The effect of sunlight on the ascorbic acid content of strawberries.

Although it is generally realized that environmental factors may influence the nutritive value of fruits and vegetables, there has not been a great deal of research reported to show the extent to which climatic variants may exert their effect. The work reported in this paper is concerned with the relationship between sunlight and the ascorbic acid content of strawberries. Reports in the literature on the ascorbic acid-sanlight relationship for strawberries are rather conflicting, although they are agreed that there is such a relationship. McCrt)ry {3f found that long-stemmed fruits were higher in ascorbic acid than those with shorter stems, and that fruit exposed to sun was higher than that shaded by leaves. He also reported that fruit harvested on clear days had a higher ascorbic acid content than those harvested on cloudy days. However, these observations were not supported with data. Hansen and Waldo (2) studied the problem by shading entire plants, or the berries alone, with muslin bags and concluded that under the former condition a much lower amount of ascorbic acid was synthesized. The effect of shading the berries alone was not so great. However, the statistical significance of these observations could not be determined by the data presented. Ezell and associates (1) found that when entire plants or only the berries were shaded, less ascorbic acid was accumulated than with full illumination. These workers used one and four thicknesses of cheesecloth for the plot-shading experiments and brown manila bags for the shading of the fruit alone. They also related climatological data published by the United States Weather Bureau to the seasonal fluctuations of the strawberry ascorbic acid and deduced that the amount of sunlight for approximately 1 week prior to harvest is operative on the ascorbic acid production. In a survey of the ascorbic acid content of 81 varieties of strawberries in 1946 Robinson et al. (4-) found a statistically signiflcant difference of 15 percent in the average ascorbic acid content (fresh-weight basis)