Genetic Diversity Analysis of Rice (Oryza sativa L.) Genotypes for Yield and Sheath Blight Screening

Sheath blight disease, caused by Rhizoctonia solani Kühn, is considered the second most important disease affecting rice, causing yield reduction globally. In the present study thirty diverse rice genotypes were inoculated with fungal mycelia during the maximum tillering stage to assess the genetic diversity of rice genotypes for sheath blight reactions. Mahalanobis D2 statistics was performed for grain yield and yield contributing features under sheath blight stress to calculate the genetic divergence between the genotypes. Four clusters were formed from the genotypes. Cluster III has the highest number of genotypes (nine). The highest inter-cluster distance was noticed between cluster I and cluster IV (11.41) and minimum between cluster III and cluster IV (6.50). The intra-cluster distances were lower, indicating the homogeneity of the genotypes within the clusters. Maximum intra-cluster D2 value was recorded in cluster IV (6.32) and minimum in cluster II (5.36). Cluster I showed high genetic divergence from all other clusters. Hence, the genotypes from cluster I could be used for hybridization with the genotypes of other clusters to develop high yielding sheath blight resistant rice varieties.