Assessment of genetic diversity for seed vigor traits in rice (Oryza sativa L.) through principal component and cluster analysis

Seed vigor, an important characteristic of seed quality attributes, determines the rate of early, rapid, uniform germination, emergence and growth of strong seedling in any environmental condition. In the present set of experiment, 44 rice (Oryza sativa L.) varieties were assessed for different seed vigor component traits. For evaluation of these traits, basic statistics, correlation, principal component (PC) and cluster analysis were carried out to obtain genetic diversity for seed vigor traits and early seedling vigor among rice varieties specifically to select the best varieties and important seed vigor traits for its possible use in future rice breeding programme. The estimation of descriptive statistics of 20 quantitative seed vigor-related traits indicated existence of variability among the varieties. The 44 varieties were grouped into five clusters on the basis of average linkage and dendogram. Varieties in Cluster I are considered to possess very high vigor traits and cluster IV with least seed vigor traits. Principal component (PC) analysis showed first 5 PCs having Eigen value >1 explaining 77.01% of the total variation with different seed vigor traits. In the biplot analysis between PCs 1 and 2, the varieties remained scattered in all four quadrants, showing large genetic variation in quantitative traits. Seed vigor index-I, seed vigor index-II, seed dry weight, shoot length, reserve mobilization, germination percentage, dehydrogenase, mean germination rate, germination speed, and mean germination time contributed to high variability among the varieties. The seed vigor traits were positively correlated with germination percentage, shoot length, seedling dry weight, speed of germination, mean germination rate, reserve mobilization, superoxide dismutase, dehydrogenase and alpha-amylase. The positive correlation among these seed vigor-contributing traits suggested that these characteristics are important for direct selection of high seed vigor varieties and early emergence.