Despoina G. Petoumenou

Rising temperatures and increasing drought frequency threaten grapevine physiological performance, yield, and berry quality in Mediterranean vineyards. This study evaluated the responses of two field-grown Greek Vitis vinifera L. cultivars, the red Agiorgitiko and the white Assyrtiko, to contrasting water regimes and foliar application of a proline-rich yeast derivative over two consecutive growing seasons. Five field treatments were included: a fully irrigated untreated reference (C), deficit-irrigated grapevines with or without yeast application (DI-Y and DI-NY), and rainfed grapevines with or without yeast application (NI-Y and NI-NY). The four water-limited treatments constituted a 2 × 2 factorial subset for formal testing of water condition, yeast application, and their interaction. Vegetative growth and physiological parameters were assessed in 2022, whereas yield and berry composition were evaluated in 2022 and 2023. In Agiorgitiko, significant water × yeast interactions were detected for primary leaf area and shoot length and, during morning measurements, for leaf assimilation rate, transpiration, stomatal conductance, and intrinsic water use efficiency, indicating water condition-dependent responses to the yeast derivative for these traits. In Assyrtiko, such interactions were less evident for vegetative and physiological traits but were pronounced for several berry traits and for total soluble solids. Yield did not show a significant water × yeast interaction in either cultivar, despite numerical increases in NI-Y relative to NI-NY. Leaf temperature responses were mainly associated with yeast and date-dependent effects rather than a consistent water × yeast interaction. Overall, the response to the proline-rich yeast derivative was cultivar- and trait-dependent, supporting its potential as a complementary tool under water limitation while emphasizing the importance of stress level and seasonal conditions.

Smart technologies and artificial intelligence (AI) are increasingly reshaping viticulture by improving vineyard monitoring, supporting data interpretation, and enabling more targeted management decisions. This review examines how sensor networks, remote sensing, machine learning, deep learning, and decision-support systems contribute to more sustainable vineyard management and the production of high-quality grapes. Particular attention is paid to applications in grapevine stress monitoring, disease and pest detection, irrigation and nutrient management, yield estimation, grape quality prediction, and emerging automation. The review also highlights the main barriers that still limit broader adoption in commercial vineyards, including data quality issues, limited transferability across sites and seasons, interoperability gaps, vendor lock-in, and concerns related to governance, privacy, and cybersecurity. Although these constraints remain significant, the available evidence shows that smart viticulture can improve resource-use efficiency, support more precise interventions, and help growers respond more effectively to environmental variability. Future progress will depend on stronger validation under field conditions, better integration into practical vineyard workflows, interoperable digital infrastructures, and decision-support tools that are transparent, reliable, and useful for end users.

Phenolic compounds, essential for grape quality, are affected by environmental factors, including abiotic stressors such as hail. This study examined the impact of varying levels of natural hail damage on the physicochemical parameters, phenolic composition, and antioxidant capacity of Thompson seedless grapevines (Vitis vinifera L.) under Mediterranean climatic conditions. The research was carried out in a commercial vineyard in Greece during the 2015 growing season, following a major hailstorm. Three treatments were implemented: control (undamaged), moderate hail damage, and total hail damage. The results showed that pH levels and specific physiological parameters, including proline concentration, were significantly influenced across treatments. Detailed analysis revealed that the concentrations of phenolic compounds generally increased with greater hail damage, indicating enhanced antioxidant capacity and metabolic adaptation to natural hail-induced mechanical stress. Additionally, individual phenolic compounds, such as flavanols, hydroxybenzoic acids, and stilbenes, responded differently to hail damage, demonstrating complex regulatory mechanisms in grape metabolism. These findings underscore the importance of understanding grapevine biochemical responses to extreme weather events in the context of climate change, as changes in phenolic composition can directly affect grape quality.

Environmental challenges such as drought, high temperatures, and salinity compromise grapevine physiology, reduce productivity, and negatively affect grape and wine quality. In recent years, foliar applications of biostimulants, antitranspirants, and phytohormones have emerged as promising strategies to enhance stress tolerance in grapevines. This review focuses on the main effects of salinity, drought, and high temperatures and the combined impact of drought and high temperatures on grapevines and examines how foliar applications influence grapevine responses under these specific stress conditions. Synthesizing the recent findings from the last ten years (160 articles), it provides direct insights into the potential of these compounds to alleviate each type of stress, highlighting their effects on grapevine physiology, yield components, and secondary metabolites in berries. While their mechanism of action is not entirely clear and their efficacy can vary depending on the type of compound used and the grapevine variety, most studies report a beneficial effect or no effect on grapevines under abiotic stresses (either single or combined). Future research is necessary to optimize the concentrations of these compounds and determine the appropriate number and timing of applications, particularly under open-field experiments. Additionally, studies should assess the effect of foliar applications under multiple abiotic stress conditions. In conclusion, integrating foliar applications into vineyard management represents a sustainable technique to mitigate abiotic stresses associated with climate change, such as salinity, water deficit, and heat stress, while preserving or enhancing the quality of grapes and wines.

One of the biggest environmental challenges that most of the traditional and modern grape-growing areas are facing is the frequency, severity, and unpredictability of extreme weather events as a result of climate change. Sustainable tools such as chemically inert mineral particles could be a valid alternative for the promotion of environmentally-friendly viticultural techniques to enhance yield, improve physiological processes, and increase tolerance to biotic/abiotic stressors and grape quality. In regard to this concept, the effects of kaolin (KL) and zeolite (ZL) application was tested in the rosé grapevine cultivar Roditis, field-and rainfed, under the Mediterranean conditions of central Greece. In a two-year trial, the whole vine canopy was sprayed with kaolin and zeolite until runoff at a dose of 3% (w/v) twice throughout the growing season; the first at the beginning of veraison and the second one week later; treatment of the untreated control plants was also performed (C). The assimilation rate in morning and midday, the stomatal conductance, and the WUEi of the leaves of the treated and untreated plants were monitored one day after each application and at harvest. During the same time period of the day (i.e., morning and midday) in July, August, and September, the leaf temperature near the fruit zone was also recorded. At harvest, the yield parameters, cluster characteristics, grape composition, and incidence (%) of sunburned and dehydrated berries as well as berries infected by Plasmopara viticola and Lobesia botrana were recorded. The results showed that KL and ZL application decreased leaf temperature during the growing season until harvest compared to the control treatment, which resulted in an improvement in physiological parameters such as net photosynthesis and intrinsic water use efficiency. At harvest, the KL- and ZL-treated vines showed increased yield due to an increasing cluster and berry fresh weight. On the other hand, the KL and ZL application did not affect the sugar concentration and pH of the must and increased the total acidity and decreased the total phenolic compound content, but only in the first year of the experiments. Furthermore, the incidence of sunburn necrosis, dehydrated berries, and infected berries was significantly lower in the treated vines compared to the control vines. These results confirm the promising potential of kaolin and zeolite applications as a stress mitigation strategy during the summer period, with the ability to protect grapevine plants, enhance yield, and maintain or improve fruit quality in rainfed Mediterranean vineyards.

Modern viticultural areas are being confronted with the negative impacts of global warming on yield and fruit composition, with especially adverse effects on anthocyanin synthesis. Novel and sustainable tools, such as biostimulants, may represent a viable alternative to traditional cultural practices, thus promoting eco-friendly strategies to enhance the yield, fruit quality and abiotic stress tolerance of grapevines. ‘Crimson Seedless’ is a late-season red table grape variety, and due to climatic warming, its berries are frequently failing to acquire the commercially acceptable red color. Canopy applications of different biostimulants, namely, Kelpak^®, Sunred^®, Cytolan^®, LalVigne™ Mature as well as Ethrel^® Top, were tested on grapevine cv. Crimson Seedless grown under semi-arid Mediterranean conditions in order to evaluate their effects on yield and fruit quality. Some of the products were sprayed in canopies at labeled doses, and some were applied at doses reported in other studies. For the control treatment, canopies were sprayed with water. Sampling started at veraison and was repeated at 10-day intervals to measure the evolution of berry weight, length and diameter, as well as the total soluble solids and titratable acidity of the juice. The grapes were harvested when the berries of one of the treatments attained the commercially acceptable color. The greatest improvements in the red berry color were achieved with Sunred^® (at a dose of 4 L ha⁻¹) and Ethrel^® Top (250 ppm plus glycerol at 1%), each applied at veraison and 10 days later. The different applications had varying effects on productivity and qualitative parameters. Only Sunred^® improved the accumulation of anthocyanin and the overall acceptability of table grapes by consumers. The obtained results clearly demonstrate that applying Sunred^® can improve the yield and qualitative parameters of the red table grape variety ‘Crimson Seedless’, indicating that this biostimulant could be a viable alternative to the most widely used plant growth regulator, ethephon.

Hailstorms are typically localized events, and very little is known about their effect on crops. The objective of this study was to examine the physiological and vine performance responses to natural hail, registered four weeks after full bloom, of field-grown Thompson seedless (Vitis vinifera L.) grapevines, one of the most important table grape varieties cultivated in Greece and especially in the Corinthian region in northeastern Peloponnese. Leaf gas exchange, vegetative growth, vine balance indices, cane wood reserves, yield components, and fruit chemical composition were recorded from hail-damaged vines and compared with control vines. Visibly, the extent of the hailstorm damage was great enough to injure or remove leaves as well as cause partial stem bruising and partial injury or total cracking of berries. Our results indicated that natural hail did not affect leaf photosynthesis, berry weight, total acidity, and cane wood reserves but significantly reduced the total leaf area, yield, and the total phenolics of berries at harvest. At the same time, hail-damaged vines increased the leaf area of lateral canes and presented a higher total soluble solid (TSS) accumulation, while no effect on the next year’s fertility was registered. The present work is the first attempt to enhance our understanding of the vegetative yield, berry quality, and physiological responses of grapevines to natural hail, which is an extreme and complex natural phenomenon that is likely to increase due to climate change.