The common bean (Phaseolus vulgaris L.) is a global staple, but to guarantee its provision, the crop water supply must be adequate, and bioinput application can benefit plants under drought. The objective was to evaluate the common bean’s response to bioinput application when it was cropped in soils with different water holding capacities submitted to a drought period. The greenhouse experiment used sandy loam and clayey soils. Seeds were sown, and 10 days after emergence (DAE), the treatments were applied: (i) no bioinput application or (ii) bioinput application (Priestia aryabhattai, re-applied at 46 DAE). The first plant growth evaluation was performed at 40 DAE. The irrigation maintained the crops’ needs until the beginning of flowering for all the treatments, when the irrigation was differentiated (for 10 days): (i) maintenance of irrigation or (ii) a drought period. A biochemical analysis was performed of superoxide dismutase activity [SOD], hydrogen peroxide [H₂O₂], peroxidase activity [POD], and malonaldehyde [MDA] production at 52 DAE. At 57 DAE, the second plant growth evaluation was performed, and the irrigation differentiation ended. Grain harvest followed physiological maturation. Priestia aryabhattai mitigated the drought stress in the common bean cropped in sandy soil by reducing the SOD, H₂O₂, and MDA production in comparison to no bioinput application. When it was cultivated in the clayey soil, the water availability was maintained for longer, reducing the plant’s dependency on bacteria for stress mitigation.

Water deficit represents a major environmental constraint that severely limits the growth and yield of common bean (Phaseolus vulgaris L.). Although inoculation with plant growth-promoting rhizobacteria (PGPR) has emerged as a promising strategy to mitigate drought-induced stress, the efficacy of specific strains, such as Priestia aryabhattai CMAA 1363, remains to be fully elucidated. This study evaluated the morpho-agronomic and biochemical responses of common bean to seed inoculation with P. aryabhattai CMAA 1363 under two contrasting irrigation regimes: 100% (well-watered) and 40% (water-restricted) of available water capacity (AWC) under greenhouse conditions. Water restriction significantly compromised plant performance, reducing plant and pod length, root dry biomass, and yield components (pod and grain counts, and total grain mass). Conversely, bacterial inoculation enhanced vegetative traits, increasing plant length by approximately 15% and root dry biomass by approximately 25% compared to non-inoculated controls. Notably, under severe water deficit (40% AWC), inoculated plants achieved a 20% increase in total grain mass per plant relative to their non-inoculated counterparts. Biochemical profiling indicated that inoculation effectively attenuated oxidative stress, as evidenced by lower malondialdehyde (MDA) accumulation and modulated superoxide dismutase (SOD) activity, while water-stressed plants adapted by accumulating total soluble sugars and increasing peroxidase (POD) activity. Overall, P. aryabhattai CMAA 1363 promotes vegetative development, preserves grain production under drought, and orchestrates antioxidant defense mechanisms, highlighting its potential as a sustainable bioinput to improve common bean resilience in water-limited agricultural systems.