Berry Growth Research Articles

Efficacy of methyl anthranilate vapour against Botrytis cinerea in packaged strawberries

The efficacy of methyl anthranilate (MA) vapour in extending the postharvest shelf-life of fresh strawberries has been studied. For that, fruit inoculated with Botrytis cinerea was packaged in vented polypropylene (PP) clamshells and exposed to MA vapour released from a cellulose paper disc impregnated with the liquid compound and placed in the lid of the package. Fruit was stored for 12 days at 4 °C, and fungal growth of berries were monitored throughout storage. The level of fungal infection was significantly reduced in fruit treated with MA vapour. Moreover, packaged fruit with MA vapour that had not been previously inoculated maintained certain quality parameters such as colour and firmness better than control samples. Overall, MA vapour extended the shelf-life of strawberries from 6 to 9 days without causing phytotoxic effects on fruit tissue. MA was absorbed by the fruit but did not surpass the “no observed adverse effect level” (NOAEL). The maximum value of MA in fruit was reached at the end of the storage with a value of 34 µg g−1. Thus, MA presents potential as an antimicrobial volatile for the preservation of packaged strawberries.

Acumulación y degradación de solutos en bayas Vitis vinifera L. en climas contrastantes

Grape ripening is a complex process conditioned by climatic factors, which influence the evolution of solutes and define its composition. The objective of the study was to evaluate the behavior of the red Tannat variety in contracting climatic situations, considering the dynamics of berry growth, the rate of accumulation and reduction of solutes during ripening, and their composition at harvest. The trial was installed in two regions, warm and temperate climate, in rainfed commercial vineyards, during 2018 and 2019. Primary berry composition at ripening and secondary composition at harvest were determined. Multivariate analysis and comparison of means (Fisher’s LSD test) were performed. The climatic type (region) conditions the evolution of solutes at ripening, but their interaction with annual conditions determines berry composition. The annual variability is explained by rainfall, with a direct influence on the duration of the cycle and the ripening, size, and composition of the berry. In warm climates, there is greater sensitivity to the ripening year effect, with a strong influence on the rapid phase. In temperate climates, the greater stability between years results from a thermal condition more favorable to ripening processes.

Effects of GA3 Treatments on Fruit Vascular Structure and Water Transport of Grape

ABSTRACT Exogenous gibberellic acid was applied to regulate fruit growth of grapes to acquire high quality seedless berries. The vascular bundles provide the pathway of water and nutrient transport into the fruit and play an important role in berry growth and sugar accumulation. Therefore, changes in berry size and quality are closely related to the structure and function of the vascular tissue. In this study, 10-year-old “Shine Muscat” grape vines were treated with GA3 in grapevine production. Based on previous research and experimental environmental conditions, four treatments were applied: elongating cluster（5 mg L−1 GA3 on Apr. 28）+ seedless（25 mg L−1 GA3 on May. 24）+ expanding（50 mg L−1 GA3 on Jun. 7） (T1), seedless（25 mg L−1 GA3 on May. 24）+ expanding（50 mg L−1 GA3 on Jun. 7） (T2), expanding（50 mg L−1 GA3 on Jun. 7） (T3) and water (CK). Compared to CK, all fruits treated with GA3 had greater berry size. In addition, GA3 treated grapes had greater vascular bundle areas, including the areas of both phloem and xylem, as well as a greater number of vessels compared to control fruit. During the first rapid growth stage, water transport into the grape was rapid and did not differ among treatments. During veraison, the water transport rate among the four treatments differed, and the rank of speed was T2>T3>CK>T1. Therefore, we found that GA3 treatment can significantly promote the differentiation of vascular tissues and improve water transport capacity and phloem sugar unloading; T2 promoted the development of vascular bundles, enhanced water transport speed and phloem sugar unloading of fruit after veraison, and increased berry size.

The Quality of Grapes of the Moldova Variety According to the Foliar Fertilization System in the Phenophase of the Berry Growth

The fertilization of the vineyards is an important and sometimes decisive technological process in the production technology of table grapes. Knowing the nutritional needs of the grapevine in different phenophases ensures obtaining homogeneous, quantitative and qualitative harvests, but also increases the plants' resistance to adverse environmental conditions. The aim consists in the analysis of the quality indices of the Moldova table grape variety, following the application of Ca treatments, in the phenophase of berry growth. In the research, different variants of application of treatments with Ca (Calcinite) were studied, with 1-4 treatments, in different periods. Observations, measurements and determinations were carried out in the field, as well as chemical laboratory analyzes according to the methods approved in viticulture. The growth of the berries on the vine begins a few days after flowering and lasts until the grapes enter the field. Following the study, a positive influence of calcium treatments on grain firmness was observed in the variants with the highest number of foliar applications. The use of individual or combined calcium fertilization of the Moldova variety in the production conditions with 1-4 post-fertilization treatments, depending on the conditions of the year, positively influenced the quality of the harvest.

Genotyping-by-sequencing-based high-resolution mapping reveals a single candidate gene for the grapevine veraison locus Ver1.

Veraison marks the transition from berry growth to berry ripening and is a crucial phenological stage in grapevine (Vitis vinifera): the berries become soft and begin to accumulate sugars, aromatic substances, and, in red cultivars, anthocyanins for pigmentation, while the organic acid levels begin to decrease. These changes determine the potential quality of wine. However, rising global temperatures lead to earlier flowering and ripening, which strongly influence wine quality. Here, we combined genotyping-by-sequencing with a bioinformatics pipeline on ∼150 F1 genotypes derived from a cross between the early ripening variety "Calardis Musqué" and the late-ripening variety "Villard Blanc". Starting from 20,410 haplotype-based markers, we generated a high-density genetic map and performed a quantitative trait locus analysis based on phenotypic datasets evaluated over 20 yrs. Through locus-specific marker enrichment and recombinant screening of ∼1,000 additional genotypes, we refined the originally postulated 5-mb veraison locus, Ver1, on chromosome 16 to only 112 kb, allowing us to pinpoint the ethylene response factor VviERF027 (VCost.v3 gene ID: Vitvi16g00942, CRIBIv1 gene ID: VIT_16s0100g00400) as veraison candidate gene. Furthermore, the early veraison allele could be traced back to a clonal "Pinot" variant first mentioned in the seventeenth century. "Pinot Precoce Noir" passed this allele over "Madeleine Royale" to the maternal grandparent "Bacchus Weiss" and, ultimately, to the maternal parent "Calardis Musqué". Our findings are crucial for ripening time control, thereby improving wine quality, and for breeding grapevines adjusted to climate change scenarios that have a major impact on agro-ecosystems in altering crop plant phenology.

Improvement in Physiochemical Characteristics of ‘Prime Seedless’ Grapes by Basal Defoliation with Foliar-Sprayed Low-Biuret Urea and Cyanocobalamin under Mediterranean Climate

In viticulture, the main target is to achieve high yield and good fruit quality without compromising vine growth. Methods to achieve this balance will vary with regard to climate and cultivar. A two-year study was conducted on five-year-old ‘Prime Seedless’ grapevines to evaluate the effect of leaf defoliation and the foliar application of low-biuret urea (LBU) and cyanocobalamin (CCA) on berry set percentage, the compactness coefficient of the clusters and the overall quality of clusters and berries. The removal of the first four basal leaves was conducted at the full-bloom (FB) stage, while LBU (5 g·L−1) and CCA (40 mg·L−1) were sprayed at three phenological stages: (1) when the cluster length reached ~10 cm long, (2) at FB and (3) one week after the fruit set. The results demonstrated that the sole application of basal leaf removal (BLR) or in combination with LBU and/or CCA improved the vegetative growth, total yield and physiochemical characteristics of clusters and berries, whereas the same treatments decreased berry set and shot berry percentages and the compactness coefficient of the clusters, which in turn led to looser clusters compared to the control. The most pronounced effect was recorded for the combined application of BLR, LBU and CCA, which revealed the highest values of shoot length, leaf area and the contents of chlorophyll, proline, N, P, K, Ca, Mg, Fe and Zn. The same treatment recorded the lowest berry set and shot berry percentages, compactness coefficient of clusters and decay percentage. Overall, this treatment was the best in terms of total yield, cluster weight, berry firmness, soluble solid content (SSC), the SSC/acid ratio, total sugars, total carotenoids, total phenols, phenylalanine ammonialyase and polyphenol oxidase.

Emerging Roles of Epigenetics in Grapevine and Winegrowing.

Epigenetics refers to dynamic chemical modifications to the genome that can perpetuate gene activity without changes in the DNA sequence. Epigenetic mechanisms play important roles in growth and development. They may also drive plant adaptation to adverse environmental conditions by buffering environmental variation. Grapevine is an important perennial fruit crop cultivated worldwide, but mostly in temperate zones with hot and dry summers. The decrease in rainfall and the rise in temperature due to climate change, along with the expansion of pests and diseases, constitute serious threats to the sustainability of winegrowing. Ongoing research shows that epigenetic modifications are key regulators of important grapevine developmental processes, including berry growth and ripening. Variations in epigenetic modifications driven by genotype-environment interplay may also lead to novel phenotypes in response to environmental cues, a phenomenon called phenotypic plasticity. Here, we summarize the recent advances in the emerging field of grapevine epigenetics. We primarily highlight the impact of epigenetics to grapevine stress responses and acquisition of stress tolerance. We further discuss how epigenetics may affect winegrowing and also shape the quality of wine.

Ripening dynamics revisited: an automated method to track the development of asynchronous berries on time-lapse images

BackgroundGrapevine berries undergo asynchronous growth and ripening dynamics within the same bunch. Due to the lack of efficient methods to perform sequential non-destructive measurements on a representative number of individual berries, the genetic and environmental origins of this heterogeneity, remain nearly unknown. To address these limitations, we propose a method to track the growth and coloration kinetics of individual berries on time-lapse images of grapevine bunches.ResultsFirst, a deep-learning approach is used to detect berries with at least 50 ± 10% of visible contours, and infer the shape they would have in the absence of occlusions. Second, a tracking algorithm was developed to assign a common label to shapes representing the same berry along the time-series. Training and validation of the methods were performed on challenging image datasets acquired in a robotised high-throughput phenotyping platform. Berries were detected on various genotypes with a F1-score of 91.8%, and segmented with a mean absolute error of 4.1% on their area. Tracking allowed to label and retrieve the temporal identity of more than half of the segmented berries, with an accuracy of 98.1%. This method was used to extract individual growth and colour kinetics of various berries from the same bunch, allowing us to propose the first statistically relevant analysis of berry ripening kinetics, with a time resolution lower than one day.ConclusionsWe successfully developed a fully-automated open-source method to detect, segment and track overlapping berries in time-series of grapevine bunch images acquired in laboratory conditions. This makes it possible to quantify fine aspects of individual berry development, and to characterise the asynchrony within the bunch. The interest of such analysis was illustrated here for one cultivar, but the method has the potential to be applied in a high throughput phenotyping context. This opens the way for revisiting the genetic and environmental variations of the ripening dynamics. Such variations could be considered both from the point of view of fruit development and the phenological structure of the population, which would constitute a paradigm shift.

Basal defoliation, salicylic acid and cyanocobalamin to ameliorate the physiological and biochemical characteristics of flood-irrigated ‘Crimson Seedless’ grapevines in a semi-arid Mediterranean climate

ABSTRACT There is a high retail demand for ‘Crimson Seedless’ grape. Cluster shape, berry size, colour, and sugar contents influence the overall fruit quality and marketability. In many commercial vineyards of flood-irrigated clay soils under warm and humid semi-arid climates, adequate irrigation may lead to an enhanced fruit set that could potentially be associated with restricted berry growth, compact clusters, and poor berry colour and taste. To assess the role of some agronomic practices that may influence the canopy microclimate, and affect primary and secondary metabolites, seven treatments arranged in a randomised complete block design (RCBD) system with three replicates each (three vines per replicate) were applied as follow; the control (T1), 5-leaf basal defoliation at pre-bloom (BDPB) (T2), BDPB + foliar spray (FS) of 200 mg · L–1 salicylic acid (SA) (T3), BDPB + FS of 20 mg · L–1 cyanocobalamin (CCA) (T4), 5-leaf basal defoliation at full bloom (BDFB) (T5), BDFP + SA (T6) and BDFB + CCA (T7). Foliar applications were applied at 1) 2 weeks after the beginning of vegetative growth, 2) full bloom and 3) veraison stages. The analysis of variance (ANOVA), the principle component analysis (PCA) and the two-way hierarchical cluster analysis (HCA) indicated that BDPB (T2) generally has a better effect than that of BDFB (T5). The most pronounced effect on vegetative growth (shoot length and leaf area), photosynthesis activity (leaf chlorophyll and carbohydrate contents), fruit weight and dimensions, and total yield was observed in the case of T3, followed by T6, whereas concerning berry firmness, colour (anthocyanins) and sensory characteristics (soluble solids: acids ratio, total sugars and phenols), the most pronounced effect was observed in the case of T4, followed by T7.

Benchmarking Water-Limited Yield Potential and Yield Gaps of Shiraz in the Barossa and Eden Valleys

Background and Aims. Vineyard performance is impacted by water availability including the amount and seasonality of rainfall, evapotranspiration, and irrigation volume. We benchmarked water-limited yield potential (Yw), calculated yield gaps as the difference between Yw and actual yield, and explored the underlying environmental and management causes of these gaps. Methods and Results. The yield and its components in two sections of 24 Shiraz vineyards were monitored during three vintages in the Barossa zone (GI). The frequency distribution of yield was L-shaped, with half the vineyards below 5.2 t·ha−1, and an extended tail of the distribution that reached 24.9 t·ha−1. The seasonal ratio of actual crop evapotranspiration and reference evapotranspiration was below 0.48 in 85% of cases, with a maximum of 0.65, highlighting a substantial water deficit in these vineyards. A boundary function relating actual yield and seasonal rainfall was fitted to quantify Yw. Yield gaps increased with an increasing vine water deficit, as quantified by the carbon isotope composition of the fruit. The yield gap was smaller with higher rainfall before budburst, putatively favouring early-season vegetative growth and allocation to reproduction, and with higher rainfall between flowering and veraison, putatively favouring fruit set and berry growth. The gap was larger with higher rainfall and lower radiation between budburst and flowering. The yield gap increased linearly with vine age between 6 and 33 yr at a rate of 0.3 t·ha−1·yr−1. The correlation between yield gap and yield components ranked bunch weight ≈ berries per bunch > bunch number > berry weight; the minimum to close the yield gap was 185,000 bunches ha−1, 105 g bunch−1, 108 berries bunch−1, and 1.1 g berry−1. Conclusions. Water deficit and vine age were major causes of yield gaps. Irrigation during winter and spring provides an opportunity to improve productivity. The cost of dealing with older, less productive vines needs to be weighed against the rate of increase in yield gap with vine age. Significance of the Study. A boundary function to estimate water-limited yield potential returned viticulturally meaningful yield gaps and highlighted potential targets to improve vineyard productivity.

ВЛИЯНИЕ КОМПЛЕКСНОГО МИНЕРАЛЬНОГО УДОБРЕНИЯ С МИКРОЭЛЕМЕНТАМИ НА ПРОДУКТИВНОСТЬ ВИНОГРАДНЫХ РАСТЕНИЙ

Information is provided on the positive effect of complex fertilizer (NPK) with microelements in chelated form on the productivity of grape-vine plantings of Cabernet Sauvignon variety. Foliar feeding was carried out 2 times during the growing season − in the phase of inflorescence formation and in the phase of berry growth. Feeding plants with an agrochemical in doses of 4.0 and 6.0 l/ha contributed most to the increase in the number of berries in a bunch and their weight, which led to an increase in yield by 24.0...28.4 % compared to the control. With a significant increase in yield in the 6 l/ha option, a decrease in the content of soluble sugars in the berries and an increase in titratable acids were observed compared to the control. Despite the fact that the berry juice conditions in the variant with a dose of 6.0 l/ha did not go beyond the standard for the Cabernet Sauvignon variety, the recommended dose of fertilizer was − 4.0 l/ha.

Cessation of berry growth coincides with leaf complete stomatal closure at pre-veraison for grapevine (Vitis vinifera) subjected to progressive drought stress.

Drought events have devasting impacts on grape berry production. The aim of this study was to investigate berry growth in the context of leaf stomatal closure under progressive drought stress. Potted grapevine plants (varieties 'Syrah' and 'Cabernet Sauvignon') were evaluated at pre-verasion (30-45 d after anthesis, DAA) and post-veraison (90-107 DAA). Berry diameter, berry absolute growth rate (AGR), leaf stomatal conductance (Gs) at midday, plant water potential at predawn and midday (ΨPD and ΨMD, respectively), and soil relative water content were measured repeatedly. The ΨPD-threshold of 90 % loss in stomatal conductance (Gs10, i.e. complete stomatal closure) was determined. Data were related to plant dehydration phases I, II and III with corresponding boundaries Θ1 and Θ2, using the water potential curve method. At pre-veraison, berry AGR declined together with leaf Gs in response to soil drying in both varieties. Berry AGR transitioned from positive to negative (shrinkage) values when leaf Gs approached zero. The Gs10-threshold was -0.81 MPa in 'Syrah' and -0.74 MPa in 'Cabernet Sauvignon' and was linked to boundary Θ1. At post-veraison, berry AGR was negligible and negative AGR values were not intensified by increasing drought stress in either variety. Leaf complete stomatal closure under progressive drought stress coincides with cessation of berry growth followed by shrinkage at pre-veraison (growth stage 1).

EXTREME CLIMATIC PHENOMENA AND THEIR INFLUENCE ON THE STRUCTURE OF WINE GRAPES IN MINIS-MADERAT VINEYARD

The most frequent extreme climatic phenomena in the Minis-Maderat Vineyard are hail and drought. In the last 10 years, the period of extreme drought has increased from 2-3 to over 7 weeks, in the months of June-July-August, when the grapevine has the greatest need for water, in the phenophases of berry growth, bunch compaction and véraison. The mechanical analysis of the grapes for wine grape varieties from Podgoria Miniș-Măderat reveals this aspect in the composition of their structure.

Identifying the best parameters to determine genotype capability to retain adequate malic acid at harvest and in final wines

Maintaining optimal grape acidity at harvest is one of the most complicated challenges under climate change pressures, especially in early ripening cultivars. Warming trends are compressing vine phenology and fostering berry malic acid respiration. In this work, over four years, we evaluated yield components and fruit ripening in two local varieties in the Colli Piacentini, Ortrugo (ORT) and Barbesino (BRB). Our goal was to evaluate their ability to maintain satisfying acidity at harvest and understand the limits and features of the genetic control over organic acid degradation during ripening.The two varieties exhibited comparable yield and grape total soluble solids (TSS) accumulation dynamics, but BRB showed consistently higher acidity during the entire ripening process in any of the four years. BRB's higher acidity was linked to higher malic acid concentrations. ORT had earlier onset of malic acid degradation than BRB and lower maximum malic acid degradation rates. Malic acid degradation rates were lower in ORT also later in the season, until harvest. However, correlations built between malic acid degradation rates and instantaneous malic acid concentration revealed that BRB had a consistently lower malic acid loss for values of malate < 10 g/L.Our work demonstrates that there is a genetic control over the malic acid degradation rates exhibited at varying malic acid concentrations and higher acidity at harvest can be found in varieties exhibiting low malic acid degradation rates when malic acid is < 10 g/L. Post-veraison berry growth rates could interact with genotype effects. The analysis of the correlation can be used at different scales to identify cultivars retaining higher acidity at harvest.

Ultrasonic sensor-based automatic control volume sprayer for pesticides and growth regulators application in vineyards

A study was conducted to design a sensor-based control volume sprayer for vineyard cultivation. The study aimed to develop cluster-specific pesticide and growth regulator application systems with improved penetration and minimum off-target losses, thus saving chemicals and overall cost. For the determination of design values of the control volume unit, physical properties (cluster length, width, and level of compactness) of grape clusters from seventeen major genotypes selected from vineyard research farm ICAR-IARI New Delhi were studied. For the design of the grape cluster detection unit, two different types of sensors, i.e., ultrasonic sensor (HC SR-04) and infrared proximity sensor (B0115NCT4U), were evaluated for their ability to detect the target (grape cluster) and the response time. The design of the spraying unit for the control volume sprayer also involved selecting suitable nozzles and operational parameters. The developed sprayer was evaluated for application of plant growth hormone (Gibberellic acid), and the performance was assessed in terms of droplet size, chemical application per cluster, cluster and berry growth characteristics, sprayer application rate, uniformity coefficient, and application time. The data on the physical properties of grape clusters revealed a maximum cluster length and width of 24.00 ± 0.91 cm and 18.80 ± 0.15 cm, respectively. The ultrasonic sensor had a comparatively higher sensing range, beam angle, and lower price than the infrared sensor. The spray uniformity for the hollow cone and flat fan nozzle varied significantly for the operating pressure range of 2–4.5 kg.cm−2. The developed sprayer consisted of a 3D printed control volume unit, ultrasonic sensor, two flat fan nozzles, microcontroller (Atmega 328P), relay switch, voltage converter, spray tank of 16-liter capacity, and 12 VDC battery. In case of developed sensor-based control volume sprayer, 30% and 35.48% saving in chemical use and application time, respectively, were observed compared to the conventional dipping method. The PGR application method has significant interaction with cluster length and berry growth as the main effect; however, failed to show a significant interaction with cluster width. Maximum cluster growth (16.89 ± 1.72 mm) was observed in PGR application with a developed sprayer.

GrapevineXL reliably predicts multi-annual dynamics of vine water status, berry growth, and sugar accumulation in vineyards.

Climate and water availability greatly affect each season's grape yield and quality. Using models to accurately predict environment impacts on fruit productivity and quality is a huge challenge. We calibrated and validated the functional-structural model, GrapevineXL, with a data set including grapevine seasonal midday stem water potential (Ψxylem), berry dry weight (DW), fresh weight (FW), and sugar concentration per volume ([Sugar]) for a wine grape cultivar (Vitis vinifera cv. Cabernet Franc) in field conditions over 13years in Bordeaux, France. Our results showed that the model could make a fair prediction of seasonal Ψxylem and good-to-excellent predictions of berry DW, FW, [Sugar] and leaf gas exchange responses to predawn and midday leaf water potentials under diverse environmental conditions with 14 key parameters. By running virtual experiments to mimic climate change, an advanced veraison (i.e. the onset of ripening) of 14 and 28days led to significant decreases of berry FW by 2.70% and 3.22%, clear increases of berry [Sugar] by 2.90% and 4.29%, and shortened ripening duration in 8 out of 13 simulated years, respectively. Moreover, the impact of the advanced veraison varied with seasonal patterns of climate and soil water availability. Overall, the results showed that the GrapevineXL model can predict plant water use and berry growth in field conditions and could serve as a valuable tool for designing sustainable vineyard management strategies to cope with climate change.

ВЛИЯНИЕ РАЗЛИЧНЫХ ВИДОВ УДОБРЕНИЯ НА УРОЖАЙНОСТЬ И КАЧЕСТВЕННЫЕ ПОКАЗАТЕЛИ ВИНОГРАДА И ВИНА СОРТА ШАРДОНЕ

The research was carried out in order to study the effect of various foliar fertilizers on the productivity of grapes, the quality of the must and the taste characteristics of wine products. The work was carried out in 2019-2021 in Anapo-Taman climatic subzone of Krasnodar Territory. The scheme of the experiment included the following options: without fertilizers (spraying with water) - control; Gumel lux 0.1 kg/ha; Filloton 1.0 l/ha; Agrumax 1.5 l/ha. Spraying was carried out three times in the following phases: “loosening of inflorescences”, after the end of flowering and in the “growth of berries” phase. Objects of study: Chardonnay grapes, its must and wine material. The bushes were formed according to the two-armed Kazenava cordon system, the planting scheme was 3.0 m × 1.5 m. The soil of the experimental plot was soddy-calcareous, powerful, low-humus, light-clay granulometric composition, formed on tertiary saline clays. Fertility is below average. The supply of nitrate nitrogen and mobile phosphorus is low, and that of potassium is high. The treatment of Chardonnay grapes with the studied preparations had a different effect on its productivity and the technological qualities of the must. The highest yield was noted in the variants treated with Agrumax and Gumel Lux fertilizers - 9.83 and 9.50 kg/plant. The excess of their productivity over the control was statistically significant and amounted to 3.13 and 2.80 kg/plant, respectively, with an HSR05 of 2.7 kg/plant. The effect of the drug Filloton on the yield of grapes was much weaker and manifested itself only in the form of a trend. Treatment with organomineral fertilizer Gumel lux contributed to an increase in the sugar content of the juice by 10.4% and the preservation in the must of the acidity optimal for dry white wines - 7.0 g/dm3. Wine materials in the variants with the use of Phylloton and Gumel Lux fertilizers were the most extractive in the experiment, which was reflected in their taste qualities, which received estimates of 7.82 and 7.73 points, respectively. According to the ratio of yield/quality of wine material, foliar top dressing with Gumel Lux provided optimal results.

Physiological and biochemical features of the grape leaf in connection with adaptation to drought and high temperatures

The issues of grape resistance to drought have acquired particular importance due to the decrease in precipitation during the phenophase of growth and ripening of berries, which reduces their quality and yield. The purpose of these studies was to evaluate grape varieties of various ecological and geographical origin to drought and elevated temperatures according to physiological and biochemical parameters, to identify varieties with high adaptive resistance for cultivation in the conditions of the Anapo-Taman zone of the Krasnodar Krai and use in breeding. The objects of research are grape varieties (interspecific hybrids): European-American origin – Dostoyny, Krasnostop AZOS, Vostorg; Western European – Aligote; Eastern European – Zarif. The control was the Crystal variety of Euro-Amur-American origin. The article presents the results of studying the hydration of leaf tissues, the content of photosynthetic pigments and proline in leaves during the summer growing season 2020-2022. It was found that by the end of summer, the water content of the leaves decreased to the least degree in the varieties Kristall, Krasnostop AZOS, Vostorg, Zarif, in comparison with the varieties Dostoyny and Aligote, in which a decrease was noted by 4.70-4.88 %. Due to the increase in the proportion of carotenoids that perform a photoprotective function in the varieties Crystal, Krasnostop AZOS, Vostorg, Zarif, the lowest values of the chlorophylls/carotenoids ratio (2.8-3.4) were found, indicating their high adaptive ability to drought and elevated temperatures.In contrast to them, the ratio of chlorophylls/carotenoids in the varieties Dostoyny and Aligote was 4.1-4.2, indicating their low adaptive resistance. In all studied varieties, the maximum content of proline in the leaves – 43.27-59.57 μg/g wet weight was found in August in response to extremely high temperatures and lack of precipitation compared to June, when it was 17.83-30.55 μg/g fresh weight, depending on the variety. Grape varieties Crystal, Krasnostop AZOS, Vostorg, Zarif proved to be more resistant to drought and elevated temperatures in comparison with the varieties Dostoyny, Aligote, and are recommended for cultivation in the conditions of the Anapo-Taman zone of the Krasnodar Territory and use in breeding. The indicators of leaf water content, the ratio of chlorophylls/carotenoids pigments, and the proline content can be considered as reliable criteria for the adaptive resistance of grape varieties to summer stress factors.

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.

Delayed grape ripening by intermittent shading to counter global warming depends on carry-over effects and water deficit conditions

Grapevine phenology is continuously advancing due to global warming, exposing berry ripening to increasingly drier and hotter episodes that can dramatically affect yield and berry quality. This study aimed to analyse whether intermittent shading produced by panels placed over the plants can delay berry ripening to counter the impact of global warning on phenology. A two-year outdoor trial repeated on two batches of young potted grapevine (cv. Syrah) was conducted in Montpellier (South of France). Shading was created in a row using 2 m-wide horizontal panels placed 2.4 m above the ground. A moderate water deficit was also applied at the start of veraison to half the plants in both full sun (without panels) and shaded conditions to mimic usual field conditions. Variables related to budburst, flowering, veraison and sugar at harvest were analysed in all treatments. Although intermittent shading did not significantly modify air temperature within the canopy when cumulated over the growing season, the panels substantially delayed veraison by up to more than 30 days under well-watered conditions. The most marked phenological shifts were noted in the second year of treatment between flowering and veraison when carbon demand sharply increased during berry formation, suggesting there was a carry-over effect likely due to limited carbon assimilation. This was accompanied by sharp decreases in berry diameter and sugar content per berry at harvest. Higher berry growth and sugar loading were maintained when shading was combined with water deficit. However, the trigger effect of water deficit on veraison almost halved the phenological delay caused by the panels. Overall, a cooler period for ripening could be achieved with panels over the vines but at the expense of berry size and sugar amount in berries. It can be concluded that shading intensity and duration should be adapted to evaporative and soil water conditions to benefit from the phenological delay caused by panels, without altering production in the long term.