Fruit Tissue Injury by Frost to ‘York Imperial’ Apples1

Abstract

Abstract The effects of freeze injury occurring at anthesis upon young developing fruit were studied anatomically. Slight injury was characterized by separation of the hypodermis from the outer cortex during the initial stages of fruit growth. Necrotic tissues were adjacent to the main part of the injury. The internal cortical tissues and vascular bundles in the core line were uninjured. The basin or fruit apex was sensitive to freeze injury resulting in stylar abscission, abortive ovules, and large breaks in the cortical tissue. Growth distortions in the outer cortex were evident 21 days after injury, indicating sensitivity to frost and to the initiation of corking. Wound healing occurred 1 week after full bloom with the development of callus or proliferated tissues which united the wound areas.