Effect of 1-methylcyclopropene and methylenecyclopropane on ethylene binding and ethylene action on cut carnations

1-Methylcyclopropene (1-MCP), formerly designated as Sis-X, has been shown to be an effective inhibitor of ethylene responses in carnation flowers in either the light or the dark. The binding appears to be to the receptor and to be ''permanent''. A 6 h treatment at 2.5 nl l(-1) is sufficient to protect against ethylene, and 0.5 nl l(-1) is sufficient if exposure is for 24 h. As carnation flowers age, a little higher concentration appears to be needed. Most of the natural increase in ethylene production during senescence is prevented by treatment with 1-MCP. A closely related compound, methylenecyclopropane shows ethylene activity. A tritium labelled 1-MCP (60 mCi mmol(-1)) has been prepared. A higher specific activity is needed for more critical studies.