Genetic Variability and Diversity in Rice Cultivars of North Bank Plain Zone of Assam for Traits Associated with Grain Yield and Adaption under Moisture Stress

Fifty four rice cultivars from North Bank Plain Zone (NBPZ) of Assam were assessed for their genetic variability and diversity with respect to yield and traits associated with adaptation under moisture stress with a view to formulate hybridization strategies for further genetic improvement. Genotypes were evaluated following a completely randomized design with two replications under PVC pipes at the experimental field of BN College of Agriculture, Biswanath Chariali, Assam.  A higher magnitude of phenotypic and genotypic coefficient of variation was recorded for root volume, root dry weight, root length density, filled grains per panicle, shoot dry weight, root length, root-shoot ratio and grain yield per plant. High heritability coupled with higher genetic advance was registered for root dry weight, root length density, root volume, root-shoot ratio, root length and grain yield per plant. D2 analysis revealed that the genotypes could be distributed into a group of eight clusters with maximum distance between cluster III and cluster V (845.71). Root volume was found to contribute highest towards divergence (12.83%). Out of all the clusters, cluster IV with an intra cluster distance of 370.76 consisted of maximum number of accessions (17). Genotypes based on the inter se genetic distance and per se performances of specific traits were identified for undertaking hybridization programme. The implication of the diversity pattern elucidated for breeding varieties for moisture stress adaptation were discussed. Hybridization programme may be undertaken between the identified genotypes having inter se genetic diversity belonging to diverse clusters. Thus it could be expected to obtain desirable segregants out of the hybridization programme for further genetic improvement of rice in the region.