INTERACTIVE EFFECTS OF CA STORAGE, 1-METHYLCYCLOPROPENE AND METHYL JASMONATE ON QUALITY OF APPLE FRUIT

Abstract

The present study evaluated how post-harvest treatments with 1-methylcyclopropene (1-MCP) or methyl jasmonate (MJ) impact 'Fuji' and 'Braeburn' apple fruit tolerance to controlled atmosphere (CA) storage conditions. Fruit harvested from a commercial orchard in north central Washington were cooled to 0.5°C within 36 h of harvest and then stored in air or CA with 2 kPa O 2 + 0.05 kPa CO 2 ; 0.25 kPa O 2 + 0.05 kPa CO 2 or 2 kPa O 2 + 3 kPa CO 2 for up to 6 months. Fruit were treated with 2 mM MJ or 1 μl·L -1 1-MCP at harvest. Both CA conditions and 1-MCP treatment reduced ethylene production, improved maintenance of firmness and titratable acidity and reduced incidence of core flush during long-term storage compared with untreated fruit stored in air. Treatment with 1-MCP was as or more effective than low CO 2 -CA storage for reducing ethylene production and preservation of firmness and acidity for both cultivars. 'Fuji' apples stored in 3 kPa CO 2 developed internal browning (CO 2 -injury) while fruit stored in 0.25 kPa O 2 with 0.05 kPa CO 2 or air did not, regardless of 1-MCP treatment. 'Braeburn' apples also developed internal browning during air- or CA-storage, regardless of CO 2 concentration. Severity of browning in 'Fuji' and 'Braeburn' apples stored in 3 kPa CO 2 was not altered by previous 1-MCP treatment. However, browning severity increased by the 1-MCP treatment when 'Braeburn' fruit were stored in air or low CO 2 CA. Treatment with MJ reduced severity of CO 2 -injury in fruit of both cultivars stored in high CO 2 CA. The treatment with 1-MCP and storage in air or CA with 2 kPa O 2 and low (≤0.05 kPa) CO 2 may be a practical strategy for maximum retention of firmness and acidity with minimum development of CO 2 -injury in susceptible cultivars.