1-METHYLCYCLOPROPENE INHIBITS ETHYLENE ACTION IN CUT PHLOX FLOWERS

Phlox (Phlox paniculata cv. Rembrandt) flowers were found to be very s ensitive to ethylene. Exposure to ethylene enhanced flower abscission in a concentration-dependent manner, with 50% abscission attained afte r treatment with 1 mu l l(-1) ethylene for 12 h. As a result, ethylene also reduced the number of open flowers on the stems throughout their vase life. A 6-h pre-treatment with a volatile inhibitor of ethylene action, 1-methylcyclopropene (1-MCP), completely inhibited the ethylen e-induced flower abscission and hence the reduction in the number of o pen flowers on the stems. 1-MCP was maximally effective in inhibiting the ethylene response at a low concentration (25 nl l(-1)) and had no visible toxic effects, even at 500 nl l(-1). The effects of 1-MCP on f lower abscission were comparable to that of a pulse treatment with sil ver thiosulfate (STS). We therefore suggest that it may serve as an al ternative to the commercial treatment of phlox flowers with STS, the l atter being an environmental hazard.