Effects of excessive soil moisture on photosynthesis and nitrogen metabolism.

1.本试验的第一个目的是研究以硫酸铵为氮肥的氮肥是否能有效地对抗大豆的水分过多伤害。默尔。]。大豆(C.V.Tamahomare)是在一块由稻田改建的旱地上种植的。在花芽分化期，在沟深5~8 cm处浸水处理10d，然后以12g/m2施氮量施肥量，不施氮肥对种子产量影响不大，而淹水区种子产量增加约20%。种子产量的增加是由角果数的增加带来的。本试验的第二个目的是研究在花芽分化期，盆栽大豆植株的角果数是如何增加的。在花芽分化期，盆栽大豆植株在树体土壤水分条件下进行了7天的处理：水分过多(地表下5~7 cm的地下水位)、淹水(土壤表面以上2~3 cm的地下水位)和对照，然后每盆施5g的硫酸铵。在过量水分和没有追施氮肥的淹水区，每株总节数和每节的角果数减少。其结果是减少了。结荚数过多导致种子产量下降。而在施氮量较高的小区，每节角果数增加，角果数增加，种子产量增加。推测每节角果数的增加归因于光合作用速率的提高。

1. The first purpose of this experiment was to examine whether the application of nitrogen (N) fertilizer as ammonium sulfate is effective as a countermeasure against excess moisture injury to soybeans[Glycine max (L.) Merr. ]. Soybeans (C. V. Tamahomare) were grown in an upland field converted from paddy. Flooding treatment was conducted in the furrows to a depth of 5 to 8 cm for 10 days at flower-bud differentiation stage and subsequently fertilizer was applied at 12g N per m^2.In the non-flooding plot, seed yield did not increased due to the supplemental- N, however in the flooding plot, it was increased by about 20%. The increase in seed yield was brought about the increase in the number of pods.2. The second purpose of this experiment was to examine how the number of pods increased due to the supplemental N. At the flower-bud differentiation stage, soybean plants cultivated in pots were treated with tree soil moisture conditions for 7 days : excess moisture (water table of 5 to 7. cm below the soil surface), flooding (water table of 2 to 3 cm above the soil surface) and control, and subsequently ammonium sulfate was applied at 5g per pot.In the excess moisture and flooding plots without the supplemental N, the total number of nodes per plant and the number of pods per node decreased. The resultant decrease in. the number of pods brought about decrease in seed yield. However, in those plots with the supplemental N, the number of pods per node increased and the resultant increase of the number of pods brought about increase in seed yield. It was assumed that increase in the number of pods per node was attributed to increase in photosynthetic rate.