Improvement of wheat phosphorus nutrition using phosphate solubilizing bacteria

Phosphorus (P) is one of the most important nutrient elements for plant growth and it is usually considered as second limiting factor for growth of plants after nitrogen. Phosphate‏ solubilizing microorganisms (PSM) play major roles for supplying soluble phosphate to plants in a more environmental-friendly and sustainable manner. To evaluate the effect of phosphate solubilizing bacteria inoculation on growth of spring wheat cv. "Roshan" and also phosphorus uptake, a greenhouse experiment was conducted in sterile loamy soil in a completely randomized design with three replications. Four bacterial treatments were Pseudomonas putida P13 (P13), Pantoea agglomerans P5 (P5), Pseudomonas fluorescence CHAO (CHAO) and combination of P13+P5 and without inoculation as control. Data analysis on the fresh and dry weight of shoot (in the middle and end of growth), number of spikes and seed, weight of seed, concentration and content of P in shoot (in the middle and end of growth) and seed showed that bacterial treatments increased P concentration and content of wheat shoot (P<0.01), and combination of P13+P5 treatment resulted in highest concentration and content of P. Maximum increase of P concentration and content in shoot (1.8 and 1.14 fold in comparison with control, respectively) were observed in combination of P13+P5 treatment. Application of bacterial treatment did not have any increasing effect on dry matter, even though some parameters such as number of spikes, number of seed and weight of seed in some bacterial treatments (CHAO and P5) had high record compared to the control. Highest record of thousand grain weights was obtained in presence of P13+P5. However, the measured parameters such as fresh and dry weight of wheat and also P concentration and content in the middle of growth were not affected by application of bacterial inoculation. According to the results of this experiment we should expect to see the positive effect of PSM inoculation at the end of wheat growth since in the middle of growth no positive effect of PSM in wheat growth was distinguished.