Abstract
The varietal differences in thickening of storage root was investigated under different supplies of nitrogen and potassium nutrients by gravel culture. Roots were divided into two different functional parts, storage root and feeder roots. In an experiment using 5 sweet potato varieties with a diverse variation of storage root yield and top growth. (1) Treatment with nitrogen-containing culture solution greatly affected the storage root yield and top growth of each varieties. (2) There was a significant negative correlation between dry weight of tops and nitrogen content in leaves when plants were at the similar level of nitrogen supply. (3) A varietal difference was found in the effect of abundant applications of potassium on the increase of storage root yield in the case of overluxuriant growth. (4) A close relationship was found between nitrogen content in leaves and dry weight of storage root; optimum nitrogen content in leaves for the production of storage root slightly varied among varieties at optimum top weight for the production of storage root.
