Characterization of the mineral phosphate solubilizing activity of fluorescent Pseudomonas sp. isolated from rhizosphere of apple

Phosphate is one of the most vital macronutrient required for the growth and development of plants. The ability of rhizospheric microorganisms to convert insoluble forms of phosphorus to an accessible form is an important trait in plant growth-promoting bacteria for increasing plant yields. In this study, isolation, screening and characterization of phosphate solubilizing bacteria (PSB) from apple rhizosphere was carried out. A total of ten PSB were isolated on the Pikovskaya's agar medium, containing insoluble tricalcium phosphate (Ca₃ (PO₄)₂ and were screened for multifarious plant growth promoting activities. The amount of P solubilized varied between all the isolates (212.5 to 550 μg/ml). The highest P solubilisation was observed by isolate M4 (550 μg/ml). The isolate M4 also showed antagonism against Dematophora nectarix (38.46%) and Phytopathora cactoram (36.18%) and can also act as Biostimulant. Identification and characterization of soil PSB with multifarious plant growth promoting activities broadens the spectrum of phosphate solubilizers available for field application.