The influence of 140 Ruggeri rootstocks on leaf water relation traits of Cabernet Sauvignon and Syrah under hyper-arid conditions in northern Chile.

Rootstock selection is essential for mitigating stress and adapting agricultural systems to climate change. This study assessed the effects of the 140 Ruggeri (140-Ru) rootstock on the physiological responses of ‘Syrah’ (Sy) and ‘Cabernet Sauvignon’ (CS) in the hyper-arid Elqui Valley, northern Chile. Eight-year-old irrigated CS and Sy vines, both self-grafted and grafted onto 140-Ru, were evaluated in a randomized block design. While 140-Ru did not significantly impact traits related to leaf water relations between stress onset and stomatal closure, it reduced the water potential required to induce a 50% loss of leaf hydraulic conductance in both cultivars, suggesting greater leaf survival under prolonged drought. Additionally, self-grafted Cabernet Sauvignon exhibited greater sensitivity to water deficit, a response that was attenuated when grafted onto 140-Ruggeri. These findings underscore the importance of rootstock selection for improving drought resilience and vineyard sustainability under deficit irrigation.