Effects of limeted irrigation on the composition of must and wine of Cabernet Sauvignon under semi-arid conditions

Effects of irrigation were studied in a Cabernet Sauvignon vineyard in the Priorat region of Spain, in order to determine the effect of sprinkler irrigation on fruit ripening as well as on must and wine composition. The soil water potential was measured at different depths and irrigation was started when the soil water potential decreased to -1480 kPa. At this point, moderate doses of water (25 l/vine) were added every fortnight during July and August. The yield of the irrigated vines increased by 20%. The must obtained from irrigated vines showed higer levels of potassium than that of the non-irrigated vines. Total soluble solids increased earlier and more rapidly in irrigated vines. We also found higher levels of malic acid and the total acidity increased in both, must and wine. However, tannins and anthocyanins, were lower in wines of irrigated grapevines. The later result is possible due to a rainfall which occurred before harvest, since phenolics did not decresase when a similar irrigation was applied in subsequent years.