RESPONSES OF MCP-TREATED FUJI AND BRAEBURN APPLE FRUIT TO AIR AND CA STORAGE CONDITIONS

Ethylene is a plant hormone that regulates climacteric fruit ripening. Ethylene gas diffuses from fruit cells and tissues and can affect other fruit. Low temperature and controlled atmospheres (CA) with low oxygen and high carbon dioxide reduce ethylene production and action, as well as slowing ripening and loss of optimum fruit quality. MCP (1-methylcyclopropene) is a new tool for the management of ethylene action/production by climacteric fruit including apple. This compound is an ethylene action inhibitor that prevents plant tissues from responding to ethylene by combining with ethylene receptors (Sisler and Blankenship, 1996; Sisler and Serek, 1997). MCP gas applied at harvest delays ripening, improves storage life and prevents superficial scald and other physiological disorders in many apple cultivars including Delicious, Granny Smith, Fuji and Gala (Fan et al., 1999a, Fan et al., 1999b). For many cultivars, treatment with MCP is most effective when fruit are harvested at CA maturity and MCP is applied soon after harvest. Fuji and Braeburn apples fruit are susceptible to internal browning caused by exposure to high CO2 during storage (Elgar, et al., 1998, Argenta et al., 2000). Factors contributing to development of CO2 injury in these cultivars include maturity at harvest, watercore, CO2 concentration in storage, and the duration between harvest and imposition of CA conditions