Nodule Growth,Nodulation and Nitrogen Fixation in Soybean(Glycine Max L.)as Affected by P Deficiency Stress

Phosphorus deficiency stress is a serious problem in the soil,how to resolve the problem of crop production reduction resulted from P deficiency is becoming global hot research.In this paper,a sand experiment was conducted to study the effects of P deficiency stress on nodule growth,nodulation and nitrogen fixation in soybean(Glycine max L.)at glassroom condition.The results showed that P deficiency restrained nodule growth which embody in nodule dry weight declined and nodule number decreased than that of normal P supplying,meanwhile,P deficiency significantly decreased nitrogen fixation capacity of soybean which embody in nodule nitrogenase activity and leghemoglobin concentration remarkably decreased than that of normal P supplying.P deficiency reduced nitrogen fixation quantity which increased with phosphorus concentration,and the trend was rising first and then declining,finally going up with the growing stages of soybean.There is significant difference between no P(0 mol·L-1)and high P(50 mol·L-1)treatment,and low P and high P(30 mol·L-1)treatment(P5%).Therefore,P deficiency restrained nitrogen fixation in soybean and then made the efficiency of nitrogen fixation declined.