Grapevines are being challenged by climate changes, forcing winemakers to implement irrigation systems to cope with excessive water stress. Previous studies focused on a small set of international varieties, and only few data are available for terroirs hosting cultivars with possibly different responses to drought stress. In this light, we monitored grapevine water status and grape’s physical and chemical composition, as well as concentration and structural characteristics of grape extractable polyphenols, in ten different Refošk vineyards located in the Classical Karst terroir during 2018 and 2019. Grapevines did not suffer severe stress during the two years, but their response to water shortage periods was highly heterogeneous, as pre-dawn (Ψ_pd) and minimum (Ψ_min) leaf water potential significantly differed between vineyards, especially during the drier part of the season. Moreover, the timing of maximum water stress differed in the two years, as in 2019 longer water shortage periods and higher temperature occurred at flowering stage and before veraison, while in 2018 they were higher after veraison. These differences influenced berry’s quality, as titratable and malic acid concentration in juice, as well as total anthocyanin, total polyphenols and higher high molecular weight proanthocyanidins (HMWP) concentration in skins, were higher in 2019 than in 2018. Regarding seed proanthocyanidins, HMWP concentration, mean degree of polymerisation (mDP) and percentage of galloylation (G) in seeds were higher in 2018 than in 2019. The differences in water status measured in spatially close-related vineyards strongly support the importance of monitoring grapevines’ water status dynamics to design adequate and effective water management activities rather than relying on climate data solely. Moreover, the timing of water shortage periods also played a role in determining Refošk grape quality. Our analyses showed that the higher (but still moderate, with Ψ_pd and Ψ_min mean values around −0.50 and −1.25 MPa, respectively) water stress between veraison and harvest occurred in 2018 might reduce Refošk grape acidity and increase concentration, polymerisation and galloylation of seed extractable proanthocyanidins.

葡萄藤正受到气候变化的挑战，迫使酿酒师实施灌溉系统以应对过度的缺水压力。以前的研究集中在一小部分国际品种上，只有很少的数据可用于种植对干旱胁迫可能有不同反应的品种的风土。有鉴于此，我们在 2018 年和 2019 年期间监测了位于古典喀斯特风土的十个不同 Refošk 葡萄园的葡萄藤水分状况和葡萄的理化成分，以及葡萄可提取多酚的浓度和结构特征。葡萄藤没有受到严重的压力在这两年期间，但他们对缺水时期的反应是高度异质的，如黎明前 (Ψ _pd) 和最小值 (Ψ _min) 葡萄园之间的叶水势存在显着差异，尤其是在较干燥的季节。此外，这两年最大缺水的时间也不同，2019年花期和转色前缺水期较长，气温偏高，而2018年转色后则更高。这些差异影响了浆果的品质，因为 2019 年果汁中的可滴定浓度和苹果酸浓度以及果皮中的总花青素、总多酚和高分子量原花青素 (HMWP) 浓度高于 2018 年。 关于种子原花青素，HMWP 浓度、2018 年种子中的平均聚合度 (mDP) 和没食子酰化百分比 (G) 高于 2019 年。在空间密切相关的葡萄园中测量的水状况差异强烈支持监测葡萄藤水状况动态以设计适当和有效的水管理活动的重要性，而不是仅仅依靠气候数据。此外，缺水期的时间也在决定 Refošk 葡萄的质量方面发挥了作用。我们的分析表明，较高（但仍然适中，Ψ_pd和 Ψ _min平均值分别约为 -0.50 和 -1.25 MPa）在 2018 年发生的 veraison 和收获之间的水分胁迫可能会降低 Refošk 葡萄的酸度，并增加种子可提取原花青素的浓度、聚合和镓酰化。