Physiological and Biochemical Changes in Perianths of Oncidium Cut Flowers at Different Opening Stages

Key words: 
• Oncidium /
• flower senescence /
• cell membrane permeability /
• malondialdehyde /
• soluble sugar /
• soluble protein /
• amino acid

Abstract: The physiological and biochemical changes in perianths（ petals and sepals） of Oncidium cut flowers at different opening stages were observed. The observatons showed that the cell membrane permeability of petals increased slowly at the early stages of flower development,increased rapidly from pre-blooming stage to blooming stage and increased again after the initial stage of senescence. The malondialdehyde（ MDA） contents of petals and sepals fluctuated at the early stages of flower development,but after the initial stage of senescence,the MDA content increased dramatically in the petals but declined obviously in the sepals. The petals and sepals showed similar change of soluble sugar content,which increased slowly at the early stages of flower development and decreased slowly from the pre-blooming stage to the blooming stage. The soluble protein decreased generally in the petals but rose continuously in the sepals. Amino acid contents in the petals and sepals were gradually declined from the blooming stage to the senescing stage,and their proline contents also decreased after the blooming stage.