Phosphorus enhances maize yield resilience by sustaining source function and sink activity under post‐silking source–sink imbalance

Abstract BACKGROUND Enhancing maize yield resilience under post‐silking stress is essential for stable production. Most previous studies have examined the effects of phosphorus (P) on source‐ or sink‐related traits separately under normal growing conditions, whereas quantitative assessments of the extent to which P mitigates yield loss under post‐silking source–sink imbalance remain limited. A 2‐year field experiment was conducted in Xinjiang, China, using two P application rates (0 and 150 kg P 2 O 5 ha −1 ) combined with post‐silking defoliation (L1–L3) and ear‐removal (E1 and E2) treatments to simulate source limitation and sink restriction, respectively. RESULTS Under defoliation‐induced source limitation, P application significantly increased ear‐leaf net photosynthetic rate, delayed leaf senescence, and improved grain‐filling performance, with the buffering effect becoming stronger as defoliation severity increased. Accordingly, yield loss was significantly reduced, and the yield‐buffering capacity of P increased from 19.39% to 37.76% with increasing defoliation intensity. Under ear‐removal‐induced sink restriction, P fertilization maintained higher photosynthetic performance and enhanced the grain filling of the remaining kernels, thereby increasing 100‐grain weight. As a result, grain yield under P application was 15.93–18.39% higher than that under P deficiency at the same sink‐restriction level. Across both source‐ and sink‐limited conditions, P fertilization also maintained greater aboveground dry matter accumulation, indicating a better overall growth status under post‐silking stress. CONCLUSION Phosphorus fertilization enhanced maize yield resilience under post‐silking source–sink imbalance by sustaining photosynthetic source capacity and supporting grain sink activity during grain filling. Its beneficial effect was more pronounced under source limitation than under sink restriction. These findings indicate that adequate P nutrition helps stabilize yield formation mainly through coordinated regulation of source function and sink performance under post‐silking stress. © 2026 Society of Chemical Industry.