Improving drought resilience in maize through a soil-applied prebiotic: effects on plant physiology and rhizosphere microbial function

• Soil-applied prebiotic increased maize height under drought stress by 18.3%. • Prebiotic treatment enhanced bacterial abundance in soil under drought. • Rhizospheric enzymatic activity was stimulated by prebiotic application. • Soil metabolic potential was elevated following prebiotic amendment. • This soil applied prebiotic shows potential to mitigate drought effects. Drought stress is a major threat to Zea Mays L. productivity worldwide. Enhancing soil-plant interactions, via microbial stimulation, is one of the promising strategies to mitigate this stress. This study evaluated the effect of a soil-applied prebiotic on maize performance and soil microbial activity under severe drought stress. A greenhouse experiment was conducted with two water regimes: well-watered (70% water holding capacities, WHC) and severe drought (30% WHC), combined with two prebiotic treatments (with and without). Under severe drought, prebiotic-treated plants (SN) showed a significant increase in root dry weight (+31.1%), shoot biomass, and shoot length compared to untreated drought control (SC). Rhizospheric enzymatic activities involved in carbon and nitrogen cycling such as α-glucosidase, β-glucosidase, and N-acetyl-glucosaminidase were significantly higher in treated soils and positively correlated with root biomass. Community level physiological profiling using Biolog EcoPlates™ revealed enhanced metabolic potential of culturable soil bacteria in prebiotic-treated soils under both water regimes. Furthermore, bacterial 16S rDNA gene abundance increased by 17.9% in SN compared to SC, indicating stimulation of bacterial biomass under drought stress. These findings demonstrate that this soil-applied prebiotic enhances drought resilience in maize by improving plant growth and stimulating soil microbial activity, supporting its use as a sustainable strategy for maintaining crop performance under water limiting conditions.