Quality Parameters Of Berries Research Articles

Four decades in the vineyard: the impact of climate change on grapevine phenology and wine quality in northern Italy

The wine sector, among the most profitable agricultural segments, has been markedly affected by the ongoing climate change impacts, such as warmer climate conditions with higher frequency of extreme temperatures and a trend of decreasing precipitation. All this results in higher evaporative demand and therefore higher occurrence of water stress events leading to advancement of temperature-sensitive phenological stages (e.g., budburst and ripening). Such negative effects eventually affect berry development and quality, especially in historically valuable viticultural areas, forcing winegrowers to work within a compressed harvest period to maintain wine typicity. In this work we examined the relationship between environmental variables (air and soil temperature, relative humidity, precipitation, and solar radiation), phenology, berry, and wine quality for the two varieties (Chardonnay and Teroldego) in Trentino Alto-Adige/South Tyrol (Italy) over 36 years. Huglin Index (a bioclimatic heat index), growing degree days (measure of heat accumulation), and overall mean temperature showed linear increase (p < 0.001) in the last years, while no variations were recorded for precipitations. Despite no major effects being observed for phenological interval lengths, the onset of most of the phenological stages for both varieties had significantly (p < 0.001) advanced. However, i) early budburst pushed the budburst-flowering interphase by -1.2 days every two years toward putative colder periods with increased late frost probability and potential slower phenological progression towards flowering, and ii) early veraison shifted the veraison-ripening interphase by 0.25 day per year into warmer periods that oppositely impose faster phenological advancement. Hence, a substantial equilibrium in the seasonal growing length over years was maintained. Potential carry-over effects from the previous season were observed, particularly associated with heat requirements to unlock early phenological events, raising additional concerns on the additive effects of climate change to viticulture. Generally, white wine quality increased (p < 0.05) over the years, while red and sparkling wines remained unaffected. This was putatively related to accurate harvest date decision-making dictated by berry quality parameters: sugar-to-acidity ratio for Chardonnay and bunch sanitary status for Teroldego. Overall, this work provides evidence of the dynamics involved in climate change, and, to our knowledge, its overlooked effects on viticulture, thus providing new insights that can contribute to further developing adaptive strategies.

Influence of mixed and single infection of grapevine leafroll-associated viruses and viral load on berry quality.

Grapevine leafroll disease is a viral disease that affects grapevines (Vitis vinifera L.) and has a severe economic impact on viticulture. In this study, the effect of grapevine leafroll-associated viruses (GLRaV) on berry quality was investigated in clones of cultivar cv. Crimson Seedless table grapes infected with GLRaV. RT-PCR confirmed the identity of the clones: clone 3236, infected only with GLRaV-3 (termed single); clone 3215, infected with GLRaV-3, GLRaV-4 strain 9 and grapevine virus A (termed mixed); and a viral free clone of the same genetic background of the infected clones (termed control). The berry quality indices of size, sugar, acidity and anthocyanin content were measured at harvest maturity. RT-qPCR was used to determine the viral load. The study was repeated over 2year. A two-way, multivariate analysis of variance was applied with clone and year as independent variables and the measured berry quality parameters as a dependent variable. All dependent variables were significantly affected by viral infection (Wilks, λ, (2,33)=0.033895, P-value<0.001), while only titratable acidity was affected by year. The average berry dry mass decreased (P-value<0.001). The water content of both infected clones was greater than that of the control (P-value<0.001). Both infected clones displayed reduced sugar content as a fraction of the berry dry mass (P-value<0.001). The anthocyanin and the phenol content of the infected clones were significantly reduced compared with the control clone (P<0.001, P<0.05, clone 3236 and clone 3215, respectively). Finally, the viral load was highly variable, and no quantitative relationship between viral load and berry composition was found.

An autonomous Internet of Things spectral sensing system for in-situ optical monitoring of grape ripening: design, characterization, and operation

The present work proposes a novel autonomous Internet of Things (IoT) spectral sensing system for in-situ optical monitoring of grape ripening through reflectance signals. To this end, tailor-made hardware for this IoT end node was developed, characterized, and operated in both lab and field conditions. It included three complementary modules: the optical module, the host module, and the controller module. The optical module included four photodetectors and four LEDs with maximum emission wavelength centered at 530, 630, 690, and 730 nm that was placed in direct contact with the grape berry. The host module included the LED driver and the analog front-end for signal acquisition. Finally, the controller module provided full control of the system and ensured data storage, power management, and connectivity. The system was capable of measuring reflectance in the range of 4 – 100 % with a linear response (r2 > 998) and with a high reproducibility among different optical units. This design made it possible to collect reflectance signals from red (cv. Touriga Nacional) and white (cv. Loureiro) grape varieties in both lab and field environments. The relationship between this optical fingerprint (comprised of the different reflectance intensities recorded) and the evolution of grape berry quality parameters throughout the ripening period (for approximately two months), was analyzed and discussed. Lab data was used to establish a multivariate model based on Partial Least Squares for the prediction of the Total Soluble Solids (TSS) content in both varieties. The model error (Root Mean Square Error in Cross Validation) was 2.31 and 0.73 °Brix for Touriga Nacional and Loureiro, respectively. This model was applied to data acquired in the field in an illustrative example of the potential of the system to predict TSS in real time. The field observations collected during the monitoring period also provided relevant information about the potential issues that may occur during the unattended operation of the optical sensors. Additionally, the modular architecture of the optical module proposed makes it possible to use different LEDs and photodetectors, as well as the assembly of optical filters. This creates the possibility of using the same principles for measuring reflectance in different spectral ranges (e.g. IR) or even fluorescence. The results herein described paved the work for future developments of this technology that will include the development of prediction models for the most relevant grape ripening parameters based on reflectance data, as well as its operation as part of a Wireless Sensor Network.

Effect of PGR and Chemicals on Shelf Life, Bunch and Berry Quality Parameters of Sudhakar Seedless Grapes (Vitis vinifera L.)

The experiment was conducted on Sudhakar Seedless vines grafted on 110-R rootstock were selected for this study. The experiment was designed in randomized block design (RBD) having five treatments with four replications were carried out at MRDBS Nashik during 2020-2021. Pre-harvest application of treatments (Chitosan at 10 ppm, Naphthalene acetic acid at 100 ppm, activated Potassium salt @ 2.0 g/ liter, Salicylic acid at 2.0 ml/liter and Potassium Schoenite @ 2.0 g/liter along with untreated vines were applied at veraison stage of berry development. Application of Chitosan @ 10 ppm resulted in to the increase berry size and berry quality along with less Number of rotten berries in physiological loss in weight. Followed by the application of Naphthalene acetic acid at 100 ppm recorded less Number of rotten in this study. However, the lowest physiological loss of weight (%) were recorded with the application of Naphthalene acetic acid. The increasing dose of Naphthalene acetic acid resulted into decrease in pre- harvest berry drop. In grapevines, Application of salicylic acid significantly increase in berry weight, bunch weight, Total Soluble Solids /acidity ratio as compare to untreated vines. Biochemical composition of berries was influenced by the application of Activated potassium salt at different concentration. The application of Potassium schoenite in grapevines were found effective for increasing TSS of Sudhakar seedless grapes.

Effect of Bio-stimulant Application on Growth, Yield and Quality of Thompson Seedless

Bio-stimulants offers a novel approach to enhance crop growth, quality and ultimately final yield of the produce. Nowadays, bio-stimulants containing Ascophyllum nodosum seaweed extracts and protein hydrolysates are increasing interest of scientists and farming communities. However, the potential of many of these bio stimulants products has not been fully exploited in grapes due to the lack of available scientific data. Grape growing under tropical conditions of India faces various type abiotic and biotic stresses. To support grapevine growth as well as yield and quality, bio-stimulant application can play an important role. Present experimentation was conducted at the farm of ICAR-National Research Centre for Grapes, Pune during the year 2020-21 with the objective to assess the effects of bio-stimulant application on growth, yield and quality of Thompson Seedless grapes. Different doses of bio-stimulant were applied on vines at different crop growth stages such as 3-4 leaf stage, pre-bloom stage and after berry setting, followed by two bunch dipping with varied concentrations. Among the different treatments T7 [RDF + 1.5 % (Spray: 3rd) + 0.2 % Bunch dipping (Stage 1) + 0.5 % Bunch dipping (stage 2)] found better in terms of bunch and berry quality parameters. Obtained results suggested that the application of bio-stimulant (Grade-I) affects vine growth, yield and quality of the Thompson Seedless grape in positive manner.

Berry Thinning Affects the Fruit Quality Composition of Two Table Grape Cultivars under Linkage Greenhouse Conditions

Protected grape cultivation develops rapidly because of huge economic benefits. However, adverse environmental conditions (insufficient sunlight, high temperature, etc.) in protected cultivation led to low-quality berries. This study aimed to evaluate the effects of berry thinning on the quality attributes of two table grape cultivars (Baoguang and Cuiguang) under linkage greenhouse conditions. Three treatments (L, light berry thinning; M, moderate berry thinning; H, heavy berry thinning) were compared with the control (C, no berry thinning). Berry thinning increased berry weight, total soluble solids (TSS), fructose, glucose, the ratio of TSS to titratable acidity (TA), anthocyanin contents, berry firmness, and mineral contents (Ca, Fe, Na, Mg). Conversely, TA and organic acid profiles were decreased by berry thinning. Cultivars showed significant effects on most of the berry quality parameters. The interaction of cultivars by berry-thinning treatments affected sugar and acid components, anthocyanin contents, and mineral elements.

Effects of different winter pruning times on table grape vines performance and starch reserves to face climate changes

In the context of climate change, in which some extreme weather and climate events have increased in frequency and intensity because of global warming, adaptive techniques in viticulture have become necessary to reduce the resulting negative impacts. This study on four table grape cultivars has evaluated the effects of different winter pruning treatments (time of pruning) on phenology, fruit composition and starch content in canes and ≥two-year-old wood. By shifting the pruning time from leaf fall up to budbreak (BBCH 08), a neutral response on yield and berry quality parameters (TSS, TA and pH) was observed for the 4 cultivars. Late pruning treatments resulted in shorter shoot lengths and delayed phenological stages for the early ripening cultivars. The partitioning of starch between canes and older wood was almost similar, although lower in canes, with average values of 13% and a significant reduction at budbreak in order to release soluble sugars for the initial vegetative growth. Starch was mainly located in newly formed xylem, i.e., in the parenchymatic rays where amyloplasts are located, whereas a smaller amount of starch was visible in the other tissues (phloem, cortex). The possibility of a late pruning until over budbreak can be considered a practice to avoid some late spring frost risks, often occurring in viticultural areas. Thus, a ‘precise’ application of winter pruning into a global warming viticulture context could have potential benefits, performing a cost-effective tool management without negative (or very limited for early cultivars) effects on yield and quality of table grapes.

Effect of new generation bio-regulators on anthocyanins and berry quality of grape cv. Beauty Seedless

Five-year-old grapevines of Beauty Seedless spaced at 3 m × 3 m distance and trained on the 'Bower' system were sprayed with different plant bioregulators, namely, abscisic acid (ABA: 200 and 400 ppm), ethephon (200 and 400 ppm), benzothiadiazole (BTH: 0.3 and 0.6 mM), prohexadione-calcium (Pro-Ca: 200 and 400 ppm) and control (water spray) at the veraison stage during 2019-20 with the aim of studying their influence on berry physical and biochemical characteristics. The experiment was conducted in the randomised block design with three replications for each treatment. Different berry physical characteristics like weight, length, diameter and firmness were positively influenced with the different treatments except for ethephon (400 ppm) and ABA (400 ppm) treatments, which reduced the berry firmness significantly. Berry biochemical parameters were positively improved by almost all the plant bioregulators, they were most pronounced with ethephon (400 ppm) and ABA (400 ppm). The most prominent effects of ABA and ethephon treatments were noted on the total anthocyanins biosynthesis in the berries, which is major bottleneck under the warm subtropical conditions in different coloured grape genotypes. Hence, application of new generation plant bioregulators such as BTH, Pro-Ca, ABA and ethephon resulted in improvement in berry quality parameters of cv. Beauty Seedless.

Spatial Variability of Production and Quality in Table Grapes ‘Flame Seedless’ Growing on a Flat Terrain and Slope Site

(1) Background: Precision agriculture has been used mostly to study spatial variability in vineyards for winemaking. Nevertheless, there is little available information on the impacts of its use on table grape vineyards under different slope conditions. (2) Methods: The aim was to study the spatial variability of production and berry quality in ‘Flame Seedless’ vines established on a flat (3% slope) and sloping (23% slope) terrain in the Chilean hyper-arid northern region. (3) Results: The results showed that in both vineyards, the measured variables presented a high spatial variability according to their coefficient of variation, being higher in slope than in the flat vineyard. The geostatistical analysis showed that 82% of the measured variables presented a strong spatial dependence in the slope vineyard, whereas 45% and 55% of the variables measured in the flat vineyard presented strong and moderate spatial dependence, respectively. Elevation was related to berry quality parameters in both vineyards, while trunk vine circumference was related to berry quality for the slope vineyard and to yield for the flat vineyard. (4) Conclusions: There is an important spatial variability in table grape vineyards mostly those cultivated on slope sites. Therefore, precision agriculture tools can be useful for zoning table grape vineyards, and thus improving both economic returns of viticulturists and sustainability.

Proper deficit irrigation applied at various stages of growth can maintain yield and improve the comprehensive fruit quality and economic return of table grapes grown in greenhouses*

AbstractIn order to investigate the quantitative response of yield, fruit quality and economic return of table grapes grown in greenhouses under deficit irrigation applied at various growth stages, experiments were conducted in 2017 and 2018. Three irrigation levels (full irrigation, 2/3 and 1/3‐full irrigation) were applied at the fruit setting–swelling (stage 2), veraison (stage 4) and whole growth stages. The comprehensive fruit quality index (Qc) was determined in order to evaluate the overall quality of the berries and its effect on economic return. The results showed that deficit irrigation significantly decreased evapotranspiration (ET) and yield, and improved water use efficiency (WUE), individual quality parameters and Qc. Fruit quality was more sensitive to water deficit at stage 4 than at stage 2. Significant linear functions were found between a relative decrease in yield, berry quality parameters, Qc and a relative seasonal ET deficit. Net income under deficit irrigation was related to the price proportional coefficient (R). Higher net income was mainly determined by a higher yield when R was less than 1, while higher net income was determined by a higher Qc when R was greater than 3. An appropriate water deficit level at stages 2 and 4 (F2/3V2/3) is recommended as an optimal treatment as it produces a higher Qc, the highest WUE and net income without a significant decrease in yield.

Berry Quality and Anthocyanin Content of 'Consort' Black Currants Grown under Artificial Shade.

The effect of artificial shade on berry quality parameters for the field-grown black currant cultivar ‘Consort’ were investigated over two growing seasons in Urbana, Illinois. Four shade treatments reduced photosynthetically active radiation (PAR) from 37 to 83%. Shade had no effect on soluble solids in up to 65% PAR reduction but decreased 11% in 83% shade in one of two years. Shade increased titratable acidity up to 23% in both years. The effect of shade on anthocyanin content revealed greater variation between years than treatments. Shade influence on anthocyanin content was only observed in 2017, when cyanidin derivatives decreased 13–14% from open-sun to 83% shade. Shade did not affect delphinidin derivatives in either year. Environmental factors other than artificial shade may impact black currant berry quality in an understory environment. The results of our study indicate that black currants can maintain berry quality with PAR reductions up to 65%, but some berry quality parameters may decrease when PAR reductions exceed 65% of full sun.

Bio-Packaging Material Impact on Blueberries Quality Attributes under Transport and Marketing Conditions.

Blueberries are highly appreciated for their high antioxidant content but are also particularly susceptible to fungal deterioration. In this work, corn starch and chitosan, byproducts of the fishing industry, as well as active compounds obtained from citrus processing waste were used to obtain active biodegradable film packaging. Blueberries were packed in corn starch–chitosan (CS:CH) films and in active films containing lemon essential oil (LEO) or grapefruit seed extract (GSE). The effects of film packaging on the quality parameters of berries and the fungal incidence of disease during storage were studied and compared to benchmark materials. A conservation assay simulating transport and commercialization conditions was conducted. Blueberries packed in CS:CH films showed antioxidant capacity values closer to those packed in commercial PET containers (Clamshells), preserving 84.8% of the initial antioxidants content. Fruit packed in LEO films exhibited the greatest weight loss and rot incidence, and poor surface color. CS:CH and GSE films controlled the fruit respiration rate and weight loss, therefore they are materials with adequate barrier properties for blueberries conservation. Bags formulated with GSE showed adequate barrier properties to maintain fruit quality attributes without the incidence of rottenness, being an interesting option for blueberries exportation.

Commercial brassinosteroid increases the concentration of anthocyanin in red tablegrape cultivars (Vitis viniferaL.)

Background and Aims Red tablegrapes may fail to develop adequate berry colour. To correct this, abscisic acid and ethephon are applied; however, little is known about the possibility of brassinosteroids (BRs) to improve berry colour. Thus, a commercial BR formulation was tested in two commercial vineyards of Redglobe and Crimson Seedless in order to evaluate its effectiveness for improving berry colour. Methods and Results Treatment at a concentration of 0.06 mg/L was applied only one time at veraison or the application was repeated 7 days later. Anthocyanin concentration, berry colour [evaluated as colour index for red grape (CIRG)] and other berry quality parameters were evaluated. Treatment with BR increased anthocyanin in the berries of both cultivars. As a result, a higher CIRG was observed in Redglobe treated berries, whereas in Crimson Seedless the CIRG was similar to that of the Control, despite an increase in berry size generated by the BR treatment of this cultivar. Conclusions The commercial formulation tested improved the colour of Redglobe berries and maintained the colour in the resulting larger berries of Crimson Seedless. Significance of the Study This study supports the potential of BRs as a tool to improve berry colour in a commercial context, laying the foundations for future work and incorporation of BRs within tablegrape management programs.

The Interplay between Atmospheric Conditions and Grape Berry Quality Parameters in Portugal

The atmospheric conditions are a strong modulator of grape berry composition, but further research is required to better understand this relationship, which is particularly pertinent under the context of climate change. The present study assesses the relationship between interannual variability in atmospheric conditions (mean, maximum and minimum air temperatures and precipitation totals) on grape berry quality attributes in three main Portuguese wine regions—Douro, Dão and Alentejo—and targets two major varieties growing in Portugal (cv. Touriga Nacional and cv. Aragonez/Tempranillo). Berry weight, titratable acidity (TA), pH, potential alcohol (PA), anthocyanins and total phenols index (TPI) data, collected two to three weeks after the end of the veraison until technological maturity, since 1999 in Douro, 2004 in Alentejo and 2008 in Dão, were selected. Meteorological data were obtained from both automatic weather stations and a climatic database defined at a very-high-resolution grid (&lt;1 km) (PTHRES). The influence of daily mean, maximum and minimum air temperatures (November–October) and precipitation totals (April to June and July to September) on the above-mentioned berry quality parameters were first explored to identify the months/periods more influential to grape berry composition. Different statistical approaches were subsequently carried out to explore in greater detail these relationships. At technological maturity, temperature was negatively correlated to berry weight, titratable acidity, anthocyanins and TPI, but was positively correlated to pH and potential alcohol. Moreover, lowest levels of berry weight and TA (and highest levels of pH) were more frequent in warmer regions, while the opposite was seen in the cooler regions. PA, TPI and anthocyanins at maturity did not show a clear trend across regions. In addition, the maturation parameters of each site were grouped into two clusters—years where the maturation parameter is higher (cluster 1) and years where it is lower (cluster 2)—and significant differences in monthly mean temperatures between clusters were found. Overall, temperatures at veraison and maturation periods (June–August) were more influential in determining grape berry composition at harvest. The influence of precipitation was dependent on location and variety. The results also suggested that berry composition in Alentejo is more sensitive to atmospheric variability, while Aragonez seems more resilient than Touriga Nacional. These outcomes are based on a systematized and unprecedentedly large grape berry quality database in Portugal and provided the grounds for the development of grape quality forecast models, either to be used operationally in each vintage or for assessing potential modifications in berry composition in response to changing climates.

Effects of an Ascophyllum nodosum (L.) Le Jol. extract on grapevine yield and berry composition of a Merlot vineyard

Few publications in the scientific literature document effects of seaweed extracts on winegrape varieties. A 2-year field experiment was conducted to evaluate effects of foliar applications of an Ascophyllum nodosum (L.) Le Jol. extract on vine yield components, canopy chlorophyll content, berry composition and phenolic indices. The split plot experiment allowed for the investigation of extract effects with and without in-season N fertilization in a Merlot vineyard in 2015 and 2016. Great differences in vine productivity and berry composition between years were attributed to hail damage in 2015. Vines were not affected by N supply in any single year other than a decline of some berry quality parameters in 2016. Effects of seaweed extract application were evident in the absence of hail damage in 2016. The greatest vine responses were obtained with 1% extract concentration under in-season N supply by a 26% increase in yield, 35% increase in the number of berries and 21% increase in anthocyanin extractability of berry skins. These beneficial effects came about without a negative impact on other parameters of berry composition or phenolic indices and, in part, appear to be caused by direct effects on berry physiology and grapevine nitrogen status. The lower extract concentration (0.2%) also increased number of berries and anthocyanin extractability, but these were accompanied by a reduction of berry phenols and an increase of seed tannins. The results demonstrate the potential of this extract to increase production and improve wine quality in red winegrape vineyards.

Effect of varying levels of potassium on berry quality of Cabernet Sauvignon grapes under tropical conditions

Potassium, an essential nutrient for grapevine has profound effect on berry growth and development and subsequently on wine quality. A sharp increase in berry potassium levels is observed due to potassium redistribution from leaves to berries after veraison. But excessive levels of potassium in berries at harvest may reduce the quality of must and have a negative impact on wine quality, particularly in red wines. Potassium has been implicated in reduction in tartaric acid in juice with overall increase in the pH of wine. To standardize potassium requirement of Cabernet Sauvignon on 110R rootstock in relation to quality parameters of berries, present investigation was carried out during 2014–15 at ICAR-NRC for Grapes, Pune. The experiment was laid out as per RBD having five graded doses of potassium as sulphate of potash viz. 0, 50, 100, 500, 600 kg K2O/ha per year. Each treatment was replicated 4 times. Except control, more fructose content in berries were observed in comparison to glucose in all potassium treated vines. Potassium applications resulted in decreased tartaric and malic acid content in berries. More caftaric acid (53.3 ppm), chlorogenic acid (86.7 ppm), epicatechin (34.7 ppm) and quercetin hydrate (251 ppm) content was recorded in vines treated with 100 kg of potassium per hectare. Increasing trend in petiole content of K, Ca, Na and Cu was found. Juice acidity and pH increased with increasing potassium application.

Relationship between post veraison temperature and the dynamics of anthocyanin development and berry quality in red wine grape (Vitis vinifera) cultivars Shiraz and Cabernet Sauvignon

The present investigation was carried out to understand the temperature induced dynamics of berry anthocyanin development and berry quality in wine grape (Vitis vinifera L.) cultivars Shiraz and Cabernet Sauvignon. Temperature variations during fruit maturation period were achieved by altering the pruning dates. Vines were pruned at weekly intervals starting from third or fourth week of October to the end of November. The changes in berry quality parameters such as total soluble solids (TSS), titratable acidity, total anthocyanins, total phenols and total flavonoids were recorded at weekly intervals starting from veraison to harvest. All the quality parameters were significantly higher in early pruned vines of both the cultivars indicating that the best time for pruning to get good quality wine grapes is during the third or fourth week of October. The major quality parameter affected by the temperature during the berry maturation stage was total anthocyanin content. Maximum and minimum temperature (weekly average) during different week from veraison to harvest were recorded. Early pruned vines exposed to a mean day/night temperatures of 30.7°C/14.9°C and 29.6°C/14.1°C in cv. Shiraz and late pruned vines exposed to a mean day/night temperatures of 32.0°C/16.2°C and 32.1°C/16.0°C in cv. Cabernet Sauvignon during 2010 and 2011 respectively. The pattern of anthocyanin development during the berry maturation period (veraison to harvest) indicated that the maximum anthocyanin accumulation was in the second and third week of March; the concentration decreased thereafter irrespective of dates of pruning in both the cultivars during the two years of the study. Correlation coefficients between the skin anthocyanin content and mean maximum and minimum temperatures showed a negative relationship in both the cultivars indicating that the increase in both maximum and minimum temperatures caused a reduction in anthocyanin content at harvest in late pruned vines.

Vitis vinifera berry metabolic composition during maturation: Implications of defoliation.

Leaves are an important contributor toward berry sugar and nitrogen (N) accumulation, and leaf area, therefore, affects fruit composition during grapevine (Vitis vinifera) berry ripening. The aim of this study was to investigate the impact of leaf presence on key berry quality attributes in conjunction with the accumulation of primary berry metabolites. Shortly after the start of véraison (berry ripening), potted grapevines were defoliated (total defoliation and 25% of the control), and the accumulation of berry soluble solids, N and anthocyanins were compared to that of a full leaf area control. An untargeted approach was undertaken to measure the content in primary metabolites by gas chromatography/mass spectrometry. Partial and full defoliation resulted in reduced berry sugar and anthocyanin accumulation, while total berry N content was unaffected. The juice yeast assimilable N (YAN), however, increased upon partial and full defoliation. Remobilized carbohydrate reserves allowed accumulation of the major berry sugars during the absence of leaf photoassimilation. Berry anthocyanin biosynthesis was strongly inhibited by defoliation, which could relate to the carbon (C) source limitation and/or increased bunch exposure. Arginine accumulation, likely resulting from reserve translocation, contributed to increased YAN upon defoliation. Furthermore, assessing the implications on various products of the shikimate pathway suggests the C flux through this pathway to be largely affected by leaf source limitation during fruit maturation. This study provides a novel investigation of impacts of leaf C and N source presence during berry maturation, on the development of key berry quality parameters as underlined by alterations in primary metabolism.

Agronomical characterization of minority grapevine cultivars from Asturias (Spain)

Grapevine (Vitis vinifera L. ) was an important crop in the past in Asturias (Northwestern Spain), but the phylloxera and later the boom of the mining industry almost led to its extinction in the last century. Currently, the grape growers are rescuing the old cultivars present in the region from ancient times, but the long period of abandon has originated a lack of information about their characteristics. Four red (‘Albarin Negro’, ‘Carrasquin’, ‘Verdejo Negro’ and ‘Mencia’) and two white (‘Albarin Blanco’ and ‘Godello’) minority grapevine cultivars from Asturias (Spain) were studied for phenology, fertility, vigor, production and berry quality parameters for two consecutive years. Great differences between cultivars were found: ‘Verdejo Negro’ and ‘Albarin Blanco’ had an early budburst both years, ‘Carrasquin’ was the latest harvested, and ‘Albarin Negro’ presented the highest total fertility. ‘Mencia’ had the greatest bunch weight, and, together with ‘Verdejo Negro’, the lowest total acidity and highest pH. Shikimic acid was a varietal marker, its content being higher in ‘Carrasquin’, ‘Verdejo Negro’ and ‘Albarin Blanco’. Significant differences between years in the measured parameters were also found. Agronomical evaluation is the first step to recover these minority cultivars from extinction and to provide to grape growers a deeper knowledge about the characteristics of each cultivar, allowing enriching and diversifying the wine market with different products.

Kaolin Foliar Application Has a Stimulatory Effect on Phenylpropanoid and Flavonoid Pathways in Grape Berries.

Drought, elevated air temperature, and high evaporative demand are increasingly frequent during summer in grape growing areas like the Mediterranean basin, limiting grapevine productivity and berry quality. The foliar exogenous application of kaolin, a radiation-reflecting inert mineral, has proven effective in mitigating the negative impacts of these abiotic stresses in grapevine and other fruit crops, however, little is known about its influence on the composition of the grape berry and on key molecular mechanisms and metabolic pathways notably important for grape berry quality parameters. Here, we performed a thorough molecular and biochemical analysis to assess how foliar application of kaolin influences major secondary metabolism pathways associated with berry quality-traits, leading to biosynthesis of phenolics and anthocyanins, with a focus on the phenylpropanoid, flavonoid (both flavonol- and anthocyanin-biosynthetic) and stilbenoid pathways. In grape berries from different ripening stages, targeted transcriptional analysis by qPCR revealed that several genes involved in these pathways—VvPAL1, VvC4H1, VvSTSs, VvCHS1, VvFLS1, VvDFR, and VvUFGT—were more expressed in response to the foliar kaolin treatment, particularly in the latter maturation phases. In agreement, enzymatic activities of phenylalanine ammonia lyase (PAL), flavonol synthase (FLS), and UDP-glucose:flavonoid 3-O-glucosyltransferase (UFGT) were about two-fold higher in mature or fully mature berries from kaolin-treated plants, suggesting regulation also at a transcriptional level. The expression of the glutathione S-transferase VvGST4, and of the tonoplast anthocyanin transporters VvMATE1 and VvABCC1 were also all significantly increased at véraison and in mature berries, thus, when anthocyanins start to accumulate in the vacuole, in agreement with previously observed higher total concentrations of phenolics and anthocyanins in berries from kaolin-treated plants, especially at full maturity stage. Metabolomic analysis by reverse phase LC-QTOF-MS confirmed several kaolin-induced modifications including a significant increase in the quantities of several secondary metabolites including flavonoids and anthocyanins in the latter ripening stages, probably resulting from the general stimulation of the phenylpropanoid and flavonoid pathways.