Efficacy of liquid 1-methylcyclopropene to delay ripening of 'Bartlett' pears

1-Methylcyclopropene (1-MCP) has been a useful tool to extend the postharvest life of 'Bartlett' pears, but fruit response can be highly variable due to competition with ethylene. Application of liquid 1-MCP after harvest was tested to determine its efficacy as compared with gaseous 1-MCP. Fruit harvested from Sacramento and Lakeport, California at early-, mid- and late- commercial harvest maturity were treated with 0.6 μL L−1 gaseous 1-MCP at 0 °C for 24 h or dipped for 0, 15, 30, 45 or 60 s in 250, 500, 750 or 1000 μg L−1 1-MCP in four experiments across three years of study. After treatment, pears were exposed to ethylene or kept in cold storage at 1 °C for 5 weeks before ripening at 20 °C. Treatment with liquid 1-MCP delayed pear ripening as evidenced by delayed softening for a minimum of 6 d compared to the control fruit, delayed the increase in respiration and ethylene production rates, and reduced respiration and ethylene production rates. Treatment was effective in a concentration- and dip time-dependent manner. Overall, dipping in 1000 μg L−1 liquid 1-MCP for 60 s was the most consistent treatment among years and locations; however, the resulting time to ripen at 20 °C could be too long for some commercial applications. Treatment at 500 μg L−1 liquid 1-MCP is recommended for 'Bartlett' pears as this dose controls the ripening process, and provides consistent response for mid- and late-maturity fruit. A postharvest evaluation of a liquid formulation of 1-MCP provided a more consistently effective treatment for 'Bartlett' pears (Pyrus communis) than the current gaseous treatments.