Effects of Kaolin and Shading Net on the Ecophysiology and Berry Composition of Sauvignon Blanc Grapevines

Rising temperatures in most viticultural regions are associated with a higher incidence of drastic weather circumstances such as heatwaves. The consequences are reflected in qualitative and quantitative white grapes characteristics. In fact, there is an enhancement in alcohol content and a jeopardized reduction in the aromatic potential. We performed a scientific test to assuage the bump of heatwaves and exposure of grapes on Vitis vinifera cv. “Sauvignon Blanc” with exposed vines (untreated) or with kaolin foliar treatment or with partial fruit-zone shading (shading net 30 and 70%). This work aimed to evaluate the effects of shading net (SD-30% and SD-70%) and foliar kaolin (K) treatment on physiology, technological maturity, and thiolic precursors in Italy during the 2020–2021 seasons. For this purpose, four treatments were established: SD-30% (green artificial shading net at 30%), SD-70% (green artificial shading net at 70%), K (foliar kaolin), and CTRL (no application). During the two vintages, single-leaf gas exchange appraisal, leaf temperature, berry temperature, chlorophyll fluorescence, pre-dawn, and leaf water potential were measured. Moreover, berry weight, pH, °Brix, acidity (technological maturity specifications), and the following thiolic precursors were analyzed: 3-S-glutathionylhexan-1-ol (Glut-3MH), S-4-(4-methylpentan-2-one)-L-cysteine (Cys-4MMP), and 3-S-cysteinylhexan-1-ol (Cys-3MH). SD-70% and K denoted less negative water potential, a lower berry temperature, and a higher level of all precursors than the other treatments. Acidity and sugar parameters indicated significant differences among treatments. The lower berry weight and the lower tartaric acidity were found in the CTRL treatment. In comparison, SD-70% and K showed lower and more balanced sugar contents. As a result of global warming, color shading net and kaolin have been demonstrated to be good practices to counterpoise the divergence between aromatic and technological maturity in Sauvignon Blanc grapevines

Sustainable Viticulture: Effects of Soil Management in Vitis vinifera

Soil management in vineyards is of fundamental importance not only for the productivity and quality of grapes, both in biological and conventional management, but also for greater sustainability of the production. Conservative soil management techniques play an important role, compared to conventional tillage, in order to preserve biodiversity, to save soil fertility, and to keep vegetative-productive balance. Thus, it is necessary to evaluate long-term adaptation strategies to create a balance between the vine and the surrounding environment. This work sought to assess the effects of following different management practices on Vitis vinifera L. cv. Cabernet Sauvignon during 2017 and 2018 seasons: soil tillage (T), temporary cover cropping over all inter-rows (C), and mulching with plant residues every other row (M). The main physiological parameters of vines (leaf gas exchange, stem water potential, chlorophyll fluorescence, and indirect chlorophyll content) as well as qualitative and quantitative grape parameters (technological and phenolic analyses) were measured. Significant differences in gas exchanges related to the different season and inter-row management were observed. C showed more negative values of water potential, due to the grass–vine competition, especially when water availability was lower. The competition exerted by C led to differences in fruit setting with impact on yield; therefrom, significant differences also in sugar and anthocyanic content were observed

Effect of Agronomic Techniques on Aroma Composition of White Grapevines: A Review

Climate change with rising temperatures and the unpredictability of rainy events during ripening leads to tough challenges for the winemakers in preserving the quality of white grape varieties. Grape quality is a complex concept that mainly refers to berry chemical composition, including secondary metabolites such as aroma compounds that in white berries play a key role in the identity of the wine. Terpenes, thiols, C13-norisoprenoids, methoxypyrazines, and nonterpenic alcohols are the most important aroma compounds in white grapes and several of them can be found as free volatiles or bound as glycoconjugate molecules. Agronomic practices in vineyards, such as biostimulant application, irrigation, defoliation, training systems, foliar fertilization, and bunch thinning, can have a positive effect on their concentration. This review aims to highlight the aromatic characteristics of the most utilized white grape cultivars and focus on agronomic techniques in the vineyard to enhance, implement, and intensify their aromatic characteristics. The purpose of this review paper is therefore to investigate the state of the art regarding the exaltation of aroma in white grapes in the scientific literature through sustainable agronomic techniques, but further future investigations are considered necessary given the uncertainty concerning some mechanisms of biosynthesis and their correlation with such agronomic practices

Modeling the microscopic electrical properties of thrombin binding aptamer (TBA) for label-free biosensors

Aptamers are chemically produced oligonucleotides, able to bind a variety of targets such as drugs, proteins and pathogens with high sensitivity and selectivity. Therefore, aptamers are largely employed for producing label-free biosensors, with significant applications in diagnostics and drug delivery. In particular, the anti-thrombin aptamers are biomolecules of high interest for clinical use, because of their ability to recognize and bind the thrombin enzyme. Among them, the DNA 15-mer thrombin-binding aptamer (TBA), has been widely explored concerning both its structure, which was resolved with different techniques, and its function, especially about the possibility of using it as the active part of biosensors. This paper proposes a microscopic model of the electrical properties of TBA and the aptamer-thrombin complex, combining information from both structure and function. The novelty consists in describing both the aptamer alone and the complex as an impedance network, thus going deeper inside the issues addressed in an emerging electronics branch known as proteotronics. The theoretical results are compared and validated with Electrochemical Impedance Spectroscopy measurements reported in the literature. Finally, the model suggests resistance measurements as a novel tool for testing aptamer-target affinity.Comment: 5 figures, 1 tabl

Influence of water stress on grape quality and aroma precursors in Sauvignon Blanc grown in Bolgheri area (Tuscany)

Climate change has a direct impact on the phenological stages of the grapevine, with consequences on the anticipation of aging and on the qualitative characteristics of the grapes. In fact, there is a decrease in the skin/pulp ratio, with possible reduction of the aromatic potential. This work was aimed at assessing the effects of water stress on technological maturity and thiol precursors of Sauvignon Blanc grapes in two vineyards of Bolgheri. To this purpose, 3 theses have been established: WW, well watered; WS, moderate stress; CTRL, control. During the season, measurements of single leaf gas exchange, stem water potential were made; moreover parameters of technological maturity (° Brix, acidity, pH and berry weight) and thiol precursors were analyzed. As expected, the water potential was less negative in the irrigated thesis due to the greater availability of water, as well as the highest rates of photosynthesis, transpiration and stomatal conductance. Technological analyses showed no significant differences among the treatments. The analysis of the 3MH/3-mercaptoesan-1-ol precursors showed that the WW had a greater accumulation than the other theses. These results suggest that lower water stress favors a better aromatic content

Effects of Arthrospira platensis Extract on Physiology and Berry Traits in Vitis vinifera

Several advantages on physiology, productivity, and grape quality have been reported for grapevine treated with seaweed extracts, but little is known about the importance of cyanobacterial-based biostimulants in viticulture. The purpose of this pioneering work was to analyze the broad-spectrum effects of the Arthrospiraplatensis F&M-C256 extract on Vitis vinifera L. cv. Pinot Nero grown in pots in optimal conditions and under water stress. To evaluate the effects, major physiological parameters of the plants and the quali-quantitative parameters of grape were analyzed. According to the results obtained in this study, ameliorating effects in leaf gas exchanges induced by A. platensis F&M-C256 treatments were detected in both irrigation regimes. Above all, A. platensis F&M-C256 allowed keeping stomata open without negative consequences in water potential in treated vines under water-stress conditions. In terms of berry traits, A. platensis F&M-C256-treated vines presented higher berry weight in comparison with untreated vines in both water regimes and improved berry composition in treated vines subjected to drought. The results of the present study demonstrated an A. platensis-dependent physiological response in case of abiotic stress, which prominently affects grape traits at harvest