Growing Conditions and Quality of Vegetables

I. Effects of Fertilization and Foliar Spray Treatment on the Ascorbic Acid Content of Leaf Vegetables

Abstract

Effects of fertilization and foliar spray treatment on the ascorbic acid content of lettuce and garland chrysanthemums were investigated.
1. The growth of garland chrysanthemums was not affected by the treatment of different compositions in nutrient solution, but that of lettuce was greatly influenced and dry weight decreased in 1/2N, 1/2P, 1/2K, 1/2Ca, and 1/2Mg regimes. The ascorbic acid content of both vegetables were inclined to decrease in 3/2N, 3/2K, and 1/2Mg regimes and to increase in 3/2P, 1/2Ca, and 3/2Mg regimes of nutrient solutions. Urea foliar spray treatment largely increased the ascorbic acid content.
2. The fresh weight of lettuce grown in 1/4 fold of standard nutrient solution was decreased 27-46% as compared with that of 1/2 fold or more concentrations, but the ascorbic acid content was singularly increased at that time. There are positive correlations between the ascorbic acid and sugar content, and these relationships were discussed. A total of four or five foliar spray treatments of 0.5% of urea solution every 5 days was expected to increase the ascorbic acid content.
3. The treatment of very low concentration of s-triazine herbicide did not increase the growth of lettuce. But foliar spray treatment of 2.5% simazine solution increased the ascorbic acid and sugar content, and decreased the NO_3-N content.