Grapes are a globally important fruit with significant economic value, influenced by factors such as sugar content, organic acids, hormones, and antioxidants. Understanding the dynamics of these compounds during grape development and ripening is critical for optimizing berry quality and production. This study investigates the changes in sugar, organic acids, hormones, and antioxidants in two grape varieties, ‘Italia’ and ‘Bronx Seedless’, at various growth stages (BBCH-77, BBCH-79, BBCH-81, BBCH-83, BBCH-85, and BBCH-89). Regarding sugars, significant variations were observed due to grapevine cultivar and phenological stage. ‘Bronx Seedless’ grapes consistently displayed lower sugar content than ‘Italia’ grapes, regardless of the type of sugar being examined. The BBCH-77 stage consistently exhibited lower sugar levels compared to BBCH-89. The varieties ‘Bronx Seedless’ and ‘Italia’ exhibited distinct nutritional profiles, each with their unique advantages in terms of sugar content and organic acid composition. Both varieties were rich in the primary sugar glucose and fructose, with ‘Bronx Seedless’ displaying notably high levels of the beneficial tartaric acid, enhancing its nutritional value. On the other hand, ‘Italia’ stood out for its higher concentrations of fumaric, butyric, and oxalic acids, contributing to its unique taste and health benefits. Throughout their growth stages from BBCH-77 to BBCH-89, an increase in organic acid levels was observed, peaking at the BBCH-85 stage, except for maleic acid. In terms of hormonal content, ‘Italia’ exhibited higher levels compared to ‘Bronx Seedless’. The predominant hormone, abscisic acid (ABA), alongside lower quantities of zeatin, indicated a strong physiological response to environmental and developmental cues in both varieties, with hormone levels increasing as the grapes approached maturity. Antioxidant profiles also varied between the two varieties, with ‘Italia’ consistently showing higher antioxidant levels than ‘Bronx Seedless’. Antioxidant levels consistently increased from BBCH-77 to BBCH-89. This comprehensive analysis contributes to our understanding of the complex processes underlying grape berry development and ripening, with potential implications for enhancing grape quality and refining production strategies.

Understanding the impact of pre-treatment methods on the phytochemical composition of grapes is essential for optimizing grape quality and producing raisins with desirable characteristics. Therefore, this study meticulously analyzed the impact of two distinct pre-treatment methods, oak ash and potassium carbonate (K₂CO₃), on the composition of essential phytochemical components in grapes. This research encompassed phenolic compounds, anthocyanins, phenolic acids, flavonoids, and phytoalexins. This study investigates the impact of pre-treatment methods, oak ash and K₂CO₃, on the phytochemical composition of grapes. Significant differences were observed in anthocyanins, flavonoids, phytoalexins, and phenolic acids between the treatments. Oak ash exhibited advantages in preserving specific compounds, including higher levels of anthocyanins, flavonols, flavones, flavanones, catechins, resveratrol, pterostilbene, and viniferin, compared to K₂CO₃. Notably, the delphinidin-3-O-glycoside content was significantly higher in the oak ash treatment. An analysis of phenolic compounds revealed distinctions in hydroxycinnamic acids, hydroxybenzoic acids, benzaldehyde, and phenylacetaldehyde. Additionally, gallic acid, vanillic acid, trans-caffeic acid, trans-p-coumaric acid, and (-)-epicatechin were significantly more prevalent in the K₂CO₃ treatment, while ferulic acid and quercetin were more prevalent in the oak ash treatment. These findings underscore the pivotal role of pre-treatment methods in shaping the phytochemical content of grapes, thus holding critical implications for grape-derived products’ quality and potential health benefits.

Understanding the variations in amino acids, phenolic compounds, elements, and vitamins between grape varieties is essential for optimizing grape production, fine-tuning dietary recommendations, and harnessing the health potential of grapes. In this regard, this comprehensive study investigated the compositional diversity of two distinct table grape cultivars, ‘Bronx Seedless’ and ‘Italia’, at various critical phenological stages (BBCH-77, -79, -81, -83, -85, and -89). The research findings demonstrated remarkable differences in the concentrations of key nutritional components. Bronx Seedless consistently exhibited higher levels of several amino acids, including glutamate, phenylalanine, and aspartate with concentrations reaching 49.6, 52.7, and 24.8 pmol μL⁻¹, respectively, in contrast to Italia. Regarding phenolic compounds, Italia emerged as the richer source, with concentrations notably higher for compounds such as vanillic acid (18.2 µg g⁻¹ FW) and gallic acid (37.4 µg g⁻¹ FW). Mineral analysis revealed variable concentrations, with Italia grapes containing higher levels of Fe (91.0 mg/kg) compared to Bronx Seedless (87.1 mg/kg); however, Bronx Seedless had slightly elevated levels of K (31,089 mg/kg) compared to Italia (28,184 mg/kg). Concidering vitamins, Italia grapes showcased superior levels of Vitamin B1 (14.1 mg/100 g FW) and Vitamin A (11.0 mg/100 g FW), while Bronx Seedless had higher concentrations of Vitamin B6 (29.5 mg/kg), C (3.9 mg/100 g FW) and Vitamin B2 (36.9 mg/100 g FW). Principal component analysis (PCA) elucidated complex relationships within these components, offering insights into potential correlations and interactions. The heatmap visualization further indicated the concentration gradients across various samples, unveiling the intricate nutritional profiles of these grape cultivars. This research can aid grape growers and consumers in making informed decisions about grape cultivars and their corresponding health advantages.

Grapevine sustainability is impacted by the timing of dormancy initiation and freezing tolerance in fall and winter and chilling fulfillment and bud break in the spring. These traits have genetic and local temperature contributing factors; therefore, this study was undertaken to develop an understanding of these characteristics in four recently developed cold climate cultivars. The cold hardiness and chilling fulfillment profiles were monitored in Brianna, Frontenac gris, La Crescent and Marquette using differential thermal analyses and bud break assays. Bud cold hardiness of all cultivars increased with the declining temperatures from November through February, after which the buds began to lose freezing tolerance. There were significant differences in cold hardiness and chilling fulfillment between cultivars during the endodormant and ecodormant period of winter. Marquette had the greatest freezing tolerance from early November through midwinter suggesting it has potential as a sentinel cultivar for comparisons of new cold climate selections. Brianna was slower to acclimate and deacclimated more rapidly than the other cultivars. Chilling fulfillment under natural field or constant 4 °C conditions showed no main effect differences for chilling accumulation condition; however, there were significant cultivar, condition, and time point interactions, indicating the cultivars differed in chilling fulfillment responses.

Climate change and drought are increasing soil lime content globally, a major threat to crop productivity and quality, especially for viticulture. High lime concentrations disrupt nutrient uptake, leading to chlorosis and reduced growth in plants. While exogenous putrescine applications have shown potential in enhancing plant defense responses against various environmental stresses, their efficacy in modulating lime stress has not been previously explored. In this regard, we studied the effects of putrescine on grapevine saplings under varying lime conditions. The experiment used the Karaerik grape variety, an economically important indigenous cultivar from Eastern Black Sea Region of Turkey, grafted onto three American rootstocks with different lime tolerances: Fercal (high), 5 BB (moderate), and 3309 C (low). These were tested under four lime levels (0%, 20%, 40%, and 60% CaO) and treated with different putrescine concentrations (0, 0.05, 0.1, and 0.2 mM) to examine their morphological, biochemical, and physiological responses under lime stress conditions. The results indicated that lime stress adversely affected the growth and development of grapevine saplings by reducing growth parameters, SPAD index, stomatal conductance, and relative water content (RWC), while increasing membrane damage and malondialdehyde (MDA) content. However, different rootstock/cultivar combinations exhibited distinct strategies to cope with lime stress. The highly tolerant Fercal/KE combination maintained higher chlorophyll content, better RWC, and stomatal conductance, supported by increased production of protective enzymes, along with higher proline and protein accumulation, ultimately leading to improved growth and development under lime stress. Exogenous putrescine applications effectively improved plant performance across all rootstock/cultivar combinations, with different concentrations showing optimal results for each combination. The 0.2 mM putrescine treatment significantly enhanced growth parameters, chlorophyll content, stomatal conductance, RWC, and protective enzyme levels while reducing membrane damage and lipid peroxidation in 3309 C/KE combination, which typically shows low lime tolerance. For the moderately tolerant 5 BB/KE, 0.1 mM putrescine was most effective, while the already lime-tolerant Fercal/KE responded best to 0.05 mM putrescine applications. These optimized concentrations demonstrated that putrescine can effectively enhance lime stress tolerance, particularly in more sensitive rootstock/cultivar combinations. This study demonstrated that exogenous putrescine applications effectively mitigated lime stress effects in grapevine saplings by improving physiological parameters and reducing oxidative damage, with optimal concentrations varying according to rootstock tolerance levels (0.2 mM for 3309 C/KE, 0.1 mM for 5 BB/KE, and 0.05 mM for Fercal/KE). The findings revealed that putrescine’s protective effects were most pronounced in lime-sensitive rootstock combinations, suggesting its potential as a protective compound for improving lime stress tolerance in grapevine cultivation.

Carbon dots (CDs), which have been included in the family of carbon-based nanomaterials since 2004, can be easily prepared from different carbon-based sources and are being tested as fertilizers, micronutrients, nanopesticides, and nanoherbicides with their mechanical, thermal, and chemical properties. Although it is reported that it can improve yield and product quality in different species, studies on its effects on grape varieties are insufficient. In applications, the effects of CDs on plant growth, biochemical content, photosynthesis, and plant yield are examined. Nitrogen-doped graphene quantum dots (N-GQDs) used in this study were produced by dissolving 1 mmol citric acid and 3 mmol urea in 5 mL of water, keeping in the oven at 160 ˚C for 4 h, then adding ethanol and centrifuging at 5000 rpm for 5 min. N-GQDs were applied to cv Ekşi Kara and cv Gök Üzüm at different doses (0, 0.10, 0.25, 0.50, 1 g L ^-1 ) by foliar spraying with four replications at four stages approximately (1) week before flowering, (2) at the berry setting stage (when berries reached approximately 2–3 mm in diameter), (3) at the berry coarsening stage (when berry size reached 5–7 mm in diameter), and (4) at the veraison stage The effects of the applications were evaluated by the parameters of cluster and berry sizes, °Brix, pH, titratable acidity (TA), total phenolic content, total antioxidant activity, berry skin colour, berry stemming resistance, berry skin tearing resistance, stomatal conductance, leaf temperature, chlorophyll content, photosynthetic rate in harvested grapes. For all descriptive analyses, analysis of variance (ANOVA), Tukey test, and post-hoc analysis were performed with the statistical packages available in R Studio. Principal Component Analyses (PCAs) with the ggplot2 package and the heatmap produced by the Pheatmap package were used to better understand and depict the correlations between variables. While N-GQDs applications provided improvement in all yield and quality traits examined, the effectiveness of the 0.10 g L ^-1 dose was more pronounced. Genetic divergence was evident in the effectiveness of the treatments. In PCA analysis, the first two principal components (PC1 and PC2) of the samples in panicle, berry, and leaf datasets explained 41.3% and 18.6% of the variance, respectively. As a result of this study, it was determined that N-GQDs applications improved photosynthesis, yield, and quality parameters and accelerated ripening in two different grape cultivars. In conclusion, 0.10 g L ^-1 N-GQDs can be tested as a locally produced tool for promoting quality improvement in grape cultivars.