An evaluation of phosphorus uptake in Sesbania cannabina when ferric phosphate is applied in the presence of phosphate-solubilizing rhizobia

Deficient available phosphorus (P) in soils can majorly limit crop production. Furthermore, nodule formation in legumes is inhibited in P-deficient soil. Phosphate-solubilizing rhizobia are supposed to improve the plant P uptake even in insoluble P accumulated soil. We investigated the utilization of insoluble ferric phosphate, which is generally less available for agricultural crops, by Sesbania cannabina inoculated with phosphate-solubilizing rhizobia. Our evaluation of the P-solubilizing capacity showed that P was mineralized from ferric phosphate in inoculated rhizobia. In the soluble P treatment, nodule dry weight was significantly correlated with shoot dry weight and P content. Nodule dry weight and nitrogenase activity in S. cannabina supplied with ferric phosphate were significantly higher than those in the soluble P treatment. But, these increases were not necessarily effective on P status in the plants supplied with ferric phosphate.