Characterization of the Transpiration of a Vineyard under Different Irrigation Strategies Using Sap Flow Sensors

Lysimeters are the reference method for determining ETc, but they are expensive and complex, which limits their use. The first objective of this work was to adjust and evaluate the robustness of sap flow sensors in order to determine the transpiration of a vineyard and, together with an evaporation model, to calculate the ETc of the vineyard. For this purpose, we compared water consumption data obtained from a vineyard weighing lysimeter (ETcLys) with the sum of transpiration obtained from sap flow sensors (TSF) and evaporation estimated empirically over four years (2012, 2013, 2014 and 2015). The second objective was to obtain the relationship between the vegetative growth and transpiration of the vines with different water availability (irrigation and rainfed treatments), as an alternative method for estimating vine water needs adjusted to their real development. The third and last objective was to evaluate the transpiration response of the vines when subjected to water stress. We carried out the work in an experimental vineyard which has a well-established weighing lysimeter. As a result, a good match was obtained between vine sap flow and transpiration (R2 = 0.85) as well as a good relationship between vegetative growth and vine transpiration (FiPAR: R2Irrigation = 0.34. R2Rainfed = 0.54; LAI: R2Irrigation = 0.68. R2Rainfed = 0.53).