Long-term monitoring of evapotranspiration in a Sardinian vineyard

A good estimate of the vineyard water consumptions is crucial to optimize irrigation management and obtain elevated quantity and quality of grapes for wine production. Ecosystem functional processes are driven by net radiation (Rn), representing the energy available to the system. Net radiation is partitioned into sensible (H) and ground (G) heat flux and to vaporize water and contribute to latent heat flux (LE). The latent heat flux corresponds to the actual evapotranspiration (ETa) of the system, and the analysis of the energy balance components permits better understanding of the physiological mechanisms underlying vineyard productivity and crop water requirements. In this study the eddy covariance technique was used to estimate energy and mass fluxes and estimate ETa of a vineyard located in Southern Sardinia (Italy), starting from June 2009 through 2011. A meteorological station was used to calculate the reference evapotranspiration (ETo). Results showed the vineyard energy balance behaviour under the different water conditions. No strong water deficit was recorded during the monitoring period. Measurements provided useful information about the water requirements in relation to the phenological stages and weather conditions. Grapevine crop coefficient (Kc) values were calculated and were compared with FAO Kc values and those estimated using measured LAI. This study shows the importance of micrometeorological techniques to determine the irrigation information needed for scheduling irrigation.