冬小麦返青后腾发量时空尺度效应的通径分析

作物腾发量（ET）的时空尺度效应是作物高效用水调控与节水灌溉管理中需面对的基础科学问题。该文对返青后冬小麦生育期内试验小区实际腾发量（ETa）和区域水分通量（LE）以及作物生长环境因子进行实测，利用通径分析方法，对冬小麦ET时空尺度效应及其主要影响因子进行分析。结果表明，不同时间尺度和空间尺度下，作物蒸腾蒸发的影响因子不同，显示了其不同的时空尺度效应。对试验小区实际腾发量ETa来说，以全日24 h的数据来分析，其主要影响因子是叶面积指数LAI和净辐射Rn，而白日时段（7:00-18:00）分析显示主要影响因子是空气饱和水汽压差VPD_7-18和叶面积指数LAI。对田间尺度的区域水分通量LE来说，全日24h数据的主要影响因子是净辐射Rn和作物高度H，白日时段（7:00－18:00）数据的主要影响因子是饱和水汽压差VPD_7-18和作物高度H。冬小麦返青后的时间尺度效应表现是全日24h作物腾发量的主要影响因子是净辐射，而白天时段影响腾发量的主要因子是空气饱和水汽压差；空间尺度效应表现是小面积的作物腾发量大小对作物的叶面积指数变化敏感，区域水分通量的大小与下垫面植被高度的变化有关。

Path analysis on spatio-temporal scaling effect of crop evapotranspiration in growing seasons for winter wheat after reviving

The spatio-temporal scaling effect of crop evapotranspiration (ET) is a scientific basis for efficient water using and water saving management. In this paper, the path analyses method was used to investigate the main impact factors and spatio-temporal effects of ET at different scale for winter wheat after reviving. The actual evapotranspiration (ETa) in plot was measured by weighing lysimeter and the areal latent water flux (LE) was monitored from the eddy covariance system in the agricultural field. The results showed that the scaling effects were significant for ET in space and time scale, and main impact factors were diverse for ETa and LE in whole day (24 hours) and daylight (7:00-18:00). For ETa in plot, main impact factors were the crop leaf area index (LAI) and net radiation (Rn) in whole day, the saturation vapour pressure deficit (VPD_7-18) and the LAI in daylight (7:00-18:00). Otherwise, for LE in area, Rn and crop height (H) were the main impact factors in whole day, the VPD_7-18 and H in daylight, respectively. In conclusion, the temporal scaling effect on ET was that the main impact factor was Rn for whole day and VPD for daylight. The spatial scaling effect on ET was that the ET in plot was sensitive to the crop LAI and the areal LE was related to the undersurface crop height.