Genetic Variability and Divergence in ‘New Plant Type’ Rice Genotypes

A set of 35 ‘New Plant Type (NPT)’ rice breeding lines of early and medium duration having few tillers-heavy panicle eco-ideotype were assessed for genetic variability and divergence of yield and yield attributing traits along with three checks during kharif 2003. The results revealed ample genetic variability among the characters under study. The h²_(bs)was high for most of the characters except panicles/hill and number of leaves. Genetic divergence based on Mahalanobis D² statistic grouped the 38 genotypes into seven clusters. Cluster I and III were the largest, while the clusters II, IV, V, VI and VII were monogenotypic. Genotypes in the cluster III had the highest intra-cluster distance, while maximum inter-cluster distance was observed between clusters IV and VII. Days to 50% flowering had the maximum contribution (74.96%) to the total divergence followed by yield (9.10%) while flag leaf breadth had no contribution. Cluster means for the twelve characters revealed that cluster VI showed highest mean for yield (8829 kg/ha) followed by cluster V (6431.50 kg/ha), while cluster VII was early (90 days to 50% flowering). Hybridization among genotypes IR 65600-38-1-2-1, IR 70491-33-2-2, IET 14238 and IET 13380 drawn from divergent clusters is likely to produce heterotic combinations and high variability in segregating generations.