ABSTRACT
The pod growth was obviously slow in soybean compared with that in the other three crops. Soybean pods reached the maximum length about 25 days after flower opening against 7 days in mung bean, and 10 days in azuki bean and common bean. , the delay of seed growth on the racemes opened the flower late was shorter than those of pod growth, such as it was reduced to 3.1 against 6.6 in the pod growth on secondary raceme and was reduced to 12.0 against 13.5 in the pod growth on tertiary raceme. However, the overtaking of pod and seed growth in late opening flower was more dramatic during pod elongation more than seed growth. Various methods for estimating rate and duration were compared, and such estimates were compared with yield, along with mature seed weight, seed number, and days from planting to maturity. Three estimates of seed filling period were all highly correlated with each other, but the final seed weight, divided by its growth rate during the linear phase of dry matter accumulation, or the 'effective filling period', correlated best with yield. Soybean with high-level of yield is reachable through high harvest index and the allocation of most of the photosynthetic materials into reproductive organs, whereas increasing surface of leaf until graining has contradictory relation with seed yield.
