Effect Of Nitrogen Application On Symbiotic Nitrogen Fixation And Growth Of Soybean(Glycine Max L.)

In this paper, a pot experiment was conducted to study the effects of different nitrogen forms, different nitrogen application rate and supply patterns on the dry weight of plant, root morphology, nutrition content, and the effect of N application at different N forms, N application rate and N supply style on dry matter accumulation, nutrient accumulation, nitrogenase activity, Lb and yield of soybean were analyzed。The result showed that the dry matter accumulation, root dry weight and root morphology were raised by N application. There some thing different between before and after stages, which the basal nitrogen application of different nitrogen forms, and the ammonium-N can raised the dry matter accumulation and the growth of root, while the nitrate-N reversed. Protein-N had the highest effect on dry matter accumulation and root weight.The result of different nitrogen application rate and nitrogen supply style showed that the dry matter accumulation, root dry weight and root morphology characteristic first increased then decreased with the nitrogen application rate under discrete nitrogen supply (DNS, fertilizer applied once as base fertilizer). However those signals increased with the nitrogen application rate under continuous nitrogen supply (CNS, fertilizer applied for several times during the plant growth) .The dry matter accumulation, root dry weight and root morphology of CNS were all higher than that of DNS, and the result was more significant with the development of nitrogen application. Those results showed that the optical nitrogen application rate was benefit to dry matter accumulation and keep the root lively, which were a good basement for nitrogenase activity.The nutrient accumulation of different growing stages were effect by nitrogen application, the phosphorus accumulation increased with the growing stages, and peak stage was at the maturing stage. However, the nitrogen accumulation peak stage was at the podding stage. The trend of nitrogen and phosporus accumulation under different nitrogen forms treatments was like this: N_NO3＞N_protein＞N_glycine＞N_urea＞N_NH4＞CK, there was significantly difference between those treatments. The trend of nitrogen and phosporus accumulation under different nitrogen application rate treatments was N₁₅₀＞N₂₂₅＞N₇₅＞CK, and underthe different nitrogen supply style, the order was N_75/4＞N_150/4＞N_225/4＞CK. The two nitrogen application style, which were under same nitrogen application rate, the nitrogen and phosporus accumulation were all higher than the other treatments. The dry matter accumulation strongly correlated with the nitrogen accumulation(r = 0.900^**) and phosphorus accumulation (r = 0.871^**). The root weight strongly correlated with the dry matter accumulation(r = 0.945^**), moreover, the nitrogen accumulation correlated with phosphorus accumulation before maturing stages(r = 0.983^**).The nitrogen application did not inhibit the nodule produce, but increased. The nodule number, dry matter, nitrogenase activity and Lb concentration were all decreased with the nitrogen application rate. Moreover, the Lb concentration was related with the nitrogenase activity(r = 0.819^*). The nitrogenase activity and Lb concertration were obviously related with the nitrogen application rate, respectively (r = -0.796^*, r = -0.965^**).The yield was definitely related with the dry matter accumulation(r = 0.798*), nitrogen accumulation(r = 0.924^**) and phosphorus accumulation(r = 0.913^**). The N_protein treatment had the highest yield in those nitrogen forms treatments. The N_75/4 treatment was the most optical nitrogen application measurement.