Response of Maize to Inoculation with Azotobacter under Drought Stress Conditions

A wide range of Iranian agricultural lands is located in arid and semi-arid regions and, hence, crops face some drought stress. Therefore, sustained agricultural production is important in these circumstances. Azotobacter is a molecular-nitrogen-fixing bacterium, which promotes plant growth by various mechanisms and may provide drought resistance. Inoculation of crops with superior bacterial isolates compatible with dry areas may increase plant tolerance to drought stress. In this study, the effect of inoculation of native isolates of Azotobacter isolated from arid and semi-arid regions of Iran under drought stress conditions was investigated on the growth of maizesilage cultivar i.e. Single Cross 704, in greenhouse conditions. The experiment was conducted as a completely randomized block design (RCBD) with three replications including inoculations with 15 Azotobacter isolates, blank (no inoculation and no drought stress), control (no inoculation but with drought stress). In order to apply drought stress by weighing method, soil moisture content in the vegetative stage was allowed to drop to 40-50% of allowable moisture depletion, and at flowering stage to harvesting, a range of 50-60% was maintained. The results showed that drought stress significantly decreased shoot dry weight, plant height, and dry weight of corncob compared to non-stress control. Inoculation with Azc10 resulted in a significant increase in the shoot dry weight compared to the control. This isolate increased the shoot yield by about 20% compared to non-inoculated treatment under drought stress conditions.