Pseudomonas aeruginosa strain PS1 enhances growth parameters of greengram [Vigna radiata (L.) Wilczek] in insecticide-stressed soils

Plant growth promoting rhizobacteria (PGPR) are known to increase growth and vigor of legumes in conventional cropping systems. Considering this as a basis, this study was aimed at identifying phosphate-solubilizing (PS) rhizobacterial strains expressing higher tolerance to insecticides, fipronil and pyriproxyfen, and synthesizing plant growth regulators even amid insecticide stress. The impact of selected rhizobacteria endowed with multitude of activities was investigated on greengram, grown in soils treated with different concentrations of insecticides. The fipronil and pyriproxyfen tolerant Pseudomonas aeruginosa strain PS1 produced plant growth promoting substances, both in the presence and absence of the insecticides. Both insecticides at recommended and higher rates, in general, had phytotoxic effects and decreased phytomass, symbiotic properties, nutrients uptake, and seed yield of greengram plants. Interestingly, P. aeruginosa PS1 even when used with all concentrations of the two insecticides significantly increased the measured parameters at 50 and 80 days after sowing, compared to the plants grown in soils treated with the same concentration of each insecticide but without inoculants. P. aeruginosa PS1 can be used as biofertilizer to augment the growth of greengram exposed to insecticide-stressed soils.