Changes in Enzyme Activities of Perianth of Cut-flower Oncidium Orchid at Different Opening Stages

Key words: 
• Oncidium /
• peroxidase /
• superoxide dismutase /
• protease

Abstract: An attempt was made to determine the changes in enzyme activities of petals and sepals of cut-flower Oncidium orchid at different opening stages to study the physiological mechanism of senescence of orchid cut flowers. The results showed that peroxidase（ POD） activity continuously increased during the whole life span of the flower,and that superoxide dismutase（ SOD） activity rose to the peak at the pre-blooming stage and then decreased,while protease activity of the petals and sepals increased slowly,reached a maximum value at the pre-blooming and half-opened stage,then decreased sharply in the petals and sepals during the development and senescence of Oncidium orchid cut flower,respectively. This study reveals the changing modes of activities of three enzymes in the petals and sepals of cut flowers of Oncidium orchid at different opening stages. The results can be used to explain the mechanism of Oncidium flower senescence and provide the basis for varietal improvement of Oncidium orchid with longer vase life through genetic engineering in the future.