Abstract
Experiments were carried out to test the rest period of the three types of seed tubers using five varieties of potato, in relation to the spring culture. 1) Three varieties, Ojiro, Unzen, and Norin No. 1, had a short rest period of two months; Irish Cobbler, the longest period of four months; Wheeler, the medial one of three months. 2) The rest period of the summer grown seed tubers is longer than that of the spring grown seed tubers. The rest period of the fall grown seed tubers, however, is longer than either of them. A little difference in rest period is found in the varieties of the shorter rest period, while those of the longer rest period have much difference. 3) The varieties of the shorter rest period have a character of the faster process of emerging from the resting state than those of the longer one. The differences in emerging process are also found in the seed tubers; the spring grown seed tubers have the faster process than that of the summer ones. 4) In view of these properties of resting state of both the varieties and the seed tubers, the time to complete their rest period are as follows: [table] The results of these experiments suggest that, though the summer grown seed tubers of Irish Cobbler completing its resting state in January have been usually used for the spring culture up to now fall grown seed tubers, which have the shorter rest period and complete its state in February can be also used for the spring culture. (Contribution From the Laboratory of Plant Breeding Hyogo Agricultura College, No. 41)
