Chemical Studies on the Plants of Dioscorea Species. II

On the Growth and Constituent Variations in Tsukune

Abstract

Seed tuber of Dioscorea Batatas DEONE forma Tsukune MAKINO was planted in a fertilized plot and variation in the content of phosphorus, potassium, nitrogen, and starch during growth of terrestrial stem and leaves and formation of new tubers was examined. Seedling sprouted about 30 days after planting and a new tuber formed 80 days after sprouting, during which there was no marked change in the contents of phosphorus, potassium, and nitrogen in the seed tuber. There was apparent decrease of phosphorus and nitrogen and increase of potassium just prior to the formation of a new tuber but the content calculated by excluding starch remained practically unchanged (Table II). Later, phosphorus and nitrogen decreased, with potassium remaining almost unchanged. The same variation was witnessed in the new tuber, the three inorganic matter seeming to decrease by the rapid increase of starch but the amount excluding starch remained fairly constant. Phosphorus alone decreased with the growth of a new tuber. The amount of phosphorus, potassium, and nitrogen in the total plant from the planting of seed tuber to harvesting is illustrated in Fig. 2 and the rapid increase of these three elements about 90 days after planting indicates that these elements had been adsorbed from outside. It was also observed that no change takes place in the content of these elements in the tuber during winter storage.