A Study on the Genetic Difference of Parents and Its Relation to Heterosis in Three-line Hybrid Rice

Using 4 maintainer lines and 16 restorer lines as the materials,the genetic difference of the parents and its relation to F1 heterosis were studied through principal component analysis and cluster analysis of 9 yield characters and related characters.The results showed that the genetic difference was comparatively small among maintainer lines,and comparatively larger in restorer lines,and comparatively larger between maintainer lines and restorer lines.The analysis of correlation between the genetic distance of both parents and heterosis of their F1 hybrids showed that there was not a correlation between them among the parents.However,it was found that the grain yield of F1 hybrids was closely related to that of both the parents,especially to the mean value of grain yield of the both parents,which indicated that parental improvement was of great importance to increase hybrid rice yield.