Effect of Phorate on Phosphate Solubilization and Indole Acetic Acid Releasing Potentials of Rhizospheric Microorganisms

Twelve phosphate solubilizing bacteria (PSB) isolated from various rhizospheric soils were identified as Serratia (2), Pseudomonas (7) and Bacillus (3) and were examined for solubilization of phosphate and production of indole acetic acid (IAA). Both of the measured parameters varied considerably among the isolated PSB(s). Among the bacterial cultures, Serratia T2, showed greater solubilization of tricalcium phosphate (TCP) while Pseudomonas M4 produced maximum amounts of IAA. Further, an insecticide, phorate, was used to determine its effect on the phosphate solubilizing and IAA producing potential of the selected PSB(s). Phorate (100 & 500 mg ml-1) in general, stimulated the phosphate solubilizing activities of the selected bacteria whereas IAA production was significantly reduced.