Promoting winter wheat sustainable intensification by higher nitrogen distribution in top second to fourth leaves under water-restricted condition in North China Plain

Improving winter wheat yield and resource utilization efficiency (i.e., sustainable intensification) under water-restricted condition is crucial for ensuring food security in arid regions such as the North China Plain. Developing more effective cultivation measures is one of the directions to achieve sustainable intensification. This study was a two-year cultivation experiment in the North China Plain, aimed to explore the effects of the combination of water-fertilizer coupling and various planting densities at early (October 10, D10), optimum (October 17, D17), and delayed (October 24, D24) sowing dates. As a consequence, we proposed a limited-irrigation and high-yield cultivation pattern that included 15 m3 ha−1 chicken manure, 192 kg ha−1 nitrogen (N), 138 kg ha−1 P2O5, 112.5 kg ha−1 K2O, and irrigated twice, while the limited-irrigation and low-yield cultivation pattern (similar to regional farmers' average yield) irrigated once. Compared to the limited-irrigation and low-yield treatment, the limited-irrigation and high-yield treatment increased yield, water use efficiency, and partial factor productivity from applied N by about 22.4%, 11.4%, and 23.0%, respectively. The limited-irrigation and high-yield treatment increased the nitrogen distribution in top second to fourth leaves, while decreasing it in glume, top first stem, and top second stem at filling stage, which contributed to higher yield and resource use efficiency. As such, pursuing higher nitrogen distribution in top second to fourth leaves at filling stage is an effective direction for sustainable intensification under water-restricted condition. These results will provide cultivation measures for winter wheat sustainable intensification in arid regions, and found a theoretical basis for elaboration of water-fertilizer coupling effect on the accumulation and distribution of dry matter and nitrogen in wheat plants.