Studies of the Formation and Translocation of Carbohydrates in Plants: I. The Carbohydrates of The Mangold Leaf

Abstract

1. The formation and translocation of the sugars in the mangold have been studied under actual conditions of growth, in which translocation was normal.2. Starch is entirely absent from the leaf after the very earliest stages of growth. As soon as the root begins to develop so that the sugars formed in the leaf can be translocated to it, starch disappears almost entirely from the leaf. Maltose is entirely absent from leaf, mid-ribs and stalks at all stages of growth and at all times of night and day.3. During the early stages of growth of the mangold, when leaf formation is the principal function, saccharose is present in the leaf tissue in excess of the hexoses. Later in the season, when sugar is being stored in the root, the reverse is true, hexoses largely predominating in the leaf.4. In the mid-ribs and stalks the hexoses always predominate greatly over the saccharose and vary widely in amount during the day and night, and throughout the season, whilst the saccharose remains practically constant. In passing from leaves to mid-ribs, from mid-ribs to the tops of stalks and from the tops of stalks to the bottoms, the ratio of hexoses to saccharose steadily and rapidly increases. As the season advances the predominance of the hexoses in leaf, mid-ribs and stalks becomes more and more marked.