Phyysiological and Morphological Studies on Potato Plants :Part 8 Especially on the Senility of Potato Tuber and its Abmormal Sprouting (Epitomic Report)

Abstract

It is mot at all uncommon to find potato tubers with very irregular shape of sprout tuber, due to the senility of the tuber during storage being kept for a long duration over their rest period. It seems quite clear, accordingly, that an attack on the problem f the problem of the senility and on the effect of external conditions, by which the tuber produces such abnormal sprouting, is a practical necessity in the agricultural field. In the present paper are described the behavior of carbohydrate contents, together with the variations of soluble and protein nitrogen fractions in the tuber. And at the same time the respiration rate of the sprout was also determined. The experimental results obtained may be summarized as follows: (1) Under the condition of humid storage, the growth of the tender sprout was accelerated enormously, resulting in high contents of reducing sugar, soluble nitrogen and moisture at the expense of a decrease of starch and protein nitrogen in the tuber. Under these conditions the senility of the tuber was very striking, though the shrinkage of the tuber wes inconsiderable in appearance. (2) under the condition of dried storage, on the other hand, due to the check of longitudinal growth of the sprout, new growth may form an irregular lump on the mother tuber and be progressively developed to the typical sprout tuber after the storage of two months. In such a small sprout tuber the contents of starch and protein nitrogen were high, while moisture, sugar and soluble nitrogen contents were low. According to the shrinkage of the tuber due to the dehydration and the consumption of the reserve substances, the senility of such a tuber was also striking. (3) under the conditions of dried and high temperature storage, being accompanied with the decrease of reducing sugar content and the accumulation of starch for a very short period, a remarkable retardation of the longitudinal growth and a rapid acceleration of the lateral growth of the sprout was recognized. And at the same time a rapid falling off in the rate of respiration was ascertained. (4) judging from the results described above, it seems reasonable to assume that the formation of the abnormal sprout, such as sprout tuber, might be due to changes of the reserve substances in the mother tuber and of the respiratio rate of the sprout and tuber according to their storage conditions.