Comparative study of agronomic characters in 18 combinations of two-line hybrid rice indicated that the heterosis was shown to be in the order: Indica/Japonica>Indica/ Javanica>Indica/Indica>there-line hybrid rice" Weiyu 64". The same two-line hybrids showed different heterosis performance between early and late season rices. Low seed setting and low grain-straw ratio were the main problems for utilization of indica-Japonica hybrid.
