Influence of cover crop on water use and performance of vineyard in Mediterranean Portugal

Grapevine yield, vigour, fruit quality and vineyard dynamics were studied in the Estremadura Region of Portugal with a Mediterranean oceanic bioclimate. A 3-year study was carried out in a 15-year-old ‘Cabernet Sauvignon’ non-irrigated vineyard. Three treatments were compared: soil tillage (control), permanent resident vegetation, and permanent sown cover crop. The sward treatments induced changes in the weed dynamics by increasing annual and perennial grasses and perennial broad-leaved species, while annual broad-leaved species spread and persisted under a tillage system. Compared to soil tillage, the two sward treatments showed a higher water use, primarily during the spring. In the third season of the experiment, compared to cultivation treatment the two sward treatments showed a significant, favourable reduction in vine vegetative growth. The sward treatments did not affect grapevine yield or berry sugar accumulation compared to the control, but reduced must acidity and increased berry skin total phenols and anthocyanins.