Abstract: In this paper, the characters of yield and yield components of three rapeseed(Brassica napus) genotypes and the ecological relationship between yield and photo-temperature were studied. The feasible way of improving rapeseed yield of multiple cropping in middle reaches of the Changjiang River was also discussed. The results show that different photo-temperature condition during rapeseed growing period induced by different seeding date resulted in a great difference in yield and yield components.There existed a very significant correlation between numbers of pods per plant, PAI(pod area index), main inflorescence yield and branch yield and accumulated temperature and dylight hours respectively, but no significant correlation for 1000-seed weight and SNPA(seed numbers per unit pod area). Seeding date mainly affected branch development and growth and branch yield formation,resulting in a highly significant effect on yield. So the seeding date of rapeseed of multiple cropping was appropriately shifted to an earlier time, and if seeding after October 20, the plant density may increase to 375～450 thousand plant·hm^-2 to make up branches with main inflorescence and to improve rapeseed yield.

Key words: Brassica napus, Seeding date, Component structure of yield, Accumulated temperature, Daylight hour