Effects of various nitrogen, phosphoric acid and potassium concentrations on growth and yield of the Nijisseiki pear under sand culture

Abstract

1. Growth, yield and quality of Japanese pears (Nijisseiki) as affected by the concentrations of nitrogen, phosphoric acid and potassium were observed under sand culture. The experiment was conducted for a four-year period with the same trees which were of non-bearing for the first three years and fruited only in the fourth year. The standard constitution of the cultural solution was 80ppm in each nutrient, and the only one of the three nutrients was varied so as to be 0, 20, 40, 80, 120 or 160 ppm in each treatment.
2. The optimum concentration of each nutrient for the vegetative growth of trees was found at 80 ppm or somewhat lower though it varied sometimes with tree age and fruit load.
3. Yield and fruit growth were most superior at 80ppm of each nutrient, while the solids content of fruit juice was highest at 120 or 160ppm of phosphoric acid and at 0 or 20ppm of potassium.
4. The number of seeds per fruit increased with an increasing concentration of potassium, promoting the growth of fruit.
5. From the standpoint of vegetative growth and fruit bearing, the optimum leaf content of nutrients seemed to be 2.0-2.2% N, 0.25% P and 1.8% K.