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6. Germplasm Evaluation and Utilisation - T.A. Thomas and P.N. Mathur


Introduction
Components of germplasm evaluation
Some practical considerations
Information management of evaluation data
Recent concepts related to utilisation
NBPGR's coordinating role
Germplasm utilisation
Summary
References

Introduction

The role of germplasm in the improvement of cultivated plants has been well recognised. However, the use of germplasm collections, particularly in the developing countries, is still limited despite this wide recognition (Frankel and Hawkes, 1975; Hawkes, 1981; Holden and Williams, 1984; Gill, 1984). Until a collection has been properly evaluated and its attributes become known to breeders, it has little practical use. Germplasm evaluation, in the broad sense and in the context of genetic resources, is the description of the material in a collection. It covers the whole range of activities starting from the receipt of the new samples by the curator and growing these for seed increase, characterization and preliminary evaluation, and also for further or detailed evaluation and documentation.

The germplasm collection of any crop consists of diverse types of collections such as:

1. Those derived from centres of diversity
(a) Primitive cultivars,
(b) Natural hybrids between cultigen and wild relatives,
(c) Wild relatives (wild and weedy races), and
(d) Related species and genera.
2. Those derived from areas of cultivation
(a) Commercial types,
(b) Obsolete varieties,
(c) Primitive varieties, and
(d) Special purpose types.
3. Those derived from breeding programmes
(a) Pure line from farmer's stock,
(b) Elite varieties or hybrids,
(c) Breeding lines,
(d) Mutants,
(e) Polyploids, and
(f) Intergeneric and interspecific hybrids.
In view of the wide range of genetic variability in germplasm collections of cultivated plants ranging from wild and weedy types to high yielding varieties, all necessary care should be taken before making any strategy for their evaluation and characterization. Also, the breeding aims change rapidly. By and large, for effective evaluation of germplasm, a close organisational and personal contact between curator and breeder is necessary in the context of breeding objectives vis-a-vis evaluation programme.

Components of germplasm evaluation


Seed increase
Preparation of descriptor list
Types of characters and measurement data

After collection of germplasm, there is need for its systematic evaluation in order to know its various morphological, physiological and developmental characters including some special features, such as stress tolerance, pest and disease resistance, etc. The following steps and components of germplasm evaluation can be distinguished.

Seed increase

The first step is the seed increase. This needs care as it involves the risk of losing a particular accession due to poor adaptation, disease and pest damage, introducing admixtures through contamination or error and altering the genetic composition of the original genetic make up through conscious (human) or unconscious (natural) selection. Therefore, it is essential to increase seed stocks sufficiently in one cycle so that the harvested seeds can be used for evaluation, differentiation and storage. On receiving the samples, it is always wiser to save a portion of the seeds for another planting, in case the first effort fails, besides serving as a reference sample. It is also important that the site for multiplication should be as close as possible to that of its original collecting site to avoid the effect of natural selection. During initial seed increase, data on many morphological traits and other traits of interest are recorded. Duplicate accessions are also identified at this stage and promising ones are identified for intensive evaluation. The plant quarantine needs can be met during this stage as well.

Preparation of descriptor list


Passport data
Characterization
Preliminary evaluation
Further characterization and evaluation

The process of evaluation begins with the adoption of descriptor lists. Depending on the circumstances, it may be compiled by the national organisation, collection manager, developed by Crop Advisory Committee, or an existing list might be adopted. The IBPGR's descriptor lists are quite exhaustive and are, by and large, widely used by PGR scientists. These help in maintaining uniformity in data processing and management. Descriptors for 62 agri-horticulture crops have already been published by the IBPGR and many more are under preparation. Based on these descriptors, the data recorded for each accession fall into the following four sections:

Passport data

1. Passport data: Passport data includes all basic information recorded during the time of collecting samples or the information provided by the sender regarding source/origin, etc. Such information is very useful for all phases of genetic resources work. Site identification is perhaps the most significant evidence available to the curator for designating a 'core collection' and is of great help in identifying duplicates (Frankel, 1989). It is also essential information for eco-biological, evolutionary or population genetic research and for planning further collections. Records on topography or soil characteristics can be valuable for plant breeders too for improving adaptation to particular conditions or tolerance of edaphic or climatic stresses. The important passport descriptors are the site of collection (village/state/country); collector's number; type of material (population or pure line); date of collection; altitude, latitude and longitude for site of collection; status (wild, weedy, landrace, cultivar); growing conditions; and source (field, farm store, institute, etc.).

Characterization

2. Characterization: According to a recent IBPGR (1985) definition, it consists of recording those characters which are highly heritable, can be easily seen by the eye and are expressed in all environments. Characterization should provide a standardised record of readily assessable plant characters which, together with passport data, go a long way to identify an accession (Frankel, 1986). Characterization descriptors include spike/panicle shape, seed shape and colour, and other characters which are generally more of taxonomic type. Their recording along with the passport data provides an overall picture of the range of diversity in the collections, so badly required by the users.

Preliminary evaluation

3. Preliminary evaluation: Preliminary evaluation consist of recording a limited number of additional agronomic traits thought desirable by users of the particular crop. Characterization of physiological characters by curators can be of considerable help to the breeders through providing baseline data, such as vernalisation requirement, tillering, times of flowering and maturity, which would help to narrow the selection of potential breeding stocks.

Most important characterization and preliminary evaluation descriptors and descriptor states to be used are given below:

(a) Site data: Information on evaluation site (centre/institute, state, country), evaluator's name and evaluation date (month and year).

(b) Planting data: Propagation method (seed, cutting, grafts), habit, height, density of branches (sparse, dense), crown diameter, etc.

(c) Leaf characters: Type of leaf, petiole type, leaf size, leaflet type, etc.

(d) Floral characters: Arrangements of flowers, position of flowers, type of inflorescence, colour of flower bud, length of pedicel, length of bud, number of stamens, flower aroma, pollination, etc.

(e) Fruiting characters: Number of days from flowering to harvest, main harvest season, yield, etc.

(f) Fruit characters: Number of fruits/cluster, fruit length and width, protein (%), fat (%), shattering habit, seeds/fruit, etc.

(g) Seed characters: Seed size, hilum size and colour, 100-seed weight, etc.

Further characterization and evaluation

4. Further characterization and evaluation: Further characterization consists of recording potential agronomic characters which will determine the usefulness of an accession for a specific purpose in specific circumstances. Typically, these include stress tolerance, disease and pest resistance and quality characters. Evaluation for many of these traits is outside the ability of most curators. In the widest sense, the detailed evaluation of large collections requires multidisciplinary approach, specific testing conditions involving disciplines of cytogenetics and evolution, physiology, pathology, entomology, biochemistry and agronomy. They all contribute information that bears on the choice and utilisation of genetic resources by the breeders. Cytogenetic information is essential for the use of many wild relatives of crops. The genetics of host-parasite interaction is equally essential for the choice of resistant genotypes of any status.

Such systematic and detailed evaluation operations, though expensive and time consuming, are of great value. The principal goal in exploiting useful genes from germplasm collections vary greatly among crops and for different ecological zones within a crop. For example, stable resistance to races of rusts, semi-dwarfness, improved quality, tolerance to drought and cold, and wider adaptability in wheat; higher yield potential, wider adaptability, improved quality and multiple resistance to pests and diseases in rice; resistance to viruses, nematodes and bacterial diseases, wider adaptability and improved quality, in potato; tolerance to extreme temperatures, resistance to disease and pests and high TSS and better transportability in tomato, etc. In case of horticultural plants, selection of root stocks is also important and hence, root stock evaluation is necessary. Appropriate and most efficient root stock should be used while increasing the plants for characterization and evaluation.

Since evaluation needs may well change in response to change in agricultural practices, farm economics, breeding strategies and pest and disease races, it should be kept in mind that this aspect of detailed evaluation work should always be open-ended and need not be confined to characters on the descriptor list. In general, characterization and preliminary evaluation is done by the curator/germplasm scientists; further evaluation or detailed evaluation is mostly done by the breeders for taking additional information. However, no hard and fast rule prevails and the detailed evaluation can also be done by the curator in collaboration with breeders, pathologists, entomologists, agronomists and biochemists as per needs.

Types of characters and measurement data

The characters of concern to plant breeders can be broadly divided into two groups which are functionally and, to a large degree, genetically distinct. These are grouped into qualitative or observable and quantitative or non-observable characters (Frankel and Soulé, 1981).

1. Observable characters: These characters can be identified in single plants or their immediate progenies. They are expressed under growing conditions which are normal for the crop or they may require special conditions for expression such as a specific parasite or environmental stress. They are either simple or may be polygenic, in inheritance and can be easily selected in hybrid generations. Observable characters include morphological, physiological or biochemical characters relating to survival, productivity or quality and can be transferred from an exotic source to an adapted cultivar by repeated back crossing.

2. Non-observable characters: These characters are subject to environmental variation and are polygenic. They are largely responsible for adaptation and productivity. Evaluation for complex characters such as yield can be meaningfully evaluated only in the breeder's environment and the capacity to raise yields above current levels can be assessed either indirectly, by yield testing of accessions, or directly and more meaningfully by compatibility tests with locally adapted cultivars. However, such approach is only feasible on small collections.

There are four types of measurement data which cover the range of quantitative to qualitative characters (Dillon and Goldstein, 1984) and are presented in Table 1. Both interval and ratio scale depend upon real units or are derived from them. Ordinal data generally require the construction of a standard scale, frequently on a 0-9 basis, and definition in words and/or diagram of each component of the scale. For nominal scales, the score has no meaning as a number is either absolute or in relative terms, but it may be the most convenient way to represent the data.

Traits covered under characterization are generally qualitative, easy to score and, in theory, need only to be scored once. Handling and interpreting quantitative data presents greater problems since the absolute value obtained may depend greatly on the environment as it varies within and among trials. For this reason, a number of check lines need to be included as standards for comparison to determine: (i) as to what variation is there within a trial and what confidence can be placed on the scores, (ii) the variation among trials, and (iii) whether a scored value can be considered 'good' or 'bad' (Chapman, 1989). The choice of check lines will depend very much on circumstances. For preliminary evaluation, locally adapted cultivars familiar to breeders, provide understandable comparisons and a dependable way of monitoring trial-to-trial (often year-to-year) variation. For further evaluation, which usually addresses one trait at a time, there will often be a well recognised set of checks that cover the likely range of scores (e.g. known resistant and susceptible cultivars or accessions for disease work).

Table 1. Types of measurement data (W. R Dillon and M. Goldstein, 1984)

Scale

Basis of observation

Examples

Internal

Direct measurement of attribute

Height, days to flowering, tuber weight, number of flowers per plant

Ratio

Combination of two direct measures or inference from a single measurement

Harvest index and % of protein, oil or sugar

Ordinal

Assigning, sometimes subjectively, a related value from a standard scale

Susceptibility to pests and diseases, overall processing quality, leaf or seed shape

Nominal

Assignments of qualitative character states into arbitrary number and classes

Flower colour and seed patterns

Some practical considerations

There is no rigid rule about characterization/preliminary evaluation and further evaluation. The principles and procedures to be applied should be flexible, since the diverse group of crops have different problems. However, the following considerations should be taken into account during multiplication, characterization and evaluation.

1. Factors affecting seed multiplication: A pure line can be multiplied by growing only a few plants and the actual number will depend on the multiplication rate and the seed quantity required, whereas, a heterozygous population would need to be multiplied from a much larger population sample and much care should be taken to ensure the maintenance of genetic integrity.

2. Germplasm maintenance of cross-pollinated crops: A cross-pollinated population consists of a mixture of genotypes, no two of which are alike. Collectively, these genotypes form a population with a specific set of characteristics. Seeds from one or a few plants are unlikely to contain a representative sample of the genes of the population and, therefore, cannot reproduce its structure. Thus, seeds from many plants of a cross-pollinated species should be collected in order to sample adequately its genes and retain its population structure. Likewise, further multiplication of such accessions must involve many plants from seed of the original collections (Burton and Davies, 1984).

Further, collections of cross-pollinated crops, when planted for the first time after collection, fail to reveal most of their recessive alleles because they are suppressed by dominant alleles. Such accessions cannot be effectively screened for their recessive alleles until they are selfed. In general, genes for short stature and many of those for pest and disease resistance are recessive. The seed derived from the first selfed generation (S1) from an accession can be screened immediately for both dominant and recessive genes. For many crops, the production of S1 seed is less laborious than sibbing. Further, increasing an accession by selfing is also less likely to result in loss of alleles, and reduces exposure to genetic contamination compared to increasing it by sibbing.
3. Population size and genetic drift: After germplasm is collected from nature or from farmer's field and placed in a gene bank or regenerated, loss of genetic variation or change in the genetic structure of the collection may occur. One of the most important duties of curators is, therefore, to minimize such genetic changes. In order to do so, a sufficiently large effective population size must be preserved and, whenever the population is regenerated, a sufficiently large number of plants must be grown and enough pollinations should be made or facilitated to maintain large effective populations.
In small populations, allelic frequencies are subject to random fluctuations arising from the sampling of gametes. Therefore, small populations drift toward fixation of particular alleles - 'genetic drift'. This will lead in increasing the frequency of homozygotes at the expense of heterozygotes. Many of the deleterious alleles, which are otherwise masked in the heterozygotes, will become fixed and will ultimately be eliminated from the population. Although, the change of gene frequency resulting from sampling is random in the sense that its direction is unpredictable, its magnitude can be predicted in terms of variance of the change (Falconer, 1960). Since the fixation of alleles is a function of initial gene frequency, the size of the population and the number of generations of sexual reproduction are important factors in reducing genetic drift. Therefore, larger the population size, the slower will be the fixation of genes (Wright, 1952). The genetic drift towards fixation occurs at the same rate in small populations whether the mating system is outbreeding or predominantly selfing (Allard and Hansche, 1964). Therefore, it is suggested that, in order to minimize loss of heterozygosity, inbreeding depression and allele loss, a minimum effective population number of 50-70 plants is required to constitute a population. Nevertheless, population genetic theory and practical experience have shown that the changes do occur in allelic frequencies. Hence, practical compromises are necessary - the objective will be to choose options that cause minimum change.
4. Optimum environment for multiplication and evaluation: The strategy and tactics of growing genetic resources for multiplication, maintenance and evaluation have been widely discussed (Allard, 1970; Sevchuk, 1973; Erskine and Williams, 1980; Frankel and Soulé, 1981). According to them, the environmental conditions of the multiplication site(s) should be as near as possible to those under which the accession evolved or was cultivated for a long period. Since the distribution ranges of accessions of all major crops vary greatly, it is likely that two or more multiplication sites will be necessary to determine adaptability and site x genotype interaction. The advantage of choosing such a range lies in reducing the evaluation period, because the complete range of climatic factors may be encountered over a shorter period of time.
When the germplasm is grown across locations and over years, a knowledge of the nature and relative magnitude of various types of genotype-environment interaction is important in making decisions regarding ranking of accessions. Several investigators have highlighted the importance of these interactions as well as shown their use in setting up selection and testing regimes for applied breeding and genotype testing programmes (Comstock and Moll, 1963; Allard and Barawshaw, 1964; Knight, 1970; Paroda and Hayes, 1971; Brown et al., 1983).

However, the identification of testing sites which give results with wide applicability has not been given the attention it deserves. Knowledge of the correlation between the value of a genotype relative to a test environment and its value relative to the whole population of environments where it is to perform is necessary for such optimum sites to be identified.

5. Experimental design: Single row (3-5 m) plot or small plots of more than one row, depending upon the quantity of seeds available and the nature of plant species, are generally grown for germplasm evaluation. Enough space should be kept between rows and between plants to permit them to express their differences and avoid competition. Accessions belonging to the same maturity group should be planted together on one date of sowing. Accessions suspected to be duplicates should be grown side by side to facilitate comparison while evaluating in the field. During the process of growing, attention should be given to minimise natural cross pollination, contamination and erroneous labelling. Some of the basic requirements for field evaluation are field of rectangular shape, uniform fertility, dependable water supply, drainage facility, equipments for seed processing, and supply of agricultural chemicals and other materials such as bags, labels, stationery, etc.
When the germplasm collections are large, it is always preferable to grow and evaluate the germplasm in an augmented block design (Federer, 1956). The augmented block design provides a welcome flexibility to block design where not all treatments appear to warrant full replication. By reducing replication, representative size may be reduced. A major advantage of this design is that such treatments, no matter how discripant their values may be, do not contribute to the experimental error of the experiment.
6. Multiplication/rejuvenation of germplasm: The need for multiplication/rejuvenation of germplasm is a function of size of the initial sample, user demand and seed longevity under the condition of storage. As mentioned earlier, the aim during rejuvenation should be to retain the essential genetic characteristics of the accession and obtain sufficient quantities of high quality seed to satisfy requirements for storage and user demand. It is also necessary during the regeneration process to consider how best to reduce changes due to contamination through mutation, foreign pollen or seed, and to minimize genetic drift or shift by ensuring sufficient population size and reducing opportunities for natural selection. Mutation rates are too low to pose a serious problem. The main dangers are due to inappropriate seed handling during harvesting, threshing, cleaning, sub-sampling and packing. For the outbreeding populations, another important factor is to maintain proper isolation distance. Maintaining proper isolation distance becomes difficult when a large number of accessions have to be multiplied simultaneously and, under such conditions, controlled hand pollination is the only correct approach. However, in any case, regeneration cannot avoid natural selection which, in turn, leads to genetic shift. It is therefore, advisable that regeneration should be carried out as infrequently as possible. In the recent years, better storage conditions of the germplasm have greatly extended the storage life of seeds, thus reducing the need for frequent rejuvenation.

Information management of evaluation data

Both evaluation and documentation are seen as pre-requisites for the utilisation of germplasm collections. The passport and characterization data should be readily available to the users in order to select the desired germplasm. Hence, information and management, and manipulation of information are essential parts of all practical work with plant genetic resources. Such information includes most or all of the following tasks (Mc Millan and Salhuana, 1983):

1. To determine what primary information is required and how it is to be recorded.

2. To assemble the primary information.

3. To provide convenient means by which the primary information can be stored and retrieved.

4. To determine what derived or secondary information is required.

5. To provide convenient means by which the secondary information can be obtained, stored and retrieved.

6. To obtain the secondary information by using these means.

7. To communicate the primary and secondary information to users.

These seven points are a formal way of analysing the system and must be recognised as such in establishing the documentation system. Such information can be assembled, recorded, manipulated and retrieved in a variety of forms. The use of (personal) computers in modern genebank documentation greatly facilitates sorting, retrieval, analysis, collation, etc. of data which are indispensable to the potential users of germplasm collection.

Recent concepts related to utilisation


Concept of core collection
Concept of pre-breeding

Concept of core collection

The principal idea behind the concept of the 'core collections' was described by Frankel and Brown (1984). Given the need for economic size, it was argued that a collection could be pruned to what was termed a 'core collection', which would represent with a minimum of repetitiveness, the genetic diversity of a crop species and its relatives. The accessions not included in the core would be retained as the 'reserve collections'. The main purpose of the core fraction is to provide efficient access to the whole collection which should be representative of the diversity at hand. The accessions in a core collection should not be selected on the basis of percentage of the entire collection, but should be selected with the following objectives:

1. To have a manageable collection scaled down to the needs of the breeder and/or other users; and
2. To include the widest possible range of variability.
Three different groups of arguments support the concept of a core collection (Brown, 1989). The first includes statistical sampling considerations which essentially stem from the assumption that breeders, through crossing and selection, can recover desirable alleles when required. Hence, in principle, they need access to only one copy of such alleles. The second covers those reasons relating to the genetic structure of plant populations, in general, and germplasm collections in particular. The third has to do with making easier the management of germplasm collection.

To encourage greater use of a germplasm collection by breeders, it is suggested that a core collection needs to be designated by the curator. This core would represent the genetic diversity in the collection and its selection does require quality passport and characterization data. For older collections of accessions which are lacking comprehensive passport data, the selection of a core would have to rely on pedigree and characterization data.

Concept of pre-breeding

'Pre-breeding" is the early phase of any breeding programme utilising germplasm. Many improvement programmes concerned with the utilisation of plant germplasm include the process of pre-breeding, also called developmental breeding or germplasm enhancement, as part of the total project. Though the end products of pre-breeding are usually deficient in certain desirable characters, they are attractive to plant breeders due to their greater potential for direct utilisation in a breeding programme than the original unadapted exotic sources. There are several sources of germplasm with pest resistance and/or tolerance to environmental stresses that could be incorporated into the cultivars through a comprehensive germplasm enhancement programme.

NBPGR's coordinating role

One of the main objectives of the NBPGR is to evaluate and characterize the available germplasm and to coordinate such activities with other crop based institutes, coordinated projects, agricultural universities and international institutes, and to help in preparing inventories and catalogues on available genetic resources. The work on germplasm evaluation and characterization is being carried out at the Bureau's Headquarters and its Regional Stations (located in different eco/agro-climatic zones) for more than 75 major and minor crops. Crop curators for all major crops have been identified within NBPGR and also in the ICAR crop based institutes and state agricultural universities (see Chapter 14).

Preliminary evaluation and seed increase is done by the crop curators by growing one or two rows of the germplasm (as per seed availability) in an augmented design using 2-3 locally adapted checks for a period of minimum two years. The germplasm is being evaluated based on IBPGR descriptors list, if available, or such lists are prepared by NBPGR. Based on the evaluated data, over the years, several crop catalogues/inventories, viz. on wheat, barley, maize, amaranth, tomato, cluster bean, French bean, winged bean, cowpea, field bean, moth bean, soybean, lentil, Sesbania, Trigonella, opimum poppy, safflower, sunflower, sesame, oat, okra, etc. have been prepared (Paroda and Arora, 1985). These crop catalogues are distributed to concerned plant breeders for identifying the useful germplasm for utilisation in their breeding programmes. The NBPGR also holds field days, whenever a sizable germplasm of a particular crop is being grown either at the Headquarters or at its Regional Stations to which breeders, crop coordinators and other concerned scientists handling germplasm are invited. During field visits, they select the promising germplasm for use in their on-going breeding programmes. The Bureau also screens the germplasm against various pests and diseases and for some important quality characters.

In recent years, much emphasis is placed on multilocational evaluation of germplasm and the NBPGR is playing a leading role in this work in India. Several thousand germplasm accessions of the five mandate crops of ICRISAT, i.e., sorghum, pearl millet, chickpea, pigeonpea and groundnut are being jointly evaluated by the NBPGR and the Genetic Resources Unit, ICRISAT at different locations since 1986. This will enhance the identification and further utilisation of new and useful germplasm accessions.

Germplasm utilisation


Cereals and millets
Pulses
Vegetables
Fruits
Plantation crops
Fibre crops
Medicinal plants
Oilseeds
Forage crops

The plant breeder is the principal user of germplasm collections and, therefore, it is pertinent to consider the kind of information that the breeder will want about each accession. Though, the potential of a germplasm sample is largely unknown at the time of its collection, it has been observed that a number of desirable characters are identified whenever a diverse group of germplasm samples are evaluated and screened. The breeder is only interested in a small fraction of the entire collection for its immediate objectives. His working collections will consist of superior genotypes for yield and yield components and for resistance to diseases, pests and stress conditions and also for some of the important quality components.

The current trends in the utilisation of germplasm of some major crops in India are briefly discussed below (for details refer Paroda et al., 1988). Achievements in crop sciences, referring to crop improvement have been covered separately in Chapter 7.

Cereals and millets

Rice

Collection and evaluation of local rice varieties in India was initiated in the first quarter of this century. During 1911 to 1956, about 400 cultivars were released through pure line selection of the traditional cultivars. These improved local types were virtually the cream of the traditional rice germplasm of India and made 10 to 20 percent increase in yield over the traditional types under local agronomic practices and ecological conditions. They have continued to play a significant role in the varietal improvement of rice even to the present day by providing a well adapted genetic background for incorporating other desirable characters (Sharma et al., 1988). Many of these cultivars were adapted to and selected for upland and/or drought conditions (N 22, Lal Nakanda 41, Jhona 349, MTU 17, CO 31, PTB 28), deep water and/or flood conditions (HBJ 1, HBJ 2, HBJ 3, HBJ 4, AR 1, EB 1, EB 2, FR 13A, BR 15, BR 41, BR 46) and saline soils (Kumargone, Patnal 23, Getu, Damodar, SR 26B).

Scientists in India also had extensive testing of indigenous germplasm to pests and diseases and the breeders have made effective use of the indigenous genepool which provides resistance to pests or tolerance to eco-edaphic stresses. The drought-resistant N 22 was used in breeding Bala. TKM 6, which has multiple resistance to insects and diseases, became a parent of Ratna, Saket 4, Parijat, CR 44-1 and other improved varieties. The gallmidge-resistant Es-warkorra was used to breed W 1251, W 1256, and W 1263; the latter lines were widely used inside India as well as in Sri Lanka and Thailand (Chang, 1982). The Tungro virus-resistant PTB 10 has been bred into improved varieties such as Aswini, Bharathi, Jyothi, Rohini, Sabari and Triveni. Similarly, PTB 18, possessing multiple resistance has been widely used in India (Anon. 1980) and at IRRI (Khush, 1977; 1980).

Some of the promising introductions which have been utilised in the breeding programmes include Taichung Native 1, IR 8, Mahsuri, Leb Mue Nahng and China 1039. Taichung Native 1 and IR 8 were the principal source of semi-dwarfism during the mid-1960s. Mahsuri of Malaysia and Leb Mue Nahng of Thailand were used to develop photoperiod-sensitive varieties. Rajendra Dhan 20 and Pusa 4-1-11 derived their disease resistance from Tadukan of Philippines (Chaudhary, 1979). Chinese indicas were also introduced for the temperate hilly regions. CH 2, CH 45, CH 47, CH 972, CH 988, CH 1007 and CH 1039 performed very well and are still popular in the Western Himalayan regions. Some of the japonicas performed well in the Himalayan regions and one of them Norin 18 was released for general cultivation in Himachal Pradesh. Later ponlai types were introduced into India and some of them (Tainan 3, Kaohsiung 22, Taichung 65) have been released with or without further selection.

Indian rice germplasm has also provided resistance source to many improved cultivars developed at IRRI, viz. Pankhari-203 for tungro virus; many accessions from the Assam rice collection and TKM-6 and BJ-1 to bacterial leaf blight; Oryza nivara germplasm for grassy stunt virus resistance; Assam rice collection for sheath blight; TKM-6, CO-13, Patna-6 and PTB-10 for stem borer; and PTB-18 and PTB-21 for gall midge.

Wheat

The importance of introducing exotic germplasm was realised fairly early in the Indian wheat improvement programmes. Some of this material subsequently proved useful as direct introduction such as of Ridley, Padova I and Padova II, while other introductions provided sources of disease resistance. From mid-sixties onwards, there has been a mass scale introduction of improved germplasm, carrying the Norm-dwarfing genes from international organisations (mainly CIMMYT, ICARDA and USDA), procured through the NBPGR. In the National Genetic Stock Nursery (NGSN), nearly 8000 stocks are estimated to have been evaluated for multiple features since 1965 and a large number of confirmed sources of resistance to the three rusts (black, brown and yellow), loose smut, powdery mildew, Alternaria leaf blight, Helminthosporium leaf spot; and sources for high protein content, gluten strength, maturity period and grain appearance have been identified (Tandon and Mathur, 1988).

The systematic screening of indigenous wheat germplasm was also initiated at Punjab Agricultural University, Ludhiana for various diseases, and a number of resistant types have been identified to one or more diseases. IC 35119 and IC 35127 from Karnataka in Triticum durum; IC 36706 and IC 36729 from Himachal Pradesh, and IC 47490 from Karnataka in T. aestivum; and IC 47453 from Karnataka in T. dicoccum, showed high level of resistance to rust diseases under epiphytotic conditions. IC 28594, a durum collection from Gujarat, observed to be highly resistant to brown and yellow rusts, also showed resistance to loose smut and powdery mildew. Wheat germplasm was also screened for salinity tolerance at the Central Soil Salinity Research Institute, Karnal, and some promising germplasm were identified with tolerance to saline/alkaline soils, such as IC 26727, IC 26729, IC 26734, IC 26740, IC 28609, IC 28674, Kharchia 65, KRL 2-22, KRL-4-1, KRL 4-2, KRL 4-3, K-7435, HD 2177, BHP 10, BHP-31, CSW 538, CSW 540 and Rata wheat.

Barley

The utilisation of genetic variability in barley breeding programmes has so far resulted in the development of about 104 improved varieties for cultivation under different agro-climatic conditions (Gulati and Verma, 1988). Of these, 26 percent of the total varieties were developed through indigenous x indigenous crosses, 43 percent are from indigenous x exotic crosses, and 1 percent from exotic x exotic crosses. The other 19 varieties were developed as introductions, pure line selection and induced mutations. More than 8000 collections are being maintained and evaluated by the All India Coordinated Barley Improvement Project, Karnal; IARI, New Delhi; NBPGR, New Delhi; HAU, Hisar; CSAUA and T, Kanpur; and Sukhadia University Regional Station, Durgapura. In recent years, much material has been received by NBPGR in the form of International Nurseries from ICARDA, CIMMYT and other sources for use of breeders.

LSB-2 (USA 94), Dolma (USA 115), both hull-less, and HBL-87 (hulled) are primary introductions made at Bajaura for cultivation in northern hills. Clipper, a two-rowed hulled variety was introduced in India from Australia during the seventies for its good malting and brewing qualities. The other promising genetic stocks identified include Ab-14, BHS 4-7-1, Bigo, C 164, DL 36, DL 70, DL 80, DL 144, DL 145, EB 145, EB 410, EB 438, EB 1368, EB 1556, EB 1626, EB 1880, EB 7948, HBL 161, HBC 171, Kailash and P 267 for resistance to yellow rust; EB 581, EB 582, EB 873, EB 928, K 12, K 24 and Odessa for loose smut resistance; Algerian, Black Russian, EB 2507, Fartodi, Goldfoil, Herry, and Ricardo for resistance to powdery mildew; DW 472, DL 70, DL 85, DL 165, EB 1366, EB 1988, Haran 16, Mex 5-13, P 103, Promesa, RDB 1, RD 103, Toluca and WPG 6213-528 for lodging resistance; and Amber, BL 2, C 251, DL 3, DL 88, DL 120, DL 157, K 24, K 122, K 127, K 141, K 276, K 289 and Ratna for resistance to saline/alkaline conditions. DL 443, DL 362, EB 1051, EB 1053, IB 65, Karan 3, Karan 4, Karan 18, Karan 19, LSB 2, KN 26, KN 27, CN 292, CN 294, Puskin, Kiari and Amber have contributed towards hull-less grains (Gulati and Verma, 1988).

Maize

The efforts during the early period were concentrated on the exploitation of indigenous germplasm to identify improved populations and to develop inbred lines. An improved local 'KT-41' was developed in Uttar Pradesh. In 1956, 'Punjab Hybrid No. 1', the first hybrid in India was released for general cultivation in Punjab. All the four parents of 'Punjab Hybrid No. 1' were from indigenous open - pollinated varieties. However, this hybrid was put into limited commercial cultivation, because the increased yields were not as high as those obtained in USA and other countries. Later, a number of hybrids from USA, Canada and Australia were introduced and evaluated at 17 different centres. Hybrids such as Texas 26, NC 27, and Dixie 18 gave high yields.

Through intensive research work on varietal improvement in 50's, from indigenous materials, a number of double-cross and three-way hybrids were developed. However, it was evident that the local varieties did not have enough genetic diversity to provide high-yielding hybrids. Maize hybrids involving Indian x exotic (or flint x dent) materials generally yielded better than Indian x Indian (flint x flint) materials and had acceptable semiflint grain type. Through the systematic mobilisation of elite Indian materials and germplasm introduced from Central and South America and the USA, with the help of Rockefeller Foundation, four high yielding double-cross hybrids were identified in 1961. The parental lines of these hybrids were vigorous and possessed a good level of resistance to diseases and insect pests of major economic importance. Later, a number of additional hybrids were developed and recommended for commercial cultivation in various parts of the country. These include: Ganga 1, Ganga 101, Ranjit, Deccan, Ganga Safed 2, Ganga 3, Ganga 4, Ganga 5, Ganga 7, Ganga 9, Him. 123, Hi-Starch, Him. 128, VL 54, VL 42, Deccan 101, Deccan 103 and Sangam.

In early 1960s, work was also initiated to develop broad-based composites from which more productive and better combining inbred lines could be extracted for the synthesis of more productive hybrids. Six composites (Vijay, Kisan, Amber, Sona, Jawahar, and Vikram) were released in 1967. Three Opaque-2 composites (Shakti, Rattan and Protina) were released in 1971 and two early-maturing composites were released in 1982. The bulk of the Indian maize germplasm, however, has been assigned to three of the six lineages (Palomero Toloqueno, Confite Morocho and Kculli). Beginning in 1973-1974, CIMMYT formed a number of genepools and populations that are used throughout the tropics and sub-tropics by the maize breeders in the national programmes. Races of maize in India have been described by Singh (1977).

Sorghum

The first major attempt to assemble a world collection of sorghum was made in the 1960s by the Rockefeller Foundation in the Indian Agricultural Research Programme (Murty et al., 1967; House, 1985) and a total of 16,138 accessions were assembled from different countries, of which 8,691 accessions were transferred to ICRISAT in 1974. At present, ICRISAT is the major repository for Sorghum germplasm with a total collection of 28,072 accessions (Prasada Rao and Mengesha, 1988).

Since the establishment of the All India Coordinated Sorghum Improvement Project (AICSIP) in 1969, nearly 500 hybrids and 1000 varieties from various breeding programmes were tested and 45 cultivars released (Vidyabhushanam et al., 1989). The major germplasm sources utilised so far in varietal improvement include temperate lines from USA, Zerazera line's from Ethiopia and Sudan, and some lines of Indian origin. The male-sterile gene sources were mainly CK 60, 172, 2219, 3675, 3667 and 2947. For the development of restorer parents and varieties, the basic germplasm sources used were IS 84, IS 3691, IS 3687, IS 3922, IS 3924, IS 3541, IS 6928, ET 2039, Safra, E-12-5, E-35-1, E-36-1, IS 1055, IS 1122, IS 1082, IS 517, IS 19652, Karpar 1593, IS 10927, IS 12645, IS 12622, IS 19652, IS 18961, GPR 168 and IS 1151.

Among the insect pests, the most exhaustive screening was carried out for shoot fly and stem borer. The resistant sources identified are predominantly of Indian origin (IS 1082, IS 2205, IS 5604, IS 5470, IS 5480), while a few are from Ethiopia (IS 18551), Nigeria (IS 18577, IS 18554), Sudan (IS 2312), and USA (IS 2122, IS 2134 and IS 2146). Extensive screening of germplasm was also carried out for midge, and many resistant sources, such as DJ 6514 (IS 18700), IS 18961, S-GIRL-MR-1 (IS 18699), TAM 2566 (IS 18697), IS 3443, IS 12573 C and AF 28 (IS 18698) were identified. The multiple disease resistance lines were identified based on multi-locational evaluation over the years by AICSIP. These include ICSV 1, 120, 138, 2058, IS 18758 and SPV 387 for anthracnose and rust; IS 3547 for grain moulds, downey mildew, anthracnose and rust; IS 14332 for grain moulds, downey mildew and rust; IS 17141 for grain moulds and anthracnose; IS 2333, and IS 14387 for grain moulds and downey mildew; and IS 3413, IS 14390 and IS 21454 for grain moulds and rust. These lines are currently being used in breeding programmes.

The high-lysine sorghum lines IS 11167 and IS 11758 from Ethiopia are being used in the breeding programme. Several sweet-stalked sorghum lines were also identified, which can be very useful in developing quality fodder varieties of forage sorghum. Notable among these are: IS 20963, 15428, 3572, 2266, 9890, 9639, 14790, 21100, 8157, and 15448.

Looking to the need for forage sorghum genotypes, NBPGR started a collaborating project with Genetic Resources Unit of ICRISAT. In the past 5 years, NBPGR has evaluated more than 9000 germplasm from the World Sorghum Collection at ICRISAT for various fodder yield components. From this multi-locational evaluation, around 500 accessions have been identified as consistently superior at all locations. These will be further tested for use in forage breeding programmes. Interestingly, many of these lines came originally from India, Yemen Arab Republic and Chad, where sorghum is grown as a dual purpose crop.

Pearl millet

Before the establishment of the All India Coordinated Millets Improvement Project (AICMIP) in 1965, mass selection led to the development of several varieties (Co 2, Co 3, AKP 1, AKP 2, RSJ, RSK, N-28-15-1) from Indian landraces, and Co 1 and S 530 from African landraces. Pearl millet germplasm assembled at IARI, New Delhi, during the 1960s led to the development of Improved Ghana and Pusa Moti by mass selection. The pearl millet hybrid era in India started in 1962 with the introduction of the male-sterile line Tift 23A from Tifton, Georgia, USA. Five hybrids (HB 1, HB 2, HB 3, HB 4 and HB 5), based on this line, were released during 1965-69 and three hybrids (BJ 104, BK 560 and CJ 104) in 1977. During 1981-84, another 10 hybrids were released, of which only 3 were of any significance (MBH 118, GHB 27 and GHB 32). Following the breakdown of 5141 A and J 104 to downey mildew, four hybrids (ICMH 451, ICMH 501, MH 182, HHB 30) were released in 1986 and three others (ICMH 423, MH 169, HHB 50) in 1987. Of these, only ICMH 451 has been cultivated widely.

Indian landraces provide excellent sources of early maturity, better tillering and shorter height. In contrast, African sources, particularly those from the West African region, provide excellent sources of large head volume and seed size, higher degrees of resistance to diseases and better seed quality. The increasing use of the African germplasm at ICRISAT and in almost all Indian National Programmes, has substantially contributed to the diversification of the genetic base of breeding programmes (Harinarayana et al., 1988; Harinarayana and Rai, 1989). Development of effective field screening techniques at ICRISAT had led to the identification of excellent sources of resistance in the germplasm and breeding lines, originating mostly from West Africa.

In the recent years, systematic efforts were made by both ICRISAT and NBPGR to evolve and accelerate germplasm collection, multi-locational evaluation at some selected locations representing different agro-climatic conditions and cataloguing of genetic resources. 8,460 accessions of pearl millet have been evaluated from 1986 to 1989 at NBPGR Headquarters, New Delhi; NBPGR Regional Station, Jodhpur and AICMIP, Pune for a set of 14 descriptors, and these include promising fodder types (267 accessions), grain types (156 accessions), dual purpose types (53 accessions), early maturing types (54 accessions), and bold seed types (20 accessions).

Pulses

The important pulse crops grown in India are chickpea (Cicer arietinum), pigeonpea (Cajanus cajan), mung bean (Vigna radiata), urid bean (Vigna mungo), lentil (Lens culinaris), field peas (Pisum sativum), cowpea (Vigna unguiculata), moth been (Vigna aconitifolia), horse gram (Macrotyloma uniflorum) and French bean/rajmash (Phaseolus vulgaris).

Chickpea

Varietal development in India was initiated in 1920s and most of the variability in the initial stages was limited to the collection and evaluation of landraces. Single plant selection of landraces or hybridization to a limited extent were made. This resulted in the identification of several improved varieties like NP 17, NP 25, NP 28 and NP 58 from IARI, New Delhi; Pb-1 (Kabuli), Pb-7, S-26 and G-24 from Punjab; T-1, T-2, T-3, K-4 (Kabuli) and K 5 from Uttar Pradesh; RS 10 from Rajasthan; Dohad yellow from Gujarat; Adt. T.V. No. 10, EB 28, A-1-8, D-8, Gwalior-2 and Ujjain-2 from Madhya Pradesh; Chaffa, Gulab, No. 10, N-29, N 30 and N 31 from Maharashtra; Kadale 2 and Kadale 3 from Karnataka; and Sel. 75 and Sel. 98 from West Bengal. This was followed in the mid-60's by more promising varieties e.g. C 235, G 130, C 214, G 543, L 550 (Kabuli), H 208, H 335, L 144 (Kabuli), Gaurar, Radhey, K 850, Pant G 114, Avrodhi, RS 11, GNG 146, JG 62, JG 74, JG 221, JG 315, BDN 9-3, Phule G5, Annegeri-1, B 100, B 115, Pusa 209, Pusa 212, Pusa 240, Pusa 244, Pusa 256, Pusa 261, Pusa 408, Pusa 415, Pusa 417, ICCC4 and ICCC 33 (Kabuli). Out of these varieties, Pusa 212, Avrodhi and JG 315 (all desi types) showed high degree of wilt resistance, and C 235, G 543, GNG 146, Gaurav and Pusa 261 are blight resistant varieties.

Pigeonpea

Improvement work in pigeonpea was started in the beginning of this century, and several high yielding varieties were evolved. Some of the important varieties developed from various states are: RG 72, RG 97, RG 434, RG 476 and RG 56 from Andhra Pradesh; Vijaypur-49 from Gujarat; No.-148, Cross-86 and Gwalior-3 from Madhya Pradesh; C-11, T-8, K-132 and Tur. Hyderabad from Maharashtra; C-21, Thogar 115-016, T-136.1 and T-S-24 from Karnataka; B-7 from West Bengal; and T-17, T-105, T-1, T-21 and T-7 from Uttar Pradesh. After the intiation of AICPIP in 1965, the entire germplasm was classified for different maturity groups, and extra-early (120-140 days) and high yielding varieties were developed from these different maturity groups. Some of the recent improved varieties are: Pusa Ageti, T-21, Sharda, Mukta, HPA-1, UPAS-120, Pusa-84, AL-15, Prabhat, H77-216, BS-1 Pant-A3, Gwalior-3, BDN-1, Pusa-74, Tur. 15-15 and CO-2.

Recently, the responsibility for maintenance and evaluation of germplasm has been assigned to two stations, i.e., Kanpur in the north and Coimbatore in the south. ICRISAT has also taken up a programme for exhaustive collection, evaluation, utilisation and maintenance in collaboration with NBPGR. At present, there are about 11,034 accessions in ICRISAT genebank, of which 9084 are of Indian origin.

Lentil

Varietal improvement in India was initiated by collecting mixed market samples all over the country in 1924. Single plant selections were picked up from the bulk populations and 66 types (T 1 to T 66) were isolated. Similarly, state departments of agriculture also isolated promising genotypes from the bulk populations. Some of the old selections like NP-11, NP 47, T 36, T-8, L-9-12, BR-25 and B-77 proved promising and are still popular. With the initiation of AICPIP, the breeding work on lentil was intensified. As a result, a number of varieties suitable for cultivation in different agro-climatic regions of the country and for further use in breeding programme have been identified, such as L-9-12, T-36, Pant-209, Pant 406, TT-2, Pusa-4, and Pusa-6 for north-western zone; Pusa-1, L-9-12, BR-75, B-77, Pant-209, Pant-406, Pusa-4 and Pusa-6 for north-eastern zone; and T-36, L-9-12, Pant-209, Pant-406, PL-8 and Bombay-18 for central and peninsular zone.

Mung bean

The earliest efforts to collect land races from all over India and Burma in mung bean were made in 1925. Pure lines from these stocks were isolated and 40 different types were established at IARI, New Delhi on the basis of colour of stem, foliage, flower, unripe and ripe pods, seed colour and texture and other morphological features. Simultaneously, efforts were made in other states of the country to collect the available local landraces. The types selected were best suited in their respective regions mostly under a low level of management. The varieties that were developed in different states are: Kopergaon, Jalgaon 781, Krishna-11, Gwalior-3, Ujjain-16, Khargaon-1, Jawahar-45, T-1, T-2, T-44, T-51, COH-1, 367/2, 367/4, ADT-1, CO-2, KM-1, R288-8, D-66-26, RS-4, Kanke Multipurpose, NP-23, BR-2, B-1, B-105, T-10, Mung-54, Mung-305, Shinning mung-1, D-45-6, Gujarat-1 and Gujarat-2. The new varieties developed through utilising wide genetic base are Pusa Baishakhi, S-8, PS-16, PS-10, PS-7, G-65, ML-73, K-851, Pusa 101, Pusa 105, PIMS-1, PIMS-2, PIMS-3 and PIMS-4. These varieties have high harvest indices (22-35 percent) than older varieties (10-20 percent) and also find an important place in multiple and intercropping patterns.

Black gram

Early work started at Pusa in 1925, when local cultivars were collected from various states in India. These collections resulted in identification of 25 superior types. In early 40s to mid 50s, work by ICAR was taken up on collection, study and selection from locally adapted landraces. Several varieties were developed, namely, B.G-369 (Andhra Pradesh) ADT-1 (Madras), Mash 48, SL-1 and S 8-2 (Punjab), Khargaon 3 (Madhya Pradesh), T-9, T-27, and T-77 (Uttar Pradesh) and Sindkheda 1-1 (Maharashtra). Realising that the genetic base must be widened, a more extensive genetic stock collection effort was initiated in the mid-60's under AICPIP. Presently, around 1300 collections are being maintained at NBPGR, New Delhi and Directorate of Pulses, Kanpur. Some of the new improved varieties developed are: UPU-1, UPU-2, UPU-3, LU-211, LU-237, LU-220, UG-117, UG-135, UG-152, UG-157, Rewa-11, B-76, CO-1, CO-2, CO-3, CO-4, KM-1, KM-2, ADT-2 and TMU-1.

Moth bean

The landraces have been collected from almost all parts of the moth growing areas during 1932-33. From these collections, single plant/progenies were selected, which showed superiority over the original bulk, and released as improved varieties. The varieties so far identified are Type-3 from Punjab; B 18-54, B-15-54 and Jadia from Rajasthan; Nadiad 8-3-2, Jugudan 9-2, Yawal 12-1 and Dhulia 3-5-6-2 from Maharashtra; types 4301-12, 4312 and 4313 from Uttar Pradesh; and Baleshwar-12 and G-1 from Gujarat.

Horse gram

Some of the improved varieties developed through single plant selection from the bulk collected include CO-1, No-35, 5-122, and 123 from Madras; Sel. 33, Sel. 34, Sel. 36 and Sel. 42 from Hyderabad; and black kulthi from Mysore. Some more promising varieties/selections developed in the last decade or so are 8-1-1-8, Belgaum 1-8-3, Bizapur 1-6-5, Hyderabad A-3-2-3; and Hebbal Hurali 1 and 2. Out of these, Hebbal Hurali 1 and 2 were developed by selections made from lines PLKU-32 and EC-1460, from the material supplied by NBPGR, New Delhi.

Rice bean

Germplasm collection was initiated by NBPGR, New Delhi during 1960s, particularly from the north-eastern region. Both indigenous and exotic collections (530) were grown and evaluated during 1970s at NBPGR (Chandel et al, 1988). The study indicated a wide range of genetic variation for a set of morpho-agronomic attributes and a good number of strains/accessions were identified. The most promising genotypes identified in the indigenous collections were IC-17656, IC-16706, IC-16710, IC-16751, IC-16771, IC-16772 and IC-14667 from north-eastern and peninsular region. Promising exotic introductions were from PNG, Indonesia and other material received from USDA. NBPGR also bred an early maturing ricebean, C x M P12-1, utilising an introduction from China and an indigenous collection from Mysore.

Vegetables

Indigenous variability was utilised in breeding innumerable varieties including Pusa Red (from Patna Red) and N 53 (from Nasik Red) in onion; Pusa Purple Long (Selection from Betia) and Pusa Purple Cluster in brinjal; Pusa Sawani (Pusa Makhmali x Bengal collection) in okra; Hara Madhu (from Kutona and Arka tech. Lucknow Safeda) in musk melon; Pusa Deepali (from Punjab collection) in cauliflower; Pusa Summer, Prolific Long and Round (local selections) in bottle gourd; Pusa Do-Mausmi in bitter gourd; Pusa Nasdar (from M.P. collection) in ridge gourd, Pusa Chikni (from Bihar collection) in sponge gourd; Pusa Jwala (using Puri Red), Pant C-1 (using perennial type), Andhra Jyoti (G-5) and Bhagyalakshmi (G-4) in chillies.

In vegetable crops, there are several examples where the primary introductions have been directly utilised in crop improvement programmes, and some introductions were successfully utilised in breeding programmes in developing new varieties. These details have been given in Chapter 4. Thomas et al. (1983) have recently reviewed the utilisation of genetic resources for vegetable crop improvement in India.

Fruits

Most of the present day commercial cultivars are selections from the variability generated by the germplasm collected/introduced in the past. The IIHR, Bangalore and the All India Coordinated Fruit Projects - on tropical/sub-tropical, arid zone and temperate fruits, have made valuable contributions.

Some of the notable introductions are given in Chapter 4. The use of indigenous variability is more pertinent here. Some of the promising collections have been identified in mango (regular bearing Paushia scented Haldibas, bunch bearing-Seetabhog, flavoured Topisundari Baunia, Karpurkeli, Theki, Chanamunda, Mahorajpas - and, Manda Sagarlangra); in banana (seeded Ladigrit and Ladison, Rigitechi and other elite types, Hatigola, Eboke, Ginde, Egitchi and Essing); in Citrus (Mimangnarang, Chinora, Sohkwit, Sohsyng etc.); in jackfruit (Varikka, Kooza and Nerarikka-Pozem-Varikka), besides the incorporation of attractive pulp colour to the local varieties from the introduced cultivar Beaument from Hawaii.

Most important arid zone fruits are ber or jujube, datepalm, pomegranate, aonla or Indian gooseberry, fig arid custard apple. The project on the Arid Zone Fruits (Pareek, 1988), holds much indigenous and exotic diversity/cultivars in Zizyphus species, ber/Z. mauritiana, pomegranate, fig, Annona species and hybrids, custard apple, Indian gooseberry/Emblica officinalis, bael/Aegle marmelos, datepalm, jamun/Syzygium cumini and phalsa/Grewia asiatica. Over 500 collections are maintained and evaluated for utilisation at different stations. Some of the promising germplasm identified includes: in pomegranate - Ganesh, Bassein Seedless, Jalor seedless, Muskat, Jodhpur Red etc., in date-palm - Halawy Barhae (for raw eating), Gola, Mundia-murera, Umran, Medjool, Khadrawy and Shamran (for dry dates) and Zahidi (for soft date) and in aonla - Krishna, Kanchan, Pratapgarh and Anand selections and several others.

Plantation crops

Efforts to collect and conserve genetic resources in coconut were initiated in early part of this century. The first exotic introductions from Cochin China (Indo-China), Papua New Guinea, Java, Thailand, Malaysia, Philippines and Fiji were made in 1924 and planted at Coconut Research Station, Nileswar, Kerala (currently under the Kerala Agricultural University). These collections form the nucleus population for many of the crop improvement programmes (Bavappa and Bhaskara Rao, 1988). In arecanut, the germplasm collections date back to the late 1950s. In cashew, the oldest collections are being maintained at Kottarakara (Kerala), Ullal (Karnataka) and Bapatla (Andhra Pradesh). Cacao and oil palm are recent introductions into India. Cacao germplasm was introduced at Vittal in 1964 as a mixed crop with arecanut. Few dura palms of African origin introduced in 1949 are probably the first introductions in oil palm.

The major germplasm holdings in coconut, arecanut, oil palm, cashew and cacao are being maintained at Central Plantation Crops Research Institute (CPCRI), Kasaragod. In coconut, VLT-3 (introduced from China), VLT-17 (introduced from Singapore) and VLT-11 (introduced from Indonesia) were identified as superior genotypes and were released under the name Mangala; Sreemangala, and Sumangala, respectively. In cashew, based on the superior performance, four germplasm selections from Andhra Pradesh (BPP-3 to BPP-6), one from Kerala (BLA 139-1), two from Maharashtra (V-1 and V-2), two from Karnataka (Ullal-1 and Ullal-2) and one from Tamil Nadu (M10/4) were released by the State Agricultural Universities for cultivation in respective states. In cacao, Landas 358 and Landas 364 were identified as superior accessions. In oil palm, the tenera hybrids produced with pisifera pollen introduced from Nigeria, were found to be superior with an estimated oil yield of 4.5 t/ha/year. In coffee (251 Coffee arabica and 37 C. robusta), collections were established and evaluated for their superior characteristics at Central Coffee Research Institute, Chikmagalur during 1925-40. In recent years, several exotic wild and cultivated materials of arabica, robusta and other species were introduced to built up a massive field germplasm repository, comprising 415 collections. Selections from these germplasm have resulted in the release of several promising varieties. As a result of intensive breeding programme undertaken, utilising both the indigenous and exotic collections, eight new arabica selections and two robusta lines were also released for commercial cultivation.

In tea, about 1,517 accessions of cultivated types and 90 accessions of wild types were collected/introduced over the years (1900-1986) from north-eastern India, Burma, China, Kampuchia, Japan, Sri Lanka, Vietnam and the United States of America. These germplasm collections are being maintained and systematically evaluated at the Tea Research Association, Nagarakata, Jalpaiguri. So far, 113 clonal and seed cultivars have been released to the tea industry of north-eastern India, where 147 germplasm accessions were used. Besides, another 120 accessions have been in various breeding programmes, either in intra-specific or inter-specific hybridization, to produce biclonal and polyclonal hybrid cultivars (Singh, 1988).

Fibre crops

In cotton, the approximate number of collections maintained in various centres in the four cultivated species and wild stocks is estimated at 20,750 (Bhale and Narayanan, 1988). Enormous intra - and racial variability occurs in Gossypium arboreum, landraces of bengalense like sanguineum, multani cotton, roseum and chracterised by high boiling potential, high yields, low ball weight, medium to high ginning out-turn, fine and long fibre susceptibility to boll worm and late maturity. The race cernuum is extremely coarse-fibred, highest in ginning out-turn (up to 50 percent), boll height (3.5-6 percent) and seed number (10-16 seeds/locule). Similarly, G. herbaceum grown in Gujarat (Wagad, Broach, Lalio and Goghari Cotton) and Karnataka (Kumpta Cotton) differ from each other in plant habit, maturity, leaf lobation, boll size, lint colour, ginning out-turn and seed characters (Singh and Raut, 1983).

The Indian hirsutum types are represented by Punjab American Cotton, Buri Types, CTI Types, Indo-American Types and Madras Cambodia Uganda Types. The present day Punjab American Cotton varieties being cultivated in North India are selections from LSS and 216 F (e.g. 320 F, Bikaneri-Nerma, H-777, F 444, SH 131 etc.). The types Buri 1007 and Buri 0394 are resistant to wilt, jassids and frost. Several CTI varieties (Bandnawar-1, Bandnawar-3 Khandwa-2 etc.) were released through hybridization between Cambodian variety Co-2 with G. tomentosum and have high degree of jassid resistance due to hairy leaves. Inter-specific hybridization involving G. hirsutum and Asiatic diploid species carried out at Surat in Gujarat gave rise to several Indo-American types (e.g. 170-Co-2, 134-Co 2-M, Gujarat-67, etc.). These varieties are genetically divergent from rest of the hirsutum varieties developed in India and are good examples of commercial varieties developed from tetraploid x diploid species for the first time. Pure line selections of Cambodian types at Coimbatore and Tamil Nadu gave rise to variety C-2. This variety was further crossed with two Uganda types, viz. 4-4/4 and A-12, and the selections from these crosses were established as Madras Cambodian Uganda (Mc4) types. This resulted in developing long-linted superior quality cottons like Mc 4-5, Mc 4-8 and Mc 4-9.

G. barbadense was introduced in India during the thirtees. However, its cultivation was restricted to limited area in southern states of the country. In 1967, a variety Sujata - a selection from Egyptian variety Karnak, was evolved. The first Indian variety of hybrid origin Suvin was evolved in 1971 from a cross of Sujata and SIV 135. Therefore, the present day G. barbadense cotton in India has these three stocks.

The success in hybrid cotton in India was achieved at Surat where an intra-hirsutum cross of Gujarat-67 x American Nectar-less (an exotic from USA) was released for commercial cultivation in 1968 as Hybrid 4. The first commercial interspecific hybrid Varalaxmi acceptable to farmers and industry was developed at University of Agricultural Sciences, Bangalore in 1972 from a cross between Laxmi (an adapted G. hirsutum) and SB 289 E (a Russian barbadense variety). Later, a large number of inter-specific hybrids have been developed in India, such as CBS 156, J.K.H-1, J.K.H-11, Savitri, Godavari, Suguna, H-6, Jayalaxmi, GDH-22, etc. which are widely grown in different parts of the country. In jute, the two species, Corchorus capsularis and C. olitorius, are being cultivated. The Jute Agricultural Research Institute (JARI), Barrackpore, is maintaining diverse germplasm of jute and wild fibres for its utilisation in breeding programmes (Sinha et al., 1988). Selections from indigenous material have resulted in improved varieties like D-154, JRC-321 and JRC-212 of C. capsularis, and Chinsuirah Green, JRO 632, JRO 753 and JRO 620 of C. olitorius.

Hybridization involving indigenous and exotic types has helped in the development of several promising varieties like JRC 5854, JRC 1108, JRC 4444 and JRC 7447 of C. capsularis, and JRO 514, Kalyani Tosa, JRO 878, JRO 7835 and JRO 524 of C. olitorius.

Medicinal plants

Efforts have been made to utilise native as well as exotic variability (Gupta et al., 1988). 80 collections of Psyllium (Isabgol) were made from Gujarat and its systematic evaluation and utilisation at NBPGR has resulted in the development of two varieties viz. Gujarat Isabgol-1 (a composite) and Gujarat Isabgol-2 (a selection from a mutant line developed through irradiation). The multilocational evaluation of germplasm in opium poppy at 5 locations for 2 years have resulted in the identification of 2 promising lines viz. Aphim 16 (JA-16) and Trishna (IC-42). In Palmarosa, IW 312245 (indigenous wild material) has been identified as promising. In vetiver, Hybrid-8 which is a cross between Bharatpur and Kerala genotype, has been released. This hybrid retains high oil yield of Southern Indian genepool and superior aroma contributing compounds of Bharatpur material (North Indian genepool). In lemongrass, the Odakkali station under the Kerala Agricultural University, holds about 398 collections. OD-19 and OD-440 are two improved selections made from the germplasm collected. Lately, commercial cultivation of some of the recent introductions viz. Japanese mint, Java citronella, geranium, anise, hops and Dioscorea; has been taken up to meet the current requirements.

Oilseeds

Among the oilseed crops, promising types developed/identified so far include 44 straight introductions and/or selections from them (Ranga Rao and Ramachandram, 1988). Limited screening trials carried out in potential and problem areas have resulted in the identification of number of valuable germplasm sources possessing desirable resistance/tolerance to one or the other stresses, such as insects, pests and diseases. The promising germplasm have been identified for leafy spot resistance (MK 374 and Tifton 1108), rust resistance (EC 76446 and PI 259747), leafminer resistance (CGS 101 and others) and thrips resistance in groundnut; mustard aphid resistance (T 6342 and B 85), Alternaria blight (Brassica tournefortii) and white rust resistance (B. alba, B. napus) in mustard; Alternaria leaf spot resistance (B 67 and RAUSS 17-4) and gall fly resistance (SP 87-39) in sesame; powdery mildew resistance (LCK 119 and Kangra), wilt resistance (NP-RR 5) and rust resistance (LCK 119, NP 440 and EC 1456) in linseed; rust resistance (APRR 1, APRR 2 and APRR 3) and wilt resistance (UFSTP. 1) in safflower; wilt resistance (HC 5, Baker, CO. 1, JM 6 and SH 1), root rot resistance (4589/5, TMV 2, RUS 1 and 48 1) in castor; and rust resistance (IB 29 and R 265) in sunflower.

Forage crops

A large number of varieties of fodder crops have been developed in India using the exotic germplasm. These include Giant Bajra (evolved through a cross between Australian bajra and local bajra) of Pennisetum americanum; Pusa Deenanath Grass (a selection from African material) of Pennisetum pedicellatum; Punjab Guinea Grass-1 (an introduction from Australia under the name CPI-59985) of Panicum maximum, Nandi (selection from African germplasm) of Setaria anceps; Marwar Dhaman (a clonal selection from exotic material EC 17655) of Cenchrus setigerus; Marwar Anjan (a clonal selection from exotic material EC 14369) of Cenchrus ciliaris; Kent (an introduction from USA), UPO-90 (a single plant selection from American material) of Avena sativa; Mescavi and Fahl (introductions from Egypt), BL-1 (a selection from mescavi) of Trifolium alexadrium; Kohinoor (a selection from material obtained from Iran) and UPC-5286 (a single plant selection from germplasm line 5286) of Vigna unguiculata, etc.

Summary

Germplasm utility depends on the information generated by evaluation. It covers the whole range of activities starting from the receipt of the material by the curator and its growing out for seed increase, characterization and preliminary evaluation, and also further evaluation, documentation, utilisation and maintenance. In this chapter, principles and methodologies of evaluation in the above context have been discussed. The use of proper descriptors, characterization, preliminary evaluation and further evaluation is stressed. Emphasis is laid on germplasm maintenance, population size, experimental design, rejuvenation, and information management and documentation of data. The value of core collection and pre-breeding concept is pointed out. The coordinated role of NBPGR in evaluation activities has been highlighted.

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