Influence of different concentrations of 1-methylcyclopropene and times of exposure on the quality of 'Galia'-type melon harvested at different stages of maturity

This study evaluated the influence of different 1-methylcyclopropene (1-MCP) concentrations (150, 300 or 450 nl l^-1) applied for 6, 12 or 24 h at 20°C on 'Galia' type melon (Cucumis melo L., reticulatus cv. 'Trooper'), harvested at three stages of maturity, based on epidermal colour: green (∼ 116 h° [Hue angle]); green/yellow (∼ 105 h°) or yellow (∼ 90 h°), and stored for 15 d at 5°C then 3 d at 20°C. The optimal treatment with 1-MCP to suppress ripening of fruit harvested at the green/yellow stage of maturity was 300 nl l^-1 for 24 h at 20°C, as evaluated by delayed colour development, retention of firmness, and low weight loss. This treatment also significantly reduced chilling injury (CI) and the development of decay, compared with non-treated fruit, or fruit treated with 150 nl l^-1 1-MCP. However, 1-MCP did not suppress senescence in fruit harvested at the yellow stage of maturity, as evaluated by external and internal quality parameters. 1-MCP did not affect total soluble solids contents. When fruit was harvested at the green stage, 450 nl l^-1 1-MCP reduced the rate of post-harvest ripening significantly, resulting in fruit of unacceptable colour development and firmness. 1-MCP delayed by 8-9 d the onset of the climacteric peak of CO₂ production and ethylene evolution in fruit harvested at the green/yellow stage of maturity. The quantities of CO ₂ and ethylene production in 1-MCP-treated fruit were lower than those in controls.