ABSTRACT
Measurements of net radiation, soil heat flux, air temperature and water vapor pressure gradients were used to evaluate crop evapotranspiration (ETc) by the energy balance method in grape vine crop. The reference evapotranspiration (ETo) was obtained by the methods of Penman-Monteith and Class A pan evaporation. Daily values of the crop coefficient (kc = ETc / ETo) were obtained throughout the phenological phases. The results showed that the mean daily values of ETc increased from 2.8 mm day-1 at the 18th day after pruning to 7.0 mm day-1, at the 94th day after pruning. After this, values decreased to 4.4 mm day-1, at the 117th day after pruning. In the whole growing period ETc accumulated was found to be 503.0 mm. Crop coefficient values were different, according to the method used to calculate ETo but, in general, they were higher than those recommended by FAO.
Key words:
evapotranspiration; energy balance; crop coefficient; Vitis vinifera L