Changes in the chemical composition of apples during development, and near picking time

During the development of apples the most striking difference in mineral uptake is that between the potassium and calcium patterns. Potassium uptake continues throughout growth, being an essential constituent of the buffer system in the vacuole. Calcium uptake falls off appreciably after the initial period of cell division. It is suggested that the initial supply or availability of calcium in the tree may be of importance in determining the later development of physiological disorders. The mineral content of apples is not appreciably affected by normal variations in date of picking, although there may be small changes. The most obvious drift is a consistent late uptake of sodium.