Effects of 1-methylcyclopropene on ascorbate-glutathione cycle enzyme activities of postharvest Dendrobium 'Khao Sanan'

White orchids, especially Dendrobium 'Khao Sanan', are amongst the most important cut flowers in Thailand. However, owing to the effects of ethylene, such orchids experience rapid flower senescence. This presents a serious problem with regard to the exportability of quality flowers in the cut orchid industry. Following harvesting, 1-methylcyclopropene (1-MCP) is used to inhibit ethylene; thus, the aim of the present study was to determine the effects of 1-MCP on ascorbate-glutathione cycle enzyme activities in Dendrobium 'Khao Sanan'. We treated the inflorescences of white orchids with 0.5 mu L L-1 1-MCP for 3 h and/or 0.4 mu L L-1 ethylene for 24 h. The ascorbate-glutathione cycle underwent a significant increase in the activities of dehydroascorbate reductase (DHAR) and glutathione reductase (GR) in the 1-MCP-treated flowers. These results suggest that 1-MCP has the ability to stimulate certain antioxidant enzymes via the ascorbate-glutathione cycle in Dendrobium 'Khao Sanan', and may be used to retard senescence in this cultivar.