Improving our knowledge on biotic and abiotic factors that influence the composition of the grapevine mycobiome is of great agricultural significance, due to potential effects on plant health, productivity, and wine characteristics. Here, we assessed the influence of scion cultivar on the diversity and composition of fungal communities in the berries and leaves of three different cultivars. We generated DNA metabarcoding data, and statistically compared the richness, relative abundance, and composition of several functional groups of fungi among cultivars, which are partly explained by measured differences in chemical composition of leaves and berries and physiological traits of leaves. Fungal communities in leaves and berries show contrasting patterns among cultivars. The richness and relative abundance of fungal functional groups statistically differ among berry and leaf samples, but less so among cultivars. Community composition of the dominant functional groups of fungi, i.e., plant pathogens in leaves and saprotrophs in berries, differs significantly among cultivars. We also detect cultivar-level differences in the macro- and microelement content of the leaves, and in acidity and sugar concentration of berries. Our findings suggest that there appears to be a relatively diverse set of fungi that make up the grapevine mycobiome at the sampled terroir that spans several cultivars, and that both berry and leaf mycobiomes are likely influenced by the chemical characteristics of berries and leaves, e.g., pH and the availability of nutrients and simple carbohydrates. Finally, the correlation between fungal community composition and physiological variables in leaves is noteworthy, and merits further research to explore causality. Our findings offer novel insights into the microbial dynamics of grapevine considering plant chemistry and physiology, with implications for viticulture.

The effects of cane girdling on the berry texture characteristics were studied in three table grape cultivars. The application was carried out at véraison. The total soluble solids (TSS, °Bx) of berry must and berry weight were measured. The berry mechanical properties were investigated by a texture analyser. A double compression test was used to determine berry hardness and its derived parameters. A puncture test was also applied to assess skin hardness, skin elasticity and skin break energy. Skin thickness was also investigated. The sugar concentration of the must and the berry weight after the girdling treatment were significantly higher compared to those of the control. Berry hardness, skin hardness and skin thickness were significantly affected by this technique. The changes in berry mechanical and quality parameters with this application did not show the same pattern as those observed during control ripening. Notably, in our experiment, after the girdling treatments, the higher berry hardness was accompanied with a higher sugar concentration compared to the control. The skin hardness showed lower values as a result of girdling. However, skin thickness was significantly higher in the girdled berries compared to the non-treated vines.

The marketability of table grapes is mainly characterized by berry size, color, taste and texture. Mechanical measurements of table grape berries could provide objective information on the textural qualities of grape berries. In addition, this method might be suitable to study the effects of phytotechnical methods (such as girdling) on table grape quality. The aim of this preliminary work was to demonstrate how instrumental testing could be used to examine the effects of girdling on berry grape texture and define the textural characteristics of table grape berries. Cane girdling was carried out at veraison in two table grape varieties. Texture analysis was performed several times during the maturity. Besides this examination another five varieties were analyzed to assess their berry mechanical properties. Double compression test was used to determine berry hardness and its derived parameters. Puncture test was applied to evaluate skin hardness, skin elasticity and skin break energy. Skin thickness was also investigated. Berry hardness, skin hardness and skin thickness of the girdled grapevines were significantly affected by this technique. Most of the textural parameters showed differences among the seven cultivars.

In our 2023 experiment, Nero and Muscat Pölöskei grapevines were treated with gibberellic acid (12 mg L-1) during flowering, followed by stem-end girdling at the onset of berry development. Photosynthetic activity was monitored regularly. Assimilation rate (A, µmol CO₂ m⁻² s⁻¹) and transpiration rate (E, mol H₂O m⁻² s⁻¹) were measured under natural light. Sugar content and acidity were assessed via refractometry, while berry dimensions and texture (e.g., berry hardness [Bh, mN]) were recorded. Gibberellin treatment increased sugar content compared to both control and girdled samples. However, girdling significantly enhanced sugar accumulation in Muscat Pölöskei compared to untreated samples. Gibberellin also induced berry elongation, increasing the longitudinal axis in Nero (19%) and Muscat Pölöskei (24%). Girdling temporarily reduced photosynthetic activity, which recovered post-healing. The elongated berries due to gibberellin treatment led to a looser cluster structure, which is beneficial for Nero, which is prone to fungal diseases due to dense clusters.