Abstract
To clarify the relation between coloration of grape berry skins and temperature in Hiroshima, skin coloration, temperatures as well as berry characteristics and cultutivation methods were measured among 7 vineyards of ‘Aki Queen’ grape (Vitis labrusca L.×V. vinifera L.), in 2001. Moreover, the effects of girdling and cluster thinning on skin color were examined in 3 vineyards where coloration was restricted, in 2005. Coloration markedly different among vineyards, with color index values (0-5 grade) between 0.2 and 4.5. Despite differences in culturing methods and vine age, there were positive relationships among total soluble solids (TSS), the duration of plant exposure to temperatures between 20 and 25°C from 8 to 21 days after the onset of coloring and the coloration. Girdling and cluster thinning increased the coloration and TSS in the vineyards where temperatures from 8 to 21 days after the onset of coloring were high. However, the effects of girdling and cluster thinning were low when shoot growth was vigorous. These findings indicate that factors other than temperatures and TSS are involved in the coloration of berry skins.
