EVAPOTRANSPIRATION RATE OF A VINEYARD AND ITS RELATION TO THE REFERENCE OF THE FAO PENMAN-MONTEITH METHOD

Timely and adequate irrigation scheduling in agriculture requires information corresponding to the daily rate of crops ET established or to be established in different agricultural regions. Therefore, the objective of this study was to determine the daily rate of current ET (ETa) of the vine cultivation, from the reference ET (ETr) obtained with the FAO Penman Monteith method and its comparison with the crop ETa obtained with an eddy covariance system. We conducted the study in a vineyard of Vinicola San Lorenzo, Parras, Coahuila, during the production cycle of the vine (Vitis vinifera cv Shiraz) from April to September 2014. Within the vineyard we delimited two sections of 5.2 ha, and on each we installed eddy system sensors to obtain the daily rate of crop ET (ETa). Simultaneously, we continuously measured the total incident solar radiation, temperature and relative humidity and wind speed. With this information, we obtained the daily reference ET rate (ETr). The daily rate (ETa) of one of the sections of the vineyard was compared to the ETr to obtain the monthly adjustment coefficients of crop development (Kc). The study results showed that based on the Wilcoxon test for paired populations (p <= 0.01), the daily rate of ETa measured in the vineyard (with the eddy covariance method) was equal to the Eta rate obtained from the ETr (with the FAO Penman Monteith procedure) corrected by the plant coverage ratio factor and the monthly coefficients (Kc) of crop development.