EVALUATION OF PLANT GROWTH PROMOTING BACTERIA FOR INDUCING STRESS TOLERANCE IN PLANTS AGAINST PETROLEUM HYDROCARBONS

Petroleum hydrocarbons are among the most common recalcitrant group of organic pollutants. Use of plants in association with microorganisms for degradation of petroleum hydrocarbons is an innovative and publically accepted green technology. Twenty seven bacterial isolates possessing bioremediation potential and ACC-deaminase activity were assessed for plant growth promotion with alfalfa, maize and canola. Out of 27 bacterial isolates 8 were further used in pot experiment with alfalfa, maize and canola grown on sand bearing 10000 mg kg(-1) petroleum hydrocarbons contamination. Sixty days after sowing, the plants were harvested and various growth attributes such as plant height, root length and biomass production were recorded. The results revealed that bacterial inoculation induced stress tolerance in plants as compared to un-inoculated control. Bacterial inoculation compensated the reduction in growth by their plant growth promoting activity. It was observed that bacterial isolate PM32Y was the most efficient that caused 63%, 77% and 66% increase in root length of alfalfa, maize and canola, respectively as compared to un-inoculated control. The same bacterial isolate increased plant height by 59%, 63% and 59% of alfalfa, maize and canola, respectively. The study concluded that the bacterial inoculation induced stress tolerance in all three crops as compared to un-inoculated control and thereby converged use of plants and bacteria can be more successful tool for remediation of petroleum contaminated soil.