淮北平原冬小麦作物系数的变化规律研究

Spatiotemporal Variation of Crop Coefficient of Winter Wheat in Huaibei Plain

【目的】研究淮北平原冬小麦作物系数的时空变化规律。【方法】采用水量平衡法、涡度相关法和Bouchet互补关系理论,结合Penman-Montieth方程,计算得到1991—2018年淮北平原冬小麦的作物系数;采用线性拟合法、Mann-Kendall趋势检验法和突变检验法滑动t检验法,结合ArcGIS,研究了作物系数在淮北平原的时空变化规律,并对影响因素进行分析。【结果】①淮北平原冬小麦全生育期的实际蒸散量的多年平均值为429.3 mm,参考作物蒸散量为541.3 mm,作物系数为0.79;②作物系数在不同生育阶段的变化为先减小后增大再减小;③作物系数在淮北平原全生育期由西北角向周围逐渐增大,高值中心呈现北移趋势;④作物系数与气候因子紧密相关,其中气温的影响最为显著,相对湿度和降水次之,风速最不显著。【结论】作物系数存在显著上升趋势,与气候因子关系紧密,需要关注作物需水量的变化。

【Background】Water uptake by plants and its subsequent transpiration is an important process in the hydrological cycle but difficult to measure and calculate.In irrigation management,the evapotranspiration is often calculated from the reference evapotranspiration multiplied by a crop coefficient.【Objective】The purpose of this paper is to study the spatiotemporal variation of the crop coefficient of winter wheat in Huaibei plain of China.【Method】Using data measured from 1991 to 2018,we calculated the crop coefficient of the winter wheat based on water balance method,eddy covariance measurements and the Bouchet complementary relationship theory.The reference evapotranspiration was calculated from the Penman-Montieth formula.The spatiotemporal variation of the crop coefficient and its determinants were calculated using linear fitting method,Mann-Kendall trend test,Mann-Kendall jump test and moving t-test,and the ArcGIS.【Result】The annual mean evapotranspiration during the growth season of the winter wheat in Huaibei plain is 429.3 mm,and the reference crop evapotranspiration and the crop coefficient were 541.3 mm and 0.79 respectively.As the wheat grew,its crop coefficient decreased first and then increased,followed by a decline.Spatially,the crop coefficient was lowest at the northwest corner,and it was higher in the north than in the south.Temperature affected the crop coefficient most,followed by relative humidity and precipitation;it was least affected by wind speed.【Conclusion】The spatiotemporal variation of crop coefficient of winter wheat calculated for Huaibei plain provided guidance for calculating water requirement by irrigation.In particular,we found that the crop coefficient had been in increase from 1991 to 2018 possibly due to the climate change,which needs to be considered in evaluating water requirements in agricultural structure design for this region.