Touriga Nacional Research Articles

Morphological and Cytogenetic Responses of In Vitro-Grown Grapevine (Vitis vinifera L.) Plants from “Touriga Franca”, “Touriga Nacional” and “Viosinho” Varieties Under Water Stress

Morphological and Cytogenetic Responses of In Vitro-Grown Grapevine (Vitis vinifera L.) Plants from “Touriga Franca”, “Touriga Nacional” and “Viosinho” Varieties Under Water Stress

Hail netting changes to spray droplets and patterns in grape canopies

While hail netting in vineyards provides effective protection to wine grapes (Vitis vinifera L.) from hail, pests, and bird damage, it may also affect the spray efficacy. This study tested the interaction between hail netting and location within the canopy in determining spray droplet characteristics. Two grape cultivars (Petite Sirah FPS 04 and Touriga Nacional FPS 05) grafted onto 1103P rootstock were examined to assess spray coverage, droplet size distribution, and deposition within grapevine canopies under netted and unnetted conditions. Spray droplets were measured using spray cards placed at five locations within the canopy. Significant interactions were observed primarily at the base of the canopy directly above the cordon, where grape clusters are most concentrated. Unnetted Touriga Nacional exhibited higher spray coverage compared to Petite Sirah, attributed to its looser cluster structure. Hail netting standardized all parameters across both cultivars, mitigating the influence of canopy and cluster differences. Hail netting created smaller, uniformly distributed droplets within the canopy, an essential characteristic of effective pest and disease control. Conversely, without netting, larger droplets were unevenly distributed, predominantly settling on the outer and lower canopy sections. Hail netting also maintained deposit densities within recommended ranges, supporting effective pest and disease management without compromising spray coverage. The consistent spray coverage achieved with hail netting across all canopy locations highlights its role in improving application uniformity and grapevine health, leading to evenly ripened, high-quality fruit. Contrary to the perceived risk of reducing spray efficacy, hail netting appears to enhance vineyard spraying outcomes, potentially offsetting netting costs.

Selection of Reference Genes and HSP17.9A Expression Profiling in Heat-Stressed Grapevine Varieties

Background: “Touriga Franca” (TF) and “Touriga Nacional” (TN) are grapevine varieties cultivated in the ‘Douro Superior’ subregion (Northern Portugal) that experience stressful environmental conditions during the summer. Objectives: Aiming to profile the expression of stress-responsive genes by quantitative real-time PCR (qPCR) in TF and TN plants growing naturally, three candidate reference genes were first tested under controlled conditions. Methods: To simulate a summer’s day, TF and TN in vitro plants were exposed to 32 °C–3 h (heat acclimation) and 42 °C–1 h (severe heat stress, HS) followed by two recovery periods (32 °C–3 h and 24 °C–24 h). Leaf samples were collected at the end of each phase. Control plants were kept at 24 °C. Results: Among the candidate reference genes, the UBC and VAG pair showed the highest stability. The suitability of these genes for qPCR was validated by heat shock protein 17.9A (HSP17.9A) gene profiling. The HSP17.9A expression was up-regulated in both varieties and all experimental phases except in TF control plants. TN showed the highest HSP17.9A relative expression ratio after severe HS. Conclusions: TN responded faster than TF to the induced heat shocks. The UBC, VAG, and HSP17.9A genes revealed to be suitable for further qPCR assays in TF and TN grapevine varieties.

Wine authenticity throughout the wine-chain: Exploring the potential of HRM-SNP assays in varietal discrimination and quantification in wine blends

Varietal identity is an essential part of wine authentication and should be assessed throughout the winemaking process. DNA markers such SSRs have been applied for grapevine identification but can underperform in wine sample analysis. SNP markers combined with High Resolution Melting represent an alternative approach for wine analysis. Our aim was to develop HRM assays targeting ∼100 bp fragments, applicable for varietal discrimination in must and wine, and evaluate their potential as quantification tool in wine blends. Varieties Cabernet Sauvignon, Donzelinho Tinto, Touriga Franca, Touriga Nacional and Rufete were used. Four SNP markers were selected for HRM assays development. Three assays discriminated the varieties using must samples. Using wine DNA, the results varied but all HRM assays were successful in Touriga Franca and Touriga Nacional samples. Regarding varietal quantification in blends, two HRM assays allowed the discrimination of Touriga Nacional and Touriga Franca monovarietal samples and 90%/10% wine blends.

Study of the fruity aroma of red wines made from grape varieties potentially adapted to climate change using a semi-preparative HPLC method

Under climate change, the fruity aroma of Bordeaux red wines is changing, tending toward undesirable aromas like dried and cooked fruits. To adapt to these changes in aroma, a strategy could be to introduce to Bordeaux vineyards late-ripening grape varieties more suited to drier, sunnier and warmer conditions. A comparative analysis involved traditional Bordeaux red wines (Merlot, Cabernet-Sauvignon, and Cabernet franc) and those from late-ripening grape varieties originating from high-temperature climates (Yiannoudin, Syrah, Agiorgitiko, Xinomavro, Touriga Nacional, Grenache, and Tempranillo). Using a semi-preparative HPLC method, aroma extracts from these ten red wines were fractioned, isolating fruity notes for HPLC–Fruity Aromatic Reconstitutions (FAR). Through a free sorting task, three clusters emerged. Targeted GC-MS analysis highlighted nine compounds characterizing sensory clusters, including ethyl 2-methylpropanoate, ethyl hexanoate, ethyl 6-hydroxyhexanoate, linalool, α-terpineol, α- and β-ionones, hexanol and (Z)-3-hexenol. Through the realization of sensory profiles, it has been demonstrated that by incorporating these compounds into a fruity model solution, fresh red- and black-berry fruit notes are intensified.

Biochemical analysis of three red grapevine varieties during three phenological periods grown under Mediterranean climate conditions.

In Mediterranean regions, severe summers are becoming more common, leading to restrictions to vine productivity and yield quality, requiring sustainable practices to support this sector. We assessed the behaviour of three red grapevine varieties from the Douro Region to examine their tolerance to summer climate stress from the perspective that the less common varieties may have potential for increased use in a climate change scenario. Leaf and fruit biochemical profile, antioxidant activity and fruit colorimetric parameters were assessed at different phenological stages in Aragonez (AR), Tinto Cão (TC) and Touriga Nacional (TN) grape varieties. All three varieties exhibit significant variability in phenological timing, influenced by genetic and environmental factors. Photosynthetic pigment strategies differed among varieties. Chlorophyll content in AR was high to cope with high radiation, while TN displaying a balanced approach, and TC had lower pigment levels, with higher levels of phenolics, antioxidants, and soluble sugars, particularly during stress. The variations in berry biochemical profile highlight the distinct characteristics of the varieties. TC and TN show potential for coping with climate change, having elevated total acidity, while AR has larger and heavier berries with distinct coloration. These findings reinforce the need to study the behaviour of different varieties in each Terroir, to understand their diverse strategies to deal with summer climate stress. This will help in selecting the most suitable variety for these conditions under vineyard management in the Douro Region.

Exploring the Benefits of Nutritional and Chemical Characteristics of Touriga Nacional and Arinto Varieties (Vitis vinifera L.).

Environmental degradation leads to an unsustainable food system. In addition to this issue, the consumption of foods that improve people's health and well-being is recommended. One of the alternatives is undoubtedly the use of by-products of winemaking, namely in the form of grape pomace flour (GPF). To verify the benefits of using the Touriga Nacional and Arinto (Vitis vinifera L.) flour varieties, analytical determinations were made to identify and quantify different components. In terms of nutritional characterization, the Touriga Nacional GPF showed results that indicate better nutritional quality than the Arinto GPF. The Touriga Nacional and Arinto samples had protein contents of 10.13% and 8.38%, polyunsaturated fatty acids of 6.66% and 5.18%, soluble dietary fiber of 14.3% and 1.7%, and insoluble dietary fiber of 55.1% and 46.4%, respectively. The anthocyanins, proanthocyanidins, and flavonols presented in samples were detected by HPLC-DAD/ESI-MS. Atomic absorption spectrometry revealed elevated concentrations of certain elements in Touriga Nacional compared to Arinto, with the former showing higher levels of aluminum (130 mg/kg) and iron (146 mg/kg) against the latter's Al (120 mg/kg) and Fe (112 mg/kg) content. GPF could become a valuable ingredient due to its nutritional quality and high content of various polyphenols.

Metabolic effects of Type 2 Diabetes mellitus might be mitigated by grape pomace flour

Type 2 diabetes mellitus (T2DM) is a multifaceted metabolic disorder characterized by insulin resistance and pancreatic β-cell dysfunction, leading to varying metabolic insults. Grape pomace, a byproduct of the winemaking industry, is under investigation as a potential therapy for T2DM due to its abundant content of bioactive polyphenols and dietary fiber. Within the current backdrop of environmental concerns, the conversion of grape pomace into a safe and applicable form, with the aim of promoting sustainable management of environmental waste, acts as a catalyst for the emergence of viable alternatives. Grape pomace flour (GPF) represents an economical and feasible solution. We hypothesized that dietary supplementation of GPF would improve the glycemic control and the associated risk factors in T2DM-induced animals. In this sense, the present study, approved by CEUA UFPel No 033578/2022-14, aimed to evaluate the effect of the GPF from ‘Arinto’ and ‘Touriga Nacional’ grape varieties on biochemical and histopathological parameters in an animal model of T2DM. To induce T2DM, rats were given a high-fat diet and a Streptozotocin (STZ) injection (35 mg/kg). The rats were divided into five groups: Control (CT), T2DM, T2DM+Metformin (Met) (250 mg/kg), T2DM+'Arinto' GPF 10% (WGPF), and T2DM+'Touriga Nacional' GPF 10% (RGPF). Results showed that Met, WGPF, and RGPF groups had significantly lower blood glucose ( p<0.05, P<0.001, and p<0.01, respectively) and triglyceride levels ( p<0.001) compared to the T2DM group. Also, we observed a significant increase in serum cholesterol levels in the T2DM when compared to the CT ( p<0.01), that was reversed in the treated groups. Additionally, the T2DM+RGPF group had higher levels of high-density lipoprotein (HDL) compared to the control group ( p<0.05). Histopathological analysis revealed structural changes in the pancreas in the T2DM animals, while tissue damage was not observed in the Met and GPF supplementation groups. In conclusion, both 'Arinto' and 'Touriga Nacional' GPF demonstrated protective effects against increased blood glucose, triglycerides, and cholesterol levels in a T2DM animal model. 'Touriga Nacional' GPF also increased HDL levels and showed protective effects on pancreatic cell structure. This suggests that GPF could be a promising dietary option for T2DM and its complications. FCT-Foundation for Science and Technology (UIDB/04567/2020 CBIOS, and UIDP/04567/2020 CBIOS), Pelotas Federal University (UFPel), and Brazil's Federal Government (CNPq). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A comparative physiological study of three red varieties in the Demarcated Douro Region

In certain regions, especially those with a Mediterranean climate, that are highly susceptible to climate change, viticulture is expected to become less suitable for the production of high-quality wines. From an evolutionary perspective, grapevine varieties have evolved genetic adaptations in the form of protective mechanisms to withstand summer stress, reflecting the climatic conditions in which grapevines were initially domesticated. The in-depth knowledge of the structural and functional characteristics of grapevines can aid in the identification and selection of varieties that are better suited to adverse environmental conditions and to the increasingly challenging conditions imposed by climate change. Following, this study aims to evaluate the extent to which the water status adjustment and the leaf biophysical and biochemical processes influence the respective photosynthetic performance of a currently neglected grapevine variety, Tinto Cão (TC) and two commonly used varieties in the Douro region, Touriga-Nacional (TN) and Tinta-Roriz (TR). The experiment was undertaken in the Baixo-Corgo sub-region of the Demarcated Douro Region in the north of Portugal. Grapevine water status, chlorophyll contents, leaf reflectance indices, chlorophyll a fluorescence (modulated and transient) and leaf gas exchange (including A/PPFD and A/Ci curves) were evaluated in three different phenological stages. The results indicate that, compared to TN and TR varieties, the TC minimizes the light-harvesting system while promoting thermal energy dissipation, which can be interpreted as photoprotective mechanisms at the photosynthetic apparatus level. These mechanisms imply the downregulation of the photochemical reactions but without significant losses of net productivity compared to TN, while TR remained increased. Despite the minor expression of Tinto-Cão nowadays, this variety can also have great adaptability for very hot and sunny wine-growing regions.

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.

Impact of aging on the physical-chemical and phenolic stability of tropical red wines from Brazil produced with grapes harvested in the summer season

The São Francisco Valley in the Brazilian Northeast is characterized by the production of tropical wines from grapes obtained from at least two annual harvests. Previous studies showed that wines made with grapes harvested from the second semester (summer season, with high temperatures and solar radiation, as well as low rainfall) presented a shorter shelf-life than those made from grapes harvested in the first semester (winter season). This study aimed to characterize the changes in the chemical composition of three red wines from the summer season, during aging. Wines elaborated with grapes harvested between November and December 2014, with the main red varieties commercially used, were analyzed 12, 24 and 36 months after bottling. Decreases occurred in the concentrations of anthocyanins, flavonols, organic acids, potassium, and condensed tannins, as well as increases in polymerized pigments, hue, turbidity, and calcium. Flavanols and flavonols were associated with Syrah and Touriga Nacional wines, while myricetin was the metabolite considered to be the main indicator of the aging of ‘Alicante Bouschet’ wines. Rootstock vigor was affected by variety. This study showed that the choice of rootstock and variety combination could increase the wine stability after bottling, using grapes harvested from the second semester.

Australian Red Wines Made from Non-Traditional, Emerging Red Grape Varieties: Distinguishing Sensory Profiles and Consumer Perceptions

To sustain the Australian wine sector, it needs to adopt innovative strategies to adapt to rising temperatures brought by climate change. A potential approach is cultivating more drought-resistant emerging grape varieties with diverse flavour profiles to reduce, in part, the current reliance on major varieties. The study aimed to 1) explore sensory profiles of Australian wines made from three emerging red wine grape varieties, 2) determine consumer perceptions and liking of these wines and 3) evaluate whether these three emerging varietal wines display similar sensory characteristics to three major Australian varietal wines. An expert sensory panel (n = 8) performed a sorting task with 38 commercially available Australian wines (10 Montepulciano, 10 Nero d’Avola and 9 Touriga Nacional) and three each produced from Shiraz, Grenache and Cabernet-Sauvignon for exploration of sensory similarity and quality screening purposes, with three wines removed from further study. A Rate-All-That-Apply (RATA) panel of trained wine tasters (n = 36) evaluated the wines to produce sensory profiles and collect preliminary liking. Finally, a subset (n = 9 total) of the emerging wines was selected for consumer trials. Red wine consumers (n = 116) liked all wine samples independent of their knowledge and wine behaviour. Similarity scores indicated that consumers found the most significant similarity between Shiraz and Montepulciano, and Cabernet-Sauvignon and Touriga Nacional wines. The expert and trained tasters also drew similar comparisons between Shiraz and Montepulciano, but also between Grenache and Nero d’Avola wines, yet not towards Cabernet-Sauvignon and Touriga Nacional wines. The findings support the consumer acceptance and perceived similarities between the sensory profile of Shiraz and Montepulciano and Nero d’Avola and Grenache varietal wines, highlighting the potential for producers to adopt these more drought-resistant varieties as alternatives in a warmer future.

Optimization of the Extraction Methodology of Grape Pomace Polyphenols for Food Applications.

This study aims to take advantage of the wine industry by-products and extract bioactive compounds from grape pomace by applying methodologies susceptible to be integrated easily into industrial workflows because of the association with standard instrumentation and facilities, while the main factors affecting the efficiency of the process have been optimized. The sampling consisted of two grape varieties: 'Touriga Nacional' and 'Sousão'. A response surface methodology (RSM) method was used to optimize the extraction conditions based on three independent variables according to the chemical characteristics and stability/lability traits associated with polyphenols; the main bioactive phytochemical in grape pomace: solvent (50%, 70%, and 90% ethanol); temperature (20 °C, 40 °C, and 60 °C); and pH (0.5% HCl, 2% HCl, and 3.5% HCl). The phytochemical profile, as well as the radical scavenging and reducing powers were determined on 27 different samples. The highest yield and antioxidant activity corresponded to extracts obtained at 60 °C using 3.5% HCl and 70% ethanol. The values for total phenols and flavonoids were 44.93 mg of gallic acid equivalents (GAE) and 22.95 mg of catechins equivalents (CE) per gram, respectively. Concerning the evaluation of antioxidant capacity using various assays such as ABTS, DPPH, and FRAP, the results obtained were 0.30, 0.43, and 0.36 mmol of Trolox equivalent antioxidant capacity (TEAC) per gram, correspondingly. The analysis of the extract obtained with the best extraction performance using these parameters via High-Performance Liquid Chromatography-Mass Spectrometry has been also performed, allowing us to identify fourteen (14) compounds, including phenolic acids (n = 3), flavonols (n = 7), and anthocyanins (n = 4). As a result of this process, the best conditions for the production of a natural and environmentally friendly dye, not only avoiding waste but also reusing these by-products, were achieved.

Effect of Grape Pomace Flour in Savory Crackers: Technological, Nutritional and Sensory Properties.

The wine industry generates large amounts of by-products that are usually destined as waste. Grape pomace is the residue of the winemaking process and is rich in compounds with functional properties, such as dietary fiber and phenolic compounds. The aim of this research was to study the influence of white and red grape pomace flour (GPF) addition in the enhancement of functional properties of savory crackers. Different levels of incorporation were tested (5%, 10% and 15% (w/w)). Analysis of physical properties, nutritional composition and sensory acceptability were conducted to evaluate the effect of GPF incorporation. GPF cracker stability throughout a four-week period was achieved with regard to firmness and color. These products presented distinctive and appealing colors, ranging from a violet (GPF of Touriga Nacional variety) to a brown hue (GPF of Arinto variety). Concerning nutritional composition, both crackers incorporated with 10% GPF of Arinto or Touriga Nacional varieties could be considered "high in fiber", as per the Regulation (EC) No. 1924/2006, suggesting a functional food. GPF crackers demonstrated an overall great acceptance of this kind of innovative foods, with the majority indicating that they would certainly/probably buy them. Moreover, the cracker with 10% Arinto GPF achieved the most balanced and overall preference.

Canopy management through crop forcing impacts grapevine cv. ‘Touriga Nacional’ performance, ripening and berry metabolomics profile

Climate changes are speeding up the maturation of grapes in numerous areas of the world, including in the Mediterranean basin, but warmer temperatures often uncouple technical and phenolic maturity, resulting in unbalanced wines. We tested the efficacy of crop forcing (CF) in delaying the maturation of cv. ‘Touriga Nacional’ vines of the Douro Region, and their impacts on plant performance, berry quality attributes and metabolome were also evaluated. In two consecutive seasons (2019 and 2020), CF was conducted 15 (CF1) and 30 (CF2) days after fruit set by hedging growing shoots to five nodes and removing summer laterals, leaves and clusters. Results showed that while CF2 delayed ripening up to 51 days till first autumn rainfall, which compromised optimal sugar ripeness, CF1 delayed the technical maturation by one month, but both treatments severely impacted the production, mainly CF1, which reduced grapevine yield up to 90 %. The effect of CF in protecting vines against drought stress was not evident, judging by the values of leaf pre-dawn water potential measured along both seasons. CF1 and CF2 resulted in berries with lower pH and higher titratable acidity than controls, while total phenolics content increased by up to 48 % in 2020. A UPLC–MS-based targeted metabolomic analysis showed that CF increased the relative abundance of key metabolites like flavan-3-ols (i.e., catechin gallate increased by up to 661 %), trihydroxylated anthocyanins (i.e., delphinidin-3-O-glucoside increased by up to 656 % after CF2) and stilbenes (resveratrol increased by up to 700 % after CF2) with potential positive impacts in wine quality.

Nutracêuticos à base de bagaços de uva portuguesa como potencial aditivo em produtos alimentares

Abstract Portuguese wine industry by-products are often undervalued but constitute a potential source of bioactive phenolic compounds that can be applied as a natural additive in several industries. In this context, the present study aimed to evaluate the nutritional composition, and the phenolic profile of two Portuguese Vitis vinifera L. grape pomaces (Touriga Nacional (red variety) and Alvarinho (white variety), and to correlate their chemical characterizations with their antioxidant activities. Strong correlations were observed between the presence of phenolic compounds and antioxidant activities, which enhances the application of pomace extracts in food and pharmaceutical areas. The high content of total phenolic compounds (25 - 41 g/ kg dry extract) and of flavonoids (9.2 - 18 g/ kg dry extract) found in both samples make these pomaces excellent candidates as food additives in food products, as well as antioxidant agents, such as natural dyes. Some polyphenols were identified by High Performance Liquid Chromatography (HPLC), being rutin and catequin the highest compounds found in red grape pomace (Touriga Nacional) while quercetin was only quantified in white grape pomace (Alvarinho). Cis-resveratrol was quantified in both grape pomace, which opens horizons for its use since this compound has considerable chemopreventive effects in the three main gains of carcinogenesis. As expected, the anthocyanin content was significantly higher in red grape pomace (37 g/ kg dry extract), emphasizing its interest as a natural food additive. Based on the findings, it is possible to conclude that these by-products have additional value, making them potentially useful in the food, pharmaceutical, and cosmetic industries.

Potential Use of Grape Stems and Pomaces from Two Red Grapevine Cultivars as Source of Oligosaccharides

Grape pomace (grape skin and seeds) and stems are major by-products of winemaking, of lignocellulosic nature. The aim of this study was to value grape pomace and stems to produce prebiotic oligosaccharides (OS). Grapes from Touriga Nacional and Marselan cultivars (Vitis vinifera L.) were used for conventional red winemaking. The total of extractives, obtained by sequential extraction with dichloromethane, ethanol, and water, was approx. 64.0% (d.w.) for both pomaces, and 46.2% and 59.5% for Marselan and Touriga Nacional stems, respectively. Lignin contents in Marselan stems (26.4%) and pomace (20.4%) were higher than in Touriga Nacional pomace (19.3%) or stems (17.3%). Polysaccharides (hemicelluloses and cellulose) represented 9 and 8.2% of Marselan and Touriga pomaces, and 22.3 and 18.7% of respective stems. After extractives removal, the pomaces and stems were submitted to a hydrothermal treatment (autohydrolysis) to release oligosaccharides from the hemicellulose fraction. Autohydrolysis was carried out following a central composite rotatable design (CCRD) as a function of temperature (142–198 °C) and time (48–132 min). For all materials of both varieties, the production of sugars by autohydrolysis could be described by second-order models. Highest sugar productions were: 81.2 g/kg (d.w.) extracted Marselan pomace; 76.3 g/kg (d.w.) extracted Touriga Nacional pomace; 116.3 g/kg (d.w.) extracted Marselan stems; and 168.4 g/kg (d.w.) extracted Touriga Nacional stems. Yields of 99% OS were obtained by autohydrolysis at 170 °C/90 min.

Canopy VIS-NIR spectroscopy and self-learning artificial intelligence for a generalised model of predawn leaf water potential in Vitis vinifera

This paper focuses on predicting predawn leaf water potential through a self-learning artificial intelligence (SL-AI) algorithm, a novel spectral processing algorithm that is based on the search for covariance modes, providing a direct relationship between spectral information and plant constituents. The SL-AI algorithm was applied in a dataset containing 847 observations obtained with a handheld hyperspectral spectroradiometer (400–1010 nm), structured as: three grapevine cultivars (Touriga Nacional, Touriga Franca and Tinta Barroca), collected in three years (2014, 2015 and 2017), in two test sites in the renowned Douro Wine Region, northeast of Portugal. The Ψ pd SL-AI quantification was tested both in regressive (R 2 = 0.97, MAPE = 18.30%) and classification (three classes; overall accuracy = 86.27%) approaches, where the radiation absorption spectrum zones of the chlorophylls, xanthophyll and water were identified along the vegetative growth cycle. The dataset was also tested with Artificial Neural Networks with Principal Component Analysis (ANN-PCA) and Partial Least Square (PLS), which presented worse performance when compared to SL-AI in the regressive (ANN-PCA - R 2 = 0.85, MAPE = 43.64%; PLS - R 2 = 0.94, MAPE = 28.76%) and classification (ANN-PCA - overall accuracy: 72.37%; PLS - overall accuracy: 73.79%) approaches. The Ψ pd modelled with SL-AI demonstrated, through hyperspectral reflectance, a cause-effect of the grapevine's hydric status with the absorbance of bands related to chlorophyll, xanthophylls and water. This cause-effect interaction could be explored to identify cultivars and cultural practices, hydric, heating and lighting stresses. • VIS-NIR spectroscopy was used to predict predawn leaf water potential (Ψ pd ). • Benchmark of SL-AI against state-of-the-art chemometrics methods in modelling Ψ pd . • Chlorophyll, xanthophyll, and water absorbance bands related to the Ψ pd . • Cause-effect of plant response to abiotic stresses explained through VIS-NIR bands.

Effect of the Combined Treatments with LC2017 and Trichoderma atroviride Strain I-1237 on Disease Development and Defense Responses in Vines Infected by Lasiodiplodia theobromae

Grapevine trunk diseases constitute one of the major problems for viticulture worldwide, with Botryosphaeria dieback considered as one of the most important of these diseases. In this work, we aimed to (i) evaluate the effect of the combination of two products, Esquive® (a Trichoderma-based product) and LC2017 (a low-copper-based product), in the control of Lasiodiplodia theobromae, by evaluating the internal lesion length caused by inoculation of this pathogen on greenhouse kept grapevines of cvs Cabernet Sauvignon and Touriga Nacional and, (ii) investigating their elicitor effect on plant defense responses, through the analysis of the expression of a set of genes. The pathogen was always re-isolated from the infected tissues and was able to cause wood discoloration. Touriga Nacional exhibited longer lesions than Cabernet Sauvignon, and the application of both products did not appear to reduce lesion length when compared to LC2017 applied alone. The elicitor effect of LC2017 on plant defense was confirmed by gene expression analysis, and no significant differences were found between plants treated with LC2017 and with both products. Moreover, a specific response related to the cultivar was verified, but this apparently unique interaction between product, cultivar and pathogen remains to be further investigated.

Climate change impacts on phenology and ripening of cv. Touriga Nacional in the Dão wine region, Portugal

AbstractThe present study is devoted to climate change impact assessment on the phenological development and ripening of cv. Touriga Nacional in the Dão Wine Region, Portugal. For this purpose, the dates of the three main phenological stages (budbreak, flowering and veraison) and two maturity stages are projected for two future periods (2041–2070 and 2071–2100), under two anthropogenic radiative forcing scenarios (RCP4.5 and RCP8.5), and compared against a baseline period (1991–2020). The phenological and maturity stages are simulated using phenological development models (PDMs) and a temperature‐based ripeness model (TRM), respectively. An overall advancement in both phenology and ripening stages are identified under future warmer climates, though site‐dependent. Furthermore, the advancements in phenology are more pronounced (a) for stages between the beginning of veraison and end of ripening than for the earlier stages, (b) for the long‐term future period (2071–2100) under RCP8.5 and (c) for the vineyard site “Viseu.” These changes are due to the combination of budbreak advancement with a shortening of some phenophases. The strongest shortening is found in the ripening period, while no significant changes in flowering timings and duration of the berry development period are projected. The advancement and the shortening of the grapevine growing season will shift ripening to the warmest part of the year. This twofold climate change impact of the air temperature on ripening may affect the sugar and organic acid balance, as well as the colour of the must. The current findings can be used by the regional winemaking sector in planning and implementing suitable climate change adaptation to enhance its climate resiliency and sustainability. Subsequent studies for this wine region should be carried out to assess the climate change impacts on late frost risk, on climatic viticultural zoning, on yield and berry quality at harvest.