Temperature-driven regulatory mechanism of dry matter accumulation and yield optimization in summer maize under mulched water–nitrogen coupling

Water and nitrogen are key factors limiting maize growth and yield formation, and optimizing water and nitrogen regulation is particularly important for improving the maize yield of farmland in semi-arid areas. In this study, the characteristics of “sandy water” in the irrigation area of the Yellow River Basin were combined. A two-year field experiment was carried out in 2023-2024 by using the muddy water film-hole irrigation technique. Logistic models were applied to investigate the dynamic accumulation characteristics of dry matter. We analyzed the effects of different sediment concentrations (3, 6 and 9 kg·m -3 ), irrigation volumes (0.50-0.65, 0.65-0.80, and 0.80-0.95 FC), and nitrogen application (120, 180, and 240 kg·ha -1 ) on dry matter accumulation and translocation in maize. The results showed that the logistic models for root dry matter (RDM) and shoot dry matter (SDM) of summer maize based on effective accumulation temperature were biologically significant ( R 2 =98.99%-99.99%, NRMSE=4.0%-13.12%). Medium water nitrogen supply T5 treatments (6 kg·m -3 , 0.65-0.80 FC and 180 kg·ha -1 ) significantly promoted dry matter accumulation, advanced the rapid growth phase of SDM, reduced the effective cumulative temperature required to reach the maximum growth rate, and the average growth rate was significantly higher than the other treatments. In addition, medium water nitrogen supply significantly increased soil organic carbon content and reduced nitrate nitrogen residues. T5 treatments significantly increased dry matter accumulation, translocation efficiency, agronomic efficiency of nitrogen (AE N ) and yield, with the highest post-anthesis dry matter accumulation and post-anthesis dry matter contribution to grain. Comprehensive TOPSIS evaluation showed that T5 treatment was the best water and nitrogen management strategy, which can provide a theoretical basis and technical support for high-yield and high-efficiency cultivation of maize in semi-arid areas. • T5 (6 kg·m -3 , 0.65-0.80 FC and 180 kg·ha -1 ) boosts maize yield by 19–21% compared to CK2 • T5 delays senescence, increasing post-anthesis assimilate contribution to grain • Shoot dry matter in T5 increases by 13.6% versus conventional water–N treatment • Logistic models capture maize growth dynamics across water–nitrogen regimes • T5 improves water productivity by 37–40% compared with CK2 treatment