Deficit irrigation in Mediterranean vineyards - a tool to increase water use efficiency and to control grapevine and berry growth

Water is increasingly scarce in Mediterranean Europe and irrigated agriculture is one of the largest and most inefficient users of this natural resource. Ecological topics such as the "water foot print" have become more relevant for the academy, consumers, governments and food industry. The wine sector needs solutions to improve its economical and environmental sustainability. Agronomical solutions, such as deficit irrigation (water supply below full crop evapotranspiration) have emerged as a tool for more efficient water use in irrigated viticulture and with likely positive effects on berry quality. Improving our understanding on the physiological and molecular basis of grapevine responses to water stress is an important task for research on irrigated viticulture. Better knowledge of the different genotypic responses (e. g., leaf gas exchange) to water stress can help to optimize crop/soil management and improve yield as well as berry quality traits under unfavourable climate conditions. Mild water deficits have direct and/or indirect (via the light environment in the cluster zone) effects on berry growth and composition. Another important challenge is to determine how soil water deficit regulate genes and proteins of the various metabolic pathways influencing berry composition and consequently wine quality.