An experiment was conducted during 2020 and 2021 in the Region of Murcia (southeastern Spain) to evaluate the impact of increased temperature on ‘Monastrell’ vine performance. Two rootstocks, 140Ru and 110R—known to confer distinct physiological and agronomic responses—were used. Vines were subjected to control (ambient) and high‐temperature (HT) conditions, the latter being induced with open polycarbonate structures from fruit set to harvest. This system increased the cluster‐zone temperature by an average of 1.15°C across 2 years. Rootstocks did not affect air temperature or humidity; however, 140Ru exhibited elevated shallow soil temperatures and decreased volumetric water content at a depth of 15 cm, indicating rootstock‐dependent dynamics within the shallow layer. In contrast, 110R under HT had higher soil respiration and evaporation rates. The heating treatment elevated VPD and evapotranspiration without inducing water stress, as Monastrell maintained high levels of stomatal conductance and photosynthesis even when cluster temperatures exceeded 35°C. Stomatal regulation differed between rootstocks: 140Ru restricted stomatal aperture under HT, whereas 110R maintained a wider opening. Despite the rise in temperature, vine growth was unaffected and similar across rootstocks. However, HT increased leaf nitrogen and yield parameters (number and weight of clusters and berries) and altered the sugar–acid balance in berries. Furthermore, HT delayed the onset of veraison and early ripening in 110R but not in 140Ru. These results underline Monastrell’s resilience to elevated temperatures and demonstrate the influence of rootstock selection on physiological responses in hot, semiarid regions such as SE Spain.
Navarro et al. (Thu,) studied this question.