Suppression of ripening and induction of asynchronous ripening in tomato and avocado fruits subjected to complete or partial exposure to aqueous solutions of 1-methylcyclopropene

This study was designed to determine the effects of aqueous 1-methylcyclopropene (1-MCP) formulation applied as a brief, topical dip on the ripening of early ripening-stage tomato (Solanum lycopersicum L. ‘Florida 47’) and avocado (Persea americana Mill. ‘Hass’) fruits. Tomato and avocado fruits were subjected to either total or partial (approximately half of fruit surface) immersion in aqueous 625 μg L−1 1-MCP for 1 min and stored at 20 °C. Liquid-formulated 1-MCP strongly delayed ripening in both tomato and avocado fruit, and in tomato fruit exhibited efficacy comparable to that of gaseous 1-MCP (SmartFreshSM Quality System) applied at 500 nL L−1 for 9 h. Tomato fruit treated with liquid 1-MCP exhibited a strongly delayed ethylene climacteric, suppressed respiration, a reduction in the rate of softening, delayed and reduced accumulation of polygalacturonase activity and lycopene, and delayed changes in surface hue angle. Tomato fruit exposed to partial immersion for 1 min exhibited strong ripening asynchrony, with immersed and control fruit portions diverging significantly in all measured ripening parameters. The asynchronous ripening of partially immersed tomato fruit was observed independently of direct exposure of the stem-scar. Avocado fruit ripening was also delayed following a 1 min immersion in 625 μg L−1 1-MCP though less striking ripening asynchrony was observed in response to partial immersion. The results demonstrate the efficacy of relatively brief exposures to liquid-formulated 1-MCP on fruit ripening and illustrate that these formulations, designed to facilitate field or preharvest exposure to 1-MCP, may have postharvest applications as well.