Effect of viticultural practices on grapevine characteristics associated with the quality of wines from Xinomavro variety (Vitis vinifera L.)

The Greek winegrape variety ‘Xinomavro’ is late ripening, vigorous and productive, while the resulting wines are characterized by reduced color, high acidity and astringency due to the increased content of tannins in the skins and seeds. The final organoleptic characteristics of Xinomavro wines are decisively influenced by the growing conditions and the applied agronomic practices. In order to investigate the response of the 'Xinomavro' variety to the most important cultivation practices, four independent experiments were set up: irrigation at different developmental stages of the annual vine cycle, defoliation in the fruiting zone at different stages of the annual cycle, modification of pruning length and bud load and, finally, the use of rootstocks of different vigor. Irrigation application time had a significant effect on all parameters of water relations and physiology. The reduced values of photosynthetic parameters and water potential in non-irrigated plants were accompanied by the reduction of shoot growth and the creation of more favorable conditions for the accumulation of sugars and anthocyanins in berries. On the contrary, continuous irrigation was associated with increased vigour and production and decreased color stability. Irrigation at the end of the ripening period increased production only slightly, compared to non-irrigated plants, without a significant reduction in grape sugar and anthocyanins. The application time of defoliation affected the growth, yield and the characteristics of the grapes, due to changes in the microclimate of the grapes as well as in the distribution of the photosynthates within the plant. Early defoliation (berry set) reduced leaf area and production, while defoliation at veraison did not have a significant effect on growth and yield components compared to the control (without defoliation). Both application times modified grape microclimate, increasing the accumulation of sugar and phenolic components in the berries, with a higher percentage of the more stable forms of anthocyanins. In addition, early leaf removal had a significant effect on berry anatomical properties (higher skin / flesh ratio) which suggests that early leaf removal is a very effective viticultural technique for the production of rich red wines but also in preventing fungal infections. On the contrary, defoliation at veraison is a practice with milder effects on both vine production and berry chemical components. The modification of bud load and pruning length proved to be extremely effective in controlling the size of leaf area and yield. Doubling the load on canes was associated with fewer buds / vine as well as lower grape weight. In contrast, the increase in load on spurs led to a large growth of the secondary leaf area leading to the creation of a dense foliage with greater shading. Microclimate modification altered the skin/flesh ratio and the concentration of phenolic compounds in berries. Finally, in terms of rootstock selection, the use of rootstocks of lower vigour (101-14 MGt and 3309 C) conferred lower growth and yield potential to the scion variety, improving the quality characteristics of grapes through the mediation of water conditions and canopy microclimate.Η οινοποιήσιμη ποικιλία αμπέλου ‘Ξινόμαυρο’ είναι όψιμη, ζωηρή και παραγωγική, ενώ οι οίνοι που προκύπτουν χαρακτηρίζονται από μειωμένο χρωματισμό, υψηλή οξύτητα και στυπτικότητα λόγω αυξημένης περιεκτικότητας των ταννινών σε φλοιούς και γίγαρτα. Οι τελικοί οργανοληπτικοί χαρακτήρες των οίνων του Ξινόμαυρου επηρεάζονται καθοριστικά από τις συνθήκες καλλιέργειας και τις εφαρμοζόμενες πρακτικές. Προκειμένου να διερευνηθεί η απόκριση της ποικιλίας ‘Ξινόμαυρο’ στις πιο σημαντικές από τις καλλιεργητικές επεμβάσεις, εγκαταστάθηκαν τέσσερις ανεξάρτητοι μεταξύ τους πειραματισμοί: άρδευση σε διαφορετικά αναπτυξιακά στάδια του ετήσιου κύκλου της αμπέλου, ξεφύλλισμα σε διαφορετικά στάδια του ετήσιου κύκλου της αμπέλου, ύψος και κατανομή του φορτίου κατά το χειμερινό κλάδεμα και χρήση υποκειμένου διαφορετικής ζωηρότητας. Ο χρόνος εφαρμογής της άρδευσης είχε σημαντική επίδραση σε όλες τις παραμέτρους των υδατικών σχέσεων και της φυσιολογίας. Οι μειωμένες τιμές των φωτοσυνθετικών παραμέτρων και του υδατικού δυναμικού στα μη αρδευόμενα φυτά συνοδεύτηκαν από τη μείωση της βλαστικής ανάπτυξης και τη διαμόρφωση ευνοϊκότερων συνθηκών για την συσσώρευση σακχάρων και ανθοκυανινών στην ράγα. Αντίθετα η συνεχής άρδευση συνδέθηκε με αύξηση της ζωηρότητας και παραγωγής και μείωση της σταθερότητας του χρώματος. Η άρδευση στο τέλος της περιόδου ωρίμανσης αύξησε την παραγωγή, σε σύγκριση με τα μη αρδευόμενα πρέμνα, χωρίς σημαντική μείωση των σακχάρων και των ανθοκυανινών στις ράγες. Ο χρόνος εφαρμογής του ξεφυλλίσματος επηρέασε την αύξηση, την παραγωγή και τα χαρακτηριστικά της σταφυλής, εξαιτίας αλλαγών στο μικροκλίμα των σταφυλιών όσο και στην κατανομή των προϊόντων της φωτοσύνθεσης στο πρέμνο. Το πρώιμο ξεφύλλισμα (καρπόδεση) περιόρισε την φυλλική επιφάνεια και την παραγωγή, ενώ το ξεφύλλισμα στον περκασμό δεν είχε σημαντική επίδραση στη βλαστική αύξηση του πρέμνου και στην παραγωγή σε σχέση με το μάρτυρα (χωρίς ξεφύλλισμα). Και οι δύο χρόνοι εφαρμογής διαφοροποίησαν το μικροκλίμα στο περιβάλλον των σταφυλιών αυξάνοντας τη συσσώρευση σακχάρων και φαινολικών συστατικών στις ράγες με μεγαλύτερη ποσοστιαία αναλογία των σταθερότερων μορφών ανθοκυανινών. Επιπλέον, το πρώιμο ξεφύλλισμα είχε σημαντική επίδραση στα ανατομικά χαρακτηριστικά της ράγας (μεγαλύτερη αναλογία φλοιού/σάρκας) γεγονός που επιτρέπει την πρόταση του πρώιμου ξεφυλλίσματος ως μιας τεχνικής καλλιέργειας της αμπέλου ιδιαίτερα αποτελεσματικής στην παραγωγή πλούσιων ερυθρών οίνων αλλά και στην πρόληψη μυκητολογικών προσβολών. Αντίθετα, το ξεφύλλισμα στο περκασμό θα μπορούσε να αποτελέσει μια πρακτική με ηπιότερες επιδράσεις τόσο στην παραγωγή όσο και στα χημικά συστατικά της ράγας. Η τροποποίηση του φορτίου στο κλάδεμα αποδείχθηκε εξαιρετικά αποτελεσματική στον έλεγχο της αύξησης της φυλλικής επιφάνειας και των σταφυλιών. Ο διπλασιασμός του φορτίου σε κλάδεμα αμολυτής συνδέθηκε με λιγότερους οφθαλμούς/πρέμνο, όσο και από μικρότερο βάρος σταφυλής. Αντίθετα, η αύξηση του φορτίου σε κλάδεμα βραχύ οδήγησε σε μεγάλη ανάπτυξη της δευτερεύουσας φυλλικής επιφάνειας οδηγώντας στη δημιουργία ενός πυκνού φυλλώματος με μεγαλύτερη σκίαση. Η τροποποίηση του μικροκλίματος οδήγησε σε αύξηση της συμμετοχής φλοιών και γιγάρτων στη ράγα στις μεταχειρίσεις αμολυτής και μεγαλύτερη συγκέντρωση φαινολικών ενώσεων. Τέλος, σε ό,τι αφορά την επιλογή υποκειμένου, τα υποκείμενα μικρότερης ευρωστίας (101-14 MGt και 3309 C) προσέδωσαν μικρότερη ζωηρότητα και παραγωγή ενώ βελτίωσαν τα ποιοτικά χαρακτηριστικά των σταφυλιών μέσα από τη διαμόρφωση περισσότερο ελλειμματικών υδατικών συνθηκών και πιο «ανοικτού» μικροκλίματος στο περιβάλλον των σταφυλιών

Effects of Chromium Toxicity on Physiological Performance and Nutrient Uptake in Two Grapevine Cultivars (Vitis vinifera L.) Growing on Own Roots or Grafted onto Different Rootstocks

Chromium toxicity is considered within the most severe and dangerous nutritional disorders, and it can often be observed in crops grown in industrial areas. The present study aims to determine the effects of Cr(VI) toxicity on the growth, nutrition, and physiological performance of grapevines. In a pot hydroponic experiment, own-rooted Merlot and Cabernet Franc grapevine cultivars or cultivars grafted onto 1103P and 101-14 Mgt rootstocks were exposed to 120 μM Cr(VI). Leaf interveinal chlorosis appeared after forty-five days of treatment. Overall leaf chlorosis and brown root coloration after sixty days was reported. A significant effect on the majority of the measured parameters due to the Cr(VI) treatment was observed. Chromium stress increased the total Cr concentrations in all parts of the vines, i.e., leaves, shoots, roots, and trunks. When comparing between the studied plant sections, the roots presented the highest Cr concentrations, ranging from 396 to 868 mg kg−1 d. w., and then, in descending order, the Cr concentrations ranged from 41 to 102 mg kg−1 d. w. in the trunks, from 2.0 to 3.3 mg kg−1 d. w. in the leaves, and from 1.9 to 3.0 mg kg−1 d. w. in the shoots. Between the assessed rootstocks, 1103P was identified to be a better excluder of Cr concentration in the roots and other aerial parts of the vines. Additionally, chromium toxicity negatively affected the concentrations and compartmentalization of the most important nutrients. Leaf chlorophyll (Chl) concentration decreased down to approximately 53% after sixty days of Cr stress. Chromium toxicity significantly reduced the stem water potential (SWP), net CO2 assimilation rate (A), stomatal conductance (gs), and PSII maximum quantum yield in all the cases of grafted or own-rooted vines. At this stage, chromium stress increased the leaf total phenolic content from 46.14% in Merlot vines to 75.91% in Cabernet Franc vines

Assessment of Laser Scanner Use under Different Settings in Two Differently Managed Vineyards for Estimating Pruning Wood Parameters

Precision viticulture employs various sensors for assessing nondestructively key parameters in vineyards. One of the most promising technologies for this purpose is the laser scanner sensor. Laser scanner uses the LiDAR (Light Detection And Ranging) method for the calculation of the distance from the sensor. However, the number of cultivation operations affects the credibility of sensors such as the laser scanner. The main aim of this study was to assess a laser scanner sensor at different measurement settings for estimating pruning wood parameters on two wine grape cultivars (Sauvignon Blanc and Syrah) that received different numbers of farming interventions. The experiment was conducted in the two vineyards situated in the same farm for two successive years (2014 and 2015). The results indicated that the use of a laser scanner in the Syrah vineyard presented more accurate results (r = 0.966 in 2014 and r = 0.806 in 2015) when compared to the Sauvignon Blanc one (r = 0.839 in 2014 and r = 0.607 in 2015) regarding pruning wood parameters estimation. Different measurement settings and weather conditions had different effects on the accuracy of the sensor. It can be concluded that the laser scanner is a very helpful sensor for estimating pruning wood parameters in vineyards

Row Orientation and Defoliation Effects on Grape Composition of

Vineyard row orientation and canopy side exert a significant role in determining grape microclimate. The latter can be further manipulated by selective defoliation in the bunch zone. The aim of this study was to investigate the combined effects of row orientation and basal leaf removal on grape ripening of Vitis vinifera L. cv. Agiorgitiko in Nemea, Southern Greece. The experiment was conducted in 2017, on two adjacent vineyard blocks planted in 1990 on a flat site with two row orientations, North-South and East-West. Both blocks were grafted onto 41B rootstock and trained on a double cordon vertical trellis with uniform vineyard operations. Defoliation treatments included full leaf removal in the bunch zone performed at berry set and a non defoliated control, replicated three times in both blocks. Grapes were sampled at three time points from veraison to harvest from all canopy sides (i.e. E and W on North-South oriented rows and N and S on East-West oriented rows) and defoliation treatments and were analyzed for yield components and berry chemical composition. In addition, approximately 5 kg of grapes were collected from all plots and processed according to a standard winemaking protocol. Total yield and berry mass were lowest in the W-exposed and in the defoliated grapes. Must sugar and acid content, as well as wine alcohol and acidity did not depend on either factor. Skin anthocyanins and phenolics generally increased with defoliation. Skin anthocyanins and total berry phenolics were highest for north-south oriented rows, in the grapes of the cooler canopy side (E). Wines made from grapes of the E and W canopy sides showed the highest wine color, phenolic richness and the lowest pH. No interaction between row orientation and defoliation was detected for any of the measured parameters. According to the results, the E-facing grapes on the north-south oriented rows showed generally a superior grape and wine composition for Agiorgitiko variety, under the semiarid conditions of the Nemea area

Assessment of Laser Scanner Use under Different Settings in Two Differently Managed Vineyards for Estimating Pruning Wood Parameters

Precision viticulture employs various sensors for assessing nondestructively key parameters in vineyards. One of the most promising technologies for this purpose is the laser scanner sensor. Laser scanner uses the LiDAR (Light Detection And Ranging) method for the calculation of the distance from the sensor. However, the number of cultivation operations affects the credibility of sensors such as the laser scanner. The main aim of this study was to assess a laser scanner sensor at different measurement settings for estimating pruning wood parameters on two wine grape cultivars (Sauvignon Blanc and Syrah) that received different numbers of farming interventions. The experiment was conducted in the two vineyards situated in the same farm for two successive years (2014 and 2015). The results indicated that the use of a laser scanner in the Syrah vineyard presented more accurate results (r = 0.966 in 2014 and r = 0.806 in 2015) when compared to the Sauvignon Blanc one (r = 0.839 in 2014 and r = 0.607 in 2015) regarding pruning wood parameters estimation. Different measurement settings and weather conditions had different effects on the accuracy of the sensor. It can be concluded that the laser scanner is a very helpful sensor for estimating pruning wood parameters in vineyards

Leaf removal and deficit irrigation have diverse outcomes on composition and gene expression during berry development of <i>Vitis vinifera</i> L. cultivar Xinomavro

The quality characteristics of a certain grapevine cultivar are determined by the combinatorial action of the genotype and environmental factors, such as soil, landscape and climate. Another critical parameter is the viticultural techniques utilised to improve grape berry quality. The influence of two viticultural practices, deficit irrigation and leaf removal, on the Greek Vitis vinifera L. cultivar ‘Xinomavro’ was investigated during the 2019 and 2020 vintages. Physiology measurements and berry sampling were performed at three phenological stages (green berry, veraison and harvest). The expression of specific genes known to control grape colour, aroma and flavour was studied in conjunction with berry growth and composition. All the parameters contributing to final yield, such as berry size, cluster weight and yield/vine, were reduced in non-irrigated and defoliated vines compared to their control (irrigated and non-defoliated) vines. Both treatments showed a significant increase in anthocyanin level, whereas total phenols increased in the deficit irrigation treatment only. Water deficit had no effect on total soluble solids, whereas leaf removal resulted in significantly increased levels compared to the controls. The expression profile of the genes examined was altered during ripening. Although both water deficit and defoliation positively influenced gene expression, there were several diverse responses among the phenological stages that depended on the vintage

Row Orientation and Defoliation Effects on Grape Composition of Vitis vinifera L. Agiorgitiko in Nemea (Greece)

Vineyard row orientation and canopy side exert a significant role in determining grape microclimate. The latter can be further manipulated by selective defoliation in the bunch zone. The aim of this study was to investigate the combined effects of row orientation and basal leaf removal on grape ripening of Vitis vinifera L. cv. Agiorgitiko in Nemea, Southern Greece. The experiment was conducted in 2017, on two adjacent vineyard blocks planted in 1990 on a flat site with two row orientations, North-South and East-West. Both blocks were grafted onto 41B rootstock and trained on a double cordon vertical trellis with uniform vineyard operations. Defoliation treatments included full leaf removal in the bunch zone performed at berry set and a non defoliated control, replicated three times in both blocks. Grapes were sampled at three time points from veraison to harvest from all canopy sides (i.e. E and W on North-South oriented rows and N and S on East-West oriented rows) and defoliation treatments and were analyzed for yield components and berry chemical composition. In addition, approximately 5 kg of grapes were collected from all plots and processed according to a standard winemaking protocol. Total yield and berry mass were lowest in the W-exposed and in the defoliated grapes. Must sugar and acid content, as well as wine alcohol and acidity did not depend on either factor. Skin anthocyanins and phenolics generally increased with defoliation. Skin anthocyanins and total berry phenolics were highest for north-south oriented rows, in the grapes of the cooler canopy side (E). Wines made from grapes of the E and W canopy sides showed the highest wine color, phenolic richness and the lowest pH. No interaction between row orientation and defoliation was detected for any of the measured parameters. According to the results, the E-facing grapes on the north-south oriented rows showed generally a superior grape and wine composition for Agiorgitiko variety, under the semiarid conditions of the Nemea area

Grape Maturity Estimation for Personalized Agrobot Harvest by Fuzzy Lattice Reasoning (FLR) on an Ontology of Constraints

Sustainable agricultural production, under the current world population explosion, calls for agricultural robot operations that are personalized, i.e., locally adjusted, rather than en masse. This work proposes implementing such operations based on logic in order to ensure that a reasonable operation is applied locally. In particular, the interest here is in grape harvesting, where a binary decision has to be taken regarding the maturity of a grape in order to harvest it or not. A Boolean lattice ontology of inequalities is considered regarding three grape maturity indices. Then, the established fuzzy lattice reasoning (FLR) is applied by the FLRule method. Comparative experimental results on real-world data demonstrate a good maturity prediction. Other advantages of the proposed method include being parametrically tunable, as well as exhibiting explainable decision-making with either crisp or ambiguous input measurements. New mathematical results are also presented

Greek Wine Quality Assessment and Relationships with Climate: Trends, Future Projections and Uncertainties

Grapevine phenology is particularly sensitive to temperature variations, with changes in climate shifting events earlier and advancing berry maturation into a hotter part of the growing cycle. Consequently, serious concerns regarding the negative influences of climate change on global wine quality have been raised, with the scientific community focusing on documenting these changes to better understand and address the impacts. This study adds to this knowledge by investigating air temperature and precipitation trends over the last 40 years (i.e., 1980–2019). Over the most recent period of records (i.e., 2000–2019), minimum air temperatures significantly increased at a higher rate than maximum temperatures. On the other hand, precipitation showed the least significant trends over time. In addition, wine quality assessment and identification of the most significant weather variables and climatic indices that correlate with wine quality rating scores have also been performed. To serve this purpose, data of wine quality ratings for nine white (W) and two red (R) indigenous winegrape varieties (Vitis vinifera L., cvs) grown in Greece were obtained from the database of Thessaloniki International Wine and Spirits Competition. The results showed a statistically significant upward trend over the recent past in the majority of the varieties studied. To examine future periods, mixed-effect model outputs for Greek wine-producing regions combining an ensemble dataset using RCP4.5 and RCP8.5 emission pathways during two future periods (i.e., 2041–2065 and 2071–2095) predicts wines of higher quality, especially during the latter time period. These results reveal that Greek wine quality rating variations are mainly driven by higher maximum temperatures and drier conditions during the growing season of the grapevines. However, two important issues need to be more fully explored in Greece and elsewhere; (1) non-linear responses to warming where wine quality could suffer above varietally specific optimum temperature thresholds and (2) a better understanding of how other non-climate-related factors (e.g., canopy management, winemaking innovations) affect wine quality in the face of a changing climate

An Optimized HPLC-DAD Methodology for the Determination of Anthocyanins in Grape Skins of Red Greek Winegrape Cultivars (Vitis vinifera L.)

A rapid and simple HPLC-DAD analytical method was developed and optimized for the determination of anthocynanins in three red Greek winegrape varieties (Kotsifali, Limnio, and Vradiano). The critical parameters, such as the acidifying solvent and the extraction temperature, which affect the extraction of anthocyanins from the grapes, were studied to find the optimum values. The developed methodology was validated in terms of selectivity, linearity, accuracy, and precision and presented satisfactory results. The limits of quantification (LOQs) ranged between 0.20 mg/kg to 0.60 mg/kg, and the limits of detection (LODs) ranged between 0.06 mg/kg and 0.12 mg/kg. The RSD% of the within-day and between-day assays were lower than 6.2% and 8.5%, respectively, showing adequate precision. The accuracy ranged between 91.6 and 119% for within-day assay and between 89.9 and 123% for between-day assay. Sixteen samples from the main regions of each variety as well as from the official ampelographic collections of Greece were collected during the 2020 growing season and were further analyzed by HPLC-DAD. Notable differences in the anthocyanin content were detected among the cultivars using hierarchical cluster analysis (HCA)