Changes in the phenological and temperature requirements during cultivation of the Rubin variety in the southern wine-growing region of Bulgaria

This study aims to characterize the phenology and the corresponding temperature requirements of the Rubin variety grown on SO4 rootstock. The experiment was conducted in a private vineyard under the supervision of viticulture researchers` team. The assessments of the phenology and vines temperature requirements were conducted from pruning to harvest. The climate in the studied area is transitional continental, with a slight mountain influence and a large amplitude in seasonal temperatures. In 2022, the average rainfall was approximately 572.4 mm, and in comparison, to the previous year - 755.4 mm. The total difference accounts for 183 mm with the highest precipitation in June – 103.8 mm. Such variations in precipitation significantly affect the vine growth and productivity. The study results showed the possibilities of obtaining a sufficient yield ranging from 759.24 kg to 865.80 kg per 0.1 ha due to larger individual mass of clusters - 173 and 179 g, for V1 and V2, respectively. Furthermore, the application of canopy technique can be useful in the production of wine grapes, especially in uneven rainfall distribution or in non-irrigated area during the vine vegetation period. Keywords: viticulture, Rubin, climate, phenology, region, terroir