Cover cropping in a slopping non-irrigated vineyard: II - effects on vegetative growth, yield, berry and wine quality of "cabernet sauvignon" grapevines

Grapevine vegetative growth, yield, fruit composition and wine quality were studied in the Estremadura Winegrowing Region of Portugal in a ‘Cabernet Sauvignon’ slopping non-irrigated vineyard. During three seasons three treatments were compared: soil tillage (control), permanent resident vegetation, and permanent sown cover crop. When compared to soil tillage, the inter-row sward treatments displayed a lower predawn leaf water potential from bloom to mid-ripening. These differences in vine water status did not affect vine yield or berry sugar accumulation; however, in the third season after experiment setup it induced a significant reduction in vegetative growth in the sward treatments, compared to soil tillage. This vegetative growth reduction had a positive effect on grape composition by reducing titratable acidity and increasing berry skin total phenols and anthocyanins. Those differences were also detected in the wines by the judges who gave a better classification to the wines from the sward treatments. Our results indicate that cover cropping can be a valuable tool for controlling vigour and enhancing wine quality in this winegrowing region.