Water consumption of 'Superior' grapevines grown in a semiarid region

Water use of grapevines (Vitis vinifera 'Superior') trained to a gable system was measured in 12 drainage lysimeters for 4 growing seasons (1999, 2001-2003) in a semiarid region of southern Israel. The drainage lysimeters, with a volume of 1.3 m³ each, were installed in a 1 ha vineyard. The vines were drip irrigated with 4 emitters at a rate of 2.4 L h^-1. The volume of water supplied each day exceeded the estimated vine water consumption by 20%. Maximum crop evapotranspiration (ET_c) ranged from 7.6 to 8.2 mm d^-1 (based on an area of 7 m² per vine) across the 4-year study. Seasonal ET_c ranged from 988 to 1081 mm. The seasonal pattern of the crop coefficient (K_c) was similar from one year to the next. Monthly leaf area index (LAI) was measured the last two years of the study. The LAI measured with the SunScan Canopy Analysis System was highly correlated (R² = 0.99) with direct leaf area measurements. Maximum LAI was 4.2 and 4.9 in 2002 and 2003, respectively. The increase in the seasonal K_c was explained primarily by the increase in LAI (R² = 0.84). The high water consumption of the lysimeter-grown vines may be explained by higher LAI and stomatal conductance values due to the fact that those vines were supplied with unlimited amounts of water.