Twelve Azospirillum isolates were isolated from the roots of rice plant collected from various places of Varanasi region. The isolates were purified and tested for their nitrogen fixation efficiency (nitrogen fixed mg g−1 of sodium malate) and growth parameters. Out of these isolates, one was selected on the basis of fast growth and better nitrogen fixation capacity. This isolate was tested for its effect on plant vigour grain yield and total biomass production along with standard biofertilizer strain (from IARI) on rice cultivars in pot experiment. Inoculation of Azospirillum isolate significantly increased the vigour of the rice plant, plant height, total biomass and root biomass per pot and grain yield per pot in comparison to their respective uninoculated control in all cultivars. The local isolate showed more increase in grain yield, total biomass and plant vigour than standard biofertilizer strain (IARI strain) on rice plant but the effect was not statistically significant. The increased root biomass and availability of more nutrients around root rhizosphere in the treated plants might have helped the rice plants to tolerate moisture stress more efficiently than uninoculated control during unfavorable conditions.
