Abstract
It is well known that the Chinese yam grown on sandy soils has good appearence and excellent quality, matures early, and is easily dug up at harvest. Therefore, it is one of the important crops in the sandy soil area of Tottori Prefecture.
This report deals with the results of some experiments on the productivity of the seed tubers in relation to their position in the mother tuber from which they were cut, or to their size, on the sandy soil.
1. Pieces of 56.3g each were taken from various parts (from top to base) of long mother tubers, and were planted as seeds. The pieces cut from the top portion of the mother tubers germinated earliest, made most vigorous early vine growth, and produced highest early yield. As the position of the seed piece was far apart from the top, its germination was delayed, its yield of new tubers became less, though there was little difference among several sections of the basal portions.
2. Whole tubers which had been cultivated for one year from the aerial tubers are prefered as seeds, since they are less likely to be rotted after planting than the cut pieces. Tubers of from 37.5 to 150g were compared on their productivity in early harvesting (middle of August). The result revealed that the larger the size of the seed tuber, the higher was the early yield of new tuber, within the range of the size tested. To obtain of good size (750g or more) in middle August, it was desirable to use the seed tubers of larger size (112.5 to 150g).
