Influence of abscisic acid functional analog natenpac on grape coloring and quality improvement

Grape coloring is an essential stage in the grape ripening process, which has a very important influence on the quality of grape berries. In this paper, nine-year-old grape variety Frey was used as the research object and the influences of a novel abscisic acid (ABA) functional analog, natenpac, on grape coloring and quality improvement in the field were studied. At the initial stage of fruit coloring, foliar spraying, root irrigation, and fruit soaking were carried out with 2, 5, and 10 mg/L natenpac, respectively, and clean water treatment as the blank control. By comparing the apparent changes, such as average transverse diameter, color, and single fruit weight, and internal quality changes, such as soluble solids, anthocyanin, and soluble sugar contents, the optimal application mode and concentration were determined. The results showed that natenpac could make Frey grape finish coloring 7-10 days earlier than the control by foliar spraying or root soaking modes, and contributed to significant increases in soluble solid content and coloring degree, and slight increases in the transverse diameter and single fruit weight of berries. The three treatment modes showed a great difference in efficacy. Root irrigation and foliar spraying were better than fruit soaking and 2 mg/L of foliar spraying was the best. This study clarified the best application mode and concentration of natenpac to Frey grape and provided the basis for guiding the field application of natenpac in grape coloring.