Effects of post-veraison irrigation on the phenolic composition of <i>Vitis vinifera</i> L. cv. ‘Xinomavro’ grapes

Abstract

‘Xinomavro’ (the second planted red Greek variety behind ‘Agiorgitiko’) generally produces wines that are light in colour but with increased astringency, possibly related to grape flavonoid amount and composition; although irrigation is accepted as an effective means to enhance grape phenolic maturity, its role has not yet been sufficiently studied in the case of Xinomavro. This study aimed to determine the effect of post-veraison irrigation on berry anthocyanin and proanthocyanidin amount and composition, of field-grown Xinomavro vines (Vitis vinifera L.), under the typical summer conditions of Northern Greece. In a 10-year-old Xinomavro vineyard, two post-veraison watering regimes were applied—irrigation starting 20 days after veraison (mid-ripening irrigation, MRI) and irrigation starting immediately after veraison was completed (after veraison irrigation, AVI)—alongside non irrigated vines (NI), and vines irrigated continuously from berry set through harvest (continuous irrigation, CI). Proanthocyanidin composition was determined in both skins and seeds by employing phloroglucinolysis followed by HPLC-UV and MS detection (high-performance liquid chromatographic with tandem mass spectrometric and ultraviolet absorbance detection), and the anthocyanin profile was identified only in the skin extracts by HPLC-UV (high-performance liquid chromatographic with ultraviolet absorbance detection). Post-veraison irrigation increased yield parameters and reduced anthocyanin levels and the proportion of their stable forms (acylated vs. non-acylated, tri-oxygenated and methoxylated on the B-ring vs. di-oxygenated and hydroxylated), compared to NI vines; however, these effects were more pronounced in the case of early post-veraison irrigation (AVI) than late-season irrigation (MRI). Irrigation also increased the mean Degree of Polymerization (mDP) and prodelphinidin percentage of skin tannins and decreased mDP of seed tannins. In the light of the necessity to control the accelerated ripening under the increasingly hotter and drier climatic conditions, late irrigation (MRI) might provide a solution to avoid excessive sugar levels and allow a slightly higher yield without significant reductions in berry phenolic content. The results suggest that the optimisation of the timing of irrigation could provide an effective adaptation strategy to climate change in Mediterranean viticultural areas.

Post-Veraison Water Stress and Pruning Level on Merlot Grapevine (Vitis vinifera L.): Effects on Berry Development and Composition

“…Generally, the accumulation of total soluble solids per berry decreased with increasing the pruning level from minimal to severe, while increased with postveraison water stress from none to an intense. is result is in agreement with recently published works [18,33,[40][41][42][43], where higher crop loads per grapevine resulted in a limitation in the final sugar level attainable in the fruit at harvest. is phenomenon was also demonstrated by the studies in [44,45], who found that water deficit combined with increased crop load led to a significant reduction in the rate of sugar accumulation.…”

“…Besides, since berry weight was significantly affected by pruning level and water stress, it can be concluded that the increase was associated with an increase in the skin:flesh ratio. is finding is in line with other authors [40,42,46] whom reported that the increase in total anthocyanins and phenols under heavy pruning was due to an increase in grape berry weight and biochemical response of the anthocyanin and phenol metabolic pathway to the induced signals caused by water stress which led to increase the total anthocyanin and phenolic concentration per gram and contents per berry. In other previous studies [26,41,45], correlation analysis of potential factors contributing to altered metabolism in the anthocyanin pathway showed that color was negatively correlated with vigour indices, canopy density, and stomatal conductance and positively correlated with light penetration into the canopy.…”

“…TA in severely pruned and adequately irrigated grapevine was higher by 49.07% compared with minimally pruned grapevines under intense water stress (Figure 9). Other authors [1,26,[41][42][43]45] have also observed higher TA content in heavy pruned grapevine with well-irrigated grapevines probably related to a delay in ripening at which the bunches will not be able to reach target ripeness levels due to a restricted carbon allocation from the canopy and reduction of sugar accumulation.…”

Vineyard practices reduce the incidence of Aspergillus spp. and alter the composition of carposphere microbiome in grapes (Vitis vinifera L.)

“…Measurements of SWP were performed on vines of IR and NIR treatments to verify the impact of the contrasting irrigation treatments on grapevine water status. Indeed, grapevine water status considerably differed between the IR and NIR treatments, with the SWP values for both ranging from −1.20 to −1.22 MPa and − 1.50 to −1.56 MPa, respectively (Supplementary Figures S2A,B), suggesting a higher water deficit for the NIR plants at harvest since SWP values at the range of −1.10 to −1.30 MPa are considered as a moderated water deficit, whereas values inferior to −1.50 MPa are representative for severe water deficit (Theocharis et al, 2021).…”

Classification of Cabernet Franc Wines from Different Geographical Indications of Mendoza, Argentina, by Descriptive Sensory Analysis and Phenolic Profiles

“…Grapevine origin is relevant in the wine industry because it is associated with the definition of wine quality . Agronomic and environmental characteristics, such as soil, and climate, irrigation practices, pruning techniques, and soil physicochemical properties, are the main factors responsible for origin differences . In this vein, “terroir” has been defined as the interaction between the plant (genotype), combined with environmental and human factors related to crop management and winemaking techniques at each site .…”