Deficit irrigation differently affects aroma composition in berries of Vitis vinifera L. (cvs Sangiovese and Merlot) grafted on two rootstocks

Abstract

Background and Aims: Water deficit modifies the concentration of the aroma compounds of grape berries, but little information is available on the effect of deficits applied at different phenological stages. We evaluated the effect of deficit irrigation on glycosylated volatile organic compounds (VOCs) responsible for the aroma of berries of Sangiovese and Merlot cultivars grafted on 1103P or SO4 rootstocks. Methods and Results: Vines were subjected to either pre-or post-veraison water stress, and berry composition compared against that of fruit of fully irrigated vines. At harvest, a higher concentration of glycosylated VOCs was measured in berries from vines stressed pre-veraison, but while it increased as water deficit increased in Sangiovese, this occurred only at a low or moderate level of stress in Merlot. Post-veraison water stress had a negative or negligible effect on the concentration of glycosylated VOCs in berries at harvest. The rootstock affected the concentration of glycosylated VOCs, particularly in vines stressed pre-veraison, with higher glycosylated VOCs observed for SO4 grafted vines than for 1103P grafted vines. Conclusions: Pre-veraison water deficit enhanced the concentration of berry glycosylated VOCs, while post-veraison deficit did not. The rootstock-scion interaction might amplify the irrigation effect on berry glycosylated VOCs. Significance of the Study: Modifying the timing and volume of irrigation might allow management of berry flavour for improved fruit and wine composition. Irrigation protocols should be tailored for specific cultivar-rootstock combinations.

Water deficit before veraison is crucial in regulating berry VOCs concentration in Sangiovese grapevines

“…The phenological stage at which stress was imposed affected berry total VOCs (glycosylated+free) concentration. In both years, the highest berry total VOCs were measured in berries from vines subjected to water deficit from pea size through veraison, confirming previous results ( Palai et al., 2022b ). On the contrary, the post-veraison water deficit did not significantly affect the concentration of berry total VOCs, showing values similar to those measured in FI berries.…”

“…This pattern of correlation is consistent with what was previously reported for cv. Sangiovese ( Palai et al., 2022b ). On the other hand, no significant differences were induced by severe or moderate stress after veraison, validating the relevance of the pre-veraison in VOCs biosynthesis modulation and indicating how the period of water shortage prevails on its severity.…”

“…The monoterpenes geraniol, linalool, and α-terpineol derivatives were grouped following the aggregation based on their common biosynthetic derivation as proposed by D’Onofrio et al. (2017) with additional revisions suggested by Palai et al. (2022b) .…”

Berry flavonoids are differently modulated by timing and intensities of water deficit in Vitis vinifera L. cv. Sangiovese

“…Wine grapes are often grown in regions characterized by dry and warm summers where irrigation is needed to support vine growth and yield. A proper irrigation strategy is essential for obtaining high-quality berries and wines ( Van Leeuwen et al., 2009 ; Buesa et al., 2021 ; Romero et al., 2022 ; Palai et al., 2022 ). The primary metabolism of grape berry is strongly affected by deficit irrigation strategies.…”

Heat stress, not water stress, dominates in eliciting metabolic and transcriptomic responses of grape berries

“…Alternatively, water stress may indirectly affect grape composition by reducing canopy size and density, which increases sun exposure of the fruit clusters and hence berry temperature (Keller et al, 2016). A hybrid model of both direct and indirect effects of water stress on berry metabolism and associated gene expression has also been proposed (Castellarin et al, 2007;Palai et al, 2022).Thus, it remains unclear whether the presumed water stress effect on berry composition is direct or whether it is mediated by berry temperature (and light). The interaction between water de cit and temperature is expected to impact biological pathways associated with the production of key metabolites for wine production, such as sugars, organic acids, anthocyanins, and other phenolics, as well as diverse aroma volatiles that contribute to the avor and quality of the wine (Gambetta et al, 2020;Rienth et al, 2021).…”