The delicate balance of defining grapevine drought tolerance Prof. Gregory Gambetta Institut des Sciences de la Vigne et du Vin, Bordeaux Sciences Agro, France

Climate change is raising concerns about increased intensity and frequency of drought. One of the most sustainable means of adapting to this new reality is through the use of more drought tolerant cultivars and/or management systems. To this end the knowledge of how grapevines are hydraulically integrated, and how they regulate their water use in response to drought, has been increasingly studied in recent years. The hope is that an increased knowledge of the vine will help guide the choice of more tolerant cultivars and/or vineyard designs. This talk will provide a brief overview of the state-of-the-art of a grapevine’s hydraulic behavior under drought, and discuss how this knowledge can help us understand what it means for a plant or production system to be “drought tolerant”. We are discovering that drought tolerance is not a static and innate property of a vine, but instead is a developmentally dynamic and environmental responsive balance that results from the integration of numerous related traits.