INFLUENCE OF THE CHLORIDE ION ON THE CONTENT OF CARBOHYDRATES IN POTATO LEAVES

From the literature and from numerous experiments made at the Scientific Institute of Fertilizers, it is well known that high amounts of chlorides lower the percentage of starch in potato tubers. While the depressing influence of fertilizers containing chlorine on the total yield of potatoes is not always manifested, the decrease of the starch content in the tubers may be considered a constant attendant of the introduction of high amounts of chlorides. There are some indications that the use of sulphate of potassium is preferable when fertilizing plants which are cultivated for carbohydrates (2). The depressing action of the chloride ion on the accumulation of starch in potato tubers may be called forth by various causes. It is known from literature (5) and from our experiments (1), that large doses of chlorides lower the content of chlorophyll in plants. MONTFORT (4), who observed a sharply decreased synthesis in leaves when immersed into chloride solutions, explains this phenomenon by the destruction and therefore by the decrease of the total amount of chlorophyll in those leaves. On the other hand the chlorides may also exert an influence on the activity of the amylase and therefore on the conversion of starch secondarily formed in the tubers. The increased conversion of starch under the influence of chlorides was observed by SCHMETZ (6), MONTFORT (4) and others. However, these authors confined themselves mostly to qualitative indices; they estimated the synthesis and the conversion of starch by the intensity of the iodine color test. Much attention has been given in this laboratory during recent years to the study of the physiological action of chlorine. It is the purpose of our work to show the influence of chlorine on the photosynthetic activity and on the accumulation of carbohydrates in the potato leaves. In this paper are presented the results of experiments concerning the influence of chlorides only on the content of carbohydrates. We considered two groups of carbohydrates, starch, and the total soluble sugars. The experiments were conducted with an early variety of potato, "Epicure," lduring the years 1933 and 1934.