Effect of Bacillus subtilis on phosphorus uptake by cucumber as affected by iron oxides and the solubility of the phosphorus source

In this work, we examined the effects of Bacillus subtilis strain QST713 by assessing plant P uptake from variably P compound .The experiment performed involved three factors: (i) P source [KH2PO4 at 100 mg kg–1, and phosphate rock (PR) at 100 or 200 mg kg–1]; (ii) plant inoculation with QST713 (inoculated and non-inoculated); and (iii) Fe oxide (ferrihydrite) in the growth medium (0 or 300 mg kg–1 concentration of citrate–ascorbate-extractable Fe). Ferrihydrite decreased dry matter yield in plants by more than 50 %. Inoculation with QST713 increased plant growth, and total accumulation of P and P uptake in plants. Overall, QST713 increased P uptake by 40 %, the effect being independent of the presence of ferrihydrite and P source. The increased P uptake observed can be ascribed to increased solubilization of P and to increased root growth. Therefore, QST713 improves P nutrition in plants grown on media with a high P adsorption capacity irrespective of the solubility of the P compound.