Bacillus aryabhattai strain CMAA 1363 mitigates drought effects during the vegetative stage of maize and enhances post-stress productivity

Maize ( Zea mays L.) is highly susceptible to drought stress during its vegetative stage, which can lead to significant yield losses at later growth stages. Inoculation with Bacillus aryabhattai strain CMAA 1363 has emerged as a promising strategy to alleviate drought stress across various crops. This study aimed to mitigate drought stress during the vegetative stage of maize through inoculation with B. aryabhattai strain CMAA 1363 and to assess its subsequent effects on crop productivity following stress recovery. The study was conducted at the Campus Rural experimental farm of the Sergipe Federal University, Sergipe, Brazil. A randomized complete block design (RCBD) was adopted in a split-plot arrangement, with four replicates. The main plot factor consisted of water availability treatments—well-watered (100% ETc) and drought stress (50% ETc)—while the subplot factor consisted of the presence or absence of inoculation. Evaluations included relative water content (RWC), electrolyte leakage (EL), chlorophyll indices, chlorophyll a transient fluorescence (OKJIP), proline content, and the activity of antioxidant enzymes—superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX)—as well as morpho-agronomic and yield-related traits. Inoculation with the B. aryabhattai strain CMAA 1363 proved effective in alleviating drought stress, as demonstrated by increased RWC, reduced EL and proline content, and enhanced protection of the photosynthetic apparatus, including chlorophyll retention and improvements in the oxygen-evolving complex (OEC), PSII reaction centers (RC/ABS and RC/CS), and performance indices (PIabs and PIcs). These physiological enhancements led to improved morpho-agronomic characteristics and increased grain yield. Accordingly, B. aryabhattai strain CMAA 1363 modulates multifaceted drought-responsive mechanisms, contributing to greater productivity during the reproductive stage, even after drought exposure during the vegetative stage.