Assessment of changes in Grenache grapevine maturity in a Mediterranean context over the last half-century

This study aims to i) evaluate some descriptive variables for Grenache berry composition over the last 50 years in the southern Rhône Valley wine-growing region and ii) analyse the impacts of climate on the main annual developmental phases of the Grenache berry to understand recent changes observed in the vineyard. A large and spatialised historical, open database from the Rhône Valley grape maturity network (1969–2020) was used to explore trends in grape profile during maturity and at harvest. Then, gridded climate data was used for processing phenological stages and ecoclimatic indicators. Significant changes in grapevine phenology and maturity dynamics were found and linked with changes to ecoclimatic indicators by carrying out a correlation analysis. Depending on the phenological phases, a limited number of ecoclimatic indicators had a significant effect on the maturity profile. The results highlight direct climate impacts on different maturity and yield variables over the last 50 years. These results provide important information about future issues in grape production and the implications for managing viticulture adaptation strategies and thus serve as a basis for assessing, prioritising and optimising technical means of maintaining current grape quality and yield.This study uses an ecoclimatic approach for examining in detail the effects of climate change on the Grenache grape variety in a Mediterranean context. The open database provides the latest information from a large network of plots and over a long period of time, making it possible to validate many results recorded in the literature. This is the first study to use this open database and we wish this database could lead to further explorations and results in viticulture and climate change issues.

Sustainable Valorization of Sambucus nigra L. Berries: From Crop Biodiversity to Nutritional Value of Juice and Pomace

Improvement of dietary and ecological biodiversity, namely by exploring autochthonous varieties, is a key point to the construction of a more sustainable food system and planetary health. However, the environmental sustainability continues to face huge challenges, reflecting the importance of achieving a better understanding about the functional role of biodiversity in ecosystems. Thus, the main objective of this research is to contribute to the sustainable valorization of Sambucus nigra L. berries through a comprehensive approach to evaluate the effects of elderberry’s cultivar, harvest year, and plantation field on the physicochemical berry composition. Moreover, the nutritional value of elderberry juice and respective dried pomace was determined. This complementary information is of huge utility for the rational and, as much as possible, integral use of elderberries. The harvest year, followed by field and the interaction of harvest × field, accounted for the highest impact on the berry’s physicochemical parameters, indicating the importance of the combined impact of the macro- and mesoclimate conditions on plant metabolism. Elderberry juice and dried pomace are a good source of carbohydrates (ca. 12 and 82%, respectively) and have low amounts of fat (≤2.5%), making them low-energy foods. Dried pomace may also represent a potential alternative source of vegetal protein (ca. 6%).

Effect of Climate Change on Polyphenols Accumulation in Grapevine

Phenolics compounds in grapes contribute to berry and must color, organoleptic properties, nutritional value, antioxidant properties and provide protection against environmental challenges. Climate change has place mammoth challenges for the viticulture industry in different viticulture regions. Environmental variables determine to the greater extent, suitable grapes varieties for fresh as well as premium quality wine production. Grape berry composition is particularly affected by heat, drought, and intensity of solar irradiation. It is expected that climatic extremes will have an adverse effect on berry quality traits such as phenolic compounds in different grape cultivars. Polyphenols particularly anthocyanins decrease at elevated temperature, similarly flavanols levels increase with better exposure to solar radiation. Water availability is crucial for better vine growth and good production, however modest water stress particularly near veraison, upregulates the activity of key enzymes of the phenylpropanoid and flavonoid pathways. Therefore, it is important to know that how and when phenolic substance accumulate in berries and how various cultivars respond. This review elaborates the effect of weather conditions on biosynthesis of different phenolic compounds in grapes. Berry phenolic substances e.g., total phenolic compounds (TPC), total anthocyanins (TAC) and total flavonoid contents (TFC) synthesis is strongly regulated under the influence of environmental conditions during growing season. In this chapter we, shall focus on accumulation of phenolic compounds in grapevine in relation to climatic variations.

Pre-processing Cooling of Harvested Grapes Induces Changes in Berry Composition and Metabolism, and Affects Quality and Aroma Traits of the Resulting Wine

Due to the greenhouse gas increase, grapes are often exposed to high temperatures in several growing areas especially during the final developmental stages, and this is particularly true when early ripening cultivars are harvested. This may cause undesirable effects on berry metabolism and composition and wine quality, particularly concerning the aroma profile. Harvesting at night or keeping the harvested grapes in cold rooms before vinification are empirical protocols applied in specific viticultural areas. To study the effects of decreasing berry temperature after harvest, white-skinned berries (cv Vermentino) were maintained at 4 or 10°C for 24 or 48 h before processing (pre-cooling). Control grapes were kept at 22°C. Grapes cooled at 10°C for 24 and 48 h resulted richer in polyphenols and showed a significant up-regulation of genes involved in polyphenols biosynthesis (i.e., VvPAL, VvSTS2, and VvFLS1). Similar behavior was observed in samples kept at 4°C for 48 h. Pre-cooling induced specific changes in the volatile organic compound (VOC) profiles. In particular, higher amounts of a specific subcategory of terpenes, namely sesquiterpenes, were detected in cooled samples. The induction of the expression of key genes involved in terpenoids biosynthesis (VvHDR, VvDX3, VvTER, VvGT14) was detected in cooled grapes, with variable effects depending on temperature and treatment duration. In both cooled samples, the evolution of alcoholic fermentation followed a regular trend but ended earlier. Higher phenolic content was detected in wines obtained from the 10°C-treated grapes. Higher residual concentration of malic acid at the end of fermentation was detected in wine samples from grapes pre-cooled at 4°C. Sesquiterpenes also showed a general increase in wines from cooled grapes, especially after pre-cooling at 10°C for 48 h. Different sensory profiles characterized the wine samples, with the best scores in terms of general pleasantness obtained by the wine produced from grapes pre-cooled at 4°C for 24 h. These results demonstrate that pre-cooling harvested grapes induces specific effect on the VOC profile and other quality parameters of Vermentino wine, and this appears to be the result of specific metabolic and compositional changes occurring in the berries.

From the Autochthonous Grape Varieties of the Kastav Region (Croatia) to the Belica Wine

Research background. Coastal region of Croatia is rich in autochthonous grape varieties. Many of them have been almost abandoned such as the autochthonous varieties of Kastav (Croatia), used for the production of the Kastavska Belica wine. Therefore, the rationale of the presented study was to characterize autochthonous varieties 'Verdić', 'Mejsko belo', 'Jarbola', 'Divjaka' and 'Brajkovac' grape varieties. In addition, we performed a molecular characterization of the corresponding Belica wines. Experimental approach. Firstly, for five autochthons grape varieties, their genetic origin and ampelographic and economic characteristics were determined. Standard physico-chemical profiles and phenolic components by use of liquid chromatography coupled to triple quadrupole mass spectrometer (LC-QQQ) were determined for 12 corresponding wines from different producers. Fourier-transform infrared spectroscopy (FTIR) was used for determination of standard physico-chemical parameters Results and conclusions. Ampelographic analysis, which includes the data on producing characteristics and cluster and berry composition of varieties, revealed significant differences between analysed grape varieties. Results of physico-chemical analysis of the Belica wine showed that all wines met the requirements needed for the production of quality and top quality wines labelled with protected designation of origin (PDO) in Croatian coastal region. The LC-QQQ analysis confirmed the presence of different phenolic components in the Belica wines, where the most prominent phenols were flavonoids from the flavan-3-ol group. Overall, these results showed that autochthonous grapes from the Kastav region can be used for production of wines with added market value due to a growing demand for autochthonous products on the global market. Novelty and scientific contribution. The presented results represent scientific insight and a basis for further determination of the optimal cultivation technology aimed to take advantage of the best characteristics of each variety for production of a wine with desirable features.

Effect of Shading Nets on Yield, Leaf Biomass and Petiole Nutrients of a Muscat of Alexandria Vineyard Growing under Hyper-Arid Conditions

Background: Currently, viticulture is exposed to extreme weather fluctuations and global warming, thus the implementation of short-term adaptation strategies to mitigate climate change impacts will be of a wide importance for the sustainability and competitiveness of wine industry. This research aimed to study the effect of shading nets on the viticultural performance of a Muscat of Alexandria vineyard growing under hyper-arid conditions. Methods: Three treatments were randomly arranged in the vineyard: (i) a control (without shading), (ii) a white shading net (25% of shading), and (iii) a black shading net (40% of shading). Subsequently, yield, vine vigor, berry composition, leaf biomass and petiole nutrient content were assessed. Results: Both shading nets decreased the incidence of solar radiation in vines. The application of white shading nets induced a high bunch weight and a higher number of berries per bunch than the black shading nets. Black shading nets increased pruning weight, decreased Ravaz index and induced a considerably accumulation of soluble solids in grapes. This treatment also decreased bunch weight and the number of berries per bunch, and increased rachis length compared to control. Black shading nets decreased Mg petiole content, leaf dry weight and leaf biomass at flowering compared to uncovered vines. Conclusions: Shading considerably affected the viticultural performance of Muscat of Alexandria vines growing under hyper-arid conditions, modifying yield, leaf biomass and petiole nutrients.

Modeling Carbon Balance and Sugar Content of Vitis vinifera under Two Different Trellis Systems

Environmental factors might influence the carbon balance and sugar content in grapevine. In this two-year research, the STELLA software was employed to predict dry matter accumulation in Sangiovese vines, comparing the traditional vertical shoot positioning (VSP) and the single high wire (SHW) trellis systems. Every week, vegetative, eco-physiological and grape quality parameters were collected for 15 tagged vines per trellis system to set up the software. Significant differences in photosynthesis were recorded in 2014, with higher values in VSP (23–25% more). Shoot growth was significantly higher in VSP (20–25% more), whereas higher dry matter (30%) and yield (9–11% more) were detected for SHW. At harvest, berry composition suggested a slower ripening in SHW compared to VSP, which was linked to the shading of clusters in SHW. Finally, for the first time, linear regressions were found between measured berry sugar content and STELLA-estimated dry matter (R2 = 0.96 in VSP; R2 = 0.95 in SHW). This latter evidence allowed the estimation of berry sugar content, showing this software to be a practical tool to support winegrowers in decision making. Other studies are already underway to calibrate and validate the model for other varieties, training systems and environments.

Impact of Rootstock and Season on Red Blotch Disease Expression in Cabernet Sauvignon (V. vinifera)

Grapevine red blotch virus (GRBV), the causative agent of grapevine red blotch disease, is widespread across the United States and causes a delay in ripening events in grapes. This study evaluates the effects of GRBV on Cabernet Sauvignon grape berry composition, grafted on two different rootstocks (110R and 420A) in two seasons (2016 and 2017). Total soluble solids, acidity, and anthocyanin concentrations were monitored through ripening and at harvest. Phenolic and volatile compounds were also analyzed at harvest to determine genotypic and environmental influences on disease outcome. Sugar accumulation through ripening was lower in diseased fruit (RB (+)) than healthy fruit across rootstock and season. GRBV impact was larger in 2016 than 2017, indicating a seasonal effect on disease expression. In general, anthocyanin levels and volatile compound accumulation was lower in RB (+) fruit than healthy fruit. Total phenolic composition and tannin content was higher in RB (+) fruit than healthy fruit in only 110R rootstock. Overall, GRBV impacted Cabernet Sauvignon grape composition crafted on rootstock 110R more than those crafted on rootstock 420A.

Across-population genomic prediction in grapevine opens up promising prospects for breeding

Crop breeding involves two selection steps: choosing progenitors and selecting offspring within progenies. Genomic prediction, based on genome-wide marker estimation of genetic values, could facilitate these steps. However, its potential usefulness in grapevine (Vitis vinifera L.) has only been evaluated in non-breeding contexts mainly through cross-validation within a single population. We tested across-population genomic prediction in a more realistic breeding configuration, from a diversity panel to ten bi-parental crosses connected within a half-diallel mating design. Prediction quality was evaluated over 15 traits of interest (related to yield, berry composition, phenology and vigour), for both the average genetic value of each cross (cross mean) and the genetic values of individuals within each cross (individual values). Genomic prediction in these conditions was found useful: for cross mean, average per-trait predictive ability was 0.6, while per-cross predictive ability was halved on average, but reached a maximum of 0.7. Mean predictive ability for individual values within crosses was 0.26, about half the within-half-diallel value taken as a reference. For some traits and/or crosses, these across-population predictive ability values are promising for implementing genomic selection in grapevine breeding. This study also provided key insights on variables affecting predictive ability. Per-cross predictive ability was well predicted by genetic distance between parents and when this predictive ability was below 0.6, it was improved by training set optimization. For individual values, predictive ability mostly depended on trait-related variables (magnitude of the cross effect and heritability). These results will greatly help designing grapevine breeding programs assisted by genomic prediction.

Influence of Berry Ripening Stages over Phenolics and Volatile Compounds in Aged Aglianico Wine

The harvest time of grapes is a major determinant of berry composition and of the wine quality, and it is usually established through empirical testing of main biochemical parameters of the berry. In this work, we studied how the ripening stage of Aglianico grapes modulates key secondary metabolites of wines, phenolics and volatile compounds. Specifically, we analyzed and compared four berry ripening stages corresponding to total soluble solids of 18, 20, 22, and 25 °Brix and related aged wines. Wine color intensity, anthocyanins level and total trans-resveratrol (free + glycosidic form) increased with grape maturity degree. Wines obtained from late-harvested grapes significantly differed from the others for a higher content of aliphatic alcohols, esters, acetates, a-terpineol and benzyl alcohol. The content of glycosidic terpene compounds, such as nerol, geraniol and a-terpineol, was higher in wines obtained with grapes harvested at 25 °Brix compared to the earlier harvests. Our work indicated that the maturity of the grape is a determining factor in phenolic and volatile compounds of red Aglianico wines. Moreover, extending grape ripening to a sugar concentration higher than 22 °Brix improves the biochemical profile of aged wine in terms of aroma compounds and of phytochemicals with known health-related benefits.