DIURNAL AND SEASONAL CHANGES IN THE ASCORBIC ACID CONTENT OF SOME VEGETABLES

As part of a general study concerned with improving the food value of crop plants, a number of experiments have been conducted to determine the factors which control the ascorbic acid content of plants. The most important papers on this subject have been reviewed by Re?d (6) and more recently by Maynard and Beeson (3). In spite of some inconsistencies in their results, these investigations lead to the following general conclusions : 1. Mineral nutrition has little influence on the ascorbic acid content of plants except under conditions where normal growth is seriously disturbed by deficiencies in one or more essential elements. 2. Genetic factors play an important r?le. Different varieties of the same species frequently show large differences in the quantity of vitamin C they contain. 3. Some data indicate that the growing temperature affects the rate at which ascorbic acid accumulates in the plant. Moldtman (4) and Re?d (5) observed that at moderate temperatures an inverse relation exists between the ascorbic acid content of plants and the temperature at which they are