Light Enrichment, Flowering Asynchrony and Reproduction Success in Two Field-Grown Soybeans in Northern China

The flowering process at single plant level in soybean is a continuous dynamic system. Whether a flower can survive to mature depends on where it is located and when it is initiated. A field experiment was conducted to analyse the effect of flowering asynchrony on single flower survival and response of flowers or pods distribution to light enrichment. Our data suggest that early flowers (number 1–5) definitely survive and develop into mature pod because they don't encounter fierce assimilates competition from other flowers or pods. Later flowers are usually prone to abortion, especially when five or more flowers at the same node in two soybean cultivars (Glycine max L. Merr. namely, Heinong35 and Kennong18). The flowers on sub-raceme frequently fail to develop into pods. Compared with the flowers on main-raceme, that on sub-raceme maybe have weak competitive ability to assimilation. Most flowers on bottom branches successfully develop into pods due to the strong supply of assimilation from the leaves of branches. Light enrichment significantly increase the number of flowers or pods across the main axis. However, the rate of flower abortion is still relatively high by observing the distribution curves of flowers or pods under light enrichment. Soybean plant has the characteristic of excessive flower production and flower abscission is more likely to be expression of biological adaptability.