Abstract:
In order to explore the potential and compensation ability of soybean flowering, three soybean cultivars with different termination habit and similar growth period, Zhonghuang 13(with determinate habit), Handou 5 and Williams 82(with sub-indeterminate habit), were used as experimental materials. The continuous defloration treatments of short-term(3, 5 and 7 d) and long-term were set to evaluate the effect of artificial defloration on flowering dynamics, podding, and yielding in soybean. The results showed that:(1) The total flower number was similar among the materials sown at the same time, but various natural flowering dynamics was closely related to stem termination habits i.e., Zhonghuang 13 had a flowering tendency of sharp-rise-then-drop with short duration. However, Handou 5 and Williams 82 had relatively stable flowering with longer duration;(2) In the long-term defloration treatments, new flowers were grown continuously to compensate defloration loss, and the flowering period was prolonged as well. The total number of flowers of Zhonghuang 13 and Handou 5 were 2.46 and 3.07 times in the long-term defloration treatments compared to the corresponding controls, respectively. Moreover, the palingenetic flowers had normal reproductive ability. Under the natural condition, long-term defloration treatment resulted in stay-green syndrome, and the secondary stems grew from leaf axils at the lower nodes;(3) The short-term defloration treatments stimulated new flower genesis in the treated nodes, and without effect on adjacent nodes in sub-terminate soybean varieties. The opposite effect of short-term defloration on yield in Handou 5(yield loss) and Williams 82(yield gain) was resulted from difference of palingenetic flowers, the flower-pod transformation rate, and seed weight. Therefore, soybean defloration, because of pollination and fertilization(simulated with artificial defloration), can be compensated by palingenetic flowers with enormous potential, which accompanied by prolonged growth period. However, the prolonged growth period of soybean is contradicted with autumn chilly weather in the northern China. These results can be referred to the related research on environmental stress in soybean flower stage.