Using δ<sup>13</sup>C and hydroscapes for discriminating cultivar specific drought responses

Measurement of carbon isotope discrimination in berry juice at maturity (δ13C) provides an integrated assessment vine water status and use efficiency (WUE) during the period ripening, when collected over multiple seasons, can provide indication drought stress responses. Berry δ13C measurements were carried out on 48 different varieties planted a common garden experiment Bordeaux, France from 2014 through 2020 found important differences across this large panel varieties. Cluster analysis showed that values are likely affected by differing phenology each variety, resulting ripening taking place under conditions soil availability within same year. Accounting for these phenological differences, cluster created classification corresponds well to our current empirical understanding their relative tolerance. In addition, using predawn midday leaf potential four seasons subset six varieties, hydroscape approach was used develop list metrics indicative sensitivity stomatal regulation (i.e., an/isohydric behaviour). Key also be correlated with some metrics. A variety’s as characterized minimum critical determined hydroscapes strongly well-watered conditions, suggesting latter may useful indicator response.