Acetylene Reduction Activity of Glycine max in Response to Inoculation, NPK Application, and Soil Environment

Summary Soybean ( Glycine max ) was grown under natural greenhouse conditions in a non-sterile pot culture system, containing either perlite or soil. Sandy calcareous soil and chernozem soil, 4 levels of nitrogen (0.0, 40, 80, and 160 mg N kg −1 soil), 2 levels of phosphorus (0.0 and 80 mg P kg −1 ), and 2 levels of potassium (0.0 and 200 kg kg −1 ) were used. The net values of acetylene reduction activity (ARA) were calculated as the difference between inoculated and non-inoculated plants. 40 mg N kg −1 soil was found to be an optimum dose in addition to either P or K or both together for stimulating the ARA of soybean plants. Rates of ARA were closely related to soil environment and responded to NPK application.