ウイルスフリーぶどう樹‘カベルネ•ソービニオン’及び‘カベルネ•フラン’のウイルス再感染について

Abstract

We carried out a comparative test with mixed planting in the same field using virus-free and virus-infected (leafroll and fleck) vines of red wine-grape cultivars, ‘Cabernet Sauvignon’ and ‘Cabernet Franc’ (Vitis vinifera L.). Although initially virus-free vines were 7 or 8 years old, they have been reinfected.In this paper, seasonal changes in °Brix and titratable acidity of grape juice were investigated over a 3 year period (1985 to 1987, tree age: 6 to 8 years), and we detected and identified the viruses of these cultivars.The results are as follows;1. At full maturity, the °Brix values of the juices of virus-free ‘Cabernet Sauvignon’ and ‘Cabernet Franc’ were higher than those of virus-infected vines, in 1985 (6-year-old vines). However, in 1987 (8-year-old vines), the °Brix values of the virus-free varieties were lower than those of virus-infected vines.2. Titratable acidities of the juices of virus-free ‘Cabernet Sauvagnon’ and ‘Cabernet Franc’ were lower than those of virus-infected vines at full maturity in 1985. However, in 1987, titratable acidities of virus-free ‘Cabernet Sauvignon’ and ‘Cabernet Franc’ were higher than those of virus-infected vines.3. We found that the initially virus-free vines were reinfected by leafroll and fleck viruses. We think that in 1987, the infection by leafroll and fleck viruses caused the decrease in °Brix and the increase in acidity of juices, as well as light-colored fruits and red leaves in these initially virus-free vines.