Histological studies on the fruit development of pears as related to the nitrogen, phosphoric acid and potassium. II.

On the effects of three nutrients applied at different stages of fruit growth on the cell-division and cell-enlargement of fruit flesh of Nijisseiki

Abstract

1. With 6-year old treees of Japanese pears (Nijisseiki) under sand culture, two experiments were conducted separately at different stages of fruit growth. One was performed during the division period of flesh cells from March 20 (12 days before sprouting) to May 19 (fruit thinning time). The objective of it was to observe the effect of N, P₂O₅ and K₂O on the size of cells and their number per fruit in relation to fruit size. The data obtained on May 19 showed that non-application of any of the three nutrients retarded inclusively 20 to 37% of cell number per fruit, 4 to 12% of cell size, and consequently 17 to 21% of fruit size. Fruit growth at its beginning stage was more influenced by cell division than cell enlargement, the activity of cell division being inferior in the order of at N minus plot, P₂O₅ minus plot and K₂O minus plot.
2. Another experiment was carried out during the enlargement period of flesh cells from May 19 to Aug. 21 (harvest time), to investigate the effect of concentration of each nutrient on the cell size and fruit size. As the result, both cell size and fruit size were most superior at 80 or 160ppm N, at 80 ppm P₂O₅ and at 160ppm K₂O respectively among different plots of each nutrient. The lower the concentration of each nutrient than these values, the more inferior were both cell size and fruit size. The trend was most remarkable at N minus plot, followed by K₂O minus plot and P₂O₅ minus plot in the order.