Effect of Irrigation and Crop Level on Growth, Yield and Wine Quality of Cabernet Sauvignon

Abstract

Four drip irrigation schedules were applied to a Cabernet Sauvignon vineyard during five seasons. The vines of each irrigation schedule were subjected to three cluster thinning treatments resulting in three different crop levels. Water uptake from soil reserves was increased by restricted irrigation, intensive vegetative growth, and low crop load. Restricted irrigation also increased water uptake from soil reserves located at the periphery of the wetted soil zone. Total water uptake was the highest in the most intensive irrigation schedule (A), and the total water uptake from the soil decreased as a function of depth and distance from the tricklers in all treatments. Vines with low crop load extracted more water in the continuous irrigation schedule, whereas the vines with high crop load extracted more water in schedules with irrigation cutback before harvest. The interaction between increased irrigation quantity and frequency with either extremely high or low crop load resulted in delayed sugar accumulation. Delayed ripening was associated with low wine quality only in the most intensive irrigation schedule (A) with the low crop load treatment tending to give the lowest wine quality. The reduced wine quality in the intensive irrigation treatment was expressed by low tasting scores and wine color and by high pH. Wine K was negatively correlated with crop load in all irrigation schedules though no clear relation of K to quality was apparent.