Study on heterosis groups of key parental lines in indica hybrid rice(Oryza sativa L.)in China

According to the grouping result of 48 parental lines by SSR analysis,the heterosis among 14 parental lines selected from 48 parents was studied by a set of diallel crosses and an analysis method of independent comparison of single degree of freedom.The results indicated that there were genetic difference among thermo-sensitive genic male sterile line group and 9308,Zhenshan 97 sub-group,Xieqingzao sub-group,exotic sub-group,Minghui 63 sub-group,IR24 sub-group and two-line restorer line sub-group by F_1 heterosis analysis.These heterotic groups or sub-groups could constitute 28 kinds of potential heterosis patterns.The heterosis patterns of Minghui 63 sub-group×maintainer line group and Zhenshan 97 sub-group×two-line restorer line sub-group,widely used in hybrid rice production exhibited a higher degree of heterosis.The combinations crossed by the heterosis pattern of maintainer line group×thermo-sensitive genic male sterile line group also showed considerable heterosis,this new heterosis pattern could be promising.The combinations from heterosis patterns related to two-line restorer line sub-group were outstanding in grain yield,though most of these patterns could not be used directly in production,these two-line restorer lines would play an important role in promoting hybrid rice breeding after being directionally enhanced.