Physiological and Morphological Studies on the Potato Plants. : Part16. Some contribution to the physiology of dormancy, with special reference to the interrelation between ascorbic acid, phosphorylase and phosphatase in the potato tuber during the rest period.

Abstract

While many of the practical problems concerning dormancy in the potato tubber have been solved, the internal physiological factors that govern this state are little understood. One of the more obvious methods of approaching this basic problem is to determine what changes occur in the enzymatic activity. In the present investigation, with a desire to obtain some further understanding of the physiology of dormancy, particular attention was paid to the interrelation between ascorbic acid, phophorylase and phophatase in the potato tubers during the storage period. The experimental results obtained may be summarized as follows: 1). Generally speaking, the activities of phosphorylase and phophatase showed little variation during the rest period. On the other hand, the ascorbic acid contents (reduced- and oxidized-forms) in the tuber decreased gradually with the again of the tuber during this peiod. 2). After the termination of the rest period, concomitant with the increase of the reduced ascorbic acid content in the apical bud of the tuber, remrkable high activities of phosphorylase and of phophatase were recognized, except for the phosphorylase activity in the pith of the tuber. 3). When considering the physiological role of the ascorbic acid in the germination and the biochemical action of the ascorbic acid as the activator of phosphatase enzyme, these increases in the terminal bud noted above, may be intimately related to the termination of the dormancy of potato tubers.