Reduction of ethylene-induced physiological disorders of carrots and iceberg lettuce by 1-methylcyclopropene

Whole carrots (Daucus carota L.) and midrib tissues of iceberg lettuce (Lactuca sativa L.) were treated with 42 mu mol.m(-3) MCP, then exposed to ethylene. Exposure to 42 mu mol.m(-3) ethylene at 10 degreesC increased isocoumarin content approximate to 40-fold in both peel and pulp of nontreated carrots within 4 days, but treatment with MCP for 4 hours at 20 degreesC before exposure to ethylene prevented isocoumarin accumulation. Ethylene-induced acidity loss and respiration rate increase in carrots were also prevented by MCP treatment. Ethylene treatment (126 mu mol.m(-3)) of lettuce at 6 degreesC had induced russet spotting >5 % to 10 % of the midrib tissue by day 3 and 30 % to 35 % by day 9, while pretreatment with MCP for 4 hours at 6 degreesC prevented development of russet spotting. The results indicate that ethylene-induced physiological disorders and quality loss in carrots and iceberg lettuce can be prevented by MCP treatment prior to exposure to ethylene. Chemical name used: 1-methylcyclopropene (MCP).