Cabernet Franc Research Articles

Pruning cuts affect wood necrosis but not the percentage of budburst or shoot development on spur pruned vines for different grapevine varieties

Two experimental studies were performed in this trial. In the first, the aim was to quantify wood necrosis generated by pruning cuts on aboveground permanent (arms and trunks) and non-permanent (spurs) woody structures of 'Cabernet Sauvignon' vines. In the second, the goal was to evaluate the effect of cutting distance from the basal end of the shoot in spur pruned vines on budburst and further shoot development for 'Grenache', 'Cabernet Franc' and 'Malbec' varieties. Based upon the first experiment, the area and depth of wood necrosis was highly influenced by the distance where the pruning cut was performed over the node. Furthermore, the diameter of the spur that was cut was not significantly related to either the area or the depth of the necrotic wood generated after the cut. Aboveground vine wood necrotic area ranged from 9 to 44 % of the total wood area measured in 'Cabernet Sauvignon' cordon trained spur pruned 25-year-old grapevines. For each vine a larger proportion of the necrotic wood (20 to 46 % of necrotic area) was present in the arms when compared to the trunks (1 to 28 % of necrotic area). As a result of the second experiment, spur budburst and further shoot development was not affected by the distance from the node where the pruning cut was performed for any of the cultivars considered in the study contrary to what is commonly believed.

Cultivar Susceptibility to Natural Infections Caused by Fungal Grapevine Trunk Pathogens in La Mancha Designation of Origin (Spain).

Grapevine trunk diseases (GTDs) are one of the main biotic stress factors affecting this crop. The use of tolerant grapevine cultivars would be an interesting and sustainable alternative strategy to control GTDs. To date, most studies about cultivar susceptibility have been conducted under controlled conditions, and little information is available about tolerance to natural infections caused by GTD fungi. The objectives of this study were: (i) to identify tolerant cultivars to GTD fungi within a Spanish germplasm collection, based on external symptoms observed in the vineyard; and (ii) to characterize the pathogenic mycoflora associated with symptomatic vines. For this purpose, a grapevine germplasm collection including 22 white and 25 red cultivars was monitored along three growing seasons, and their susceptibility for esca foliar symptoms was assessed. Fungi were identified by using morphological and molecular methods. Cultivars such as, ‘Monastrell’, ‘Graciano’, ‘Cabernet Franc’, ‘Cabernet Sauvignon’, ‘Syrah’, ‘Moscatel de Alejandría’, ‘Sauvignon Blanc’, and ‘Airén’ displayed high susceptibility to GTDs, whereas others such as ‘Petit Verdot’, ‘Pinot Noir’, ‘Chardonnay’, and ‘Riesling’ were considered as tolerant. The prevalent fungal species isolated from symptomatic vines were Phaeomoniella chlamydospora (27.9% of the fungal isolates), Cryptovalsa ampelina (24.6%), and Dothiorella sarmentorum (21.3%).

Modifying Shoot Tip Management to Reduce Cluster Compactness and Lateral Emergence in ‘Cabernet franc’ Grapevines

To manage excessive vine vigor, Vitis vinifera L. ‘Cabernet franc’ grapevines were subjected to shoot wrap, shoot tuck, and hedge (control) techniques at one of two growth stages (shoot tips at 30 cm or at 90 cm above the top catch wire) in the Finger Lakes region of New York from 2016 to 2019. Shoot tuck and shoot wrap both reduced fruit zone lateral counts, with reductions up to 33% and 56% compared with the control, respectively. Shoot wrap reduced fruit zone lateral lengths by up to 50% and cluster compactness by up to 2.4 fewer berries per centimeter rachis. Although shoot wrap improved spray penetration to the clusters by up to 28% in one year of the study, enhanced point quadrat analysis indicated that occlusion layer number was not affected by the treatments. Shoot tip management treatments did not affect yield or fruit composition consistently. Phenological timing of shoot tip management had little impact on vine growth. Although the impacts of these modified shoot tip management practices on lateral emergence and cluster morphology were generally positive, the required hand labor to apply the treatments on a large scale may discourage the use of these management practices.

Rootstock influences the effect of grapevine leafroll-associated viruses on berry development and metabolism via abscisic acid signalling.

Grapevine leafroll‐associated virus (GLRaV) infections are accompanied by symptoms influenced by host genotype, rootstock, environment, and which individual or combination of GLRaVs is present. Using a dedicated experimental vineyard, we studied the responses to GLRaVs in ripening berries from Cabernet Franc grapevines grafted to different rootstocks and with zero, one, or pairs of leafroll infection(s). RNA sequencing data were mapped to a high‐quality Cabernet Franc genome reference assembled to carry out this study and integrated with hormone and metabolite abundance data. This study characterized conserved and condition‐dependent responses to GLRaV infection(s). Common responses to GLRaVs were reproduced in two consecutive years and occurred in plants grafted to different rootstocks in more than one infection condition. Though different infections were inconsistently distinguishable from one another, the effects of infections in plants grafted to different rootstocks were distinct at each developmental stage. Conserved responses included the modulation of genes related to pathogen detection, abscisic acid (ABA) signalling, phenylpropanoid biosynthesis, and cytoskeleton remodelling. ABA, ABA glucose ester, ABA and hormone signalling‐related gene expression, and the expression of genes in several transcription factor families differentiated the effects of GLRaVs in berries from Cabernet Franc grapevines grafted to different rootstocks. These results support that ABA participates in the shared responses to GLRaV infection and differentiates the responses observed in grapevines grafted to different rootstocks.

Proximal sensing of vineyard soil and canopy vegetation for determining vineyard spatial variability in plant physiology and berry chemistry

Proximal sensing is used in vineyards to precisely monitor and manage spatial and temporal variability while reducing laborious and repetitive measurements. Soil electrical conductivity (EC) and canopy vegetation indexes are two frequently assessed variables with off-the-shelf sensors. In this study, the ecophysiological variability of a commercial vineyard comprising three varieties in three blocks, Cabernet-Sauvignon (CS), Cabernet franc (CF), and Petit Verdot (PV), was investigated. Random sampling was used to continuously assess spatial variability in plant physiology and berry composition. Soil EC and NDVI were also continuously monitored throughout the season. There was a noticeable spatial pattern in the normalised differential vegetation index (NDVI) in the vineyard and soil EC. The spatial pattern of NDVI can be partially elucidated by the season-long stem water potential (Ψstem), which was lowest in the CS block. However, leaf photosynthesis did not match this spatial pattern. The spatial distribution of NDVI and soil EC did not satisfactorily explain the spatial variations in yield components and berry chemistry. Principal component analyses (PCA) were performed resulting in a clear discrimination of each of the three cultivars. Soil EC showed a significant relationship with Ψstem integrals, total skin anthocyanins and tri- to di-hydroxylated flavonoids. In each cultivar block, soil EC showed some capability to be related to plant water status, and NDVI showed a relationship with yield. Overall, this study provided evidence of the spatial variability of grapevine physiology in a commercial vineyard with three cultivars. Also, it showed that the cultivar effect and uniform crop level management can diminish the efficiency of proximal sensing, thus weakening the relationship of soil and canopy indexes with plant physiology and berry chemistry. Nonetheless, our study showed that it is possible to apply temporal proximal sensing methods when assessing plant water status, primary metabolism, yield and berry secondary metabolism, which give an indication of the possibility of managing the spatial variability of both plant physiology and berry chemistry.

Modification of Sensory Expression of 3-Isobutyl-2-methoxypyrazine in Wines through Blending Technique.

Sensory interactions exist between 3-alkyl-2-methoxypyrazines and various volatiles in wines. In this study, the binary blending of Cabernet Franc wines containing high levels of MPs and three monovarietal red wines with two proportions was conducted after fermentation. Volatiles were detected by gas chromatography-mass spectrometry (GC-MS), and wines were evaluated by quantitative descriptive analysis at three-month intervals during six-month bottle aging. Results showed blending wines exhibited lower intensity of ‘green pepper’, especially CFC samples blended by Cabernet Sauvignon wines with an even higher concentration of 3-isobutyl-2-methoxypyrazine (IBMP). Based on Pearson correlation analysis, acetates could promote the expression of ‘tropical fruity’ and suppress ‘green pepper’ caused by IBMP. Positive correlation was observed among ‘green pepper’, ‘herbaceous’, and ‘berry’. The concentration balance between IBMP and other volatiles associated with ‘green pepper’ and fruity notes was further investigated through sensory experiments in aroma reconstitution. Higher pleasant fruity perception was obtained with the concentration proportion of 1-hexanol (1000 μg/L), isoamyl acetate (550 μg/L), ethyl hexanoate (400 μg/L), and ethyl octanoate (900 μg/L) as in CFC samples. Blending wines with proper concentration of those volatiles would be efficient to weaken ‘green pepper’ and highlight fruity notes, which provided scientific theory on sensory modification of IBMP through blending technique.

Terroir of winter hardiness: bud LT50, water metrics, yield, and berry composition in Ontario Cabernet franc

Winter hardiness may be influenced by vineyard terroir-driven factors, and vineyard zones with low water status [leaf water potential (ψ)] could be more winter hardy than vines with high water status (higher leaf ψ). Six Cabernet franc vineyards were chosen throughout the Niagara region in Ontario. Data were collected at fruit set, lag phase, and veraison [soil water content (SWC), leaf ψ], at harvest (yield components, berry composition), and three times during winter (LT50; the temperature at which 50% of buds die) in the 2010–2012 seasons. Interpolation by kriging and mapping of variables was completed using ArcGIS, and statistical analyses (linear correlation, k-means clustering, principal components analysis, multilinear regression) were performed. Spatial trends were observed in each vineyard for SWC, leaf ψ, yield components, berry composition, and LT50. Geographic information systems (GIS) and statistical analysis revealed that leaf ψ could predict LT50, with strong positive correlations between LT50and leaf ψ values in most vineyards in 2010–2011. In the dry 2012 season, leaf ψ (particularly at veraison; range −1.3 to −1.6 MPa) was positively correlated to LT50, yield, titratable acidity (TA), pH, and Brix and negatively to SWC, color, anthocyanins, and phenols. Overall, vineyards in different appellations (Niagara Lakeshore, Lincoln Lakeshore, Four Mile Creek, Beamsville Bench) showed many similarities. These results suggest that there is a spatial component to winter injury, as with other aspects of terroir. Furthermore, this study allows for means by which to compare winter hardiness to other critical variables to better understand the terroir of the Niagara region.

Influence of cluster positions in the canopy and row orientation on the flavonoid and volatile compound profiles in Vitis vinifera L. Cabernet franc and Chardonnay berries

Sunlight conditions around grape clusters vary with their positions, and can have a significant effect on grape berry compounds. This study investigated the influence of cluster positions in the canopy (interior and two exterior canopy sides) and vineyard row orientation (north–south and east–west) on flavonoid and volatile compound profiles of Vitis vinifera L. cvs ‘Cabernet franc’ (CF) and ‘Chardonnay’ (CH) berries in two consecutive years. The experimental vineyard was located in Jiaodong Peninsula of China, which is characterized by a temperate monsoon-type climate and relatively short sunlight duration. Clusters located in the interior of the canopy received less sunlight irradiation than the exterior positions, and the average temperature around clusters located in different positions differed slightly. The results showed that over two years, the positions of clusters in the canopy had no consistent impact on cluster weight, berry weight, juice total soluble solids or titratable acidity for either cultivar. For both cultivars, the interior clusters had lower total flavonol concentrations than the exterior clusters, while the position of clusters in the canopy had no major impacts on the composition of anthocyanins and flavan-3-ols. The volatile compounds were somewhat influenced by the positions of clusters in the canopy, while some bound norisoprenoids and terpenoids had lower levels in interior clusters than in exterior clusters. These results will help winegrowers make decisions regarding harvest strategies.

Effects of Salinity and Rootstock on Nutrient Element Concentrations and Physiology in Own-Rooted or Grafted to 1103 P and 101-14 Mgt Rootstocks of Merlot and Cabernet Franc Grapevine Cultivars under Climate Change

Under the current and future climate crisis, a significant rise in soil salinity will likely affect vine productivity in several Mediterranean regions. During the present research, the rootstock effects on salinity tolerance of Merlot and Cabernet Franc grapevine cultivars were studied. In a pot hydroponic culture, own-rooted Merlot and Cabernet Franc grapevine cultivars or grafted onto the rootstocks 1103 P and 101-14 Mgt were drip-irrigated with saline water. A completely randomized 3 × 2 × 2 factorial experiment was designed with two vine rootstocks or own-rooted vines, two scion cultivars, and 100 mM NaCl salinity or control treatments, with six replications. A significant effect of scion cultivar, rootstock, and salinity was observed for most of the measured parameters. At the end of salinity stress period, leaf, shoot, root, and trunk nutrient concentrations were measured. Salinity stress increased Chloride (Cl) and Sodium (Na) concentrations in all parts of the vines and decreased leaf concentrations of Potassium (K), Calcium (Ca), Magnesium (Mg), Nitrogen (N), and Iron (Fe). In contrast, salinity stress increased leaf Boron (B) concentrations, whereas that of Manganese (Mn) remained unaffected. Leaf chlorophyll concentration decreased from 42% to 40% after thirty and sixty days of salt treatment, respectively. A similar trend was observed for the CCM-200 relative chlorophyll content. Salinity significantly decreased steam water potential (Ws), net CO2 assimilation rate (A), and stomatal conductance (gs) in all cases of grafted or own-rooted vines. Sixty days after the beginning of salt treatment, total Phenolics and PSII maximum quantum yield (Fv/Fm) decreased significantly. The rootstock 1103 P seems to be a better excluder for Na and Cl and more tolerant to salinity compared to 101-14 Mgt rootstock.

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.

Comprehensive Classification and Regression Modeling of Wine Samples Using 1H NMR Spectra.

Recently, 1H NMR (nuclear magnetic resonance) spectroscopy was presented as a viable option for the quality assurance of foods and beverages, such as wine products. Here, a complex chemometric analysis of red and white wine samples was carried out based on their 1H NMR spectra. Extreme gradient boosting (XGBoost) machine learning algorithm was applied for the wine variety classification with an iterative double cross-validation loop, developed during the present work. In the case of red wines, Cabernet Franc, Merlot and Blue Frankish samples were successfully classified. Three very common white wine varieties were selected and classified: Chardonnay, Sauvignon Blanc and Riesling. The models were robust and were validated against overfitting with iterative randomization tests. Moreover, four novel partial least-squares (PLS) regression models were constructed to predict the major quantitative parameters of the wines: density, total alcohol, total sugar and total SO2 concentrations. All the models performed successfully, with R2 values above 0.80 in almost every case, providing additional information about the wine samples for the quality control of the products. 1H NMR spectra combined with chemometric modeling can be a good and reliable candidate for the replacement of the time-consuming traditional standards, not just in wine analysis, but also in other aspects of food science.

Sensorial and Volatile Analysis of Wines Made from Partially Dehydrated Grapes: An Ontario Case Study

Winemaking in cool climate viticultural areas can pose challenges due to difficulties in achieving optimal ripeness from climatic conditions that tend to vary vintage-to-vintage. To stabilize quality, the use of partially dehydrated grapes has been indicated as beneficial to the production of high-quality wine (“appassimento” style) despite climatic variation. Postharvest wine grape dehydration is a complex process that involves the concentration or formation of sugars, aromas, and flavours. One of the quality challenges facing appassimento style winemaking is elevated levels of undesirable oxidation compounds. The aim of this study was to characterize wines made from a local yeast isolate, Saccharomyces uvarum CN1, which demonstrates limited osmotolerance and may have application to this wine style, as it is a known lower producer of such compounds. Wines made with CN1 were compared to wines made with the accepted commercial standard, S. cerevisiae, EC1118. Fermentations (n = 24) were established at three target starting sugar concentrations from dehydrated Cabernet franc grapes (24.5, 26.0, and 27.5°Brix) and a control (21.5°Brix) and were assessed for volatile organic compound (VOC) composition via gas chromatography-mass spectrometry (GC-MS). Wines also underwent quantitative descriptive analysis to identify and quantify sensory attributes by a trained panel (n = 11). Results show that the wines fermented with the yeast isolate contain significant differences in the concentrations of VOCs in the wines. Sensorially, the wines differed in intensity for a number of attributes, including red fruit aroma, black fruit flavour, and length of finish both within Brix treatments and amongst yeast strains. The most important differentiating factor amongst these wines was the combination of yeast strain at the highest starting sugar concentration (27.5°Brix). These findings may assist winemakers by informing the yeast strain choice for optimizing appassimento style wine quality in cool climates.

Seasonal dynamics and tissue distribution of two major viruses associated with grapevine Leafroll under cool climate condition

Grapevine leafroll-associated virus-2 (GLRaV-2) and GLRaV-3 are both (+) ssRNA viruses of the family Closteroviridae and are involved in grapevine leafroll, the most destructive viral disease affecting the global grape/wine industry. Outbreaks of the disease were recently reported in Canada, causing serious concerns to the grape/wine industry. Reliable, sensitive and timely detection is key to the control of the disease. However, information on their seasonal dynamics and tissue distribution under cool climate conditions has been rather limited. We conducted a two-year comprehensive study to elucidate the temporal variation and spatial distribution of both viruses through symptom monitoring, Western blotting and RT-qPCR. Sampling was done monthly from commercial Cabernet Franc and Chardonnay vines from May to October in 2015 and 2016. Both viral RNA and capsid protein levels in leaves remained low during May and June, steadily increased from late July, and peaked in September or October. Interestingly, young berries collected in June contained high levels of viral RNA for both viruses. As expected, the viral RNA levels of GLRaV-2 detected by RT-qPCR using primers targeting the CP region were much higher than those by using primers targeting the genomic RNA. Surprisingly, virtually the same levels of viral RNA were detected for GLRaV-3 regardless of the targeted genomic regions. To ensure accurate detection of both viruses, we recommend using young berries early in the season and leaves and cambial scrapings from late July to harvest. To our knowledge, this is the first report on the seasonal dynamics and tissue distribution of two major grapevine viruses in Canada.

Application of a topographic pedosequence in the Villány Hills for terroir characterization

Terroir refers to the geographical origin of wines. The landscape factors (topography, parent rock, soil, microbial life, climate, natural vegetation) are coupled with cultural factors (cultivation history and technology, cultivars and rootstock) and all together define a terroir. The physical factors can be well visualized by a slope profile developed into a pedosequence showing the regular configuration of the relevant physical factors for a wine district. In the present study the generalized topographic pedosequence (or catena) and GIS spatial model of the Villány Hills, a historical wine producing region, serves for the spatial representation and characterization of terroir types. A survey of properties of Cabernet Franc grape juice allowed the comparison of 10 vineyards in the Villány Wine District, Southwest Hungary. Five grape juice properties (FAN, NH3, YAN, density and glucose + fructose content) have been found to have a moderate linear relationship (0.5 < r2 < 0.7) with the Huglin Index (HI) and aspect. Aspect, when determined on the basis of angular distance from South (180°), showed a strong correlation (r2 > 0.7) with FAN, NH3, YAN, sugar and density and moderate correlation with primary amino nitrogen (PAN). HI showed a correlation with three nitrogen related parameters FAN, NH3, YAN, density and glucose + fructose content. Elevation and slope, however, did not correlate with any of the chemical properties.

First Report of grapevine red globe virus in grapevines in Washington State.

Grapevine red globe virus (GRGV; genus Maculavirus, family Tymoviridae) has been reported in grapevines (Vitis spp.) from Italy, Greece, France, China, Spain and Germany and in California, U.S.A. (Sabanadzovic et al. 2000; Cretazzo et al. 2017; Fan et al. 2016; Ruiz-Garcia et al., 2018). During surveys of grapevine nurseries, a total of 241 composite samples, each consisting of four petioles from mature leaves/vine from five asymptomatic grapevines, from 33 grapevine (Vitis vinifera) cultivars were collected. Total RNA isolated from these samples using Spectrum Total RNA isolation kit (Sigma-Aldrich, St. Louis, MO) was subjected to high-throughput sequencing (HTS) on an Illumina HiSeq2500 or Novaseq 6000 platforms in paired-end mode (Genomics Core Facility, Huntsman Cancer Institute, Utah University, Salt Lake City, UT). After trimming raw reads based on quality and ambiguity, the paired-end quality reads of approximately 120 (HiSeq) or 145 (Novaseq) base pair (bp) length were assembled de novo into a pool of contigs (CLC Genomics workbench 12). These contigs were subjected to BLASTn analysis against the nonredundant virus database from GenBank (http://www.ncbi.nlm.nih.gov/blast). A total of 49 contig sequences, ranging from 200 to 1645 bp in length with an average coverage ranging up to 418.7, aligning with GRGV genome were detected in cvs. Aglianico, Cabernet franc, Pinot gris and Riesling. BLASTn analysis of contigs greater than 500 bp length showed sequence identity between 88.5% and 95% with corresponding GRGV sequences reported from other countries. These results indicated the presence of genetically distinct isolates of GRGV. HTS data also revealed coinfection of GRGV in all samples with one or more of the following virus and/or viroids: grapevine rupestris stem pitting associated virus, grapevine rupestris vein feathering virus, hop stunt viroid or grapevine yellow speckle viroid-1. To further confirm infection by GRGV, total RNA was extracted from two asymptomatic Pinot gris vines previously tested positive in HTS using Spectrum Total RNA isolation kit and subjected to reverse transcription-PCR using primers specific to the replicase polyprotein gene of the virus (RG4847F: 5'-TGGTCTGTTGTTCGCATCTT-3' and RG6076R: 5' CGGAAGGGGAAGCATTGATCT-3', Cretazzo et al., 2017). Sequence analysis of the approximately1,250 bp amplicons (accession number MT749359) showed 91.2 % nt sequence identity with corresponding sequence of GRGV isolate from Brazil (KX828704.1). To our knowledge, this is the first report of GRGV in Washington State. Together with the report of the occurrence of GRGV in California (Sabanadzovic et al. 2000), these/span> results indicate wide geographical distribution of the virus. Although GRGV can cause asymptomatic infections in grapevines (Martelli et al. 2002), the economic importance of GRGV as single or coinfections with other viruses needs to be examined to assess the potential significance of the virus to grape production and grapevine certification programs.

Chloroanisoles occurrence in wine from grapes subjected to electrolyzed water treatments in the vineyard

Recently the use of electrolyzed water (EW) attracted much attention as a high-performance, new technology for its potential use in the food industry. The aim of this work was to investigate the impact of grape EW treatments, applied at different time intervals prior to harvest, on the indigenous yeast populations of grape surface (Chenin blanc and Cabernet franc) and the occurrence of 2,4,6-trichloroanisole (TCA) in Cabernet franc wine. In addition, the evolution of inoculated and spontaneous fermentations on treated and non-treated grapes was also considered. The yeast population present on grape berries surface was influenced in a grape variety and EW treatment time-dependent way, since only Chenin blanc grapes treated with EW 7 days prior to harvest had significantly lower yeast population levels, compared to the respective control. Concerning the yeast diversity in the grape samples, a dominance of Aureobasidium pullulans was observed in treated grapes, independently of the grape variety. At the end of alcoholic fermentation, 2,4,6-trichloroanisole was detected in wine when the EW solution was applied at one or two weeks before harvest time. After wine storage, 2,4,6-trichloroanisole and chlorophenols contents generally exhibited a loss relative to initial values. The results showed that EW treatments tended to slightly increase the TCA concentration in final wine and did not affect the fermentation performances and chromatic properties of resulting wine. On the other hand, absorption or desorption phenomena by wine lees could be involved in the change of 2,4,6-trichloroanisole concentration in wine during storage time.

Assessing grapevine phenological models under Chinese climatic conditions

The objective of this work was to perform preliminary assessment of the performance of different models for the simulation of three main phenology stages (budburst, flowering, and veraison) of grapevine in China. This work utilized observations from five representative wine regions (Changli, Laixi, Shangri-La, Xiaxian, and Yanqi) and four widely cultivated grape cultivars (Cabernet Sauvignon, Cabernet Franc, Merlot, and Chardonnay) in China. The corresponding daily temperature data were used to simulate the timing of grape phenology stages based on the different phenological models. The dates based on the simulation and the actual dates were compared and the performance of these models were assessed for different cultivars and wine regions. The GDD10 model exhibited the best performance for budburst simulation in soil-burying regions, irrespective of the cultivar and location. For flowering and veraison, the optimal model varied in performance between cultivars and locations, and non-linear models exhibited better performance than linear models. In general, the performance of these models was better for the latter two stages than for budburst. The models with relatively good performance were selected for further calibration using these limited Chinese observations. The impact of soil-burying management on budburst simulation was also estimated. These results highlight the strengths of some phenological models for use in China. This study also reiterates the strong need for establishment of a grapevine phenology observation network in China to obtain more comprehensive data.

Effects of Grapevine Red Blotch Disease on Cabernet franc Vine Physiology, Bud Hardiness, and Fruit and Wine Quality

The effects of grapevine red blotch disease (GRBD) on vine performance were studied in a Cabernet franc vineyard in the Okanagan Valley, British Columbia, over two years. Vines with GRBD had lower pruning mass and were less winter hardy than non-GRBD vines, and produced lower yields comprising fewer clusters and larger berries with more seeds. GRBD reduced photosynthesis and stomatal conductance for asymptomatic leaves through the growing season, and more so for symptomatic leaves. Leaf fall was delayed or incomplete for GRBD vines. GRBD reduced berry soluble solids, anthocyanins, yeast assimilable N (YAN), and tannins, and increased berry pH and titratable acidity. Wine made from GRBD fruit had reduced anthocyanin and alcohol, lighter color, and more yellow hue. Effects of GRBD on wine sensory characteristics included less body and aftertaste, lower intensity of black and red fruit character, and increased acidity and intensity of vegetal character. Inclusion of low amounts, up to 20%, of GRBD fruit in wine reduced red fruit character in the first year, and increased astringency and vegetal character in the second year. The deleterious effects of GRBD on yield, fruit composition for winemaking, and bud hardiness, constitute a serious threat to grape growing regions in Canada and the United States. The degree of these impacts would be difficult to mitigate through management practices, which underscores the importance of planting virus tested vines to prevent the introduction and spread of GRBD.

Maior carga de gemas da videira resulta em melhora dos índices produtivos e vegetativos da videira ‘Cabernet Franc’ cultivada em região de elevada altitude

Buscando alcançar um adequado balanço vegeto-produtivo, este trabalho teve como objetivo avaliar o efeito do aumento da carga de gemas planta-1, no momento da poda, nas características produtivas e equilíbrio vegetativo da videira Cabernet Franc cultivada em região de elevada altitude de Santa Catarina. O presente trabalho foi conduzido durante a safra 2016/2017, em um vinhedo comercial, localizado no munícipio de São Joaquim. Utilizaram-se videiras da cultivar Cabernet Franc enxertadas sobre o porta-enxerto ‘Paulsen 1103’. Os tratamentos consistiram em quatro diferentes níveis de cargas de gemas: 15, 30, 50 e 75 gemas planta-1. Avaliou-se no momento da colheita variáveis produtivas e vegetativas, e ao longo do ciclo da videira, avaliou-se o crescimento de ramos e feminelas. O delineamento experimental utilizado foi o de blocos ao acaso, com quatro blocos e cinco plantas por parcela. O aumento da carga de gemas planta-1 resultou em aumento do número de ramos e de cachos planta-1, resultando em aumento da produção por planta e da produtividade. As variáveis vegetativas foram influenciadas pelo aumento da gemas planta-1, observando-se redução do crescimento de ramos e de feminelas. O aumento da carga de gemas possibilitou melhor equilíbrio vegeto-produtivo, com redução do peso de poda, e obtenção do Índice de Ravaz mais adequado para a elaboração de vinhos de qualidade. Em vinhedos que apresentam baixa produtividade e excesso de vigor vegetativo, recomenda-se aumentar a carga de gemas planta-1 durante o manejo da poda invernal.

Effects of gibberellic acid (GA3 ) application before anthesis on rachis elongation and berry quality and aroma and flavour compounds in Vitis vinifera L. 'Cabernet Franc' and 'Cabernet Sauvignon' grapes.

Gibberellic acid (GA3 ), a plant-growth regulator, is often used to obtain enlarged table grape berries and induce seedlessness in them. However, the effects of GA3 on rachis elongation and bunch compactness have seldom been reported in wine-grape production. We assessed the effects of GA3 spraying on wine-grape inflorescences and bunches and their practical implications for viticulture in the Jiaodong Peninsula, China. Various GA3 concentrations were sprayed on field-grown Vitis vinifera L. 'Cabernet Franc' (CF) and 'Cabernet Sauvignon' (CS) grapevines before anthesis in the Jiaodong Peninsula, China, in 2015 and 2016. Inflorescence length during berry development was measured, and flavonoids and aroma compounds in the fruit were detected by high-performance liquid chromatography - mass spectrometry (HPLC-MS) and gas chromatography - mass spectrometry (GC-MS), respectively. For both cultivars, 50 and 100 mg L-1 GA3 caused significant elongation of the rachis, whereas there was no significant effect on inflorescence growth and berry seed number. Anthocyanin, flavonol, and flavan-3-ol levels in mature berries were not significantly influenced by GA3 spraying, whereas C13 -norisoprenoids were modified. The application of 50-100 mg L-1 GA3 prior to grapevine anthesis caused elongation of inflorescences and bunches, and eased cluster compactness in CF and CS, and no negative effects were observed on the yield and seed numbers. The concentration and composition of flavonoids and most aroma compounds were not influenced, except that the norisoprenoids were increased by 50 mg L-1 GA3 applications. © 2020 Society of Chemical Industry.