Effects of shading on spatial distribution of flower and flower abscission in field-grown three soybeans in Northern China

A 2-year field experiment was conducted under natural light and shading conditions to examine the responses of spatial distribution of flower and flower abscission in three soybeans, and characteristics of flowering progress also was discussed. The results showed that responses to shading occurred proportionately across the main axis node positions despite the differences in the time of development of flower and pod between the high and low node positions. Reproductive organ of middle node was more sensitive than that of low and high node in single plant. Compared with that under natural light, shading increased flowering time 7 days for H339, 3 days for HN35 and 1 day for KN18. Flowering process showed a significant four stages: early-bloom phase (4-6 days), full-bloom phase (about 15 days), slow-bloom phase (about 10 days) and final-bloom phase (about 9-16 days). Soybean has the characteristic of excessive flower production. Our data may give a hint that flower number produced per plant isn't uppermost factor determining in final pod number survived per plant. Excessive flower produced per plant maybe just is precondition as reproductive prosperity in soybean.