Genetic Analysis of Some Quantitative Traits in Hybrid Rice with Utilizing Cytoplasmic Genetic Male Sterility System

THE PRESENT investigation was conducted to study the genetic variance components, heritability, heterosis and combining ability in relation to identifying desirable parents and hybrids for hybrid rice breeding program. Three cytoplasmic male sterile (CMS) lines and five restorers (testers) were crossed in line × tester scheme in 2014 growing season. The resulted 15 F1 hybrids along with their eight parents, three maintainers lines and one standard check variety (Giza 178) were evaluated in a randomized complete block design (RCBD) with three replications at Rice Research and Training Center (RRTC) Farm, Sakha, Kafrelsheikh, Egypt during 2015 growing season. Data were recorded on eight quantitative traits, i.e. days to heading, plant height , panicle length, 1000-grain weight, panicle weight, the number of panicles/plant, spikelet fertility percentage and grain yield. The results showed that, the mean squares due to genotypes, parents, crosses and parents vs. crosses were highly significant for all the studied traits. Highly significant differences were detected among lines, testers and line × tester for all the studied traits. The non-additive genetic variance played an effective role in the inheritance of all studied traits, except days to heading, plant height and panicle weight. Heritability estimates in the broad sense (h2b%) were high for all the studied traits. However, heritability estimates in the narrow sense (h2n%) were moderate to high for some traits. Relatively high genetic advance coupled with high heritability estimates were detected for panicle weight. Highly significant and positive estimates of heterosis over better parent and the check variety (Giza 178) were detected in all the F1 hybrids for the grain yield trait. The CMS line G46A and the restorers GZ9399 and PR6 were the best general combiners for grain yield. The hybrid combinations viz., IR69625A × Giza179, IR69625A × PR5, IR70368A × GZ9399, IR70368A × WTR1 and G46A × PR5 had the best SCA effects for grain yield and some of its components.