Influence of fertilizer treatment on apple fruit composition and physiology. 1. Influence on cell size and cell number.

Cell size and cell number in Sturmer Pippin apple fruits from trees receiving different fertilizer treatments have been determined. N fruit contained larger cells than U, P, NP, or NPK fruit of the same weight (K = 2 lb sulphate of ammonia, P = 4 lb superphosphate, and K = 1 lb sulphate of potash per tree per year: U = no fertilizer). Fruit from the latter four treatments did not show any consistent differences in cell size. In fruit of the average size for each treatment, differences in cell number per fruit were present,, N fruit containing fewer and larger cells than fruit from all other treatments. Cell number of NPK fruit was greater than that of U fruit. Mean cell volumes for fruit from the various treatments were significantly correlated with the incidences of internal breakdown in storage in each of three years. IS fruit of varieties Cox's Orange Pippin and Dunn's Favourite contained larger cells than U or SPK fruit of the same size. Delicious SPK fruit contained smaller cells than U or IS fruit), the cell sizes of which did not differ.