Genetic Analysis and Combining Ability on Spikelet Fertility Related to Cold Tolerance in Japonica Rice

Abstract

Each parent, P1 and P2, ten F1 hybrids among 5 parents, eight F2, B1 (F1 × P1), and B2 (F1 × P2were evaluated for spikelet fertility related to cold tolerance in cold-water irrigated plot. Heterosis for spikelet fertility varied from8.6% to 60.5% with a mean of 20.6% and showed positive effects in all croses except for Sambagbyeo/Stejaree 45, indicatingthat the gene effect is partial dominant. Heterobeltiosis ranged from 2.9% to 25.5% with a mean of 1.6%. Thre hybrids ofUnbong 31/Sambaegbyeo, Sambaegbyeo/HR19621-AC6, and Hitomebore/Stejaree45 had higher fertility than the superior parents,for spikelet fertility. The variance of GCA effect was larger than that of SCA effect, indicating that variance components due toadditive effects might be larger than those due to non-additive effects for this character. Analysis of genetic parameters for the5 × 5 half-diallel F1s, revealed that spikelet fertility fitted to the additive-dominance model. Broad-sense heritability (h2B) washigher than narrow-sense heritability (h2Ntative character expressed by polygene. The genetic mode for spikelet fertility using the joint scaling test was shown to be additive,dominance, and additive-dominance gene effects. Additive gene effect was higher than dominance gene effect.