Assessment of Genetic Diversity in Rice (Oryza sativa L.) under Irrigated and Drought Stress Condition

A set of 48 rice genotypes were evaluated to assess the magnitude of genetic diversity under irrigated (control) and reproductive stage drought stress conditions during Kharif, 2018 at Rice Research Farm, Bihar Agricultural University, Sabour (Bhagalpur), India. On the basis of D2 statistics, all the genotypes were grouped into nineteen clusters in irrigated condition with cluster I consisting of maximum number of genotypes (24) followed by cluster III (7) and rest of the clusters were represented by single genotype in irrigated condition. Under drought stress condition, forty eight genotypes were grouped into eleven clusters, cluster I consisted of maximum number of genotypes (24) followed by cluster II and III (8 genotypes in each cluster) and rest of the clusters were mono-genotypic. The highest inter-cluster distance was recorded between cluster XVIII and XIX (28.53), followed by cluster X and VIII (24.20), cluster XIII and XVIII (23.98) and cluster VII and XVIII (23.79) in irrigated condition while in drought stress condition the highest inter-cluster distance was observed between cluster IX and X (31.72), followed by cluster V and IX (28.77), cluster VI and VII (25.98) and cluster IV and IX (25.98) indicating wider genetic diversity among the genotypes between these clusters. The hybridisation programme involving genotype of cluster XVIII and cluster XIX under irrigated condition and the genotypes of cluster IX and X under drought stress condition could be undertaken to isolate high yielding segregants, since these genotypes have high yielding potential, number of effective tillers per hill, relative water content, leaf area, root biomass, panicle length, biological yield, harvest index, plant height, number of fertile grains per panicle, total number of spikelets per panicle, leaf area and proline content with more genetic distances. The parents for hybridisation could be selected on the basis of their large inter-cluster distance for isolating useful recombinants in the segregating generations. Hence, these genotypes might be used in a multiple crossing programme to recover transgressive segregants. Therefore, it is suggested that if the diverse genotypes from these groups along with the other desirable attributes are used in breeding programmes, it is expected to produce better segregants for high grain yield and yield contributing traits due to non-allelic interaction.