Cluster-Zone Leaf Removal and GA3 Application at Early Flowering Reduce Bunch Compactness and Yield per Vine in Vitis vinifera cv. Pinot Gris

Compact bunches have been often associated with higher susceptibility to Botrytis cinerea and therefore reduction in berry quality in grapevine. The objective of this study was to evaluate three management methods (early leaf removal, gibberellic acid, and their combination) for reducing bunch compactness in Vitis vinifera cv. Pinot gris trained in two different training systems with contrasting vigor (Guyot and pergola). Treatments were applied at BBCH 62 or BBCH 65 and yield components, total soluble solids, fruit set, and bunch compactness parameters were evaluated. Both treatments individually reduced berry number, mean bunches weight and bunches compactness as well as yield per vine when compared to control-untreated vines. However, no major differences were observed when both the treatments were applied in combination for Guyot or pergola although a higher reduction in yield was detected for Guyot and a significant increase in total soluble solids was observed in pergola. Our study suggests that intense leaf removal and gibberellic acid applied at early flowering can help reducing bunch compactness in Pinot gris and showing it in two training systems. In particular, leaf removal represents a valuable alternative to plant growth regulators (i.e., gibberellic acid) as applicable in organic viticulture.

Modifications of Grapevine Berry Composition Induced by Main Viral and Fungal Pathogens in a Climate Change Scenario

The grapevine is subject to high number of fungal and viral diseases, which are responsible for important economic losses in the global wine sector every year. These pathogens deteriorate grapevine berry quality either directly via the modulation of fruit metabolic pathways and the production of endogenous compounds associated with bad taste and/or flavor, or indirectly via their impact on vine physiology. The most common and devastating fungal diseases in viticulture are gray mold, downy mildew (DM), and powdery mildew (PM), caused, respectively by Botrytis cinerea, Plasmopara viticola, and Erysiphe necator. Whereas B. cinerea mainly infects and deteriorates the ripening fruit directly, deteriorations by DM and PM are mostly indirect via a reduction of photosynthetic leaf area. Nevertheless, mildews can also infect berries at certain developmental stages and directly alter fruit quality via the biosynthesis of unpleasant flavor compounds that impair ultimate wine quality. The grapevine is furthermore host of a wide range of viruses that reduce vine longevity, productivity and berry quality in different ways. The most widespread virus-related diseases, that are known nowadays, are Grapevine Leafroll Disease (GLRD), Grapevine Fanleaf Disease (GFLD), and the more recently characterized grapevine red blotch disease (GRBD). Future climatic conditions are creating a more favorable environment for the proliferation of most virus-insect vectors, so the spread of virus-related diseases is expected to increase in most wine-growing regions. However, the impact of climate change on the evolution of fungal disease pressure will be variable and depending on region and pathogen, with mildews remaining certainly the major phytosanitary threat in most regions because their development rate is to a large extent temperature-driven. This paper aims to provide a review of published literature on most important grapevine fungal and viral pathogens and their impact on grape berry physiology and quality. Our overview of the published literature highlights gaps in our understanding of plant-pathogen interactions, which are valuable for conceiving future research programs dealing with the different pathogens and their impacts on grapevine berry quality and metabolism.

Multiple Effects of Nitrogen Fertilization on Grape Vegetative Growth, Berry Quality and Pest Development in Mediterranean Vineyards

Nitrogen is a key macronutrient for the quantitative and qualitative yield of grapes; in addition, it influences the development and reproduction of grape pests. The multiple effects of different nitrogen rates were investigated on the red berry cultivar ‘Carignano’ and the grape pest Planococcus ficus in a two-year field trial. Different amounts of ammonium nitrate were compared: 0, 80 and 160 Units ha−1 for mineral nitrogen. The amount of nitrogen fertilization supplied influenced the nitrogen status of vines and increased the pruning weight and leaf area, as well as the overall grape yield, by increasing the cluster weight. However, doubling the nitrogen rate did not generally increase the vegetative and productive parameters of grapevines. At harvest, nitrogen supply did not influence the anthocyanin content, tritatable acidity, and soluble solids, although the latter parameter showed a clear, yet not significant, decreasing trend. Planococcus ficus exhibited higher fecundity, survival and shorter development time on grapevines provided with nitrogen, whereas its fertility was unaffected by nitrogen fertilization. Ultimately, nitrogen had a direct and positive effect on grape yield and vine mealybug development, highlighting the importance of integrated cultural and pest control practices to promote grape production.

Fresh haskap berry postharvest quality characteristics and storage life

Haskap (Lonicera caerulea L.) is a relatively new berry crop in North America, and little research exists regarding its postharvest storage characteristics or storage life. Postharvest changes in berry quality, and principal factors limiting storage life at 1.1 °C and 95% relative humidity, were evaluated up to 14 days for three cultivars in 2019 and up to 28 days for six cultivars in 2020. Containerized berries were periodically assessed for soluble solids content (SSC), skin rupture force (SRF) (both 2019 and 2020) and flesh firmness, titratable acidity (TA), and Brix/acid ratio (B/A) (2020 only). External appearance was also evaluated both years, revealing berry shrivel as the primary factor negatively impacting visual appeal, followed distantly by low incidence of spoilage later in storage. All cultivars exhibited relatively constant postharvest SSC and decreasing SRF, flesh firmness, and TA (resulting in increasing B/A ratio). Postharvest quality differed slightly between years; relative SRF was consistent among cultivars while SSC was not. Some cultivars had a portion of shriveled berries at harvest, pointing to a need for cultivar-specific harvest indices. Mean days to slight shrivel for individual berries varied among cultivars evaluated, ranging from 7.5–21.9 d postharvest, with mean weight loss ranging from 1.2%–1.6% at this stage. Combined with group marketability estimates — set at a threshold of 10% severely shriveled berries — we estimate a storage life of 7–10 d for fresh haskaps. Additional research is needed to delineate maturation physiology and optimize harvest timing.

Berry Cell Vitality Assessment and the Effect on Wine Sensory Traits Based on Chemical Fingerprinting, Canopy Architecture and Machine Learning Modelling

Berry cell death assessment can become one of the most objective parameters to assess important berry quality traits, such as aroma profiles that can be passed to the wine in the winemaking process. At the moment, the only practical tool to assess berry cell death in the field is using portable near-infrared spectroscopy (NIR) and machine learning (ML) models. This research tested the NIR and ML approach and developed supervised regression ML models using Shiraz and Chardonnay berries and wines from a vineyard located in Yarra Valley, Victoria, Australia. An ML model was developed using NIR measurements from intact berries as inputs to estimate berry cell death (BCD), living tissue (LT) (Model 1). Furthermore, canopy architecture parameters obtained from cover photography of grapevine canopies and computer vision analysis were also tested as inputs to develop ML models to assess BCD and LT (Model 2) and the intensity of sensory descriptors based on visual and aroma profiles of wines for Chardonnay (Model 3) and Shiraz (Model 4). The results showed high accuracy and performance of models developed based on correlation coefficient (R) and slope (b) (M1: R = 0.87; b = 0.82; M2: R = 0.98; b = 0.93; M3: R = 0.99; b = 0.99; M4: R = 0.99; b = 1.00). Models developed based on canopy architecture, and computer vision can be used to automatically estimate the vigor and berry and wine quality traits using proximal remote sensing and with visible cameras as the payload of unmanned aerial vehicles (UAV).

Genome Wide Analysis of GH Gene Family Reveals Vvgh9 Positively Regulates Sugar Accumulation under Low Sugar Content in Grape

Sugar content directly affects grape (Vitis vinifera L.) berry quality and the resulting wine. Therefore, it is of great importance to study and explore novel genes that affect sugar accumulation in grapes. Glycosyl hydrolases (GHs) are key enzymes hydrolyzing polysaccharides into monosaccharides and play important roles in the regulation of carbohydrate metabolism. Nevertheless, the impact of GHs on the regulation of sugar accumulation in plants has rarely been investigated. In this study, we identified 11 putative GH genes in grapevines by phylogeny analysis. RNA-seq and quantitative real-time PCR results demonstrated that the expression level of VvGH9 was higher during the fruit set stage, which had lower sugar content than the véraison and ripe stages. Treatment of grape berries with exogenous sugar two weeks before véraison revealed that VvGH9 was rapidly induced by sucrose, fructose, and glucose. When ‘41B’ calli was treated with different concentrations of glucose, VvGH9 expression increased at first and then decreased with the increase of glucose concentration. Overexpression of VvGH9 in grape calli and tomatoes also confirmed that this gene could contribute to sugar accumulation. All the above results demonstrated that VvGH9 promotes sugar accumulation under low sugar content in plants.

Variability assessment of productivity traits and quality of berries in the genetic collection of garden strawberry (Fragaria ananassa Duch.) in the Orenburg region

Nowadays the study of the interrelation of the genotype of strawberry plants in garden and climatic conditions is extremely relevant. Due to the various systems of genetic control and the modifying effects of growing conditions on the manifestation of quantitative traits, there is the need to assess the genotypic variability of economically valuable features, focused on the identification of genotypes characterized by stability and adaptive qualities in growing conditions. The study examined 15 varieties of garden strawberries of domestic and foreign selection. The field experiments and surveys were carried out according to the Program generally accepted in the Russian Federation and methodology for the variety study of fruit, berry and nut crops. We studied such features as the number of peduncles (pcs/bush), number of berries (pcs/bush), average weight of berries (g), total and marketable yield (g/bush), sugar content in berries, soluble solids and ascorbic acid. The purpose of this work was to assess the genotype-year interrelation in terms of the variability of productivity features and berry quality and to identify strawberry varieties with a stable genotype. As a result of two-way analysis of variance for the variety-year interrelation, the obtained values were 1.10-8.50 at standard Fst. - 1.24. Statistically important differences had indicators of productivity of a bush between the first and second clusters (t = 5.89 at p <0.01), the first and third (t = 15.83 at p <0.01), the second and third clusters (t = 8.13 at p <0.01), as well as the average berry weight between the first and third, second and third clusters (t = 15.50 and 6.99 at p <0.01, respectively). Significant differences in the value of the Euclidean distance were revealed for varieties Mishutka (54.5), Daryonka (54.5), Pervoklassnitsa (58) realizing their productivity potential in different years of cultivation.

Missing Links in Predicting Berry Sunburn in Future Vineyards

Sunburn in grapevine berries is known as a recurring disorder causing severe yield losses and a decline in berry quality. The transition from healthy to sunburnt along a temporal trajectory is not fully understood. It is driven by light-boosted local heat impact and modulated by, e.g., past environments of the berry and its developmental state. Events of berry sunburn are often associated with heatwaves, indicating a link to climate change. In addition, the sensitivity of grapevine architecture to changing environmental condition indicates an urgent need to investigate and adapt mitigation strategies of berry sunburn in future vineyards. In this perspective, we want to identify missing links in predicting berry sunburn in vineyards and propose a modeling framework that may help us to investigate berry sunburn in future vineyards. For this, we propose to address open issues in both developing a model of berry sunburn and considering dynamic canopy growth, and canopy interaction with the environment and plant management such as shoot positioning or leaf removal. Because local environmental conditions drive sunburn, we aim at showing that identifying sunburn-reducing strategies in a vineyard under future environmental conditions can be supported by a modeling approach that integrates effects of management practices over time and takes grapevine architecture explicitly into account. We argue that functional-structural plant models may address such complex tasks. Once open issues are solved, they might be a promising tool to advance our knowledge on reducing risks of berry sunburn in silico.