Influence of Plant Growth-Promoting Rhizobacteria on Maize Growth Under Drought Stress.

Water availability is major constraint affecting the growth and yield of agricultural crops worldwide. Some studies have shown that some free living bacteria found in the plant rhizosphere can improve the tolerance of plants to water stress under drought conditions. Here we report results from a greenhouse study that evaluated the effects of two mixtures of plant growth-promoting rhizobacteria (PGPR) on root establishment and biomass production of maize (Zea mays L.) during the early growth stages using two fertilizer sources under drought conditions. Treatments included three irrigation levels (watering every 3, 6, and 12 days), two fertilizer materials (poultry litter and urea) applied at 45 kg total N ha^-1, and two PGPR strain mixtures and a non-inoculated control. Irrigation significantly affected plant growth and biomass accumulation of maize at V6 to VT stages. Compared to poultry litter, urea application increased plant height, leaf greenness, leaf area, and plant biomass. PGPR significantly improved plant height, stem diameter, leaf greenness, and root morphologies under drought stress conditions. Therefore, PGPR inoculation could stimulate plant development likely through the production of plant growth regulators by bacteria at the rhizosphere, thereby enhancing root development, which results in better absorption of water and nutrients from the soil. Future research is needed to investigate the efficacy of PGPR on crop growth under nutrient and water limited conditions often experienced in agricultural fields.