CELL ULTRASTRUCTURE IN APPLE FRUITS IN RELATION TO CALCIUM CONCENTRATION AND FRUIT QUALITY

The post-storage quality of apple fruits was found to be related to the ultrastructure of the outer tissues of the apple and to the fruit mineral composition (Mahanty and Fineran, 1975; Fuller, 1976). Well preserved cell structure is dependent upon the integrity of the membranes which bound the organelles and the cytoplasm, and on the ultrastructure of the walls. Marinos (1962) found an association between calcium deficiency and the breaking up of the nuclear envelope, and the plasma and vacuolar membranes, in barley shoot apices. The important role of calcium in membrane structure and permeability was discussed by Bangerth (1973; 1974a, b).

Marinos (1962) noted changes in the appearance of walls, and the presence of cell wall gaps, in calcium-deficient tissue.

The observations described in the present paper support many of these findings.