Estimation of Heterosis and Inbreeding Depression in Quantitative Traits of Rice

Abstract

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 population

Keywords: Genetic basis, Oryza sativa, hybrid vigor, quantitative traits, inbreeding depression