By: Alessandro Mataffo, Pasquale Scognamiglio, Boris Basile*
Department of Agricultural Sciences, University of Naples Federico II, 80055 Portici, Italy
Fruit cracking is a severe pre-harvest physiological disorder that affects many crops like cherry, grape, tomato, citrus fruits, fig, litchi, etc. (Khadivi-Khub, 2015). The damage induced by fruit cracking can be limited to the skin, but it can also be extended to the fruit flesh (splitting). Cracked fruits are no longer marketable for the fresh market and can be destined only to the transformation industry. In the worst cases, fruit cracking can also lead to rot infections (Peet, 1992) that make the fruit unsuitable even for transformation purposes (Simon, 2006). Several biochemical, anatomical, genetic, environmental, and agronomic factors can induce fruit cracking. Cherry (Prunus avium L.) is one of the most sensitive crops to this physiological disorder. There are mainly three types of cherry cracking that are classified depending on which part of the fruit is involved: i) the stem-end cracking that is visible as a circular scar near the pedicel; ii) apical-end cracking is characterized by small cracks located at the stylar end of the cherry; iii) side cracking consists of a longitudinal rupture on the side of the cherry.
Different cultivars may be more susceptible to different kinds of cracking, for example, heart-shaped varieties are particularly susceptible to the first two types of cracking, i.e., stem end-cracking and apical-end cracking, because of the deep stem cavity that facilitates water accumulation. The fruit increases in volume by absorbing the water on the surface and cracks. Some studies highlighted that the presence of water promotes the formation of micro-lesions on isolated samples of cuticle mainly due to a cuticle weakening. This kind of damage can occur even in the early stage of cherry development. Then the resulting suberification of the wound causes a significant loss of marketable value (Simon, 2006). In the worst cases, it is even possible that small wounds can increase in size and compromise the whole fruit (Knoche and Peschel, 2006).