Maize stover mulching combined with an optimized fertilization strategy reshapes rhizosphere microbial communities and functions in greenhouse potato

Protected cultivation systems offer opportunities for improving potato productivity but are often constrained by inefficient maize stover utilization and suboptimal fertilization practices. In this study, a 4 × 4 factorial experiment was conducted using the potato cultivar ‘Jishu No. 1’ to decode the rhizosphere microbial mechanisms underpinning plant growth and yield enhancement under greenhouse conditions. We hypothesized that integrated management (the synergy between stover mulching and fertilization) would modify the soil microenvironment, thereby reshaping microbial community assembly patterns and functional gene distributions. The results showed that while split fertilization combined with moderate stover mulching (F2S2, 8,500 kg·hm−2 stover mulching) was most effective in enhancing plant physiological status, full topdressing combined with the same mulching level (F3S2) achieved the highest agronomic productivity, increasing total yield to 42.33 t·hm−2. Metagenomic analysis revealed that the F3S2 strategy significantly reshaped the rhizosphere microbiome, characterized by higher α-diversity and the enrichment of pathways related to carbon metabolism and carbohydrate processing. Notably, F3S2 promoted the recruitment of copiotrophic taxa, particularly Actinobacteriota, whose relative abundance was significantly and positively correlated with soil organic phosphorus (r = 0.623, p < 0.05). In contrast, oligotrophic groups like Acidobacteriota were relatively less abundant in nutrient-rich treatments. These findings demonstrate that moderate stover mulching combined with dynamic fertilization provides a high-resource niche that favors functional microbial groups, thereby driving rhizosphere nutrient cycling to support potato performance. This study underscores the importance of optimized stover and fertilizer management strategies in protected cultivation.