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Cowpea [Vigna unguiculata L.Walp] is an important summer/rainy season legume crop which is tolerant to drought aswell as water logging conditions. It provides nutritious grain and an inexpensive source of protein. In cowpea breedingprogrammes, the major emphasis has been on the collection and conservation of genetic pools. The knowledge onthe nature and extent of genetic variability present in any crop species plays an important role in designing a suitablebreeding method. Genetic diversity is the foremos t basic requirement for a successful breeding programme. Heritabilityis a biostatistic commonly used in plant breeding and genetics works that estimates how much variation in a phenotypictrait in a population is due to genetic variation among individual plants in that population. Genetic advance is theimprovement in the mean genotypic value of selected plant families over that of base population. It depends uponphenotypic variability, heritability and intensity of selection. The evaluation of cowpea germplasm, quantification ofthe magnitude of variability existing for different characters and classification into groups help in identifying potentialdistinct genotypes which are having contrasting characters, can be used to operate effective selection of geneticallydiverse genotypes for the improvement of yield. In this review paper, the research work carried on different aspects ofgenetic divergence is discussed under the sub-heads, i.e. variation of qualitative and quantitative traits, genetic variability,heritability and genetic advance, correlation and path analysis, genetic divergence using D2 analysis and genetic diversityby using molecular markers.

The present experiment was carried out at Director Farm, CCSHAU, Hisar duringkharif2017 to evaluate the performance of 30 selected elite genotypes of cowpea. The variably was studied both within and between groups. The genotypes, KBC 9 and DC 7-15 were placed in the medium fodder-medium grain yield producing group and could be utilized for both, fodder as well as grain production. Moreover, the genotypes (UPC 12-007, KBC-6, KBC-8 and GC 901) were included in high fodder- medium grain yield, which had good potential of grain production as well as excellent potential of fodder production. Likewise, the genotypes (PL-3 Sel., CPD 240 and RC 101) were included in medium fodder-high grain yield, which had good potential of grain production as well as excellent potential of fodder production. It could be utilized for dual purpose after extensive testing over time and space. None of the genotypes was placed in high fodder-high grain yield. So, there is an urgent need to breed for high fodder-high grain so that the maximum fodder as well as grain yield could be obtained simultaneously. Therefore, the hybridization among the diverse genotypes viz., UCP 12-007 (high fodder yield) with PL-3 Sel. (high grain yield) may be suggested for developing dual purpose genotypes through the transgressive segregation.