Bacillus Haynessi, B. Aryabhattai E B. Circulans COMO ALIADOS NA ATENUAÇÃO DO ESTRESSE HÍDRICO EM PLANTAS DE MILHO (Zea Mays L.)

Abstract

Drought is a major abiotic stress that affects the development and productivity of many agricultural crops, especially maize (Zea mays L.). Several studies have been conducted on microorganisms that enhance drought tolerance under water deficit (WD) conditions. However, as far as we could determine, no product contains these three Bacillus species involved in mitigating damage caused by WD, particularly in protecting leaf cells against water stress. Therefore, the objective of this study was to evaluate how a microbiological activator (a bio-input) containing Bacillus haynesii, B. aryabhattai, and B. circulans influences the physiology and water relations of maize plants in response to drought.The experiment was conducted at IF Goiano, Rio Verde Campus, where maize seeds were sown and maintained at field capacity (FC) until the V8 growth stage. At this point, they were subjected to two water regimes (full irrigation or water deficit) and treated (inoculated) with bacteria at different times during the drought period. The experimental design was a completely randomized design (CRD) with five replicates and seven treatments, including: T1: CT (Control); T2: WD (Water deficit); T3: WD + SA (microbiological activator applied to the seed); T4: WD + SA + FA (pre_120h) (foliar pre-treatment applied before drought); T5: WD + SA + FA (pre_48h) (foliar activator applied two days after drought onset); T6: WD + SA + FA (pre_72h) (foliar activator applied three days after drought onset); T7: WD + SA + FA (pre_120h) (foliar activator applied five days after drought onset). On the tenth day of drought, measurements were taken for water potential, water content, gas exchange, chlorophyll indices, electrolyte leakage, and biomass. Drought negatively affected plant physiology, but the addition of bacteria improved water status, maintained photosynthesis, and preserved membrane integrity, with the most significant effects observed in the foliar pre-treatment applied 120 hours before drought onset.