Variability of water use efficiency in grapevines

• The current knowledge on variations of leaf WUE in grapevines is presented.
• Leaf WUE parameters do not predict the large variability of whole plant WUE.
• Canopy structure and plant respiration are involved in whole plant WUE regulation.

Predictions of climate change indicate an increase in water scarcity in Mediterranean areas. Therefore, improving water use efficiency (WUE) becomes crucial for sustainable viticulture in the Mediterranean for both grapevine growth and fruit productivity. Variability of WUE between cultivars presents an opportunity to select the most appropriate cultivars in viticultural areas with increasing aridity. In this review, an update on the variability of WUE in different grapevine cultivars and environmental conditions is presented.Most studies on WUE are focused at the leaf level and frequently used to estimate whole-plant WUE. However, there are large discrepancies when scaling-up WUE from leaf to whole-plant level. There are several structural and physiological processes, not included in leaf WUE measurements, considered as possible factors to solve the gap between leaf and whole-plant WUE. Canopy structure and plant respiration are described as the most important components involved in whole-plant WUE regulation, and proposed as potential targets for its improvement.