Horticulturae

Climate change is modifying ecoclimatic conditions, including temperature, solar radiation, and water availability, with significant impacts on grapevine phenology, berry ripening, and the polyphenolic composition of grapes cultivated in temperate regions. The influence of different meteorological conditions during ripening on the polyphenolic composition of Grignolino grapes grown in a hilly environment was investigated. Grapes were collected, over three vintages, from three vineyards differing in their vine age and bunch microclimate due to having different vineyard aspects. We considered a comparable berry weight, moderate rainfall and cool conditions before veraison, followed by a warm and dry pre-harvest stage that enhanced the phenolic and especially the anthocyanin index in the grapes (e.g., 360 mg kg⁻¹ in 2021 versus 260 mg kg⁻¹ in 2020). Intense heat and dry conditions reduced the berry weight, leading to an increase in both flavonols and hydroxycinnamoyl tartaric acids, particularly in the younger, southwest-exposed vineyard. Older vines with a cooler aspect were the most resilient to different meteorological conditions, while young vines showed greater variability over the years. The phenolic composition was strongly influenced by the intensity and the timing of thermal stress, and eventually on limited water availability during ripening; it also depended on the vine age and the vineyard microclimate determined by the hillside aspect. This knowledge may support adaptive strategies to preserve grape quality under climate change.

This study examined clonal variation in Vitis vinifera L. cv. ‘Merzifon Karası’, a Turkish wine grape. Thirty-two clones were evaluated for key growth and enological characteristics, including cluster structure, berry attributes, yield components, millerandage index, and berry skin color. Considerable variability was observed in cluster weight (95.8–254.1 g), berry weight (0.64–3.06 g), and millerandage index (1.35–9.77), highlighting the importance of clonal selection for optimizing fruit set, cluster compactness, and overall vineyard performance. Promising clones, such as F13/29, K11/27, and H20/24, combined high yield, well-formed clusters, and low millerandage indices, whereas clone K13/10 exhibited exceptional uniformity in fruit set, achieving the lowest millerandage index. Incorporating berry skin color characteristics further identified K11/27, F13/29, and K13/10 as particularly favorable for both productivity and winemaking quality due to their dark berries, consistent fruit set, and well-formed clusters. These findings illustrate the potential of targeted clonal selection to enhance sustainable viticulture and improve fruit quality in ‘Merzifon Karası’.

The genus Thymus L. is characterized by high taxonomic complexity and pronounced phytochemical polymorphism, which underlie its economic and medicinal importance. While a limited number of species (Thymus vulgaris, Thymus pulegioides, Thymus × citriodorus) are traditionally cultivated, the cultivation potential of many Balkan taxa remains poorly explored. The present study aimed to evaluate the field cultivation performance, essential oil yield, and chemotype differentiation of three traditional and three lesser-studied Thymus species (Thymus zygioides Griseb., Thymus longedentatus (Degen & Urum.) Ronniger, and Thymus pannonicus All.). Plants were established through vegetative propagation and cultivated under field conditions, followed by essential oil isolation and GC–MS analysis. The newly introduced species exhibited higher essential oil yields, reaching 2.30% in T. longedentatus, 1.48% in T. pannonicus, and 0.94% in T. zygioides, compared to 0.24–0.60% in traditionally cultivated species. Clear and species-specific chemotypes were identified: a citral (neral/geranial) chemotype in T. longedentatus, a thymol chemotype in T. zygioides, and a sesquiterpene-dominated profile in T. pannonicus. In contrast, traditionally cultivated species displayed overlapping and less differentiated chemical profiles. All species were propagated vegetatively and cultivated in an open-field experimental plantation under temperate continental climatic conditions, following environmentally responsible horticultural practices. Vegetative propagation ensured genetic uniformity and supported consistent chemotype expression of the planting material under the applied cultivation conditions. These results demonstrate that species-based selection represents a robust alternative to conventional thyme cultivation, enabling higher essential oil productivity, clearer chemotypic differentiation, and improved standardization for horticultural and medicinal plant production, while supporting the sustainable use of native Bulgarian biodiversity.