Genetic and correlation analysis of grain characters in three-line hybrid rice

[Objective] This study was to understand the genetic dynamics of three-line hybrid rice, and explore the respective effect of sterile line and restoring line on grain characters of hybrid rice. [Method] Four three-line sterile lines and 27 restoring lines(cultivars) commonly cultivated in Central China region were regarded as experimental materials to conduct 4×27NCП cross design, and the grain characters of three-line hybrid rice were analyzed at genetic and correlation levels. [Result] Four characters of grain length, grain width, 1000-grain weight and length-width ratio play the leading role in additive gene effect; these four characters were simultaneously influenced by male parent and female parent, but the effect from male parent was relatively larger. The grain length, grain width, 1000-grain weight and length-width ratio all have high broad heritabilities(respectively 99.65%, 98.31%, 95.27% and 98.81%). Correlation analysis showed that grain length was positively correlated with 1000-grain weight and length-width ratio at extremely significant level; 1000-grain weight was positively correlated with grain length and length-width ratio at extremely significant level, and was insignificantly correlated with grain width; grain width was negatively correlated with grain length and length-to-width ratio at extremely significant level. Path analysis showed that the direct path coefficients of grain length, grain width and 1000-grain weight to length-width ratio were 0.6246,-0.5559 and -0.0158, respectively. [Conclusion] This study systematically analyzed the effects of sterile line and restoring line on grain characters of hybrid rice, which provided theoretical basis for breeding high quality and yield hybrid rice.