PGPR-AMF consortia improve drought tolerance in maize through stomatal regulation, antioxidant defense, and yield...

Water deficit is a major abiotic constraint on maize productivity and is expected to intensify under increasing climate variability. This study evaluated whether inoculation with plant growth-promoting rhizobacteria (PGPR), arbuscular mycorrhizal fungi (AMF), or their consortium could mitigate moderate and severe water deficit in Zea mays.

A 4 × 3 factorial completely randomized design was implemented, comprising four inoculation treatments and three water regimes, with three biological replicates per treatment combination (36 experimental units). Physiological, biochemical, growth, and yield-related traits were jointly analyzed using two-way ANOVA, correlation analysis, and principal component analysis (PCA).

The first two PCA dimensions explained 54.0% of the total variance and separated a productivity-related axis, characterized by photosynthesis, chlorophyll status, relative water content, and yield, from an oxidative-stress axis dominated by malondialdehyde and proline. Under severe water deficit, the PGPR-AMF consortium maintained 10.7% higher relative water content and 19.5% higher yield than the non-inoculated control, while sustaining higher photosynthetic activity and lower oxidative damage. Two-way ANOVA revealed significant effects of inoculation treatment and water regime on yield, photosynthesis, relative water content, and SOD activity, whereas proline and MDA were primarily influenced by stress intensity.

The results demonstrate that PGPR-AMF inoculation mitigates drought effects in maize through coordinated maintenance of plant water status, gas exchange, antioxidant regulation, and productive stability. These findings support the use of microbial consortia as a sustainable strategy to enhance maize resilience under increasing water-limitation scenarios.