Studies on Flowering and Fruiting of Leguminous Crop Plants : VI On growth, yields and changes of chemical constituents in soybean plants induced by periodic phosphorus deficiency

Abstract

This experiment was conducted to study the effects of periodic phosphorus deficiency on flowering and fruiting of soybean plant (using Shirobanasai No. 1). The results obtained were as follows : 1. The effect of phosphorus deficiency ih the beginning and end of flowering time on dry weight was so severe that even if phosphorus was sufficiently supplied thereafter, it was extremely difficult to recover. 2. It was observed that there was a high correlation between the time of defoliation and the concentration of not only P₂O₅ but also that of total N, total sugar, and starch in petiole just prior to yellow leaf stage. 3. P₂O₅ deficiency was observed to decrease the number of node of branch. 4. Phosphorus deficiency after fruiting time reduced the contents of total N and P₂O₅ in the vegetative organ, and increased the concentration of total sugar and starch, increasing the yields. Therefore, P₂O₅ supply after fruiting time was ineffective te increase the yield.