Effects of 1-methylcyclopropene on firmness and flesh browning in Pink LadyTMapples

SummaryPink LadyTM (Malus domestica Borkh. cv. Cripps’ Pink) is an important apple cultivar, which sometimes suffers unacceptable softening after storage and shipping for export. The effects of 1-methylcyclopropene (1-MCP) treatment after harvest on flesh firmness after storage and export were investigated. Fruit were treated with 625 nl l–1 1-MCP for 14 h at 20°C, cold-stored in air for 12 weeks or in a controlled atmosphere (CA; 2.5 kPa O2, 2.0 kPa CO2) for 18 weeks at 0°C, then held in air for 6 weeks at 0°C or 4°C to simulate export shipping. 1-MCP-treated fruit maintained firmness levels 3 – 13 N higher than untreated fruit, after air- or CA-storage and at both shipping temperatures. In actual export experiments, fruit were picked from 12 orchards for CA storage (16 weeks; 0°C) and export (6 weeks; 0°C; air or modified atmosphere) to the UK. The experiments were designed and analysed as four-phase experiments: orchard; treatment (1-MCP); storage; and export. In 2002, 1-MCP-treated apples (625 nl l–1; 24 h; and 20°C) were 16 N firmer than untreated fruit. In 2003, the difference was 7 N. In each year, 1-MCP-treated apples from all 12 orchards met an import standard of 90% of fruit with a minimum firmness of 69 N, whereas the untreated fruit from approx. threequarters of the orchards did not meet this standard. 1-MCP had a greater effect when applied to less mature fruit (i.e., with a lower starch score) in 2002; but, in 2003, the effect was independent of starch score. Flesh browning after storage and export was not affected by 1-MCP treatment, but by orchard and seasonal factors. In conclusion, 1-MCP treatment can facilitate the storage and export of Pink LadyTM apples without unacceptable softening.