Impact of Raspberry Bushy Dwarf Virus on Yield and Fruit Quality of Three Red Raspberry Cultivars

This study aimed to evaluate the yield and assess changes in the chemical composition of fresh red raspberry fruits caused by the presence of Raspberry bushy dwarf virus (RBDV). The study was conducted on fruits collected from RBDV-free and RBDV-infected plants of three raspberry cultivars: Brusviana, Sugana, and Joan J, grown in Kyiv Oblast. Fruits were harvested at the appropriate ripening stages, and their physical parameters (number of fruits, weight, drupelet number) were measured. The biochemical characteristics were analyzed using appropriate methods: soluble solids content (SSC, %) via refractometry; titratable acidity (%) and ascorbic acid (AsA, mg 100 g-1) through acid-base titration; sugar content (%) using colorimetric analysis; and total phenols and anthocyanins (mg 100 g-1 fresh weight) by spectrophotometry, applying the Folin–Denis method and the pH differential method, respectively. The results revealed a statistically significant negative impact of viral infection on yield across all three cultivars, with reductions reaching up to 62%. Infected plants produced smaller, deformed, crumbly, and lower-weight berries with fewer drupelets compared to healthy ones. The AsA content in infected fruits was significantly lower in all three cultivars (7.7–9.6%). In contrast, the TA content was 40–50% higher in infected plants of Brusviana and Sugana. The levels of phenolics were notably higher in virus-infected plants of Joan J (up to 28.7%) and Sugana (up to 16%) than in the control, while anthocyanin content significantly increased in Sugana (60.4%) and Brusviana (53.7%). Statistical analysis confirmed the undeniable impact of RBDV infection on the studied traits. Considering all experimental and statistical data, it can be concluded that RBDV affects marketability, fruit quality, and chemical composition in all three examined red raspberry cultivars.