Analysis Of Combining Ability For Major Agronomic And Quality Traits In Indica Hybrid Rice

14 parents of three-line indica hybrid rice (Oryza sativa L. subsp. indica), including 7 cytoplasm male sterile (CMS) lines and 7 restorers, were used to analyze the combining ability and heterosis for agronomic traits, milling quality traits and apparent quality traits of rice by the way of p x q incomplete diallele cross design.The analysis for agronomic traits showed that both the general combining ability (GCA) and the specific combining ability (SCA) were highly significant in all 15 traits. The plant height (PH), the grain length (GL), the grain width (GW), the ratio of length to width of grain (RLW), the spikelets of per panicle (SP), the grain density (GD), and the seed setting rate (SSR) were mainly controlled by the additive effect, while the panicles of per plant (PP), the flag leaf length of main culm (FLLMC), the panicle length (PL), the filled spikelets of per panicle (FSP), 1000-grain weight (TGW), the grain weight of per plant (GWP) and the relative daily grain yield (RDGY) were mainly affected by the nonadditive effect. Except for PL, GW, RLW and TGW, all other traits were greatly influenced by restorer line than by CMS line, but there was a relatively great effect of CMS line on PP, GL, FLLMC and SSR. Based on GCA and SCA of the parents, CMS lines including Zhenong 8010 A, Xieqinzao A and Quanlong A, and restorers including J 413, Minghui 63 xuan, 95-13 and M 105 were better than others. Since the GCA and SCA were independent each other, it is essential to make broad testcrosses in the selection of hybrid combinations. There existed a positive correlation between GCA and the phenotypic value of parents, which indicated that more attention should be paid for the improvement of parent own traits in hybrid rice breeding.The analysis for the milling and apparent quality traits of rice revealed that both GCA and SCA were highly significant in all 9 traits. The additive effect was more important for the milled rice length (MRL), the milled rice width (MRW), the ratio of length to width of milled rice(RLWMR) and the chalkyness (CN), while the nonadditive effect was more significant for the brown rice rate (BRR), the milled rice rate (MRR), the head milled rice rate (HMRR), the chalky rice percentage (CRP) and the area of chalky rice (ACR). GCA and SCA were independent each other and it is essential to make broad testcrosses in the selection of hybrid combinations. A positive correlation between GCA and phenotypic value of parents was found in present experiment the great attention must be paid for the improvement of parent own traits in hybrid rice breeding. The correlations among BRR, MRR and HMRR were significantly positive. The results of path analysis suggested that HMRR were mainly related with MRR, MRL and MRW, and CRP was mainly determined by BRR and RLWMR, while RLWMR were mainly related to MRW, MRL and CN.