Factors Affecting the Vitamin C Content of Apples'

Marked variations in the vitamin C content of different varieties of apples have been observed. The values of 21 Massachusetts-grown varieties were reported by Smith and Fellers,^ and the results of several other workers have been summarized by Batchelder.^ Between different lots of apples of the same variety small differences in vitamin C concentration have been found which appeared to result from the kind of fertilizers used (Potter and Overholser) .* Nelson and Mottern ^ report that the vitamin C content of oranges is low in fruit from trees that have been heavily sprayed with lead arsenate. It seemed possible that the adverse effect of the spraying might have resulted primarily from a lowering of the effective photosynthetic capacity of the leaf. A change in the ratio of leaf area to fruit, effected by thinning of leaves to produce a low ratio and by thinning of undeveloped fruit to produce a high ratio, would afford a means of measuring directly the influence upon the vitamin C content of fruit of a change in its supply of the products of photosynthesis. Hence, in this investigation of the factors that affect the vitamin C content of apples, a study was made of the concentration of this vitamin in apples grown with a high ratio of leaf area to fruit as compared with apples grown with a low ratio of leaf area to fruit. A study was also made of size of individual apples as a factor in the measurement of the vitamin C content. Two varieties of apple, Delicious and Winesap, were used. Both varieties were grown with different ratios of leaf area to fruit in connection with the experimental work of the Division of Horticulture of the Washington Agricultural Experiment Station at Pullman. Each variety was grown under uniform conditions of fertilization, spraying, and other environmental factors, the sole variant being ratio of leaf area to fruit.