Flowering-stage reinoculation with Priestia aryabhattai mitigates water deficit in grain sorghum: impact on agronomic performance and irrigation water productivity

Although grain sorghum [ Sorghum bicolor (L.) Moench] is recognized for its tolerance to water deficit, drought conditions can compromise crop growth and yield performance. In this context, bio-inputs based on Priestia aryabhattai emerge as a promising alternative to mitigate the effects of drought stress. However, studies evaluating the use of this rhizobacterium in sorghum are still scarce, especially regarding reinoculation strategies during reproductive stages. Thus, this study evaluated whether reinoculation with P. aryabhattai during flowering could enhance root development, grain production, and irrigation water productivity of grain sorghum under water limitation. The experiment was conducted in a greenhouse, using a randomized block design in a 3 × 3 factorial arrangement, consisting of three water regimes based on soil available water capacity (AWC) [85% (no water deficit), 50% (moderate deficit), and 30% (severe deficit)] and three biological management systems [no inoculation (treatment control), seed inoculation, and reinoculation via seed + soil application at flowering]. Under water restriction, treatment control plants showed reduced root development and shoot biomass. However, P. aryabhattai application partially mitigated these effects. Reinoculation promoted up to an 81% increase in the number of grains per plant under severe deficit. Under 85% AWC, reinoculation increased grain production by 55% compared with seed inoculation and by 66% compared with the non-inoculated control, while increasing residual dry mass by 30%. Reinoculation also enhanced irrigation water productivity, reaching 10.16 kg m⁻³ under 85% AWC. These findings suggest that flowering-stage reinoculation with P. aryabhattai may represent a promising bio-input strategy to improve sorghum performance under water-limited conditions. However, field studies are still required to validate these responses under commercial production conditions.