Abstract: A partial diallel cross including 5 photosensitive genic male-sterile rice (PGMSR) lines as female parents and 10 wide compatibility (WC) varieties as male parents was made to study the heterosis and combining ability for the days to heading (DTH) of the F₁ hybrids. The result showed that 5460S and Hengnong S-1 had better general combining ability (GCA), their F₁ showed no heterosis; W6154S, W6184S and KS-9 had worse GCA, their F₁ exhibited a significant positive heterobeltiosis, suggesting the difference in the DTH of F₁ among parents and among combinations. The GCA of parents, especially the indica parents, played a more important role in controlling the DTH of F₁s. The combining ability of a parent is related to its breeding relationship and the parent derived from the southeast Asia variety has better GCA. The relation between GCA and the photosensitivity gene was discussed.

Key words: heterosis, hybrid rice, combining ability, heading date, intersubspecies hybrid

关键词: 杂种优势, 杂交水稻, 配合力, 抽穗期, 亚种间杂交稻