Estimation of Heterosis and Inbreeding Depression in Quantitative Traits of Rice

It is important to know the degree and direction of heterosis for its commercial exploitation. Heterosis and in-breeding depression were estimated in 8x8 half diallel crosses of rice. The planted materials consisted ofeight parental inbred lines, their F1 hybrids and F2 populations using randomized complete block design with three replications. Data were collected on number of days to 50% flowering, plant height, number of tillers/plant, number of panicles/hill, panicle length, number of spikelets/panicle, number of fertile spikelets/panicle, number of days to maturity, 1000-seed weight and grain yield. Significant genetic differences were observed among the parents, their F1 hybrids and F2 populations for all the characters under study. Panicle length and number of spikelets/panicle showed highly significant heterosis in F1 hybrids ranging from -6.1748 to 41.847% and -8.6957 to 41.847%, respectively while in breeding depression in the F2 population ranged from -3.93 to 13.2231% and 3.6364 to 25.85% respectively.F1 hybrids showed low level of heterosis in number of days to flowering (-11.25 to 11.95%),. The parent WAB 450-1-B-163-41 proved itself to be a good general combiner by making higher contribution towards heterosis both in F1 hybrids and in F2 populationKeywords: Genetic basis, Oryza sativa, hybrid vigor, quantitative traits, inbreeding depression