The Relationship between the Morphology and Structure and the Quality of Fruits of Two Pear Cultivars (Pyrus communis L.) during Their Development and Maturation

The flavour and nutritional values of pears are appreciated by consumers worldwide, who, however, demand specific fruit quality, that is, attractive appearance, firmness and flavour, and health safety as well as long-term shelf life and storability. Pear cultivars differ in terms of the above-mentioned traits; therefore, we undertook investigations to demonstrate the differences in structure of fruits of two pear cultivars that determine fruit quality in its broadest sense. The micromorphology, anatomy, and ultrastructure of "Clapp's Favourite" and "Conference" fruits in the fruit set stage and in the harvest maturity stage were investigated under light microscope and scanning and transmission electron microscopes. The fruits of "Clapp's Favourite" and "Conference" in the fruit set stage exhibited distinct differences in the values of anatomical parameters only. Substantial differences in fruit structure were observed in the harvest maturity stage. The analyses indicate that firmness and durability of pear fruits are largely influenced by the presence of russeting, the proportion of closed lenticels and number of stone cells, and the content of starch grains and tannin compounds. The thickness of the cuticle and presence of epicuticular waxes as well as the number of lenticels and the number and depth of microcracks play a minor role.