FRUIT CRACKING IN SWEET CHERRIES (PRUNUS-AVIUM L) - SOME PHYSIOLOGICAL-ASPECTS - A MINI REVIEW

Models based on recent advances in cell and cell wall structure describing the structure and function of the different tissue types occurring in the sweet cherry fruit are discussed with regard to fruit cracking. Tissues include the fruit cuticle, the dermal layers and the parenchymatous tissue. From water supplied through the vascular system, the fruits' parenchymatous cells build up tensile forces acting on the skin from inside the fruit. Additional osmotically moved water from a wetted fruit surface brings about degradation of the dermal cell walls. This causes leaching of the vacuolar contents and loss of the enclosing structure of the dermal layers. The fruit cuticle acts as a semipermeable membrane in this process, while the osmotically active solution is the apoplast fluid. A combination of the tensile forces acting on the fruit surface from inside the fruit and the loss of bearing structure of the fruit skin causes fruit cracking. This model offers explanations for many of the contradictory results obtained in experiments relating to sweet cherry fruit cracking, and suggests knowledge on which further studies of the problem should be based.