Effects of isolation treatment of a node on flowering and pod set in field grown soybean

Abstract

By pruning the top above the 12th node of the main stem and removing all of the leaves, petioles and tloral organs except that on the 12th node at the beginning of flowering, the-12th, node was isolated to investigate the effect of higher assimilative supply on the sink-determining process of soybean. Treatment caused an elongation of flowering duration due to the promotion of floral differentiation at the 12th node and produced 36 floral buds, which was three times more than that of the control. Treatment also increased the differentiation of the upper racemes with compound leaves. Although the pod setting ratio increased at the first-order raceme as a result of the treatment, there was only a small difference in that on the upper racemes between the plots. The isolated node produced a seed yield threefold as compared to the control due to the increase in pod number arid-seed size. These results indicated that potential sink-capacity in each node of the soybean plant is extremely large and elastic, and racemes with compound leaves play an important role for the process of sink determination. A slight increase in pod setting ratio makes clear the precedence of floral differentiation in the sink adjusting process.