Abstract Timely sowing is an important agronomic practice that ensures normal seed germination, stable seedling establishment and final yield formation for winter wheat (Triticum aestivum L.). However, delays in sowing frequently occur due to uncontrollable limitations, especially under multi–cropping. Increased seeding rate is recommended to minimize the negative impacts associated with delayed sowing, but the underlying mechanism is still unclear. A 4–year field study was conducted under winter wheat–maize (Zea mays L.) double–cropping system to determine the grain yield penalty and grain quality deterioration due to delayed sowing of winter wheat and to evaluate the potential compensatory role of increased seeding rate. The results showed that grain yield declined by 1% for each day that sowing date was delayed. Such yield penalty could be mainly explained in terms of suppression of crop growth, yield components, leaf area index (LAI) and biomass production. The reduction in yield–determining attributes was mainly caused by some key environmental limitations, i.e., adverse weather factors such as low temperature during crop vegetative growth, shortened duration of various phases of crop development, and elevated temperature during the grain–filling period. Grain protein and starch content were both increased and milled flour (%) was reduced significantly with delayed sowing. Increased seeding rate completely mitigated the yield loss for a one–week delay in sowing and partially compensated for the two–week delay in sowing. For delays in sowing of more than two weeks, increased seeding rate failed to compensate for the yield penalty. Such failure can be explained by the lack in efficiency of increased plant population under higher seeding rate to compensate for reduced biomass production, LAI and grain number under delayed sowing. Other more effective mitigatory options such as varietal selection and development that could sustain high yield even under delayed sowing should be considered for extended delays of winter wheat.

中文翻译：

---

冬小麦延迟播种造成的产量损失和增加播种率的缓解作用

摘要 适时播种是保证冬小麦（Triticum aestivum L.）种子正常发芽、稳定幼苗和最终产量形成的重要农艺措施。然而，由于无法控制的限制，尤其是在多作模式下，播种延迟经常发生。建议增加播种量以尽量减少与延迟播种相关的负面影响，但潜在机制仍不清楚。一项为期 4 年的田间研究在冬小麦 - 玉米（Zea mays L.）双作系统下进行，以确定由于冬小麦延迟播种导致的粮食产量损失和粮食质量恶化，并评估增加播种的潜在补偿作用速度。结果表明，播种日期每推迟一天，粮食产量就会下降1%。这种产量损失主要可以从抑制作物生长、产量成分、叶面积指数 (LAI) 和生物量生产方面来解释。决定产量的属性的降低主要是由一些关键的环境限制引起的，即不利的天气因素，如作物营养生长期间的低温、作物各个发育阶段的持续时间缩短、灌浆期温度升高等。随着延迟播种，谷物蛋白质和淀粉含量均增加，而磨粉 (%) 显着降低。播种量的增加完全缓解了延迟一周播种的产量损失，并部分补偿了延迟两周的播种。对于超过两周的播种延迟，增加的播种率未能弥补产量损失。这种失败可以解释为在较高的播种率下缺乏增加植物种群的效率，以补偿延迟播种下生物量产量、LAI 和谷物数量的减少。应考虑其他更有效的缓解措施，例如即使在延迟播种的情况下也能保持高产的品种选择和开发，以应对冬小麦的长期延迟。