Response of cv. Bobal to Timing of Deficit Irrigation in Requena, Spain: Water Relations, Yield, and Wine Quality

Abstract

The effects of differential irrigation regimes on vine water status, yield, berry growth and composition, and wine quality parameters were investigated during three consecutive seasons (1999 to 2001) in a mature vineyard planted with Vitis vinifera cv. Bobal/161-49 in Requena (Valencia, Spain). The soil was a deep clay loam, Typic Calciorthid. Plant spacing was 2.45 x 2.45 m and plants were pruned to an open vase with ~12 buds per plant. Treatments consisted of a nonirrigated control (T1) and four irrigation treatments in which water was applied at different levels from flowering until near harvest: T2 (50-50-0), T3 (100-100-0 in 1999–2000 and 0-100-0 in 2001), T4 (100-100-50), and T5 (100-100-100) (where numbers are the percentage of the estimated ET_crop applied, respectively, in each of the periods: flowering to fruit set, fruit set to veraison, and veraison to maturity). The experimental design was a completely randomized block with four replicates and 64 vines per plot. Irrigation increased yield in all seasons mainly because of an increase in berry weight. The concentration of juice soluble solids and titratable acidity was only slightly affected by the irrigation treatment and a similar pattern was observed for the alcoholic content of the elaborated wines. The concentration of malic acid in juice and wines increased significantly with water application, while tartaric acid concentration in wines significantly decreased. However, the concentration of anthocyanins, total phenols, and color intensity of red wines decreased with increasing water application in an inverse pattern to that of berry size. Yield, berry weight, anthocyanins, total phenols, and color intensity of red wines were closely correlated with the water stress integral (which expresses the intensity and duration of stress) calculated from stem water potential determinations.