Control of ethylene responses in avocado fruit with 1-methylcyclopropene

Mature avocado fruit (Persea americana Mill. cvs 'Ettinger', 'Hass', 'Reed' and 'Fuerte'), harvested during the commercial harvesting season, were treated with various concentrations of 1-methylcyclopropene (I-MCP) for 24 h at 22 degrees C and after ventilation, were exposed to 300 mu l l(-1) ethylene for 24 h at 22 degrees C. The fruit were then stored at 22 degrees C in ethylene-free air for ripening assessment. Ethylene production, firmness, cellulase (endo-l,4-beta-glucanase) and polygalacturonase activity, as well as color change in 'Hass' fruit, were monitored during storage. 1-MCP was found to inhibit ethylene-induced ripening of avocado fruit at very low concentrations. Treatment for 24 h with 30-70 nl l(-1) I-MCP delayed ripening of avocado fruit by 10-12 days, after which the fruit resumed normal ripening. It is suggested that I-MCP is a potent inhibitor of avocado fruit ripening which exerts its effect via inhibition of ethylene action. (C) 2000 Elsevier Science B.V. All rights reserved.