The distribution and concentration of ascorbic acid in the potato (Solanum tuberosum)

Abstract

The concentration in the leaves fluctuates considerably during the day with maximum value in the early forenoon; generally it is much greater in leaves than in stems or tubers. In tubers it is at maximum in Aug., falls as the plant ripens, and decreases further during storage, until after 6 mos. it is only about 1/3 of the value at time of harvesting. After 1 month''s storage the values for 18 varieties were 14 to 27 mg. per 100 g. fresh tissue. The amt. of dehydroascorbic acid is very small at harvesting but increases during storage. Normal manuring has no effect but there is usually a greater conc. in tubers from plants affected with severe mosaic or leaf roll than in tubers presumed to be healthy. During early stages of growth the conc. increases from the heel to the middle or tip of the sprout, the gradient being more pronounced when sprouting has taken place in the light than in the dark. No synthesis occurs during this period but rather a net loss which is greater when sprouting has taken place in the dark.