不同氮肥管理对毛豆共生固氮及产量的影响

以两个不同基因型毛豆品种为试材，研究不同的氮肥管理对毛豆产量及其共生固氮的影响，结果表明，氮肥的施用时间对毛豆的产量及固氮量具有显著的影响，二对复叶始期（Ｖ１．５），每公顷追施５０公斤尿素和在种子形成中期（Ｒ４．５）每公顷再追施２５公斤尿素，两个品种都获得了最高的饱荚产量及最大的固氮量。四对复叶期（Ｖ４），土壤中的速效氮含量与毛豆的固氮率呈正相关，但在开花期和种荚形成期表现为显著的负相关。每公顷仅施２５公斤尿素不能满足毛豆丰产及最大限度利用其共生固氮的需要。

EFFECTS OF N FERTILIZER MANAGEMENTS ON N FIXATION AND YIELD OF TWO VEGETABLE SOYBEANS

s: A field experiment was conducted to evaluate the effect of N fertilizer on yield and N fixation in two varieties of vegetable soybeans. The results showed .that the nitrogen fertilizer application could increase the vegetable soybean total pod yield and marketable pod yield by increasing the marketable pod number. 25 kg N /ha before sowing was insufficient for maximum marketable pod yield and N fixation; The time of N fertilizer application was very important to pod yield and N fixation. 25 kg N /ha was applied before sowing, 50 kg N /ha at the V 1.5 stage and 25 kg N /ha at the R4.5 stage, both two vareities got maximum marketable pod yield and N fixation. There was strong positive correlation between the available soil nitrogen content and the proportion of plant nitrogen derived from N fixation at V4 stage and this relationship became negative at R1 and R3 stage. With 25 kg N /ha before sowing, the two varieties fixed about 120 kg N/ha in 77 days. Additional N either increased or decreased the amount of N fixed .depending on the time of N top dressing.