Interactive effects of deficit irrigation and shoot and cluster thinning on grapevine cv. Tempranillo. Water relations, vine performance and berry and wine composition

The effects of crop level and irrigation on water relations, yield, grape and wine composition were studied during two seasons in a Tempranillo vineyard in Spain. Irrigation was applied at two levels: R2 (with mild deficit irrigation applied during all the season) and R1 (with more severe water stress applied before veraison). Deficit irrigated vines were compared to a non-irrigated control. Crop levels imposed resulted in 11, 20, and 27 clusters per vine. Over all treatments, yield and ratio of leaf area to yield (LA: Y) were different between years: 4.4 and 16.3?t?ha^?1 and 1.72 and 0.88?m²?kg^?1 in 2005 and 2006, respectively. In 2005, large differences in grape and wine composition occurred among non-irrigated and the irrigated treatments, but not between R1 and R2 treatments. Wines from non-irrigated vines were more acid, had higher total anthocyanins, and higher color intensity. In 2006, irrigation had less effect on grape and wine variables. The effect of shoot and cluster thinning on wine composition was different between seasons due to the different crop load values between years. Grape composition was negatively affected by high crop level only for values of LA: Y lower than 1.5?m²?kg^?1.