覆膜对黄土高原晚播冬小麦有效气积温补偿效应的研究

The temperature on the Loess Plateau has significantly increased due to global warming. The winter wheat using late sowing could effectively adapt to climate change, but with a limiting yield because of the insufficient growing degree days (GDD). Therefore, how to compensate the GDD to increase the yield of late sowing winter wheat is an urgent scientific problem. In this study, the late sowing winter wheat under plastic mulching was implemented in a typical field selected in the south of Loess Plateau. The response of late sowing winter wheat growth, development, and yield formation to plastic mulching will be studied. Meanwhile, the compensation effects of soil temperature under plastic mulching to the GDD of winter wheat will be quantitatively investigated by establishing a mathematical model. Based on the coupling model of the new mathematical model and AquaCrop model, the long-term impact of the compensation effect on late sowing wheat growth and development will be evaluated. This study will contribute to the perfection and promotion of plastic mulching compensation effect on crop GDD, and improve the simulations of AquaCrop model for winter wheat under plastic mulching. On the other hand, it will help to reveal the limiting factors for the late sowing winter wheat growth and yield formation, and provide a scientific guidance to develop the crop annual yield potential under the cultivation pattern of “late sowing winter wheat–late maturing summer maize”.

全球变暖背景下，黄土高原的气温已显著升高。冬小麦晚播可以有效适应全球变暖，但是由于冬前空气有效积温（气积温）不足，容易造成减产。如何采取有效措施补偿晚播冬小麦气积温、提高晚播冬小麦的产量是一个亟待解决的科学问题。本研究以覆膜为主要增产措施，以既要适应全球变暖，又要满足冬小麦高产为目标，通过田间定位试验与作物模型模拟相结合，研究晚播冬小麦生长和产量形成对覆膜的响应规律；研究覆膜土壤温度（地积温）对晚播冬小麦气积温补偿的定量关系，建立覆膜地积温对冬小麦气积温补偿的数学模型；与AquaCrop模型建立耦合模型，评估覆膜积温补偿效应对晚播冬小麦生长的长期影响。研究成果一方面有助于进一步揭示晚播冬小麦生长发育自身或外部环境的限制因子，提升作物周年生产潜力；另一方面也有助于进一步完善覆膜有效气积温补偿效应理论，为“冬小麦晚播、夏玉米晚收”的栽培模式的提供科学依据。

地膜覆盖通过增加土壤温度对作物生长积温有一定的补偿作用。然而，目前只有少数研究涉及覆膜积温补偿效应的量化研究；覆膜积温补偿效应对冬小麦生长和产量形成的影响有待进一步探讨。针对以上问题，本项目基于田间试验和模型模拟，开展了的覆膜积温补偿系数量化和建模研究。结果表明，覆膜措施通过加速晚播冬小麦根系生长，补偿了晚播带来的根系生长滞后的影响，促进了根系对水分和养分的吸收利用，有效保证了关键生育期（如开花期）根系对冬小麦植株生长所需养分和水分的供应，促进了冬小麦产量的形成，有效稳定，甚至增加了晚播冬小麦的产量和水分利用效率。以空气积温为自变量，冬小麦株高为应变量，logistic方程可以较好地拟合冬小麦株高累积过程线，且覆膜与不覆膜处理之间logistic曲线特征值具有显著差异，利用logistic曲线特征值表征覆膜积温补偿效应具有较好的可行性。本项目基于logistic方程建立覆膜条件下冬小麦覆膜积温补偿效应的数学模型，并以此改进了AquaCrop模型，实现了对覆膜条件下冬小麦积温补偿效应的模拟和预测。该项目的成果一方面有助于进一步完善覆膜有效气积温补偿效应理论，进一步揭示覆膜措施稳产、增产的作用机理；另一方面有助于评估覆膜条件下积温补偿效应的长期影响及冬小麦产量的提升潜力，提出既能适应气候变化，又能满足增产需求的冬小麦调控新模式。项目成果为黄土高原旱作区农业系统的可持续发展提供了较好的技术支持和理论依据。