Effects of phosphorus fertilizers and phosphorus-solubilizing rhizosphere bacteria on soil fertility, phosphorus uptake, growth, and yield of sesame (Sesamum indicum L.) cultivated on alluvial soil in dike

Abstract

The low phosphorus use efficiency (PUE) and the high P fertilizer cost are reasons why it is necessary to find sustainable phosphorus (P) sources for sesame, in which bacteria are potential candidates. The aim of this study was to determine a level of the applied P fertilizer and P-solubilizing rhizosphere bacteria (PSRB) for the maximum growth and yield of sesame. A two-factor experiment was conducted in a completely randomized block design. The first factor (i) was the P fertilizer rate, including 0%, 50%, 75%, and 100% P of the recommended fertilizer rate (RFR); the other was (ii) the supplementation of the PSRB, including no supplemented bacteria, a single strain of Enterobacter asburiae ASD-56, ASD-15, or ASD-43, and the mixture of all the three strains, with five replications. The results revealed that fertilizing with 100% P of the RFR enhanced means of the plant height (5.4 cm), the number of capsules (4.4 capsules plant−1), the total P uptake (34.3 mg P pot−1), and the sesame seed yield (16.4 g pot−1) in comparison with the case with no P fertilizer. The supplementation of the E. asburiae ASD-56, ASD-15, and ASD-43 improved values of the soluble P in soil, the total P uptake in plants, and the seed yield at 82.6 mg P kg−1, 73.1 mg P pot−1, and 15.2 g pot−1, respectively, compared with 72.2 mg P kg−1, 45.5 mg P pot−1, and 10.6 g pot−1 in treatment with no supplemented bacteria. Individually or aggregately applying the three E. asburiae ASD-56, ASD-15, and ASD-43 strains not only reduced the average amount of the P fertilizer used by 25–50% P of the RFR but also increased the P uptake in plants by 8.50–36.9% and the average sesame seed yield by 2.94–58.7%, in comparison with those in the treatment fertilized with 100% P of the RFR. The mixture of the PSRB contributed to reducing 50% of the RFR, and increasing the yield by 43.4%.