Pantnagar Journal of Research

Abstract

Maize (Zea mays L.) is a vital global food crop, but drought severely limits its productivity. This study evaluated the potential of a drought-tolerant plant growth-promoting bacterium (PGPB), Serratia sp. SRK14, to enhance maize performance under water-limited conditions. The isolate exhibited strong plant growth–promoting traits, including efficient solubilization of zinc (117.24±2.00%), phosphate (136.28±1.88%), and potassium (172.34±0.64%), high siderophore production (136.49±2.63%), and positive indole-3-acetic acid production, indicating its potential to improve nutrient availability and root development. Under polyethylene glycol (PEG-6000)–induced osmotic stress (10–40%), SRK14 maintained appreciable growth up to 30% PEG, demonstrating tolerance to moderate drought stress. Greenhouse evaluation of maize under drought at 45 days after sowing revealed that SRK14 inoculation significantly enhanced plant growth compared with uninoculated controls. Shoot length, shoot fresh weight, and shoot dry weight increased by 9.38%, 49.04% and 9.52%, respectively. Root growth was markedly improved, with increases of 42.86% in root length, 23.53% in root fresh weight, and 24.78% in root dry weight. Inoculated plants indicating better tissue hydration and membrane stability reflected through increased relative water content (46.7%) and reduced relative electrolyte conductivity (30.17%). Additionally, SRK14 enhanced stress mitigation through increased catalase activity (11.49 µmol min^-¹ g^-¹ FW) and proline accumulation (19.50 mol g^-2 FW). The present study demonstrates that Serratia sp. SRK14 combines strong PGP traits, stress tolerance, and protective effects on plant physiology, highlighting its promise as a bioinoculant for improving maize performance under water-limited conditions.