Diversified crop rotations strengthen maize drought tolerance via rhizosphere microbiota and enzymes activities

Although diversified crop rotations raise drought tolerance and system productivity, the underlying mechanisms within the crop–soil system that confer this resilience remain incomplete.The drought tolerance mechanisms of maize grown under a 20–year field experiment encompassing low, medium, and high crop diversity rotations was evaluated by combining soil zymography and high–throughput sequencing.Crop diversification increased maize biomass by 56–87% and mitigated the drought stress by 14.1-58.8%. It also reinforced root diameter stability7–2.5 times and drought tolerance 2.2–2.7 times, which linked to drought tolerance of rhizosphere microbiota. The complexity of the rhizosphere bacterial network increased with crop diversification, and the keystone taxa like biofilm–producing Pseudomonas demonstrated bolstered drought tolerance. These microbiota help stabilize niches and habitats under drought, thereby raising rhizosphere’s stress tolerance and the ecosystem's provisioning and regulatory functions. Enzyme activities and hotspot areas decreased in soils with crop diversification, but has minimal changes with drought systems, suggesting that enzymes may not directly control plant drought tolerance.Crop diversification enrich drought–tolerance soil microbial species that maintain rhizosphere microenvironment stability and facilitate root proliferation, underscoring the significance of optimizing crop–microbe interactions to bolster resilience against soil drought.