2019 Volume 18 Issue 1 Pages 81-87
Poor coloration of colored grapes grown in warm regions is a frequent problem. The application of abscisic acid (ABA) to grapes can increase the content of anthocyanins in their skins. To improve bunch color, a new plant bioregulator, S-ABA, has been approved in some countries. As no protocols have yet been established for its commercial use in Japan, we evaluated the effects of spray treatment with a liquid formulation containing S-ABA (KS-102) on the fruit quality characteristics of ‘Pione’ grapes in open field culture for 4 years and in rain-protected culture for 2 years. A spray of 500 ppm S-ABA solution to bunches at the onset of pigmentation promoted skin coloration at harvest in both experiments. The soluble solid content was not affected, but the titratable acidity was reduced, increasing the sugar-acid ratio. Treatment did not affect other fruit qualities. Coloration became stronger under lower temperatures between treatment and harvest than under higher temperatures. The improved coloration became apparent in 2 weeks and was maintained until harvest.
