Combining ability analysis and gene action for blast resistance in rice (Oryza sativa L.)

Ten rice genotypes were crossed in a line x tester mating design using four testers and six lines to produce 24 hybrids. Analysis of variance showed highly significant differences among genotypes for all the studied traits indicating a wide range of genetic diversity, different origin of these parents and prevalence of additive variance. However, mean sum of squares due to parents was significant for the studied traits except days to flowering, flag leaf length, flag leaf width and test weight. The highest GCV and PCV coupled in the character number of effective tiller. While for plant height, Shayamala, Jaldubi and Makdo exhibited highly significant negative GCA effects for short plant height. The best hybrids produced from different crosses were Mahamaya x Mehardhan, IGKV-R-1244 x Mehardhan and MTU-1001 x IR-64. These crosses could be involved in the rice breeding program. The yield attributing character that is number of effective tiller is found significantly correlated with other characters like flag leaf width, panicle length and panicle weight. Significant phenotypic correlation of ET with FLW and PL shows that yield can be increase with improvements in above characters.