Effect of two water regimes on the agronomic response od 12 grapevine varieties cultivated in a semiarid climate

The Mediterranean basin is one of the most vulnerable regions to Climate Change effects. According to unanimous forecasts, the vineyards of Castilla-La Mancha will be among the most adversely affected by rising temperatures and water scarcity during the vine’s vegetative period. One potential strategy to mitigate the negative impacts of these changes involves the identification of grapevine varieties with superior water use efficiency, while ensuring satisfactory yields and grape quality. In this work, the agronomic performance and water use efficiency of 12 grapevine varieties, including international ones, were studied under two water regimes over three consecutive growing seasons (2017, 2018 and 2019): an irrigated treatment at 25% of ETo (watered), and a rain-fed water regime (drought). Results showed significant effects of irrigation and vine variety on carbon isotope ratio (δ13C), yield components and total acidity. Airén and Malvar exhibited the highest water use efficiency in both treatments, although they showed diminished grape quality and reduced yields under drought. In contrast, certain varieties like Moscatel de Grano Menudo and Petit Verdot produced high-quality musts but demonstrated lower resilience to drought, resulting in decreased yields and δ13C values. Macabeo, Chardonnay, Bobal and Garnacha Tintorera responded well to drought, maintaining high yields and must quality. This study allowed the identification of grapevine varieties with varying levels of drought tolerance, providing valuable information for selecting the most suitable candidates for future cultivation in semi-arid regions.