Grape Wine Quality Research Articles

Influence of Bunch Compactness and Berry Thinning Methods on Wine Grape Quality and Sensory Attributes of Wine in Vitis vinifera L. cv. ‘Monastrell’

Presently, there is no information available about the effect of bunch compactness and berry thinning methods on wine grape quality and sensory attributes of wine in the ‘Monastrell’ cultivar. Thus, the main aim of the present study was to determine the influence of bunch compactness and two berry thinning methods, which consisted of the reduction of 25% and 50% of the number of berries in each bunch, on wine grape quality and organoleptic quality of wine in this cultivar. Non-compact bunches and both berry thinning methods showed a significant reduction in total yield, bunch compactness, and bunch fresh mass compared with compact and control ones, respectively. However, these methods, especially the 50% one, significantly increased the content of total soluble solids and total phenolics. Furthermore, both berry thinning methods promoted the increase in total anthocyanins concentration in berries, as well as the hydrophilic total antioxidant activity. Berry thinning methods led to wines with greater sensory descriptors, such as fruity (odor and flavor), sour, sweet, aftertaste, and color, and were preferred by consumers. Finally, 50% berry thinning is the most useful tool to decrease bunch compactness and improve the overall quality of berries and sensory attributes of wines.

English

Mulching has been used widely to improve the production capacity of the soil, yield and the quality of wine grapes (Vitis vinifera L. cv. Cabernet Sauvignon). However, the ecological mechanisms underlying the mulching materials were not well understood. This study aimed to evaluate the effects of different mulching materials on soil chemical properties, bacterial community and wine grape quality. Experiments were performed at a grape-yard on the six-year-old wine grape ‘Vitis vinifera L. cv. Cabernet sauvignon. Five kinds of mulching materials include living turfgrass (Grass), living Herba portulacae (Por), inorganic plastic black film (Film), organic chips of wood (Wood), and grape branches (Branch) were applied, while clean tillage (CK) was treated as a control. Soil chemical properties and grape quality indicators were measured. Soil bacterial community diversity was detected using the Illumina Miseq sequencing for the 16S rRNA gene V3-V4 region. Mulching with plastic film, wood chips and Herba portulacae (Por) increased the content of soil organic matter, available N, P and K, total N and P. Film, grass, branch and Por mulching materials improved the content of tannin, anthocyanin, total phenol and titratable acid in grape (p<0.05). Proteobacteria, Actinobacteria, Chloroflexi, Acidobacteria and Gemmatimonadetes were abundant bacteria. Mulching with grape branch and portulacae increased the relative abundance of Gemmatimonadetes and Chloroflexi phylum, Gemmatimonadaceae family, and decreased Micrococcaceae family and Pseudarthrobacter genus. Mulching with living, organic, or inorganic changed chemical properties and grape quality indicators. These changes might be correlated with the altered soil bacterial community diversity and richness. © 2022 Friends Science Publishers

Ground-Based Thermal Imaging for Assessing Crop Water Status in Grapevines over a Growing Season

The quality of wine grapes in dry climates greatly depends on utilizing optimal amounts of irrigation water during the growing season. Robust and accurate techniques are essential for assessing crop water status in grapevines so that both over-irrigation and excessive water deficits can be avoided. This study proposes a robust strategy to assess crop water status in grapevines. Experiments were performed on Riesling grapevines (Vitis vinfera L.) planted in rows oriented north–south and subjected to three irrigation regimes in a vineyard maintained at an experimental farm in southeastern Washington, USA. Thermal and red–green–blue (RGB) images were acquired during the growing season, using a thermal imaging sensor and digital camera installed on a ground-based platform such that both cameras were oriented orthogonally to the crop canopy. A custom-developed algorithm was created to automatically derive canopy temperature (Tc) and calculate crop water stress index (CWSI) from the acquired thermal-RGB images. The relationship between leaf water potential (Ψleaf) and CWSI was investigated. The results revealed that the proposed algorithm combining thermal and RGB images to determine CWSI can be used for assessing crop water status of grapevines. There was a correlation between CWSI and Ψleaf with an R-squared value of 0.67 for the measurements in the growing season. It was also found that CWSI from the shaded (east) side of the canopy achieved a better correlation with Ψleaf compared to that from the sunlit (west) side around solar noon. The created algorithm allowed real-time assessment of crop water status in commercial vineyards and may be used in decision support systems for grapevine irrigation management.

Foliar application of chelated sugar alcohol calcium fertilizer for regulating the growth and quality of wine grapes

Foliar application of chelated sugar alcohol calcium fertilizer for regulating the growth and quality of wine grapes

Yield performance and quality of wine grapes (Vitis vinifera) grafted onto different rootstocks under subtropical conditions

This study aimed to evaluate the productive performance and physicochemical traits of wine grape cultivars (Cabernet Sauvignon, Syrah, Cabernet Franc, Merlot, and Sauvignon Blanc) grafted on two different rootstocks (IAC 766 Campinas, and 106-8 Mgt) under subtropical conditions. The productive components (number of bunches, production per vine, yield, number of berries per bunch, fresh mass, length, and width of berries) and the grape must physicochemical composition (pH, titratable acidity, soluble solids, and maturation index) were determined after four consecutive harvest seasons. Results from analysis of variance and principal component analysis showed that Cabernet Franc and Syrah were generally more productive than the other ones. In addition to that, Cabernet Sauvignon presented the lowest production and the smallest grape berries of all. With regards to rootstocks, IAC 766 induced higher scions yield than 106-8 Mgt; besides that, IAC 766 had greater affinity with Cabernet Franc and Merlot, which was observed by the increase in the number of bunches per vine, larger and heavier bunches, as well as higher soluble solids content and pH value than the ones in 106-8 Mgt. Furthermore, IAC 766 also induced higher soluble solids content and pH value for Cabernet Sauvignon. Results showed similar effects for Syrah and Sauvignon Blanc, regardless of the rootstocks.

Cos-Oga Applications in Organic Vineyard Manage Major Airborne Diseases and Maintain Postharvest Quality of Wine Grapes

Cos-Oga Applications in Organic Vineyard Manage Major Airborne Diseases and Maintain Postharvest Quality of Wine Grapes

Effects of foliar iron spraying on Cabernet Sauvignon phenolic acids and proanthocyanidins

In order to explore the effect of different irons on the fruit quality of wine grapes, as well as the phenolic acids and proanthocyanidins of the peel, “Cabernet Sauvignon” was taken as the research object. Ferrous sulfate, EDTA-Fe, ferric citrate, ferric gluconate and ferric sugar alcohol were sprayed between the coloring periods, and the foliar sprayed water was used as the control. The results showed that foliar spraying of iron would increase the fruit sugar-acid ratio and 100-grain weight; iron spraying would up-regulate the content of phenolic acid monomers, among which EDTA-Fe and ferric citrate had significant up-regulating effects, but all iron treatments had a significant effect on the increase. The content of caffeic acid and chlorogenic acid was down-regulated; the content of proanthocyanidin monomer was up-regulated by iron spraying, and the content of proanthocyanidin monomer was significantly up-regulated by ferric citrate treatment. Foliar spraying of ferric citrate not only balanced the sugar-acid ratio of the fruit, but also increased the content of phenolic acid and proanthocyanidin in the grape peel, which further improved the quality of the grapes and helped to increase the flavor of the wine.

Study on the Influence of Physicochemical Indexes on Wine Quality

The quality of a wine is generally determined by hiring a group of qualified wine judges to taste the wine. The quality of wine grapes is directly related to the quality of wine. To explore how the physical and chemical indicators of wine and wine grapes can reflect the quality of wine and grape to a certain extent. This article is based on 2012 Chinese college students' mathematical contest in modeling A problem of data, to score as the dependent variable, wine physical and chemical indicators as independent variables, the method of using principal component analysis of physical and chemical indexes of wine grape dimension reduction, physical and chemical indexes selection of grapes, and use the decision tree regression method to establish score and wine function relation between the physical and chemical indicators. Then, after the comparison of the results of the four clustering algorithms, the hierarchical clustering method based on Agnes algorithm was used to conduct cluster analysis on the wines. Considering the rationality of classification, red and white wines were divided into four grades, and the average value of the estimated scores of each grade was used as the benchmark score for the wines of this grade.

Applied GA5, GA4, and GA4/7 increase berry number per bunch, yield, and grape quality for winemaking in Vitis vinifera L. cv. Malbec

The gibberellins (GAs) GA5 (inhibitor of GA3 -oxidase), GA4 (biologically active), GA4/7 (commercially available mixture of Ga4 and GA7 ) prohexadione-calcium (ProCa, inhibitor of dioxygenases that render GAs bioactive, negative control), and GA3 (positive control) were applied to bunches of Vitis vinifera cv. Malbec. Different techniques, doses, and timings were used in a 3-year field experiment. In year1, GA5 , ProCa, and GA3 were applied at 35, 20, and 0 days before veraison (DBV) by dipping bunches three times. In year2, single applications of GA5 and GA3 , also by immersion, were tested at 60, 45, and 30 DBV. In year3, applications at 60 and 30 DBV of GA5 , GA4 , and a mixture of GA4/7 were evaluated by dipping or spraying the bunches. Vegetative growth, berry weight, and sugar content were unaffected by treatments. ProCa did not affect the yield with respect to water control, although it reduced the levels of phenolics in berry skins, an undesirable effect for winemaking. GA5 , in the dose range 5-50 mg L-1 , raised berry numbers, thereby augmenting bunch weight and skin phenolics at harvest, so increasing berry quality for winemaking. GA4 and GA4/7 produced similar benefits to GA5 , with similar doses. The applications of GA5 , GA4 , and GA4/7 to developing grape berry bunches, in a range of concentrations and by dipping or spraying, increased berry numbers per bunch at harvest. The method can be used as a viticultural practice to improve the production and quality of wine grapes. © 2021 Society of Chemical Industry.

Salicylic acid induces tolerance of Vitisriparia×V.labrusca to chilling stress by altered photosynthetic, antioxidant mechanisms and expression of cold stress responsive genes

ABSTRACT The yield and quality of wine grapes are severely persecuted by low-temperaturestresses. Salicylic acid (SA) assists plants in coping with abiotic stresses such as drought, heavy metal toxicity, and osmotic stress. The objective of this study was to evaluate the effect of foliar spraying of different concentrations of SA on the mitigation of cold damage in grapes, which is useful for the cultivation of wine grapes.Vitisriparia×V.labruscaseedlings were treated with foliar-sprayedSA at concentrations of 0–2 mM and then subjected to chilling stress at 4°C for 2 or 4 days, while the expression of relevant physiological indicators and cold response genes (CBF1, CBF2, CBF3) were measured. The findings indicated that low temperature stresses markedly reduced chlorophyll content, and increased proline as well as soluble sugar content, enhanced superoxide dismutase (SOD) and peroxidase (POD) activities, decreased catalase (CAT) activity and inducedCBFgene expression in leaves. Physiologically, foliar spraying of different concentrations of SA greatly increased antioxidant enzyme activity (P < .05), soluble sugars, proline, and chlorophyll content of grapes leave under low temperature stress. With regard to gene expression, SA has significantly regulated the cold response genesCBF1, CBF2, andCBF3. Therefore, SA could reduce cold damage in grapevines under low-temperaturestress, and the effect of SA was most pronounced in the 1 and 2 mM concentrates.

1-Aminocyclopropane-1-Carboxylate Deaminase-Producing Plant Growth-Promoting Rhizobacteria Improve Drought Stress Tolerance in Grapevine (Vitis vinifera L.).

Plant growth-promoting rhizobacteria (PGPRs) that produce 1-aminocyclopropane-1-carboxylate (ACC) deaminase are capable of reducing limits to plant growth due to water-deficient conditions. Here, seven PGPR strains that can produce ACC deaminase were successfully obtained from the rhizosphere soil of grapevine (Vitis vinifera L.) in arid regions of China. The strains belonged to three different genera: Pseudomonas, Enterobacter, and Achromobacter, according to their 16S rDNA sequencing analysis. A drought tolerance experiment revealed two PGPR strains (DR3 and DR6) with exceptionally high phosphate solubilization, nitrogen fixation, indoleacetic acid (IAA), and exopolysaccharides secretion potential. Both strains were selected for use in a pot experiment to evaluate their growth-promoting effects on grapevines under drought conditions. Each of these two PGPRs and their mixed inoculation into grapevines were expected to alleviate the comprehensive growth inhibition of grapevines caused by drought stress. The mixed inoculation was hypothesized to elicit the best growth-promoting effects. Inoculation with the PGPRs not only enhanced the root-adhering soil/root tissue ratios and soil aggregate stability, but it also increased the nitrogen and phosphorus levels in the soil and plant leaves. Further, inoculation with PGPRs significantly altered the plant height, biomass of shoot and root organs, relative water contents, and net photosynthetic rate of leaves, enabling grapevines to better cope with drought. Moreover, the contents of IAA, abscisic acid, and malondialdehyde in these grapevines under drought stress were significantly changed by PGPRs. They indirectly affected biochemical and physiological properties of grapevines to alleviate their drought stress. Taken together, these results demonstrate that the DR3 and DR6 PGPRs might be useful for effectively weakening the growth inhibition caused by drought in grapevines. The strains might also be applied as effective bioinoculants to maintain the quality of wine grapes.

Application of a hyperspectral imaging system to quantify leaf-scale chlorophyll, nitrogen and chlorophyll fluorescence parameters in grapevine

Rapidly and accurately monitoring the physiological and biochemical parameters of grape leaves is the key to controlling the quality of wine grapes. In this study, a Pika L hyperspectral imaging system (400–1000 nm) was used to acquire hyperspectral image information from grape leaves. New vegetation indices were developed on the basis of the screened sensitive wavebands to quantitatively predict changes in these parameters (the leaf chlorophyll level (SPAD), leaf nitrogen content (LNC) and chlorophyll fluorescence parameters (ChlF parameters)). The results showed that SPAD reached its maximum at the grape turning stage and declined thereafter. The vegetation index (D735−D573)/(D735+D573) was able to predict SPAD fairly well (validation dataset R2 = 0.50). LNC reached its maximum at the grape maturity stage. D682/R525 was highly correlated with LNC. Except for NPQ, all ChlF parameters showed a decreasing trend from the fruiting to harvesting stages. Among the dark-adapted ChlF parameters, FV/Fm had the strongest correlation to the new vegetation index (D735−D544)/(D735+D544) (modelling dataset R2 = 0.68), and Fo had the weakest correlation. Among the light-adapted ChlF parameters, Y(II) had the strongest correlation to the new vegetation index D676/R571 (validation dataset R2 = 0.63); this index also had good predictive power for Fm' (validation dataset R2 = 0.52) but low predictive power for Fo'. All the calculated vegetation indices had weak relationships with NPQ. In addition, this study also verified the predictive abilities of vegetation indices developed in previous studies. This study can provide a technical basis for the nondestructive monitoring of the physiological and biochemical parameters of grape leaves with hyperspectral imaging systems.

Investigating a Selection of Methods for the Prediction of Total Soluble Solids Among Wine Grape Quality Characteristics Using Normalized Difference Vegetation Index Data From Proximal and Remote Sensing.

The most common method for determining wine grape quality characteristics is to perform sample-based laboratory analysis, which can be time-consuming and expensive. In this article, we investigate an alternative approach to predict wine grape quality characteristics by combining machine learning techniques and normalized difference vegetation index (NDVI) data collected at different growth stages with non-destructive methods, such as proximal and remote sensing, that are currently used in precision viticulture (PV). The study involved several sets of high-resolution multispectral data derived from four sources, including two vehicle-mounted crop reflectance sensors, unmanned aerial vehicle (UAV)-acquired data, and Sentinel-2 (S2) archived imagery to estimate grapevine canopy properties at different growth stages. Several data pre-processing techniques were employed, including data quality assessment, data interpolation onto a 100-cell grid (10 × 20 m), and data normalization. By calculating Pearson’s correlation matrix between all variables, initial descriptive statistical analysis was carried out to investigate the relationships between NDVI data from all proximal and remote sensors and the grape quality characteristics in all growth stages. The transformed dataset was then ready and applied to statistical and machine learning algorithms, firstly trained on the data distribution available and then validated and tested, using linear and nonlinear regression models, including ordinary least square (OLS), Theil–Sen, and the Huber regression models and Ensemble Methods based on Decision Trees. Proximal sensors performed better in wine grapes quality parameters prediction in the early season, while remote sensors during later growth stages. The strongest correlations with the sugar content were observed for NDVI data collected with the UAV, Spectrosense+GPS (SS), and the CropCircle (CC), during Berries pea-sized and the Veraison stage, mid-late season with full canopy growth, for both years. UAV and SS data proved to be more accurate in predicting the sugars out of all wine grape quality characteristics, especially during a mid-late season with full canopy growth, in Berries pea-sized and the Veraison growth stages. The best-fitted regressions presented a maximum coefficient of determination (R2) of 0.61.

Assessing wine grape quality parameters using plant traits derived from physical model inversion of hyperspectral imagery

Together with ensuring a stable yield, improving grape composition and aroma is the main goal of wine grape production management as it determines consumer acceptance and ultimately revenue. Understanding the triggers of the synthesis of aromatic components and finding methods to map their variability in the field can aid management practices during the season and planning selective harvest in views of maximizing benefit. Vegetation indices have been shown to track grape colour, sugar and acidity content but it has been demonstrated that aromatic components are the main drivers of the final palate of wine and are not correlated to sugar concentration. Leaf pigments such as chlorophyll, carotenoids and anthocyanins are involved in the metabolic pathways of aroma compounds in grapes. The physiological connections between grape aromatic components and primary and secondary photosynthetic pigments suggest that they could be used to detect processes related to aroma composition.This study investigates the links between grape quality parameters such as aromatic components and image-quantified spectral indices and photosynthetic plant traits derived by physical model inversion methods. Two sets of high-spatial resolution hyperspectral and thermal imagery were collected with an unmanned platform at veraison and harvest. The variability found in the field was partly but not fully explained by the thermal-based crop water stress index as an indicator of water stress (r2= 0.51–0.58, p-value<0.01). Fluspect-CX leaf model was coupled to 4SAIL canopy model and inverted to map the main photosynthetic pigment groups and the fraction of pigments acting in photoprotection. Results obtained through radiative transfer model inversion outperformed traditional vegetation indices related to pigment content and degradation. We found statistically significant relationships between image-retrieved pigments and terpenoids responsible for wine aroma (p-value<0.005).

Ripening-associated flattening out of inter-varietal differences in some groups of phenolic compounds in the skins of six emblematic grape wine varieties

The sensorial quality of wine grapes largely depends on the phenolic composition. Malbec, Tempranillo, Sangiovese, Petit Verdot, Cabernet Franc and Carménère are emblematic Vitis vinifera red grape varieties for wine-producing valleys around the world. This study aimed to characterize the phenolic composition (total phenols, tannins and anthocyanins, size-based proanthocyanidin fractions, anthocyanidin conjugates and low molecular weight phenolics) of grape skins from those alien varieties grown in Chile under common edaphoclimatic and cultural conditions throughout ripening. Some marked quantitative intervarietal differences were observed at corresponding phenological stages. Exceptionally, some compounds were either overexpressed (cyanidin glucoside) or not expressed (conjugated anthocyanidins) in single varieties. Despite those differences, ripening was characterized by a striking intervarietal assimilation (lower variation coefficients) mostly concerning the group of low molecular weight phenolics. Such intervarietal convergence suggests that the emblematic character can depend on the varietal gene pool and its interactions with a specific terroir and local cultural practices.

Development and performance evaluation of a machine vision system and an integrated prototype for automated green shoot thinning in vineyards

AbstractGreen shoot thinning in vineyards is an essential, perennial operation for maintaining canopy health and optimizing yield and quality of wine grapes. Use of mechanized thinning system, which is essential to reduce labor dependency and associated cost, causes high variability in shoot removal efficiency due to difficulty in precisely positioning the thinning end‐effector along cordon trajectories. Automated/robotic solution for precise positioning of the thinning end‐effector could significantly improve the performance and efficiency of mechanical green shoot thinning. This study presents: (i) a machine vision‐based cordon detection system that can estimate cordon trajectories at different shoot growth stages in a vineyard; and (ii) evaluation of an integrated green shoot thinning system capable of automatically positioning the thinning end‐effector following vine cordon trajectories. The developed machine vision system uses deep learning‐based techniques that could accurately estimate cordon trajectories with root mean square error (RMSE) of 7.3, 10.3, and 16.1 pixels for canopy images captured in 2–4 weeks of shoot growth, respectively. Then, a control strategy was presented for the integrated system, which receives the computed cordon trajectories from machine vision system to automatically position the thinning end‐effector to cordon trajectories. Field evaluations in a research vineyard showed that the integrated system can achieve an RMSE of 1.47 cm in following the cordon trajectories at 6.6 cm·s−1forward speed. Future work will incorporate additional sensing system to detect individual shoot on cordon and integrating it with an existing system to achieve higher level of precision in green shoot thinning.

The reduction of plant sink/source does not systematically improve the metabolic composition of Vitis vinifera white fruit

The quality of wine grapes depends on the balance between primary and secondary metabolites. Unlike many perennial crops that accumulate starch in the fruits before ripening, the non-climacteric grapes ripe with no previous carbon reserves. Based on the assumption that fruit carbon sink is limiting metabolite accumulation in grapes, bunch thinning is performed to limit plant Sink/Source (S/S). We studied the effects of severe bunch thinning on the accumulation of primary metabolites and on four families of glycosylated aroma precursors (GAPs) at the arrest of fruit phloem unloading of two white grape Vitis vinifera cvs. At plant level, crop reduction resulted in significant losses of metabolites to be accumulated in the fruits: i.e. up to 72% for sugars, 75% for organic acids and GAPs. Nevertheless, S/S manipulation could not modify the balance between GAPs and primary metabolites or increase the concentration in GAPs in the physiologically ripe grape.

Utilizing Pruning and Leaf Removal to Optimize Ripening of Vitis riparia-Based ‘Frontenac Gris’ and ‘Marquette’ Wine Grapes in the Northern Great Plains

Experiments were conducted to evaluate the effects of three pruning levels (20, 30 and 40 nodes per vine) and three fruit-zone leaf removal levels (0%, 50%, and 100%) on the yield and fruit quality of Frontenac gris and Marquette wine grapes in a northern production region. The study was conducted at three North Dakota vineyards located near Buffalo, Clifford, and Wahpeton, North Dakota, in 2011 and 2012. Increasing the number of buds retained increased yields and reduced pruning weights in both cultivars. Frontenac gris and Marquette yields were greatest when vines had 50% of the fruit-zone leaves removed due to heavier clusters, suggesting that the 100% fruit-zone leaf removal level was too severe. Individual berries in clusters were also heavier when vines were pruned to retain 40 buds. Frontenac gris fruit quality was similar both years and was not influenced by pruning or leaf removal levels. Marquette fruit total soluble solids content was greater in 2012 due to the warmer and longer growing season. Marquette fruit titratable acidity was lower when 100% of the fruit-zone leaves were removed. These results suggest that for the two cold-hardy hybrid wine grapes used in this study, greater bud retention levels should be investigated. Results also warrant further research into cultivar adaptiveness to northern Great Plains conditions. With further research, it is anticipated that wine grape cultivars and management practices will be identified to produce acceptable yields and fruit quality for commercial wine grape production.

Physicochemical properties of vineyard soils and its relationships with wine grape quality in Osaka, Japan

Physicochemical properties of vineyard soils and its relationships with wine grape quality in Osaka, Japan

Effect of irrigation levels on yield and quality of Cabernet Sauvignon vines of wine grapes under semiarid tropics of India

To improve quality of wine grapes, it is necessary to strike balance between vegetative and reproductive growth. Thus, developing irrigation schedule becomes important in managing vine vigour, which in turn helps in reducing the berry size, which is one of the main requirements for wine making. A three year (2010-11 to2012-13) study was conducted to develop irrigation schedule for Cabernet Sauvignon, wherein six treatmentswith various replenishment rates based upon pan evaporation at different crop growth stages were compared. All the treatments proved similar statistically in respect of yield and yield related parameters. Lower values oftartaric: malic acid ratios were observed in T1 and T6 treatments than others. Treatment T6 showed highest water use efficiency (84.30 kg of grapes/ mm) of irrigation water applied. The irrigation water applied was least in T6 treatment (209.7 mm) apart from 192 mm rainfall. Even though least irrigation was provided to vines till harvesting in treatment T6, nevertheless moisture stored in the soil profile was sufficient to meet the crop need. Thus, irrigation schedule (T6) with minimal irrigation has been found to produce fairly good yield andquality grapes, which can be comparable with other treatments providing higher quantity irrigation to vines.