Isolation of phosphate-solubilizing microorganisms from wheat rhizosphere and evaluation of the their solubilizing potential in presence of two insoluble phosphate sources

Phosphorus (P) is one of nutrient elements for plant growth. In most soils P has complex behavior and forms sparingly soluble and insoluble compounds with soil particles. Phosphorus bioavailability can be controlled by soil biological activities for optimum nutrition of plants. This study was carried out in order to isolation of P-solubilizing bacteria (PSB) as well as P-solubilizing fungi (PSF) and their screening in terms of P solubilizing potential in presence of tricalcium phosphate (TCP) and rock phosphate (RP). A total of 55 soil samples were taken from the wheat rhizosphere of Urmia region, and the isolation as well as qualitative solubilizing potential was done in solid NBRIP media. Quantitative P-dissolution ability of isolated strains were assessed in a factorial experiment based on completely randomized design including phosphate sources (RP and TCP) and selected microbial isolates at incubation condition at 28 degrees Celsius. The studied strains included control, PSB45, PSB15, PSB30, PSB2, PSB11, PSB12, PSB20, PSF1, PSF3, PSF4 and PSF7 and sampling were done at seven incubation times (0, 1, 3, 6, 9, 12 and 15 days). The results showed that P solubilization and pH of medium significantly (P