to Amazon basin of South America and is domesticated and distributed to different regions by the natives Mayas, Aztecs and Pipil- Nicaraos (Wood and Lass, 1955; Young, 1994) who consumed it as an energy drink called ‘xocoatl’ by roasting and grinding cocoa beans. When Spanish conquered Mexico in 16th century they took cocoa to Europe which is christened as ‘chocolate’ the worlds’ favourite food. From then on cocoa spread to many other countries (Wood, 1991). According to World Cocoa Foundation, currently 40–50 million people depend on cocoa for their livelihood and the production is 3.97 mt in which Africa contributes 71%, Latin America 14% and Asia and Oceania 14% (Jean Marc Anga, 2013). Ivory Coast is the major producer followed by Ghana, Cameroon, Nigeria and Brazil. In Asian continent, Indonesia and Malaysia are the leading producers (www.wcf.org.).

Abstract

The genetic improvement of crop plants is possible only through employing an appropriate breeding technique. The use of plant breeding technique depends on mode of pollination and reproduction of plant species e.g. selection and hybridization are used in sexually reproduced species, while clonal selection in asexually propagated plant species. The plant species/ varieties are usually derived through conventional techniques (vi z. introduction, selection, hybridization etc.), which are commonly used in various breeding programmes, while some modern techniques viz. transgenic breeding and marker assisted selection etc. are also available which are equally effective for improvement of all crop species. Various techniques applied for development of new varieties and hybrids are briefly described in this section.

Plant breeding is an art, science and technology of improving genetic make-up of crop plants in relation to their economic usefulness for mankind. Various techniques/methods of breeding used for genetic improvement of crop plants are: introduction, selection, hybridization, mutation, transgenic breeding etc.

Classification of Breeding Techniques: Plant breeding techniques are classified as conventional and modern breeding techniques.

Livestock is one of the fastest growing agricultural subsectors in developing countries. In India has a vast diversity of animal genetic resources. Among them, sheep is an important ‘five star’ livestock species contributing significantly to rural economy through production of mutton, wool, manure, skin and milk etc. Sheep make a valuable contribution to the livelihood of the economically weaker sections of the society. The total Livestock population is 535.78 million and total sheep population is 74.26 million in in the country showing an increase of 4.6% and 14.1%, respectively over Livestock Census-2012. And it’s ranking 3rd in the world after China and Australia. Rajasthan is the fourth largest sheep rearing state in India with 7.9 million population (Livestock Census, 2019). Malpura sheep is one amongst the heaviest sheep breed of India, widely distributed in the semi-arid region of Rajasthan, mostly Tonk, Jaipur and Sawai Madhopur districts. Malpura sheep is reared and improved for mutton production since year 1975 at CSWRI, Avikanagar. The objective since then has been to improve the growth characteristics of this sheep breed for producing more carcass yield.The sheep is known for its adaptability to the harsh environment and potential for high meat production.Coat colour of Malpura sheep is white with coarse wool. The face is light brown with short, blunt ears. Animals have square compact body and long legs. Farmers also have liking for the long tail of animals for aesthetic purpose. The farmers like Malpura sheep for its properties like good mothering ability and produce sufficient milk to sustain and accelerate the growth of their neonates (Mishra et al., 2005), higher weight gain, number of lambs weaned, wool quality, walking capacity and the ease of management.

As the ornamental fish industry expands throughout the world, genetic considerations have become more important in terms of production, sustainability and conservation. Genetic technologies are now being applied to increase food production in aquaculture through traditional and modern breeding programmes. Genetic markers can help to manage capture fisheries and distinguish farmed from wild stocks in mixed fisheries. Genetic technologies are also now finding application in post-harvest and trade to assist in product identification and traceability. Genetic improvement of fish has considerably increased the fish production from aquaculture. It includes selective breeding, hybridization, polyploidy, gene and nuclear engineering. For any genetic selection programme, induced breeding is the basic and initial step. Intensive selective breeding is practiced with various species of fish in perfecting appearance, shape and color so that new strains are produced.

Domestication

Most of the fish being widely grown in captivity are domesticated to some extent, but there are very few which have undergone genetic improvement. Just as terrestrial livestock and crops are bred to be not only productive, but productive in convenient proximity to humans, aquatic plants and animals are now undergoing these same pressures.

In comparison to agriculture crops, fruit plants and animals, aquaculture is much behind with regard to the domestication of the fish, especially ornamental fish. Never the less, a good number of ornamental fish have been domesticated which can be considered for selective breeding to improve their traits. The available technologies and tools could be used to remarkably speed up domestication and genetic improvement process.

Domestication implies much more than merely keeping wild animals in farms or homes. Domestication is a very long process, during which captive individuals become more adapted to captive environments. Domestication leads to permanent genetic modifications of a bred lin-eage, while taming or keeping wild fish in captive conditions is only conditioned behavioral modification of individuals. The entire life cycle of the domesticated fish species must be fully closed in captivity. Once full life cycle is completed in captivity, the process of domestication can proceed further.

The first truly domesticated fish species was certainly the goldfish, for which the domestication was initiated by the Chinese about 1500-2000 years ago.