Analysis On Combining Ability And Heritability Of Two-Line Super Hybrid Rice(Oryza Stiva L.)

Rice (Oryza stiva L.) plays a key role in the food security in the world. The application of hybrid rice contributed greatly to increase food production in the whole world. Chinese scientists are endlessly pursuit the high yield breeding and have already reached the yield target of phase Ⅰ (10500kg/ha.), phase Ⅱ (12000kg/ha.) and phase III (13500kg/ha.) in super hybrid rice breeding program. However, how to further break rice yield ceiling, and enhance the efficiency of rice breeding, as well as promote crop breeding which need modernization science and technology. Therefore, the evaluation of rice combining ability and heritability is one of the most important processes in the application of rice heterosis and plant type breeding in super hybrid rice. In this paper,4different plant type photo-thermo-sensitive sterile lines (Y58S, etc.) and8strong restorers (9311, etc.) were utilized by method of incomplete diallel cross (NCII) to make32crosses, which used to observe and evaluate10yield traits such as PH (Plant Height), PP (Number of panicles per plant) and functional leaves18morphological traits such as Leaf Length, Leaf Width in F1hybrid, in order to analyze on combining ability and heritability. The main results were as follows:1. The GCA (General Combining Ability) and SCA (Specific Combining Ability) variances are significantly different in all yield traits at0.05and0.01levels, respectively. In addition to NEP, SSR, YP, the other7traits of GCA variance contribute rate is more than that of SCA, which showed the additive effect is more important than the non-additive effect for most of the yield characters.2. The PH, SL, PL, NEP, SSR, YP of hybrid F1are major influenced by female lines, while PP, NGP, FGP, GW are mainly affected by restorers. To increase the super hybrid rice yield, the key method should be the improvement of both parents. Breeding for female lines should emphasize on the large sink and raise the ratio of sink/source, for restorers on enlarging the size of source and sink.3. Sterile lines Y58S, GZ63S and restorers YH2, R0293are the better parents for Fl yield improvement, because of their better GCA in all parents.4. The order of hn2of10yield traits was, PL>GW>FGP>PH>SL>NGP>SSR> NEP>PP>YP. And these characters, PL, GW, FGP, PH, are important supporting point for promotion the yield potential in super hybrid rice breeding.5. The GCA and SCA variances are significantly difference in plant type traits at0.05and0.01levels, respectively, which showed that the additive effects and non-additive effects influence in hybrid rice leaf phenotype.6. In F1progeny, the2nd leaf length,1st leaf angle,2nd leaf angle,1st leaf curling index, and functional leaves width are affected by female lines.1st leaf length,3rd leaf length,3rd leaf angle,2nd leaf curling index,3rd leaf curling index and top three leaves width, top three leaves area are major influenced by male lines. And there is the higher heritability in functional leaves width, leaves area, and leaves curling index, and3rd leaf length,1st leaf thickness,2nd leaf thickness,3rd leaf angle. So, to break the super hybrid rice yield ceiling, the important method should be the improvement of both parents’plant-leaf type. Breeding for sterile lines should emphasize better leaf gestures, and for restorers on enlarging better leaf forms.7. Sterile lines Y58S and Pei’ai64S are the better GCA effects in leaf gesture, P88S and GuangZhan63S are the better GCA effects in leaf form. Restorers YH2,9311, R1128, FH1and Q460are the better plant type parents in line with the ideal plant type requirements. Y58S/YH2, Y58S/9311, P64S/9311are excellent ideotype combinations.