FACTORS AFFECTING THE RHYTHMIC PRODUCTION OF COB2S IN TROPICAL ORCHIDS

Abstract

The rhythmicity of respiration in orchids does not show a clear relationship to the fragrance of the flower. Higher reepiratory peaks were, however, observed in scented flowers.

2. Light has an effect on the peak of the rhythm. Except Vanda 'Tan Chay Yan' , the respiratory rhythm of the following orchids namely Arachnis 'Maggie Oei', Aeridachnis 'Bogor' hybr, Oncidium haemtochilum and Vanda 'Rudy Prince' , were lower under continuous darkness. The peak renched tha same magnitude when returned to light.

3. Ethrel (5 ppm) dampened of the amplitude of rhythm. This inhibitory effect can be released following the withdrawal of ethrel. Greater inhibitory effect on amplitude of rhythm was observed with ethrel at higher concentration (50 ppm and 100 ppm). The inhibitory effect cannot be released. Similar action was observed when low concentration of ethrel was supplied for a long -duration.

4. Peroxidase activity of Vanda 'Tan Chay Yan' flower decreases with the fading of the flower.

5. Anthocyanin content of Vanda 'Tan Chay Yan' flower increased during the senescence of the flower induced by ethrel, depollination and self-pollination.