Variation of nitrogen accumulation and yield in response to phosphorus nutrition of soybean (Glycine max L. Merr.)

Phosphorus (P) is essential macronutrient for soybean [Glycine max (L.) Merr.] growth and function. The objective of this study was to determine effect of phosphorus nutrition (including phosphorus nutrition level and interruption of phosphorus supply) on nitrogen accumulation, nodule nitrogen fixation and yield of soybean plants by N-15 labeling with sand culture. The results showed that they all presented a single peak curve with improvement of phosphorus nutrition level, when phosphorus concentration of nutrient solution was about 31mg/L, they all reached the maximum and effect of phosphorus nutrition level on nodule nitrogen fixation was lower than that on yield formation level. Interruption of phosphorus supply during soybean growth period, nitrogen accumulation and nodule nitrogen fixation were seriously inhibited, and yield was decreased significantly when interruption of phosphorus supply during V-3-R-1 and R-1-R-5 period, while interruption of phosphorus supply during R-5-R-7 period had no significant effect on nitrogen accumulation, nodule nitrogen fixation and yield. So soybean nitrogen metabolism and yield were sensitive to phosphorus nutrition in the V-3-R-5 period, those were not sensitive to phosphorus nutrition after R-5 period.