Abstract

Drought severely constrains maize productivity, necessitating sustainable strategies to enhance crop resilience. In this study, drought-tolerant rhizobacteria were isolated from the rhizosphere of maize grown in Mau district (Uttar Pradesh, India). Among 90 isolates, two strains, MD-7 and MD-18 are strains of Bacillus vallismortis and Bacillus mycoides, respectively, and tolerated high temperature (45°C), osmotic stress (10–30%), and salinity (5– 15%). The effects of these isolates on maize were evaluated in a greenhouse pot experiment under well-watered and drought stress conditions. MD-18 exhibited stronger plant growth-promoting traits than MD-7, including phosphate solubilization, siderophore, exopolysaccharide, indole-3-acetic acid, ammonia, and gibberellic acid production. Inoculation with B. vallismortis MD-7 and B. mycoides MD-18 significantly increased maize root and shoot length, leaf area, chlorophyll content, and activities of catalase, peroxidase, superoxide dismutase, and proline accumulation under drought stress. These results indicate that B. mycoides MD-18, in particular, is a promising bio-inoculant for mitigating drought stress and improving maize growth.

Key words: Zea mays, Bacillus vallismortis, Bacillus mycoides, PGPR, Drought Stress, Catalase, Exopolysaccharides, Proline.