Studies on genetic divergence in lablab bean through principal component analysis

Genetic divergence study was conducted in 18 genotypes of lablab bean for 10 quantitative characters through principal component analysis (PCA). Out of 10 principal components (PCs), the first five PCs explained about 96% of total variability. In PC 1 which accounted for 32.88% of total variation, pod length, days to first harvest and days to last harvest explained the maximum variance indicating the great scope of improvement in these traits through selection. The PC 2 which accounted for 28.32% of total variation exhibited a high index for number of primary branches/plant which explained the significance of this trait in pod yield of lablab bean. The 18 genotypes were grouped into five clusters of similar characteristics based on first 2 PCs, which accounted for 61.20% of total variation. The highest positive score of 2.801 in IC 424815 and the lowest score of -3.890 in IC 424476 indicated the wide range of variability among the genotypes. The genotypes IC 424815, IC 424474 and IC 424821 in PC 1 and the genotypes IC 424813, IC 424818 and IC 424817 in PC 2 recorded significantly higher scores which indicated the great potential of these variable genotypes in lablab bean improvement programme. The grouping pattern of the genotypes indicated no relationship between genetic and geographical diversity. The Cluster II (7) contained the maximum number of genotypes followed by Cluster I (5). Each of the rest three clusters contained two genotypes only. The maximum inter-cluster distance was between Clusters III and IV while the minimum distance was between Clusters I and II. Superior performance was exhibited for earliness by Cluster III and for pod yield by Cluster V. So, to breed early and high yielding varieties, hybridization between genotypes of Cluster III and V followed by selection in the segregating generations can be made.