Parental genetic distance and combining ability analyses in relation to heterosis in various rice origins

Abstract

Information on parental genetic distance and combining ability is a fundamental prerequisite for hybrid rice breeding. Based on a study of genetic diversity using molecular markers, 12 parents representing various rice origins were selected to make diallel crosses, and hybrids were evaluated in tropical environments. Yield, yield heterosis and combining ability were investigated with the main objectives of (1) evaluating the genetic relationship between each type of rice by DNA marker, (2) estimating the heterosis and combining ability for yield of F1 hybrids from the crosses between indica and other types of rice, and (3) identifying hybrid parents for future hybrid rice breeding. Significant differences in yield, yield heterosis and combining ability were detected among parents and among hybrids. Results revealed that indica showed general combining ability higher than other type. Based on genetic distance identified, these rice varieties were classified into two distinct groups and seven subgroups. The varieties placed into the same cluster group were found to from the same origin. Results from the yield evaluation of hybrids and from clustering of genetic distance of the parents indicated that hybrids derived from crosses between parents with medium genetic distance (0.42) gave higher yield heterosis than those derived from crosses with extreme genetic distance (0.07 and 0.83). Heterotic performance and efficiency of breeding heterotic hybrid could be enhanced using selected parents within identified marker-based heterotic groups. This information is useful future for hybrid rice breeding.