Pinching cultivation of soybeans is widely acknowled ged as a method of their increased yield.
In order to know the effects of pinching upon the constituting elements of seed yield, we have practised pinching (A) at primary leaf unfolding, (B) at primary compound leaf unfolding, (C) at secondary compound leaf unfolding, and have compared the branching system and the number of flowers and ripening pods respectively with those in the control.
The fesults are as follws :
(1) In the control the branching system is composed of a main stem and eight small weak primary branches have hardly anything to do with the branching system.
In the treatment the branching system is composed of the primary brabches of apparently opposite phyllotaxis due to each method, and the secondary branches grown on the primary branches are fairly concerned with the branching systems.
(2) The number of flowers per plant increase 30～40% by treatment.
(3) In each plot the proportion of the number of flowers and pods is the greatest in the primary branches, and the later they are pinched, the greater becomes the proportion.
(4) In the treatment we have the greatest number of flowers and pods of the primary branches which have well-grown axillary buds of primary leaves; while in the later treatment we have fewer primary branches which have extended from axillars of cotyledons, and they have a small number of nodes, flowers, and pods.
(5) In the control, the nodes which have the greatest number of flowers are lower, when the number of flowers of the primary branches is added to those of the main stem, than those, when it is not added. In the treatment the nodes which have the greatest number of flowers are lower, when the number of flowers of the secondary branches is added to those of the primary branches, than those, when it is not added. It is quite the same case with the nodes which have the greatest number of pods.
(6) In the control, the nodes which have the greatest number of flowers and pods are in the highest position ; while the later the pinching is practised, the lower the nodes become.
(7) The number of pods per plant increase 45-60% by pinching. It is due to the increase of the number of flowers and the rise of the rate of ripening pods.
(8) In the conrol, the number of flowers and pods upon the main stem and primary branches is very important, when we consider the constituting element of seed yield. In the plot, where we have the earlier pinching, the number of the flowers and pods upon primary and secondary branches is very important, and in the plot,where we have the later pinching, we find the number of the flowers and pods upon primary branches very important.