Differential nitrogen demand in maize under high and low planting densities

Dynamic synchronization of nutrient supply demand across maize ( Zea mays ) developmental stages constitutes the pivotal agronomic leverage for yield optimization. For modern high-yield hybrid maize, the regulatory mechanisms by which planting density and nitrogen application rate affect nitrogen accumulation and translocation dynamics under drip fertigation with split nitrogen application remain unclear. In this study, we investigated the nitrogen accumulation and absorption characteristics, as well as the yield and yield components, of high-yield (≥ 20 t ha -1 ) maize cultivars under different planting densities and nitrogen application rates delivered through integrated drip irrigation and fertilization. Specifically, Denghai 618 and Xianyu 335 were grown at 7.5 × 10 4 or 12.0 × 10 4 plants ha -1 and supplied with 0 or 360 kg ha -1 of nitrogen fertilizer. Increasing the planting density increased the grain yield by 5.1%, which was mainly achieved by increasing the number of ears. Increasing the fertilization rate increased the grain yield by 40.3% by increasing the 1000-grain weight. Increasing the nitrogen fertilizer rate significantly increased the contribution of nitrogen accumulation after anthesis to grain nitrogen accumulation and enhanced the pre-anthesis translocation quantity and efficiency of leaves and stems. High planting density notably increased the contribution of nitrogen translocation before anthesis to grain nitrogen content and promoted nutrients recycling from leaves and stems. Compared with a planting density of 7.5 × 10 4 plants ha -1 , 12 × 10 4 plants ha -1 enabled maize to have a higher nitrogen uptake rate during the V15∼R1 stages. Under drip fertigation conditions, after increasing planting density, synchronizing nitrogen management with crop growth stages can significantly improve nitrogen fertilizer utilization efficiency, nitrogen uptake amount, and nitrogen translocation efficiency, thereby enabling a stable increase in maize yield. In this study, we examined how high-yield maize cultivars (producing ≥ 20 t ha -1 ) absorb and accumulate nitrogen and how this affects their yield and yield components, under different planting densities and nitrogen application rates. • Nitrogen fertilization significantly boosted Pre-NT Pre-anthesis transport and Post-NU Post-anthesis accumulation. • At 12 × 10 4 plants ha -1 , the yield correlation with leaf Pre-NT and Pre-NTE was heightened. • Pre-silking, 12×10 4 plants ha -1 has a higher nitrogen uptake rate.