INCIDENCE OF PHYSICAL DAMAGE ON PEACH AND NECTARINE SKIN DISCOLORATION DEVELOPMENT - ANATOMICAL STUDIES

Skin discoloration (SD) formation in peach [Prunus persica (L.) Batsch ] and nectarine [Prunus persica (L.) Batsch, var. nectarine]was relate d to physical damage (abrasion) to the fruit during fruit handling (ha rvest and hauling operations) within the orchard and during transport to the packinghouse. Vibration and rubbing treatments increased SD for mation indicating that tissue damage is involved in SD formation. Anat omical studies comparing sound and SD-injured tissues done by scanning electron and light microscopy indicated that very-low-intensity physi cal damage could induce brown and/or black spots because of cell disru ption in the epidermal and hypodermal layers. The fact that injury was specific to the exocarp tissues (cuticle, epidermis, and hypodermis), and that mesocarp tissue located below the exocarp cells remained sou nd and turgid, indicated that abrasion injury is associated with SD. S imilar types of visible and anatomical injury characteristics were ind uced by a rubbing treatment, demonstrating that physical abrasion dama ge affecting just exocarp cells was enough to induce SD.