Leakage of calcium, magnesium and potassium from discs of cortical apple fruit tissue was followed through fruit development and ripening. Leakage of potassium always exceeded that of calcium and magnesium and was little affected by the external presence of the divalent ions. Calcium and magnesium leakage was markedly increased by the external presence of either ion.
In tissue from both freshly picked fruit and that taken from storage, potassium and magnesium leakage increased when the fruit was in an advanced state of senescence, but calcium leakage decreased. During fruit development, leakage of all cations was closely related to availability as expressed in tissue concentration.
There was a marked increase in potassium leakage in association with the respiratory climacteric.
