Berry Quality Traits Research Articles

Exploring Seaweed and Glycine Betaine Biostimulants for Enhanced Phenolic Content, Antioxidant Properties, and Gene Expression of Vitis vinifera cv. "Touriga Franca" Berries.

Climate change will pose a challenge for the winemaking sector worldwide, bringing progressively drier and warmer conditions and increasing the frequency and intensity of weather extremes. The short-term adaptation strategy of applying biostimulants through foliar application serves as a crucial measure in mitigating the detrimental effects of environmental stresses on grapevine yield and berry quality. The aim of this study was to evaluate the effect of foliar application of a seaweed-based biostimulant (A. nodosum-ANE) and glycine betaine (GB) on berry quality, phenolic compounds, and antioxidant activity and to elucidate their action on the secondary metabolism. A trial was installed in a commercial vineyard (cv. "Touriga Franca") in the Cima Corgo (Upper Corgo) sub-region of the Douro Demarcated Region, Portugal. A total of four foliar sprayings were performed during the growing season: at flowering, pea size, bunch closer, and veraison. There was a positive effect of GB in the berry quality traits. Both ANE and GB increased the synthesis of anthocyanins and other phenolics in berries and influenced the expression of genes related to the synthesis and transport of anthocyanins (CHS, F3H, UFGT, and GST). So, they have the potential to act as elicitors of the secondary metabolism, leading to improved grape quality, and also to set the foundation for sustainable agricultural practices in the long run.

Delayed ripening affects the formation of berry quality traits in ‘Cabernet Sauvignon’ grapes

Delayed ripening affects the formation of berry quality traits in ‘Cabernet Sauvignon’ grapes

Temperature variability during the growing season affects the quality attributes of table grapes in Pothwar-insight from a new emerging viticulture region in South Asia.

Rising air temperature due to climate change has posed a mammoth challenge to global viticulture and key berry quality traits are compromised. Exploring the effects of seasonal temperature variability on berry ripening and quality attributes in different viticulture regions may help in sustainable viticulture industry. The present research was designed to explore the effect of temperature variables on key quality attributes of table grape cultivars in Pothwar region of Pakistan. Key berry quality traits such as total soluble solids (TSS), titratable acidity (TA), maturity indices (MI), ascorbic acid, sugars, total polyphenol contents (TPC) and total anthocyanin contents (TAC) were unlocked for four important table grape cultivars under varying environmental conditions at Chakwal and Islamabad districts for two consecutive vintages of 2019 and 2020. The district Chakwal has up to 0.92 °C, 1.35 °C, 1.12°C and 0.81°C higher Tmin, Tmax, Tmean anddiurnal temperature variation (DTV)respectively, compared to Islamabad particularly for the 2019 vintage. The results of the present study revealed that the warmer site (Chakwal) has significantly (P ≤0.05) higher juice pH, TSS (°brix) and maturity indices (MI) particularly for the relatively hotter vintage of 2019. Interestingly, MI was 33% higher for the relatively warmer vintage of 2019 compared to 2020 with relatively lower acidity (up to 38%). Moreover, higher titratable acidity (11.2%), ascorbic acid (28.5%), polyphenols (20.3%) and anthocyanins (10.6%) were noticed for the colder Islamabad compared to Chakwal. Although elevated temperature for warmer location and vintage favoured berry ripening, however key biochemical attributes such as titratable acidity, ascorbic acid, polyphenols and anthocyanins were negatively affected. The findings of the present research provide useful insight into the impact of growing season temperature on key berry attributes and may help devise adaptation strategies to improve berry quality.

Evaluation of the variability of berry quality traits in a number of varieties and hybrid forms of strawberry Fragaria × ananassa Duch

Relevance. High values of berry quality traits increase the breeding and production worth of strawberry varieties and hybrids. Important characteristics of the quality of berry are the average fruit weight, the firmness of the pulp of berry, the height and the largest diameter of berry. It is possible to achieve a high level of values of these traits by combining the maximum similarity of their variation in one genotype. The aim of this work was the description of the associated variability of berry quality traits in a number of strawberry varieties and hybrid selections and the identification of the most promising from them according to the studied characteristics.Methods. The studies were carried out in 2019–2021, 12 varieties and 8 hybrid selections were studied for a number of economically significant traits of berry quality: average fruit weight, g; berry pulp firmness, g; height and largest diameter of the berry, mm; content of dry soluble solids in berries, Brix, %. Results. It has been established that the genotype makes the greatest contribution to the diversity of the studied samples. A relatively small factorial influence of the growing year on the overall variation of varieties and selections for the studied traits (from 0.06 to 1.6% of the phenotypic variance) indicates a high adaptability potential of the studied forms for growing in this natural and climatic zone, due to the specific properties of the genotypes of varieties and strawberry hybrids. By calculating pairwise Pearson's correlations in combination with the cluster analysis by the Ward's method as one of the procedures of multivariate mathematical statistics, an evaluation of the compatibility of variability by the studied traits was given, the varieties promising for breeding and cultivation under regional conditions in terms of berry quality have been identified — Florence, Vivaldi, Nelli, Syria, Belrubi, Honeoye and Kemia, as well as valuable for breeding hybrids — 10-1-15 Belrubi × Nelli, 35-14-15 Belrubi × Onda and 35-11-15 Belrubi × Florence.

Abscisic Acid and Chitosan Modulate Polyphenol Metabolism and Berry Qualities in the Domestic White-Colored Cultivar Savvatiano

During the last decade, several studies demonstrated the effect of biostimulants on the transcriptional and metabolic profile of grape berries, suggesting their application as a useful viticultural practice to improve grape and wine quality. Herein, we investigated the impact of two biostimulants—abscisic acid (0.04% w/v and 0.08% w/v) and chitosan (0.3% w/v and 0.6% w/v)—on the polyphenol metabolism of the Greek grapevine cultivar, Savvatiano, in order to determine the impact of biostimulants’ application in the concentration of phenolic compounds. The applications were performed at the veraison stage and the impact on yield, berry quality traits, metabolome and gene expression was examined at three phenological stages (veraison, middle veraison and harvest) during the 2019 and 2020 vintages. Results showed that anthocyanins increased during veraison after treatment with chitosan and abscisic acid. Additionally, stilbenoids were recorded in higher amount following the chitosan and abscisic acid treatments at harvest. Both of the abscisic acid and chitosan applications induced the expression of genes involved in stilbenoids and anthocyanin biosynthesis and resulted in increased accumulation, regardless of the vintage. Alterations in other phenylpropanoid gene expression profiles and phenolic compound concentrations were observed as well. Nevertheless, they were mostly restricted to the first vintage. Therefore, the application of abscisic acid and chitosan on the Greek cultivar Savvatiano showed promising results to induce stilbenoid metabolism and potentially increase grape defense and quality traits.

Characterization of the Berry Quality Traits and Metabolites of ‘Beimei’ Interspecific Hybrid Wine Grapes during Berry Development and Winemaking

The development of grape varieties with cold resistance can be an advantage for the wine industry. ‘Beimei’, an interspecific hybrid wine grape variety with cold resistance and pleasant rose aroma, is now extensively cultivated in China. In the present study, the berry quality traits and metabolites of ‘Beimei’ and other “Bei” varieties were characterized. The sugar (234 g/L–391 g/L) and acid (6.2–8.3 g/L) contents of ‘Beimei’ and four additional “Bei” varieties, i.e., ‘Beihong’, ‘Beixi’, ‘Beixin’, and ‘Xinbeichun’ berries were smilar to that of traditional Vitis vinifera varieties. ‘Beimei’ grapes has the highest volatile compounds composition, especially the content of rose aroma compounds (2-phenyl-ethyl alcohol and neryl alcohol), which was significantly higher than that of the other “Bei” wine grape varieties. After fermentation, ‘Beimei’ wines showed improved quality, with a high resveratrol content (18 mg/L) compared to traditional Eurasian wines. In addition, the high content of main rose aroma compounds (acetic acid 2-phenylethyl acetate, phenylethyl alcohol, neryl alcohol and beta-damascenone) contribute to a pleasant rose aroma in ‘Beimei’ wines. In summary, these results indicate that ‘Beimei’ grapes could be used as a winemaking grape variety considering global climate changes.

Impact of Deficit Irrigation on Grapevine cv. 'Touriga Nacional' during Three Seasons in Douro Region: An Agronomical and Metabolomics Approach.

The introduction of irrigation in vineyards of the Mediterranean basin is a matter of debate, in particular in those of the Douro Demarcated Region (DDR), due to the limited number of available studies. Here, we aimed to perform a robust analysis in three consecutive vintages (2018, 2019, and 2020) on the impact of deficit irrigation on the yield, berry quality traits, and metabolome of cv. ‘Touriga Nacional’. Results showed that in the peaks of extreme drought, irrigation at 30% crop evapotranspiration (ETc) (R30) was able to prevent a decay of up to 0.4 MPa of leaf predawn water potential (ΨPd), but irrigation at 70% ETc (R70) did not translate into additional protection against drought stress. Following three seasons of irrigation, the yield was significantly improved in vines irrigated at R30, whereas irrigation at R70 positively affected the yield only in the 2020 season. Berry quality traits at harvest were not significantly changed by irrigation, except for Total Soluble Solids (TSS) in 2018. A UPLC–MS-based targeted metabolomic analysis identified eight classes of compounds, amino acids, phenolic acids, stilbenoid DP1, stilbenoid DP2, flavonols, flavan-3-ols, di-OH- and tri-OH anthocyanins, and showed that anthocyanins and phenolic acids did not change significantly with irrigation. The present study showed that deficit irrigation partially mitigated the severe summer water deficit conditions in the DDR but did not significantly change key metabolites.

Berry Cell Vitality Assessment and the Effect on Wine Sensory Traits Based on Chemical Fingerprinting, Canopy Architecture and Machine Learning Modelling.

Berry cell death assessment can become one of the most objective parameters to assess important berry quality traits, such as aroma profiles that can be passed to the wine in the winemaking process. At the moment, the only practical tool to assess berry cell death in the field is using portable near-infrared spectroscopy (NIR) and machine learning (ML) models. This research tested the NIR and ML approach and developed supervised regression ML models using Shiraz and Chardonnay berries and wines from a vineyard located in Yarra Valley, Victoria, Australia. An ML model was developed using NIR measurements from intact berries as inputs to estimate berry cell death (BCD), living tissue (LT) (Model 1). Furthermore, canopy architecture parameters obtained from cover photography of grapevine canopies and computer vision analysis were also tested as inputs to develop ML models to assess BCD and LT (Model 2) and the intensity of sensory descriptors based on visual and aroma profiles of wines for Chardonnay (Model 3) and Shiraz (Model 4). The results showed high accuracy and performance of models developed based on correlation coefficient (R) and slope (b) (M1: R = 0.87; b = 0.82; M2: R = 0.98; b = 0.93; M3: R = 0.99; b = 0.99; M4: R = 0.99; b = 1.00). Models developed based on canopy architecture, and computer vision can be used to automatically estimate the vigor and berry and wine quality traits using proximal remote sensing and with visible cameras as the payload of unmanned aerial vehicles (UAV).

Identification of QTLs for berry acid and tannin in a <i>Vitis aestivalis</i>-derived 'Norton'-based population

Acidity and tannins are among the grape berry quality traits that influence wine quality. Despite advantageous environmental tolerances of Vitis aestivalis-derived 'Norton', its acidity and tannin concentrations often deviate from expectations set for V. vinifera. Identification of the genetic determinants of malic acid, tartaric acid, pH, and tannin can assist in the improvement of new hybrid cultivars. For this purpose, a 'Norton' and V. vinifera 'Cabernet Sauvignon' hybrid population containing 223 individuals was used to construct a linkage map containing 384 simple sequence repeat (SSR) and 2,084 genotyping-by-sequencing (GBS)-derived single nucleotide polymorphism (SNP) markers. The resulting map was 1,441.9 cM in length with an average inter-marker distance of 0.75 cM and spanned 19 linkage groups (LGs). Quantitative trait loci (QTLs) were detected for malic acid, tartaric acid, pH, and tannin. QTLs for malic acid (LG 8) and pH (LG 6) were observed across multiple years and explained approximately 17.7% and 18.5% of the phenotypic variation, respectively. Additionally, QTLs for tartaric acid were identified on linkage groups 1, 6, 7, 9, and 17 and tannin on LG 2 in single-year data. The QTLs for tartaric acid explained between 8.8−14.3% and tannin explained 24.7% of the phenotypic variation. The markers linked to these QTLs can be used to improve hybrid cultivar breeding through marker-assisted selection.

Novel stable QTLs identification for berry quality traits based on high-density genetic linkage map construction in table grape

BackgroundAroma, berry firmness and berry shape are three main quality traits in table grape production, and also the important target traits in grapevine breeding. However, the information about their genetic mechanisms is limited, which results in low accuracy and efficiency of quality breeding in grapevine. Mapping and isolation of quantitative trait locus (QTLs) based on the construction of genetic linkage map is a powerful approach to decipher the genetic determinants of complex quantitative traits.ResultsIn the present work, a final integrated map consisting of 3411 SLAF markers on 19 linkage groups (LGs) with an average distance of 0.98 cM between adjacent markers was generated using the specific length amplified fragment sequencing (SLAF-seq) technique. A total of 9 significant stable QTLs for Muscat flavor, berry firmness and berry shape were identified on two linkage groups among the hybrids analyzed over three consecutive years from 2016 to 2018. Notably, new stable QTLs for berry firmness and berry shape were found on LG 8 respectively for the first time. Based on biological function and expression profiles of candidate genes in the major QTL regions, 3 genes (VIT_08s0007g00440, VIT_08s0040g02740 and VIT_08s0040g02350) related to berry firmness and 3 genes (VIT_08s0032g01110, VIT_08s0032g01150 and VIT_08s0105g00200) linked to berry shape were highlighted. Overexpression of VIT_08s0032g01110 in transgenic Arabidopsis plants caused the change of pod shape.ConclusionsA new high-density genetic map with total 3411 markers was constructed with SLAF-seq technique, and thus enabled the detection of narrow interval QTLs for relevant traits in grapevine. VIT_08s0007g00440, VIT_08s0040g02740 and VIT_08s0040g02350 were found to be related to berry firmness, while VIT_08s0032g01110, VIT_08s0032g01150 and VIT_08s0105g00200 were linked to berry shape.

Influence of organic, organo-mineral and mineral fertilisers on cane traits, productivity and berry quality of red raspberry (Rubus idaeus L.)

The present study focused on the influence of organic, organo-mineral and mineral fertilisers on primocane growth, floricane properties, yield and berry quality attributes of non-remontant cv. ‘Meeker’ red raspberry (Rubus idaeus L.) during three consecutive years under western Serbian conditions. We used organo-mineral pelleted NPK fertilizer commercially named ‘Excell Orga’ (Excell), soluble crystalline complex fertiliser commercially named ‘Scotts Solinure 1’ (Scotts), water-soluble granulated compound fertiliser commercially named ‘Multi Comp Base’ (MCB), aged mature cattle manure as a organic fertiliser and control variant (without fertilization). Obtained results showed that primocane growth, floricane traits and berry quality traits significantly varied among fertilisers application and among years with exception of berry shape, soluble solids content (SSC), glucose and fructose contents, respectively. Also, in the most cases interaction fertiliser × year was significant. Among fertilisers, MCB and Scotts significantly improved primocane and floricane properties, berry weight and its size, productivity, single and total sugars contents and bioactive compounds (total phenolic and flavonoid contents and antioxidant capacity). Control treatment induced better sweetness index than all fertilisers. Among years, rainy 2014 significantly increased primocane growth, floricane traits, yield, berry weight and size, acidity, pH juice, total sugars and sucrose contents and bioactive compounds content, whereas decreased SSC and ripening index (RI). Warm and dry 2012 decreased primocane growth, yield, some berry physical traits, acidity, total sugars and bioactive compounds, whereas increased number of drupelets, SSC and ripening index value. Manure and Excell exhibited a weak influence on the properties investigated, which were often similar to the control treatment or with minor differences.

A Deep Proteomics Perspective Into Grape Berry Quality Traits During Ripening.

Discovery-based proteomics studies have an important role in the understanding of the biochemical processes that occur during grape berry ripening. The ripening process is relevant in determining grape berry quality. For a proteome analysis of grape berry ripening, Kambiranda etal. (2018) applied a label-free mass spectrometry-based quantitative approach. The authors reported the identification of proteins associated with the production flavor, aroma and ethylene production. Despite the valuable contribution of discovery-based proteomics studies, the picture is still incomplete. Future efforts in gaining proteome coverage would benefit the identification of proteins associated with grape berry quality traits.

Grapevine field experiments reveal the contribution of genotype, the influence of environment and the effect of their interaction (G×E) on the berry transcriptome.

Changes in the performance of genotypes in different environments are defined as genotype × environment (G×E) interactions. In grapevine (Vitis vinifera), complex interactions between different genotypes and climate, soil and farming practices yield unique berry qualities. However, the molecular basis of this phenomenon remains unclear. To dissect the basis of grapevine G×E interactions we characterized berry transcriptome plasticity, the genome methylation landscape and within-genotype allelic diversity in two genotypes cultivated in three different environments over two vintages. We identified, through a novel data-mining pipeline, genes with expression profiles that were: unaffected by genotype or environment, genotype-dependent but unaffected by the environment, environmentally-dependent regardless of genotype, and G×E-related. The G×E-related genes showed different degrees of within-cultivar allelic diversity in the two genotypes and were enriched for stress responses, signal transduction and secondary metabolism categories. Our study unraveled the mutual relationships between genotypic and environmental variables during G×E interaction in a woody perennial species, providing a reference model to explore how cultivated fruit crops respond to diverse environments. Also, the pivotal role of vineyard location in determining the performance of different varieties, by enhancing berry quality traits, was unraveled.

A Grapevine TTG2-Like WRKY Transcription Factor Is Involved in Regulating Vacuolar Transport and Flavonoid Biosynthesis.

A small set of TTG2-like homolog proteins from different species belonging to the WRKY family of transcription factors were shown to share a similar mechanism of action and to control partially conserved biochemical/developmental processes in their native species. In particular, by activating P-ATPases residing on the tonoplast, PH3 from Petunia hybrida promotes vacuolar acidification in petal epidermal cells whereas TTG2 from Arabidopsis thaliana enables the accumulation of proanthocyanidins in the seed coat. In this work we functionally characterized VvWRKY26 identified as the closest grapevine homolog of PhPH3 and AtTTG2. When constitutively expressed in petunia ph3 mutant, VvWRKY26 can fulfill the PH3 function in the regulation of vacuolar pH and restores the wild type pigmentation phenotype. By a global correlation analysis of gene expression and by transient over-expression in Vitis vinifera, we showed transcriptomic relationships of VvWRKY26 with many genes related to vacuolar acidification and transport in grapevine. Moreover, our results indicate an involvement in flavonoid pathway possibly restricted to the control of proanthocyanidin biosynthesis that is consistent with its expression pattern in grape berry tissues. Overall, the results show that, in addition to regulative mechanisms and biological roles shared with TTG2-like orthologs, VvWRKY26 can play roles in fleshy fruit development that have not been previously reported in studies from dry fruit species. This study paves the way toward the comprehension of the regulatory network controlling vacuolar acidification and flavonoid accumulation mechanisms that contribute to the final berry quality traits in grapevine.

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.

Plasticity of the Berry Ripening Program in a White Grape Variety.

Grapevine (Vitis vinifera L.) is considered one of the most environmentally sensitive crops and is characterized by broad phenotypic plasticity, offering important advantages such as the large range of different wines that can be produced from the same cultivar, and the adaptation of existing cultivars to diverse growing regions. The uniqueness of berry quality traits reflects complex interactions between the grapevine plant and the combination of natural factors and human cultural practices which leads to the expression of wine typicity. Despite the scientific and commercial importance of genotype interactions with growing conditions, few studies have characterized the genes and metabolites directly involved in this phenomenon. Here, we used two large-scale analytical approaches to explore the metabolomic and transcriptomic basis of the broad phenotypic plasticity of Garganega, a white berry variety grown at four sites characterized by different pedoclimatic conditions (altitudes, soil texture, and composition). These conditions determine berry ripening dynamics in terms of sugar accumulation and the abundance of phenolic compounds. Multivariate analysis unraveled a highly plastic metabolomic response to different environments, especially the accumulation of hydroxycinnamic and hydroxybenzoic acids and flavonols. Principal component analysis (PCA) revealed that the four sites strongly affected the berry transcriptome allowing the identification of environmentally-modulated genes and the plasticity of commonly-modulated transcripts at different sites. Many genes that control transcription, translation, transport, and carbohydrate metabolism showed different expression depending on the environmental conditions, indicating a key role in the observed transcriptomic plasticity of Garganega berries. Interestingly, genes representing the phenylpropanoid/flavonoid pathway showed plastic responses to the environment mirroring the accumulation of the corresponding metabolites. The comparison of Garganega and Corvina berries showed that the metabolism of phenolic compounds is more plastic in ripening Garganega berries under different pedoclimatic conditions.

Vigour-yield-quality relationships in long-term deficit irrigated winegrapes grown under semiarid conditions

Regulated deficit irrigation (RDI) and partial root-zone drying irrigation (PRD) are two of the most-promising agronomic practices designed to increase water use efficiency (WUE) and berry and wine quality in field-grown wine grapes in Mediterranean semiarid regions. However, many growers have not yet taken advantage of the new irrigation techniques now available, which would enable them to efficiently manage irrigation in wine grapes with the aims of improving quality and making this crop more competitive and profitable. This study focused on finding significant relationships between several WUE indicators (from the leaf to the plant level) and relevant vine vigour, yield and berry quality traits in order to improve deficit irrigation management in wine grapes under semiarid conditions. Sustained deficit irrigation (SDI), RDI and PRD techniques were compared for 7 years (2006–2012), in field-grown Monastrell grapevines grafted onto 1103P in SE Spain. Five treatments were applied: SDI irrigated at 60–40 % ETc (crop evapotranspiration) for the whole season (308–211 mm year−1); a moderate RDI strategy (110–191 mm year−1) under conventional drip irrigation (RDI-1) and under PRD (PRD-1); and a more-severe RDI strategy (90–144 mm year−1) under conventional drip irrigation (RDI-2) and under PRD (PRD-2). The SDI enhanced root system development and vine vigour, improved technological berry quality but lowered WUE and berry polyphenolic content, compared to deficit irrigation (DI). In contrast, PRD and RDI resulted in lower root growth, vine vigour and leaf-plant canopy water use, but improved cluster microclimate and increased WUE and berry polyphenolic content. Among the DI treatments, the PRD-1 strategy was the one which most improved the long-term vine performance. The most-restrictive DI strategies (PRD-2 and RDI-2) did not give a substantial improvement in WUEyield (kg m−3) or berry quality. Significant interactive effects of irrigation volume (high vs. low) and irrigation placement (PRD vs. RDI) indicate distinct PRD effects on long-term yield, WUE and berry quality, depending on the volume of water applied in the wet root zone and the soil total water availability. Significant vigour-quality relationships were established. We identified a range of optimum physiological and agronomical thresholds in order to develop long-term, efficient deficit irrigation strategies in Monastrell vineyards under semiarid conditions.

Rootstock and seasonal variations affect anthocyanin accumulation and quality traits of ‘Kyoho’ grape berries in subtropical double cropping system

The double cropping system has been commercially adopted in subtropical viticulture regions. However, very limited information about rootstock and seasonal effects on berry quality traits are available for this unique production system. Developing ‘Kyoho’ berries from own-rooted vines and from vines on 5C and 1202C rootstocks were periodically sampled from veraison until harvest in two consecutive cropping cycles to document the potential seasonal influence on rootstock effects. Anthocyanin concentration in berry skin, total soluble solids content (TSS), and titratable acidity (TA) were analyzed. In both cropping cycles, own-rooted vines produced berries with the highest anthocyanin concentration while vines on 1202C produced berries with the lowest anthocyanin concentration among the three scion/rootstocks. Anthocyanin concentrations were not differentiated by the differential climate pattern between the summer and the winter cropping cycles. Berries of own-rooted ‘Kyoho’ and ‘Kyoho’/5C vines accumulated satisfactory and equal amount of TSS in both cropping cycles. 1202C rootstocks did not affect berry TSS in the summer cropping cycle but reduced TSS in the winter cropping cycle. Significant rootstock and seasonal effects on berry TA were detected. Own-rooted vines produced berries with the lowest TA while vines on 1202C produced berries with the highest TA among the three scion/rootstock combinations. TA of berries from the winter cropping cycle was significantly higher than that from the summer cropping cycle especially in ‘Kyoho’/1202C. Relationships between anthocyanins and TSS of developing berries after veraison properly fitted into a sigmoidal function regardless of rootstocks and cropping cycles. However, the duration of the initial lag phase, the onset and the trend of both quality triats in the increasing phase, and the presence and degree of the final lag phase in the relationship were all modulated by rootstocks and by seasonal variations.

Fruit-localized photoreceptors increase phenolic compounds in berry skins of field-grown Vitis vinifera L. cv. Malbec

Sunlight exposure has multiple effect on fruits, as it affects the light climate perceived by fruit photoreceptors and fruit tissue temperature. In grapes (Vitis vinifera L.), light exposure can have a strong effect on fruit quality and commercial value; however, the mechanisms of light action are not well understood. The role of fruit-localized photoreceptors in the control of berry quality traits was evaluated under field conditions in a commercial vineyard in Mendoza (Argentina). Characterization of the diurnal dynamics of the fruit light environment in a vertical trellis system indicated that clusters were shaded by leaves during most of the photoperiod. Supplementation of the fruit light environment from 20days before veraison until technological harvest showed that red (R, 660nm) and blue (B, 470nm) light strongly increased total phenolic compound levels at harvest in the berry skins without affecting sugar content, acidity or berry size. Far-red (FR, 730nm) and green (G, 560nm) light supplementation had relatively small effects. The stimulation of berry phytochromes and cryptochromes favored accumulation of flavonoid and non-flavonoid compounds, including anthocyanins, flavonols, flavanols, phenolic acids and stilbenes. These results demonstrate that the chemical composition of grape berries is modulated by the light quality received by the clusters under field conditions, and that fruit photoreceptors are not saturated even in areas of high insolation and under management systems that are considered to result in a relatively high exposure of fruits to solar radiation. Therefore, manipulation of the light environment or the light sensitivity of fruits could have significant effects on critical grape quality traits.

Skin pectin metabolism during the postharvest dehydration of berries from three distinct grapevine cultivars

Background and Aims Postharvest dehydration is used to modify certain grape berry quality traits that affect the characteristics of wine. After harvesting, berries undergo several chemical and physical changes that often reflect ongoing or specifically activated metabolic processes, such as the modification of cell wall polymers in the skin. We compared berry skin pectin metabolism during postharvest dehydration in three Italian wine grape cultivars. Methods and Results Corvina, Oseleta and Sangiovese grapes were postharvest dehydrated under the same environmental conditions and displayed different dehydration rates. The quantitative characterisation of pectins by ion-exchange and size-exclusion chromatography revealed that more demethoxylation and depolymerisation occurred in the Corvina berries, which also showed the strongest induction of pectin methylesterase and polygalacturonase gene expression (by microarray analysis) and enzyme activity (by zymography). Conclusions Postharvest dehydration affected the skin pectin metabolism of grape berries to an extent different in each of the three cultivars, reflecting differences in water loss kinetics and metabolic processes. Significance of the Study This is the first description of dynamic cultivar-specific changes in pectin metabolism during the postharvest dehydration of grape berries.