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.