Differential Accumulation and Degradation of Anthocyanins in Red Norland Periderm is Dependent on Soil Type and Tuber Storage Duration

To determine how soil type, 2,4-dichlorophenoxyacetic acid (2,4-D) treatment, and storage affects color and anthocyanin accumulation of Red Norland potatoes, tubers were grown in sand or peat, with or without 2,4-D treatment, and measured at vine kill, harvest or after storage. Tubers grown in sand were less red and accumulated fewer anthocyanins than tubers grown in peat. 2,4-D treatment increased redness regardless of soil type. Redness loss varied greatly among tubers with storage. Tubers that lost color with storage had a two-fold reduction in anthocyanins, and a two-fold increase in benzoic and cinnamic acids compared to harvest, indicating chemical degradation of anthocyanidins via B-ring cleavage and autoxidation. Sand-grown potatoes did not exhibit greater cinnamic acids compared to peat-grown potatoes, suggesting that their color differences were due more to differences in biosynthesis than degradation during skin set. To improve Red Norland tuber color, research should focus on increasing biosynthesis of anthocyanins.