气候变化条件下旱作玉米用水效率与单产变化趋势分析

以渭北旱塬合阳和长武2个试验站点为研究区域,通过多年的玉米田间试验数据评估CERES-Maize模型的适用性,再利用区域气候模式Reg CM4.0输出的气象数据对2050年前玉米单产及生产水足迹进行预测。结果表明:CERES-Maize模型可以很好地模拟雨养玉米产量和物候期,多数年份二者的绝对相对误差(Absolute relative error,ARE)在10%以内,CERES-Maize模型在渭北旱塬旱作农业区有很好的适用性。应用CERES-Maize模型模拟玉米生产水足迹,较传统水足迹计算方法得到的结果更为精确可靠。在RCP2.6气候情景下,随着温度升高和生育期有效降水量的增加,玉米产量呈上升趋势;在RCP8.5气候情景下,随着温度升高和生育期有效降水的减少,玉米产量呈下降趋势。气温上升幅度过大对玉米单产有明显的负面影响,降水与玉米用水效率呈正相关。为有效应对气候变化对旱作作物产量造成的负面影响,应采取减少温室气体排放量、增强土壤蓄水保墒能力、发展集雨补灌、筛选和培育节水抗旱新品种等措施。

Trend Analysis of Water Use Efficiency and Yield of Dryland Maize under Climate Change

Rain-fed agriculture is highly susceptible to climatic conditions. Study on analyzing the trend of yield and water use efficiency of rain-fed maize under climate change conditions is useful for agricultural production planning, which can provide adaptation strategies to climate change for agricultural production. Two test sites of Heyang and Changwu in Weibei highland were set as the study area. Experiment data in maize field was used to evaluate the applicability of CERES-Maize. Finally, the meteorological data produced from regional climate model (RegCM4.0) was used to predict maize yield and its water footprint before 2050. Results showed that the CERES-Maize model could precisely simulate the rain-fed maize yield and phenology;the absolute relative error (ARE) of most samples was less than 10%;the CERES-Maize model had good applicability in the rain-fed agricultural area in Weibei highland. Using the CERES-Maize model to simulate the water footprint of maize production was more accurate and reliable than using traditional water footprint calculation method. Under the RCP2.6 climate scenario, maize yield showed an increasing trend with increasing temperature and effective precipitation during the growing season;under the RCP8.5 scenario, maize yield showed a declining trend with increasing temperature and decreasing effective precipitation during the growth period. The excessive temperature rise had an obvious negative effect on maize yield, and the precipitation was positively correlated with the water use efficiency of maize. In order to effectively deal with the negative impact of climate change on the rain-fed crop yields, measures should be adopted, such as reducing greenhouse gas emissions, enhancing soil water storage and preserving moisture capacity, developing rainwater catchment irrigation, and selecting and cultivating water-saving and drought-resistant varieties.