Nitrogen Inhibitors Enhance Photosynthetic Potential by Delaying Maize Leaf Senescence Under Fertigation

ABSTRACT Unreasonable nitrogen fertilizer use intensifies nitrogen losses, resulting in environmental contamination. Nitrification inhibitors and urease inhibitors are widely employed to reduce environmental pollution and enhance nitrogen use efficiency. However, under fertigation, the mechanism by which nitrogen cycle inhibitors improve dry matter accumulation and yield in summer maize by influencing physiological processes remains unclear. Consequently, a field experiment was conducted from 2020 to 2021 in the Huang‐Huai‐Hai region using a fertigation management system. The experiment included five treatments: no nitrogen application (N0), urea ammonium nitrate alone (U), urea ammonium nitrate with both urease and nitrification inhibitors (U‐DN), urea ammonium nitrate with a urease inhibitor (U‐N), and urea ammonium nitrate with a nitrification inhibitor (U‐D). Nitrogen was applied at a rate of 210 kg ha −1 , with nitrogen inhibitors added at 0.05% of the total nitrogen input. The study systematically evaluated the effects of different inhibitor applications on summer maize photosynthetic characteristics, antioxidant capacity, and grain yield. The results showed that, under fertigation, the combined application of nitrogen cycle inhibitors with urea ammonium nitrate optimized nitrogen supply during the crop's later growth stages. This enhanced leaf antioxidant enzyme activity, reduced malondialdehyde content by 19.7%, effectively delayed leaf senescence, enhanced photosynthetic potential and net assimilation rate during the grain filling stage, and promoted dry matter accumulation in the late growth stage, ultimately increasing summer maize yield by 13.2%. Overall, these findings indicated that nitrogen cycle inhibitors optimize the spatiotemporal effectiveness of nitrogen supply under fertigation, thereby enhancing late‐stage photosynthetic performance and dry matter accumulation through delayed leaf senescence, and provide practical insights for achieving high and stable maize yields through optimized nitrogen management.