Rhizosphere soil organic acids closely coupled with core microbiota have functional significance in wheat productivity under optimized phosphorus fertilization

Enhancing plant capacity to acquire soil phosphorus (P) is crucial for reducing fertilizer input without compromising yield. Based on soil P availability, plants orchestrate their P acquisition strategy along morphological, symbiotic, and rhizochemical axes, most notably via the exudation of organic anions and the remodeling of rhizosphere microbial communities that facilitate P mobilization. However, how rhizosphere organic acids and microorganisms relate to wheat P uptake under optimized P fertilization remains unclear. Here, a field experiment with winter wheat at three P fertilizer levels (0, 70, and 120 kg P 2 O 5 ha −1 yr −1 ) was conducted to study the effects of rhizosphere organic acids and microorganisms on rhizosphere soil P fractions conversion and wheat P uptake at the greenup (GP), elongation (EP), and flowering (FP) stages. The results showed that P addition significantly increased the content of rhizosphere soil TP, AP, Pi, NaHCO 3 -Pt, and NaHCO 3 -Pi fractions ( p < 0.05). However, P fertilization reduced the concentrations of most organic acids at the GP and EP stages, as well as rhizosphere bacterial richness and Shannon index across growth stages. Compared with the P120 treatment, the optimized P input (P70) exhibited no significant reduction in yield or aboveground biomass, while markedly enriching core microbial taxa (e.g., Gammaproteobacteria, Actinobacteria). These microbes were significantly correlated with rhizosphere soil P fractions and wheat P uptake. Overall, this study elucidated the response patterns of core microbial taxa and organic acids in the wheat rhizosphere under optimized P fertilization on the Loess Plateau and provides new perspectives for P management in drylands.