Determination of phosphate solubilization and plant growth promotion of bacterial isolates from paddy rhizosphere

A study investigating bacterial isolates having inorganic phosphate solubilization along with plant growth promoting abilities was attempted. The isolates were from different paddy rhizosphere soil samples of Salem region. A total number of 34 bacillary isolates were successfully isolated from 315 morphologically distinct colonies and evaluated for their ‘P' solubilization ability. The colonies showing clear halo zones (≥ 2mm) around them, on the Pikovskaya agar medium containing Tri-calcium Phosphate (TCP) were selected as phosphate solubilizers. Among these isolates 11 strains (BMERF-PSB3, BMERF-PSB4, BMERF-PSB7, BMERF-PSB8, BMERF-PSB12, BMERF-PSB14, BMERF-PSB16, BMERF-PSB19, BMERF-PSB20, BMERF-PSB23 and BMERF-PSB25) had shown superior (≥ 5-29 mm) phosphate solubilization ability. Among these 11 superior (32%) PSB isolates, 4 (12%) (BMERF-PSB3, BMERF-PSB7, BMERF-PSB16 and BMERF-PSB19) were found to be having plant growth promoting characteristics by producing Auxin.