中文摘要：

提高氮肥利用效率是当前小麦生产中重要的研究方向之一。本研究以光明麦1号为试验品种,利用两年的田间试验结果,采用二次正交旋转组合设计建立回归模型,分析稻茬小麦的氮肥当季表观利用率（utilization rate of nitrogen fertilizer,NUR）受播期、密度、施氮量组合的调控效应。结果表明,对小麦NUR效应表现为氮肥〉播期〉密度。在试验条件下,实现高产和高NUR目标,三因素有多种组合模式,其中播期10月28日至11月2日＋密度160~180万株hm–2＋施氮量200 kg hm–2的组合,其产量为6800~7200 kg hm–2,NUR大于42.0%（最大值为44.8%）,可靠度达到95%;播期10月21日至27日＋密度120~150万株hm–2＋施氮量190~225 kg hm–2组合,其产量为6200~7000 kg hm–2,NUR达41.0%以上;播期11月3日至11日＋密度210~240万株hm–2＋施氮量190~210 kg hm–2组合,其产量为5900~7250 kg hm–2,NUR达39.0%以上。

英文摘要：

Improvement of utilization rate of nitrogen fertilizer（NUR） is one of research focuses in wheat. In a two-year field experiment, the NUR of wheat variety Guangmingmai 1 in the wheat–rice rotation system in response to sowing date（S）, density（D）, and nitrogen application rate（N） was studied using a mathematical model based on quadratic regression rotation-orthogonal combination design. Among the three factors, nitrogen application rate had the greatest effects on NUR, followed by sowing date and density. Several S＋D＋N combinations resulted in high yield and high NUR under the experimental conditions. The highest yield level（6800–7200 kg ha–1） was obtained in the combination of S between October 28 and November 2, D between 1.6 and 1.8 million plants per hectare, and N at 200 kg ha–1. Simultaneously, the NUR was higher than 42.0%（the maximum was 44.8%） with a credibility larger than 95%. At the yield level of 6200–7000 kg ha–1 and NUR higher than 41.0%, the optimal S, D and N were 21–27 October, 1.2–1.5 million plants per hectare and 190–225 kg ha–1, respectively. At the yield level of 5900–7250 kg ha–1and NUR higher than 39.0%, the agronomic practices were recommended to be S between November 3 and November 11, D between 2.1 and 2.4 million plants per hectare, and N between 190 and 210 kg ha–1.