Abstract
Experiments on the influences of 2.4-D upon the sweet botato plant under various conditions were carried out by the authors. The 1st experiment: Growth of sweet potato plant sprayed with 2, 4-D, its slip being planted in different ways of method, was examined. The 2nd experiment: Effect of 2, 4-D on the growth of sweet potato plant grown from the slip of different property was examined. The 3rd experiment: Growth and yield of sweet potato plant as affected by different amount of 2, 4-D applied at different gowing stage were observed. The results obtained were summerized as follows: (1) Injury of 2, 4-D upon the growth and yield were reduced by adopting the vertical planting method or by using the hardened slips. On the contrary, in case of horizontal planting method or using soft slips the injury of plant became severer. (2) Comparing various stages of the growth between each other, the sweet potato plant was found most noticeably suseceptible to the injury of 2, 4-D at planting stage. The data of the experiments showed the increment of weight in the top and root were highest when 2, 4-D was applied at 7th day or 14th day after planting slips. The dry matter percentage in tuberous root decreased, and besides the neck-portion of it became thick when sprayed with 2, 4-D.
