Genetic diversity for grain yield and its components in local rice (Oryza sativa L.) genotypes under submergence.

Genetic diversity among 49 local rice genotypes was worked out using Mahalanobis D2 statistic under submergence. On the basis of genetic distance, these genotypes were grouped into six clusters. Cluster I was the largest, consisting of 20 genotypes, while two genotypes present in cluster II, eight genotypes present in cluster III, twelve genotypes present in cluster IV, four genotypes present in cluster V and three genotypes present in cluster VI. There was no parallelism between genetic diversity and geographical distribution. The maximum inter cluster distance was between Cluster III and cluster V. Among the different characters studied, harvest index, straw yield/plant (g) and grain yield/plant (g) contributed significantly for the genetic diversity. The cluster II was characterized by maximum mean value for majority of these characters, hence,Doddiga and Hasuli may be used a parents in future breeding programme. Genotypes of Cluster III and cluster V may be intercrossed to achieve wider segregation under submergence.