Genetic studies in red gram (Cajanus cajan L.)

Abstract

The research project “Genetic studies in red gram (Csjsnus csjsn h. Mill sp.)* wae carried out at the College of Horticulture, Kerala Agricultural University, Vellanikkara, Trichur during the period 1983-86. The genetic diversity studies among the 112 genotypes of red grans obtained from NBPGR, Vellanikkera and THAU, Coimbatore during 1963-84 showed that the genotypes of the same place of origin fell into different clusters while those of diversified origin fell into seme cluster. All the genotypes studied were grouped into five clusters. Based on both the inter and intr©cluster distances 20 genotypes representing the broad spectrum of variability were selected and raised during 1965-86. The values estimated for phenotypic coefficient of variation and genotypic coefficient of variation showed that number of clusters per plant, number of pods per plant and seed yield possessed high estimates. Number of days from sowing to 50 per cent flowering and seed yield have exhibited high heritabllity

coupled with moderately high genetic gain estimate* indicating the involvement of additive gene effect* Ku:ber of days from sowing to harvest and height of plant at harvest, have high or moderately high estimates of heritability together with low values of genetic gain indicating the action of non-additive genes. In nine out of ten cases there has been significant positive correlation between component characters and seed yield both in the phenotypic and genotypic levels, however the correlation of hundred seed weight with seed yield was not significant both at phenotypic and genotypic levels* Intercorrelaticna studies have shown that characters exhibiting significant association with seed yield per plant were also highly intercorrelated indicating that these characters can be simultaneously improved. Path coefficient analysis showed that number of poda par plant, hundred seed weight, number of primary branches at harvest, number of secondary branches at harvest and length of pod bearing branches had high positive direct effects on seed yield in th at order* The residual effect wea 0*07227 indicating that about 93 per cent of the variation in yield were contributed by the ten components considered in path coefficient analysis.

The selection index formulated with characters like seed yield, number of pods per plant and hundred seed weight showed an efficiency of 8.4 per cent over direct selection and it includes 57 per cent of the factors determining the yield. Hence it is suggested for isolating superior genotypes. A comparison of different genotypes based on the index value has revealed the superiority of the genotypes NSPGR-XX-EC—10046-1 and HBPGR-124-PLA-345-1 over others. The study paved the way for understanding the source of variability for various factors contributing to yield, the degree of diversity among the genotypes, on the association between yield and its components and between themselves, and helped to formulate selection index for selecting superior genotypes.