2005 Volume 4 Issue 3 Pages 343-346
‘Aki Queen’ is a bright-red grape cultivar, but often bears an undesirable deep berry-colored grape. To improve the productivity of clusters with the desired color, the effects of crop load on coloration were investigated in ‘Aki Queen’ grape. Berry numbers per a leaf were adjusted to 0.14, 0.52, 1.53 and 2.47 by pinching and berry thinning at 32 days after anthesis, and girdling treatement was conducted at the base of the shoot. In plants with 0.14 and 0.52 fractions, total anthocyanin concentrations in the skin of the berry increased over 50 × 10-6 g · cm-2 and deep colored berries appeared frequently 76 days after anthesis. The 1.53 fraction, however, bore proper bright red berries with an anthocyanin concentration of about 25 × 10-6 g · cm-2 96 days after anthesis. The 2.47 fraction showed slight anthocyanin concentration, resulting in poor coloration. However, we could not find a clear relationship between anthocyanin composition and deep coloration. These data suggest that controling the crop load could adjust ‘Aki Queen’ berry to the proper coloration through regulation of anthocyanin concentration.
