Abstract: The soybean cultivar Yudou No.25 was sown at different dates in 5 locations of Henan Province in 2001 and 2002. One hundred and nine samples of 11S/7S ratio in soybean seeds and 29 eco-physiological factors were received. The stepwise regression was used to screen the correlated factors，which significantly affected 11S/7S ratio. Results showed that: (1) The sunshine hour at seed-filling and maturation showed in curve relation to 11S/7S ratio, and optimum value for getting higher and lower 11S/7S ratio were 459.2 h and 110.8 h, respectively. The lower diurnal temperature variation at seed-filling and maturation was favorable for getting higher 11S/7S ratio. Lower diurnal temperature variation and higher mean temperature at seedling brought on higher 11S/7S ratio, both of the two factors showed liner relationship with the ratio of 11S/7S. Higher diurnal temperature variation at branching was suitable for higher 11S/7S ratio. (2) Liner relationship also existed between 11S/7S ratio and soil K content, the maximum and minimum 11S/7S ratio emerged when soil K content were 0.83% and 1.32%, respectively. (3) The 11S/7S content would not be affected by other eco-physiological factors in the range of this test.

Key words: Soybean [Glycine max(L.).Merr.], 11S/7S ratio, Eco-physiological factors, Date-of-planting experiments