Effect of ethephon and 1-MCP treatments on the vase life of cut 'Sansai Blue' Vanda

Vanda orchid flowers were shown to be sensitive to exogenous ethylene since the sixties of the 20th century. We have recently reported that pulsing cut Vanda 'Sansai Blue' orchid flowers with the ethylene action inhibitor, silver thiosulfate (STS), significantly extends their longevity, suggesting that endogenous ethylene regulates flower senescence. The present study examined the effect of an ethylene action inhibitor, 1-methylcyclopropene (1-MCP), on vase life of cut Vanda orchid flowers cultivar 'Sansai Blue', as an alternative to STS. We examined whether 1-MCP can protect the flowers from endogenous ethylene and from the increased endogenous ethylene produced in response to ethephon (an ethylene releasing compound). The following three treatments were applied: pulsing with 10 mu L L-1 ethephon for 24 h 200 nL L-1 1-MCP for 6 h, or 200 nL L-1 1-MCP for 6 h followed by pulsing with 10 mu L L-1 ethephon for 24 h. The ethephon treatment increased rates of ethylene production, respiration, decreased water uptake and enhanced the decrease in flower fresh weight. As a result, ethephon treatment significantly increased the rate of florets senescence, and decreased the vase life from 12 days in control flowers to only 5 days. 1-MCP treatment did not affect all the above mentioned parameters, and the vase life of 1-MCP-treated flowers was similar to that of control flowers. Pretreatment with 1-MCP prior to the ethephon treatment protected the flowers from the adverse ethephon effects, and the vase life of 1-MCP + ethephon-treated flowers reached 13 days without significant differences from the vase life of control flowers. Vanda orchids were sensitive to exogenous ethylene. The protective effect of 1-MCP treatment lasted for only one week after application.