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

Abstract

The % of ascorbic acid content of snap beans, broccoli, cauliflower, Kale, spinach, and Swiss chard grown outdoors was slightly higher in the late afternoon than early in the morning. However, these differences were due to diurnal fluctuations in the water content of the tissue. On a dry wt. basis no consistent differences were found in the ascorbic acid content of samples taken in the morning and evening. Single days of cloudy weather had no depressing effect on the vitamin C content of spinach. Vitamin C in Kale declined about 20% between July and Oct. Weekly averages of total daily radiation during this period decreased about 76%. A corresponding drop in average temp, may have counteracted in part the effect of lowered light intensity.