甘藷の生理的特性に関する研究 : X. 肥大度を異にする塊根間の生理的差異について

抄録

Although numbers of studies on the growth and development of sweet potato roots have been reported by many investigators, few data concerning the physiological factors, especially on the accmulation of carbohydrates, are available. In the present paper, in extending the work on the physiological differences between the root tubers of varied developmental stages of sweet potatoes, particular attention was paid to make clear the interrelation between the activities of phosphorylase, phosphatase and amylase, together with the ascorbic acid and carbohydrate contents in the fibrous, pencil-like and tuberous roots. The variety "Okinawa No. 100" was used as material. The experimental results obtained at the later stage of its growth, are as follows : 1. The phosphorylase and phosphatase activities in the fibrous roots were least, while those in the tuberous roots were most pronounced and those in the pencil-like roots stand between them. It is interesting to note that these enzymes in the tuberous roots showed tendencies to increase their activities with increases of the growth in thickness of the root tubers. 2. Concerning amylase, the lowest activity was observed in the fibrous root, and the highest in the pencil-like root, and that in the tuberous root stands the middle of the two. In this case a negative correlation was recognized between the amylase activity and the degree of the growth in thickness of the root tuber. 3. The total and the reduced form of ascorbic acid contents were lowest in the fibrous, middle in the pencil-like, and highest in the tuberous roots. In the latter case a tendency to increase the ascorbic acid content with the growth in thickness of the root tuber was ascertained. On the other hand, the contents of oxidized form of ascorbic acid were lowest in the fibrous roots, highest in the pencil-like roots, and that in the tuberous roots stand between the two. And a tendency to decrease in its contents with the growth in thickness of the root tuber was observed. 4. The total sugar and starch contents were lowest in the fibrous, middle in the pencil-like, highest in the tuberous roots. In these cases the contents of total sugar decreased and these of starch increased with the growth in thickness of the root tubers.