Phosphate solubilizing microorganisms isolated from medicinal plants improve growth of mint

The current research project involves isolation and characterization of PSM (phosphate solubilizing microorganisms) from the rhizospheric soil of certain medicinal plants and to determine their effect on plant growth. Medicinal plants, Aloe vera, Bauhinia variegata, Cannabis sativa, Lantana camara and Mentha viridis were selected for the isolation of PSMs. Soil status of the selected medicinal plants was also checked. Phosphate solubilizing bacteria (PSB) were observed under stereomicroscope for their morphological characteristics and Gram’s staining. Phosphate solubilizing fungi (PSF) were also identified microscopically. Colony diameter, halo zone diameter and solubilization index were determined on PVK agar plates. TLC results indicated that citric acid was the most common acid produced by PSM strains. All strains were found to be non-pathogenic in pathogenicity test. A positive plant growth response to PSM inoculation was observed in all studies. In study 1, individual inoculation of PSM showed a significant increased effect on plant growth parameter i.e., fresh and dry weight, plant height and root and shoot length as compared to control. In study2, composite inoculation of PSM along with different P sources revealed that rock phosphate (RP) with PSM increased growth of plants significantly. The present study suggests that PSM inoculation along with RP amendment can be used as biofertilizer.