Consumptive Water Use and Crop Coefficients of Mature 'Tempranillo' Grapevines in La Mancha, Spain

The aim of this study was to quantify the water use of mature grapevines (Vitis vinifera 'Tempranillo'), under full water supply, during two growing seasons. The experimental work was carried out in the lysimeter facilities located in Albacete (central Spain), under semi-arid climate conditions. In 1999, a weighing lysimeter was installed in the centre of a plot (100x100 m). A monolith of undisturbed soil was placed inside the lysimeter tank which was 3x3 m and 1.7 m deep. The overall resolution of the weighing system was 250 g. Two vines under drip irrigation were planted in the lysimeter, each one occupying 4.5 m(2), the same as the vines in the rest of the plot. The lysimeter's daily mass change was used to determine grapevines water use. To schedule irrigation, ETc values were calculated from daily mass loss minus drainage loss, and water was applied to replace the loss, thus, maintaining non-limiting soil water content. Seasonal grapevine ET measured in the lysimeter differed between the two years: it was 377 mm in 2008 and increased to 505 mm in 2009. The lower ETc values in 2008 were directly related to a smaller canopy that year. Canopy cover due to pruning differences was about 15% higher in 2009 than in 2008. Such differences also affected the peak crop coefficient (K-c) values. Peak K-c in 2008 was 0.51 while it reached 0.72 in 2009. In both cases the peak values were achieved in the period between veraison and harvest.