Effect of Applied Water Amounts at Various Fractions of Evapotranspiration on Productivity and Water Footprint of Chardonnay Grapevines

Abstract

The effects of irrigation treatments with applied water amounts at various fractions of crop evapotranspiration (ET_c) on productivity of Chardonnay grapevines grafted onto two rootstocks were determined across eight years. Irrigation treatments during the first four years were applied water amounts at 0.25, 0.5, 0.75, 1.0, and 1.25 of ET_c while those in subsequent years were a no applied water treatment and applied water amounts at 0.5 and 1.0 of ET_c. Grapevine water use was determined using the soil water balance method. Year had a significant effect on all measured parameters (berry weight, soluble solids, pH, titratable acidity, and yield and its components). The highest (21.9 t/ha) and lowest (11.6 t/ha) yields differed almost two-fold across years. While rootstock had a significant effect on some of the above parameters, they were not consistent among years and there were only a few instances in which there was a rootstock by irrigation interaction. Yield per unit applied water averaged 4.43 and 13.7 t/ML for the 1.25 and 0.25 irrigation treatments while yield per unit ET_c averaged 4.28 and 6.45 t/ML for the 1.25 and 0.25 treatments, respectively. The high and low water footprint values per unit ET_c ranged from 130 to 400 m³ of water/t across the duration of the study. The large difference in the water footprint from year to year was due to differences in yield. The water footprint for the no applied water treatment was 166 m³/t in 1998 and 228 m³/t in 1999. The fact that the water footprint reported here is lower than published values for grapevines may have been due to higher yields and better estimates of vineyard ET_c.