农业技术和气候变化对农作物产量和蒸散量的影响

随着农业生产条件的改善、品种改进和有利的气象条件的变化, 世界各地的作物产量得到大幅度提高, 但作物的蒸散量却未出现大幅度提高。本文以石家庄气象站1955~2007 年的气象资料为基础, 分析了河北省冬小麦和夏玉米生长期间主要气象因素变化, 结合中国科学院栾城农业生态系统试验站长期定位灌溉试验的研究结果, 分析了农业生产条件和气象因子变化对冬小麦和夏玉米产量及耗水量的影响。结果表明,1955~2007 年冬小麦和夏玉米生长季的气象因子发生了变化, 日照时数、相对湿度、风速、气温日较差显著降低, 最低气温、平均气温和积温显著升高, 气象因子的变化对作物总蒸散量未产生明显影响, 但由于降水减少,作物生长期间的灌溉需水量呈增加趋势。长期灌溉试验结果表明, 随着农业生产条件的变化和品种的改良, 冬小麦和夏玉米的产量不断增加, 而耗水量的增加幅度小于产量增加幅度, 夏玉米的耗水量呈稳定状态。节水技术的推广和应用对维持耗水量稳定起着非常关键的作用。

Effects of climate change and agricultural technology improvement on evapotranspiration and crop yield

Along with the development of farm mechanization, improved production conditions, varietal breeding and favorable climatic changes, crop yields have drastically increased across the globe. Despite this achievement, however, evapotranspiration has not continued to increase with increasing crop yields. To that end, meteorological data for 1955~2007 at Shijiazhuang Meteorological Station were analyzed for changes in seasonal climatic factors that affected winter wheat and summer maize. Long-term (1992~2009) irrigation experiments at the Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences (or Luancheng Station in short) were also used to study the effects of climate change on evapotranspiration and yield of winter wheat and summer maize. The studies showed that the use of farm machinery in Hebei Province increased by 7.3 times in 2007 over that in 1983. Mechanization rate of cultivation, planting and harvesting was 59.65%, indicating that farm mechanization in Hebei Province had entered the intermediate stage by 2007. Summer maize yield increased by 2.08% per year, and with winter wheat straw mulching, saved about 14 mm of water. For the period 1955~2007, climatic factors during winter wheat and summer maize seasons had also changed. The average sunshine duration, relative humidity, wind speed, daily temperature range had significantly dropped during the growing seasons of two crops. Minimum temperature, average temperature and accumulated temperature had increased significantly. Although the trends of change in climatic factors had not significantly affected evapotranspiration (ET₀), water demand for the two crops increased due to decreasing rainfall. Long-term irrigation experiments showed that winter wheat and summer maize yields greatly increased due to improvements in production conditions, varietal breeding and climate change. In recent years, however, evapotranspiration had been relatively stabilized due to the extensive application of improved water-saving technologies.