Abstract:

The objective of this study is to elucidate the effect of sowing date on yield of summer soybean. Tak? ing Qihuang 34 was used as experimental materials, the differences of yield and yield components were compared under 7 sowing dates, and the relationship between rainfall, temperature factors and development process, photosyn? thetic characteristics, yield and yield components of summer soybean were analyzed. The results showed that rain? fall and temperature factors after flowering were the key factors on affecting summer soybean yield. Compared to sowing late, sowing early at suitable time would prolong growth period, increase the accumulated temperature and cumulative temperature diurnal range, and obtain abundant rainfall after flowering, and then the senescence of plant would be delayed and photosynthetic potential, dry matter accumulation and harvest index all would be increased. The influence of rainfall and temperature on yield was mainly caused by the changes of pods number per plant, seeds weight per plant, seeds number per plant and100-seed weight. Along with the delayed sowing date, the yield firstly increased and then decreased gradually, sowing early at suitable time had great advantages in increasing mat? ter production for summer soybean. This study will provided references for scientifically choosing the sowing date and the high yield cultivation of summer soybean in Huang-Huai-Hai region.

Key words:  , sowing date；temperature；rainfall；soybean；photosynthetic characteristics；yield