Abstract: It is the fact that high temperature induces seed set of the BT type of cytoplasmic male sterility (CMS) and low temperature induces seed set of the photo-sensitive genic male sterility (PGMS). By crossing the CMS line with the PGMS japonica line with maintainer gene, the photo-sensitive cytoplasmic male sterility (PCMS) lines, 2308SA and 2310SA, were bred. Because of integrating PGMS and CMS genes, the sterility of PCMS japonica is controlled by two group of male sterile genes. The results of observation on the fertility of plants by different sowing times showed: 1. Under the conditions of natural long-day photoperiod and over 35℃, the PGMS gene regulated the sterility of PCMS japonica. The higher the temperature, the lower the pollen fertility and bagged seed set of PCMS japonica, which avoided the effect of high temperature inducing the seed set of CMS. 2. When long-day photoperiod and between 35℃ and the critical sterility inducing temperature of PGMS, both PGMS and CMS gene controlled sterility of PCMS japonica, and they so which exhibit stable characters. 3. Under the critical sterility inducing temperature or short-day photoperiod and the highest daily temperature (<32℃), the BT type of CMS gene regulated the sterility of PCMS so that the PGMS gene would render the male sterility insusceptible to occasional cool summer days when this PCMS line adopted for hybrid seed production develops into panicle differetiation stage. Moreover, the fertility restoration, seed production and combining ability of PCMS japonica in order to utilize it better in future were also studied.

Key words: Oryza sativa var. japonica, Photo-sensitive genic male sterility, Cytoplasmic male sterility, Gene, Photo-sensitive cytoplasmic male sterility