Abstract
Growth process of directly planted sweet potato plant was examined from the physiological and internal morphological points of view. Seed potato directly planted in the field thickened itself into anomalous potato. Newly active cambium occured just on the outside of the old primary cambium in the seed potato at 40th day after plantating and produced a large number of cells. In the case of small thickness of seed patato, activity of the cambium was not great and lignification of cell wall progressed. Total nitrogen content of seed tuber gradually decreased as the spronts grew up until 80th day after plantating but after that time increased. Soluble nitrogen contents increased till 40th day and decreased till 80th day, on the other hand non-soluble nitrogen contents decreased till 40th day and increased a little after that time. The tendency of activity of β-amylase rather resembled to that of soluble nitrogen content.
