Sandra Pereira

Climate change makes the development and survival of grapevine pathogens increasingly unpredictable, posing challenges for winegrowers. This study evaluated the ability of plant extracts to prevent Plasmopara viticola , Erysiphe necator and Guignardia bidwellii in order to reduce the use of chemical control. A trial was conducted during two consecutive growing seasons in an experimental vineyard of the University of Trás‐os Montes e Alto Douro, including four foliar treatments: nettle extract (NE), Japanese knotweed extract (JKE), conventional treatment (CT) and a water control (C). Disease incidence and severity were assessed in leaves and berries, together with the expression of six defence‐related genes. NE and JKE showed partial effectiveness in reducing disease severity in leaves, in some cases approaching the performance of CT, but their impact on berry infections was limited. Both extracts induced the activation of several defence‐related genes, indicating an elicitor effect that varied between years and phenological stages. The results indicate that these plant extracts may contribute to grapevine defence activation, although their direct disease control capacity, particularly in berries, remains limited. Therefore, these extracts may be more effective when incorporated into an integrated disease management programme rather than used as stand‐alone treatments.

Introduction: Climate change–driven increases in heat and drought intensity pose major challenges to grapevine performance, largely through the exacerbation of oxidative stress. This study investigated the effects of combined foliar applications of kaolin (Kl) and silicon (Si) on oxidative stress regulation in Vitis vinifera L. cv. Touriga Franca grafted onto 1103P under field conditions in the Douro Demarcated Region during the 2023 and 2024 growing seasons. Methods: Grapevines were treated with different Kl + Si formulations (MiKS), consisting of 2% Kl combined with 2–8% Si, and evaluated at veraison (E-L35) and harvest (E-L38). Leaf proline content, total and specific reactive oxygen species (ROS, H ₂ O ₂ and O ₂ -), antioxidant enzyme activities (superoxide dismutase- SOD and catalase- CAT), and the expression of key oxidative stress–related genes (FeSOD and CAT) were analyzed. Results: MiKS formulations significantly modulated grapevine redox metabolism, although responses depended on season, phenological stage, and Si concentration. Intermediate formulations, particularly MiKS 2 (2% Kl + 4% Si) and MiKS 3 (2% Kl + 6% Si), consistently reduced total ROS accumulation by up to 61.7% and decreased H2O2 levels under summer stress conditions. These responses were associated with transient increases in proline accumulation at veraison, enhanced CAT activity, and strong upregulation of FeSOD and CAT expression, indicating coordinated activation of antioxidant and osmoprotective mechanisms. Although O2•- levels increased in some treatments, this pattern likely reflected controlled redox signaling rather than oxidative damage, as ROS detoxification remained effective. Correlation analysis further supported the close association between ROS modulation and antioxidant regulation. Conclusions: The combined application of kaolin and silicon, especially at intermediate Si concentrations, promoted a more balanced redox state and improved oxidative stress management under Mediterranean summer conditions. These findings provide mechanistic evidence supporting MiKS formulations as sustainable, low-impact, climate-adaptive tools to enhance grapevine resilience under increasingly hot and dry viticultural scenarios.

Introduction: Understanding grapevine responses to water deficit and rewatering is essential for developing adaptive strategies to mitigate the negative impacts of climate change in Mediterranean viticulture. Methods: This study evaluated the ecophysiological and biochemical behaviour of two emblematic Douro cultivars, Touriga Franca (TF) and Tinto Cão (TC), subjected to contrasting water regimes under potted controlled conditions. Physiological measurements of gas exchange, chlorophyll a fluorescence, relative water content (RWC), and leaf biochemical parameters (photosynthetic pigments, phenolic compounds, flavonoids, soluble proteins, soluble sugars, and antioxidant activity) were performed after drought and recovery phases. Results revealed distinct adaptive responses between cultivars. Results and discussion: TF exhibited moderate stomatal regulation, maintaining photosynthetic activity and high intrinsic water use efficiency during drought, as well as rapid recovery after rehydration. Conversely, TC showed a more conservative strategy, characterized by earlier stomatal closure, higher water retention (RWC > 90%), and increased accumulation of soluble proteins and phenolic compounds under stress. Both cultivars activated photoprotective mechanisms, with TF showing enhanced non-photochemical quenching and TC maintaining stable photosystem II efficiency. These findings highlight the contrasting strategies of TF (more anisohydric, plastic, and rapidly recoverable) and TC (more isohydric, conservative, and resilient), offering valuable insights for the selection of drought-tolerant cultivars and sustainable management of Douro vineyards under future warming and aridity scenarios.

Recycling vineyard pruning residues into compost and vermicompost represents a sustainable strategy to reduce viticulture’s reliance on chemical fertilizers. Nonetheless, their effects on plant performance remain poorly understood. This study evaluated the effect of vine pruning residues compost and vermicompost on the physiological, biochemical, and growth performance of Vitis vinifera L. cv. Touriga Franca, in comparison with mineral fertilization and an unfertilized control. A pot experiment was conducted from April to September 2024 in northern Portugal under Mediterranean climate conditions, using one-year-old grapevines and subjected to four fertilization treatments. Leaf gas exchange, chlorophyll a fluorescence, photosynthetic pigments, antioxidant and osmoprotective metabolites, and shoot and root development were assessed at three sampling dates during the growing season. Organic amendments enhanced photosynthetic performance and root growth relative to the unfertilized control. Vermicompost promoted higher CO₂ assimilation, stomatal conductance, and shoot and root elongation, whereas compost increased intrinsic water use efficiency, photochemical regulation, and root biomass. Biochemical analyses indicated that compost favored protein and carotenoid accumulation, while vermicompost increased proline and later protein levels, alongside reduced phenolic and flavonoid contents. Despite their similar chemical composition, compost and vermicompost induced distinct physiological responses driven by differences in biological activity and nutrient dynamics. These findings demonstrate that pruning-derived organic amendments can match mineral fertilization in supporting grapevine performance while offering additional benefits for stress regulation and sustainable vineyard management.

Root exudates are key mediators of plant–soil–microbe interactions, shaping rhizosphere dynamics and influencing agroecosystem resilience. Comprising diverse primary and secondary metabolites, these compounds are actively secreted through specific transport pathways and are modulated by intrinsic plant traits and environmental conditions. Root exudates serve as chemical signals that recruit and structure microbial communities, facilitating nutrient mobilization, microbial feedbacks, and the regulation of plant growth and stress responses. By modulating soil chemical, physical, and biological properties, exudates contribute to carbon cycling, soil health, and the maintenance of ecosystem services. Moreover, they play multifunctional roles in enhancing plant tolerance to abiotic and biotic stresses, while also mediating interactions with neighboring plants. This review provides a holistic perspective on root exudation, encompassing their mechanisms and drivers, roles in rhizosphere ecology and plant stress adaptation, and methodological advances, while highlighting opportunities to harness these processes for resilient, productive, and sustainable agroecosystems.

Climate change imposes significant challenges on vitiviniculture, increasing the need to identify more resilient grapevine varieties. While red grape varieties are known for their high anthocyanin content, other phenolic compounds should also be considered when assessing adaptability to biotic and abiotic stresses. For this, the phenolic composition and antioxidant capacity of 27 red Vitis vinifera L. varieties grown in Portugal were studied across two years. Under warmer and drier conditions, most varieties exhibited higher total phenolic content (TPC) and antioxidant activity, with ‘Donzelinho Tinto’ and ‘Zinfandel’ displaying the most pronounced increases. These varieties also had the highest increases in phenolic acids and flavan-3-ols, highlighting how environmental stress modulates secondary metabolites. Varieties such as ‘Aragonez’, ‘Trincadeira’, ‘Touriga Franca’, and ‘Tinta Francisca’, demonstrated stable profiles, indicating a robust response to climatic fluctuation. Correlation analysis revealed strong associations between TPC and antioxidant capacity, highlighting the importance of phenolics in mitigating oxidative stress. By identifying varieties with enhanced phenolic and antioxidant plasticity, the diversity observed in this work offers valuable insights for future varietal selection aimed at mitigating climate change-induced challenges. Overall, this work reinforces the potential of varietal selection to promote sustainable viticulture in regions increasingly impacted by climatic variability.

Introduction: Climate change is intensifying abiotic stress in viticulture, with higher temperatures, water deficits, and increased solar radiation directly affecting grape berry development, biochemical balance, and overall fruit quality. These challenges compromise the delicate balance of sugars, acids, phenolic compounds, and aromatic profiles that define the sensory attributes and typicity of the resulting wine. Innovative practices are therefore needed to sustain fruit quality and composition under increasingly variable and extreme climatic conditions. Silicon (Si) and kaolin (Kl) have already shown highly positive effects in mitigating the impacts of climate change on grapevines. Methods: Building on this, the aim of this study was to test their combined foliar application to simultaneously alleviate drought and heat stress and enhance berry quality. An integrated assessment was conducted over two growing seasons in a commercial vineyard (Vitis vinifera L. cv. Touriga Franca) located at Quinta de Ventozelo (Douro Demarcated Region, Portugal) to evaluate the effects of combined Kl (2%) and Si foliar sprays at different concentrations (2–8%). The study included analyses of fruit biochemical composition, must quality, cuticular wax profile, histological traits, carbon isotope discrimination (d ¹³ C), hormonal balance, and yield parameters. Results and discussion: Results showed that Si and Kl treatments modulated secondary metabolite accumulation (phenols, flavonoids, anthocyanins, and tannins) in a season- and stage-dependent manner, with significant increases under milder environmental conditions, particularly in seasons with lower heat and drought stress. This suggests that these products can act as elicitors or stress mitigators, depending on the environmental context. Treated vines maintained higher organic acid levels and lower probable alcohol content, indicating an improved sugar–acid balance. Moreover, the treatments influenced the cuticular wax composition, enhancing triterpenoid content and increasing cuticle thickness and epidermal cell size, which, together with enriched d ¹³ C values, support improved water-use efficiency. The hormonal profiles confirmed the role of Si and Kl in fine-tuning stress and growth signals, contributing to better fruit robustness. Conclusions: These findings demonstrate that the combined foliar application of kaolin and silicon is a promising tool to protect grape berry quality by modulating biochemical composition, cuticular wax profile, histological traits, isotopic signature, and hormonal balance, helping maintain fruit integrity and quality, and compositional stability under the ongoing challenges of climate change.