Influence of phosphorus fertilization and Bradyrhizobium japonicum inoculation of soybean onactivities of acid phosphatases in roots and rhizosphere soil under phosphorus and water limited conditions

Abstract

A pot experiment was conducted to examine the impact of Bradyrhizobium japonicumrhizobacteria along with P fertilizer on the activity of acid phosphatases (APase)in roots and rhizosphere soil of soybean under phosphorus and water limited conditions. Non-inoculated and inoculated soybean plants (cv Horboveanca)were supplied with three levels of P: 0 mg P/kg soil, (P0, insufficiency P), 20 mg P/kg (P20, medium) and 100 mg P/kg (P100, sufficient). At the flowering stage a set of plants was subjected to moderate drought stress for 12 days. Experimental results have shown that the root enzyme activity was much higher in the treatment without fertilization compared to those fertilized with phosphorus irrespective of soil moisture level. Inoculated plants with B. japonicum exhibited greater acid phosphatases activity in roots than non-inoculated plants. The same trend was observed in soil acid phosphatase activity under well-watered and water deficit conditions.