Selection for crop cultivars has largely focused on reproductive traits, while the impacts of global change on crop productivity are expected to depend strongly on the vegetative physiology traits that drive plant resource use and stress tolerance. We evaluated relationships between physiology traits and growing season climate across winegrape cultivars to characterize trait variation across growing regions and elucidate the mechanisms that adapted grapevines to hot, dry conditions. We compiled values from the literature for seven water use and drought tolerance traits and growing season climate. Cultivars with a lower maximum stomatal conductance and stem embolism resistance were associated with regions with a higher mean temperature and vapor pressure deficit (VPD) (r² = 0.20 – 0.49, P < 0.02, N = 10 – 22). A more negative water potential threshold for 50% stomatal closure was associated with cooler regions in correlations across studies, but with a higher VPD across cultivars from a common garden comparison (r² = 0.24 – 0.67, P < 0.03, N = 15 – 18). Overall, warmer, drier regions selected for traits that would reduce transpiration and conserve soil water longer into the growing season, but potentially increase stomatal and temperature limitations on photosynthesis under future, hotter conditions.

Please see Methods section of the manuscript.