INVITRO SELECTION OF PHOSPHATE SOLUBILIZING BACTERIA AND THEIR ROLE IN PLANT GROWTH PROMOTION

Phosphate solubilizing bacteria (PSB) are known to be able to solubilize different forms of inorganic phosphates. A total of twenty four phosphate Solublizing bacterial colonies were isolated on the Pikovskaya’s (PKV) agar medium, containing insoluble tri-calcium phosphate (TCP), from different pond water sediment sample in and around Tirunelveli district, Tamil Nadu, India. The colonies showing clear halo zones around the bacterial growth were considered as phosphate solubilizers. Out of 24 bacterial isolates, 6 isolates showing highest phosphate solubilisation index (SI) ranged from 1.6-2.5 were selected for the further study as qualitative as well as quantitative estimation of phosphate. Among these 6 potent isolates, Bacillus sp PSB6 showed the maximum phosphate solubilization index of 2.5 in Pikovskaya’s agar plates. A pot culture experiment was conducted to investigate the effects of isolated PSB on early development of plants. Seeds were treated with bacterial strain, and seedlings were harvested 5weeks after inoculation. Pots treated with strains showed a positive effect on plant growth. A significant increment in plant shoot, Root height (21.49, 08.64 cm) and dry weight of Shoot and Root (2.39, 2.21 cm) were determined in plants treated with Bacillus licheniformis (PSB6) has remarkably increased compared to the uninoculated control. This growth promoting action was confirmed by the molecular analysis of genomic DNA by RFLP technique