Abstract
1. The optimum concentrations of nitrogen, phosphoric acid, and potassium in the sand culture solutions of grapes (variety: Delaware) were as follows:
That is, bearing trees seemed to require more quantitative phosphoric acid and potassium than nonbearing trees, though rather less nitrogen
. 2. When the number of clusters on a tree were the same, the increased concentration of phosphoric acid induced an increase in number of berries of a cluster, thus it resulting in the increased weight of a cluster.
3. With the increased concentration of potassium, the ratio of fruits to foliage increased in weight. But, the high concentration beyond a certain degree caused the reduction of fruit yield and also that of foliage growth.
4. The result of leaf analysis of bearing and non bearing trees at the optimum concentrations of the three fertilizer elments were as follows:
