A survey of ethylene response in Dendrobium cut-flower hybrids

Export of Dendrobium cut-flower hybrids from Thailand has a problem of low quality at the consumer end because of their sensitivity to ethylene. However, there is no research on the ethylene response of various Dendrobium hybrids in Thailand. The objective of this study was to survey ethylene response to 35 cultivars of Dendrobium cut-flower hybrids in Thailand. The cultivars were divided by color into 9 groups: white, white-pink, purple-red, purple-red with white, purple-pink with white, purple-blue, white with purple lip/purple-pink, purple with strips on petal and green-yellow. They were fumigated with ethylene gas at 0.4 µL L^-1 for 24 h and the ethylene response was recorded every 6 h after being fumigated with ethylene (HAFE). It was found that all nine groups were highly to very highly sensitive to ethylene (6-12 HAFE) except for Dendrobium 'Kenny', Dendrobium 'Lucky', Dendrobium 'Yokon' and Dendrobium 'Jade Gold' which showed very low sensitivity or the least sensitivity (GROTERDAN24 HAFE). The senescence symptoms of open flowers were drooping, downward, tepal venation, yellowish at lip, and flower abscission while the symptoms of flower buds are yellowing, epinasty of peduncle, water soaking and abscission. Ethylene response of the inflorescence ranged from very tolerant to very sensitive. Both open flowers and flower buds of Dendrobium 'Kenny', Dendrobium 'Lucky', Dendrobium 'Yokon' and Dendrobium 'Jade Gold' were tolerant to ethylene at 0.4 µL L^-1. These results suggested that ethylene response in Dendrobium cut-flower hybrids in each cultivar was different. The research findings provided exporters the information for proper postharvest handling of Dendrobium cut-flower hybrids.