Abstract:

Under climate warming, asymmetric day-night temperature increases and atmospheric CO₂ concentration rising are two key features altering the distribution of water and heat resources, driving changes in the planting structure and boundaries of the three major grain crops (wheat, corn, and rice). Studying their responses to global warming is vital for food security. Using high-density meteorological station data, the paper analyzes thermal resource changes before and after 1990 during a 30-year period and their possible impacts on the potential planting areas of China’s three major grain crops using statistical method. In addition, the results from multi-site “Free-air temperature increase (FATI) under field conditions” and “Open-top chamber (OTC) experiments with controlled temperature and CO₂” are summarized, and combined with the literature meta-analysis method to explore the effects of climate warming on the growth periods and yields of the three major crops. Results are as follows: 1) Agricultural thermal resources in China are generally increasing, with the duration of the farming period and accumulated temperature significantly rising, and the frost-free period extending. The number of extreme hot days has generally increased, and in some regions (such as Shaanxi, Gansu and Ningxia), the number of extreme cold days during the farming period has also increased, intensifying the risk of extreme meteorological disasters. 2) The northern boundaries of the three major crop-growing areas have shifted northward to varying degrees, resulting in an increase in the potential suitable planting area. 3) In the early stage of climate warming, it is beneficial for winter wheat to grow. However, excessive warming will lead to earlier development, increased frost risk, shorter growth period and reduced yield for spring wheat. Although an increase in CO₂has a yield-enhancing effect, it is difficult to offset the adverse impacts induced by high temperatures. 4) Climate warming shortens the growth period of corn, reduces the number of grains per ear and the weight of 1 000 grains, thereby inhibiting the formation of yield. Nighttime warming further exacerbates the decline in yield. The effect of increasing CO₂ concentration on corn growth and yield is limited, with warming being the dominant factor. 5) Warming alone has an inhibitory effect on the yield of early rice but a promoting effect on that of late rice. Warming for early rice reduces the yield-increasing effect of CO₂, while for late rice it shows a synergistic promotion and increasing the yield.

Key words: major crops, climate warming, heat resources, planting boundaries

摘要：

在气候变暖背景下，昼夜非对称性升温和大气CO₂浓度升高成为气候变化的重要特征与驱动因素。气候变化影响水热资源分布，驱动三大粮食作物（小麦、玉米、水稻）的种植结构、种植界限等发生改变，研究主要粮食作物对气候变暖的响应，对保障粮食安全具有重要意义。基于高密度气象台站资料，采用统计方法分析1990年前、后30 a热量资源变化及其对中国三大粮食作物潜在种植区的可能影响；同时，汇总“大田条件下的自由空气增温实验（Free Air Temperature Increase， FATI）”和“控温控CO₂的开顶箱实验（Open-Top Chamber， OTC）”多站点试验结果，结合文献荟萃方法，探讨气候变暖对三大作物生育期和产量的影响。 结果表明：1）中国农业热量资源总体在增加，农耕期持续天数和积温显著上升，无霜期延长；极端高温日数普遍增多，部分地区（如陕甘宁）农耕期极端低温日数亦有所增加，极端气象灾害风险加剧。2）三大作物种植北界发生了程度不一的北移，潜在适宜种植面积增加。3）气候变暖初期利于冬小麦生长，过度升温将致发育提前、霜冻风险上升，春小麦生育期缩短、产量受限；CO₂浓度升高虽有增产效应，但难以抵消高温带来的不利影响。4）气候变暖通过缩短玉米生育期、减少穗粒数和千粒重，抑制产量形成，夜间增温加剧产量下降；CO₂浓度升高对玉米生长与产量的作用有限，增温为主导因子。5）单纯增温对早稻产量有抑制作用，对晚稻则有促进作用；早稻增温削弱CO₂的增产效应，晚稻则表现为协同促进，提升产量。

关键词: 主粮作物, 气候变暖, 热量资源, 种植界限