The study of phenolic maturity in Vitis vinifera L. requires a multidisciplinary approach to understand how the evolution of berry flavonoids and cell wall material influence the colour and the textures of red wine. This is a challenging issue which involves researchers of viticulture and enology, and the results of their work are of particular interest for the producers of high-quality red wines. This review reports the current knowledge regarding phenolic maturity, describing the sensorial traits of the different compounds, the evolution of berry flavonoids and the methodologies used to evaluate their characteristics. Finally, the role of cell wall material in influencing the extractability of anthocyanins and proanthocyanidins was shown. By means of a critical review of the results, it can be hypothesised that prolonged ripening improved colour characteristics and mouthfeel properties, thanks to the higher amounts of extractable skin flavonoids associated with lower amounts of seed proanthocyanidins, and to the increased affinity of the cell wall material for the proanthocyanidins most involved in the perception of unpleasant astringency.
High temperatures and the anomalous distribution of rainfall during the growing season may have a negative impact on grapevine yield and berry composition. In recent years, many studies have focused on the application of agronomical techniques to reduce the negative impact of heat waves on secondary metabolites such as phenols. In particular, treatments with kaolin have shown positive effects on reducing canopy temperatures, enhancing the accumulation of anthocyanins. In regard to the above, three treatments were evaluated: untreated control (C), kaolin (CAO), and chabasite-rich zeolitites (ZEO) applications on cv. Sangiovese in order to verify the cooling effects on leaves and bunches, and the impact on gas exchange, yield parameters, berry composition, and on both chemical and sensory notes of wine. Minerals were sprayed twice around the veraison on the entire canopy at a 3% concentration. The results showed that the application of the minerals was able to reduce the berry temperatures in both years of the trial as compared to the untreated control (C), without affecting vine gas exchange, yield, and soluble solid accumulation. Furthermore, the cooling effect determined an increase in anthocyanin on both the grapes and the wine. At testing, CAO and ZEO wines stood out regarding greater color intensity and were preferred by the judges.
2 May 2011 in American Journal of Enology and Viticulture
A novel grapevine training system, semi-minimal-pruned hedge (SMPH), designed for mechanized pruning and harvesting was established on Sangiovese. The system was derived from adult spur-pruned cordon (SPC) vines that were modified to form a mechanically pruned hedge. SMPH heights of 80 cm and 120 cm were compared to SPC from 2005 to 2008, with an average of 332 and 479 buds per meter of row on SMPH 80 and 120, respectively, compared to 18 count nodes per meter of row on the hand-pruned SPC. The hedged vines had a larger leaf area, greater leaf area/crop ratio, and 35 to 40% yield increase compared to SPC, but there were no differences in juice soluble solids, pH, and acidity across the treatments. Berry skin anthocyanins were higher in hedged vines, notably the SMPH 120. The SMPH had more numerous but less compact and smaller clusters free of botrytis compared to SPC. While SMPH 120 showed a tendency to alternate bearing, this effect was minimal in SMPH 80. Single-shoot growth measured in 2006 was lower in SMPH vines, and total seasonal canopy light interception was higher compared to SPC vines. SMPH single-leaf assimilation was similar to SPC vines. Mechanical harvesting of both SMPH treatments was successful. These findings suggest that the two SMPH systems warrant further commercial evaluation because of their positive response to mechanization, grape yield, and quality and low susceptibility to bunch rot.
Vitis vinifera L. adapts well to a scarce availability of water in the soil. However, in recent decades, the combination of thermal stress with prolonged water scarcity could have dramatic consequences on the vine’s physiological status. In this paper, we evaluated the effects of two canopy shapes and two irrigation regimes at veraison on vine physiology, yield parameters and grape composition through biochemical and molecular approaches. The water shortage strongly influenced the physiology of Sangiovese only when the stress was moderate to severe. Neither the water stress limited to veraison nor the canopy shape were able to influence the yield parameters and sugar content, and a strong induction of the expression of the genes involved in the biosynthesis of anthocyanins was recorded only in conditions of moderate-to-severe stress. This phenomenon led to an increase in the anthocyanin content in berry skins until the end of veraison. Conversely, no significant effects occurred in terms of biochemical and molecular performance after re-watering and at harvest. Though the shape of the canopy could play a role only under elevated temperature and prolonged drought, severe water stress can affect the vine physiology and berry ripening during the veraison stage.
Vineyard mechanical winter pruning has been spreading worldwide, and the physiological basis ascribable to it has been consolidated throughout the years. Despite labor savings and reduction of costs having been proven, the demonstration of its economic viability might be challenging. In this context, this work aims to evaluate the vine performances and the costs of different degrees of the mechanization of winter pruning over a five-year trial (2011–2015). In a vineyard of cv. Trebbiano Romagnolo (Vitis vinifera L.) located in northern Italy, three pruning treatments were laid out as follows: (a) manual pruning (MAN); (b) mechanical pre-pruning and simultaneous manual follow-up (MP + F); (c) mechanical pruning without a manual follow-up (MP). The results showed a strong increase in the node number of MP. Nevertheless, the yield compensation factors (i.e., the shoot fruitfulness and cluster weight) limited the increase in productivity. Soluble solids did not differ between the pruning treatments, while titratable acidity resulted slightly higher only on the MP berries. The MP treatment was the most economically convenient, with a vineyard surface of 1.5 hectares, while mechanical pruning with manual finishing resulted more advantageous, compared to manual pruning when the vineyard surface was greater than 2.9 hectares. The agronomic and economic results obtained in this five-year trial suggest that mechanical pruning may be profitably applied also on grapevine varieties characterized by low basal bud fruitfulness, such as Trebbiano Romagnolo.