In the present study, plant growth promoting rhizobacterial (PGPR) strains Pseudomonas fluorescence strain P2, Pseudomonas jessenii R62, Pseudomonas synxantha R81, Bacillus cereus BSB 38 (14B), Arthrobacter nitroguajacolicus strainYB3 and strain YB5 were tested for their role in enhancing plant growth and induction of stress related enzymes in Sahbhagi (drought tolerance) and IR-64 (drought sensitive) cultivars of rice (Oryza sativa L.) under different level of drought stress. PGPRs, P. jessenii, R62, P. synxantha, R81 were used as one consortium similarly A. nitroguajacolicus strainYB3 and strain YB5 were used as other consortia. Most of the PGPR inoculated plants showed enhanced growth as compared to uninoculated plants under all the level of drought stress. Quantitative analyses of antioxidant enzymes indicated that majority of the PGPRs inoculated plants in both varieties showed higher proline content, higher activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX) and lower level of hydrogen peroxide (H2O2), malondialdehyde (MDA) in leaves at all the level of drought stress. The study suggests that PGPRs alleviates oxidative damage in rice plants grown under drought by improving plant growth and activating antioxidant defense systems, thereby improving stability of membranes in plant cells. This study provides evidence for a beneficial effect of PGPRs application in enhancing drought tolerance of rice under water deficit conditions.
Key words: Plant growth promoting rhizobacterial (PGPR), plant growth promotion, drought stress, antioxidant, rice.