ETHYLENE PRODUCTION, ACC CONTENT, PAL AND POD ACTIVITIES IN EXCISED SECTIONS OF STRAIGHT AND BENT GERBERA SCAPES

Gerbera cut flowers were kept in a holding solution of 5% sucrose, 100 ppm 8-hydroxyquinoline sulfate and citric acid at pH 4. After 7 d, se ctions 4 cm long were excised 10, 20, 30 and 40 cm (basal portion) awa y from the base of the inflorescence of straight and bent scapes and a nalyzed for ethylene evolution, ACC content, PAL (phenylalanine ammoni alyase) and POD (peroxidases) activities Ethylene concentrations were much higher in bent scapes than in straight ones and increased upwards from the base of the scape; ACC content was lower in the former and d id not increase upwards. POD activity was stimulated in bent scapes an d showed the same pattern as ethylene. PAL activity was significantly higher in the basal portion regardless of the curvature of the scape b ut bent scapes showed higher activities than straight ones. A potentia l senescence process involved in the ''stem break'' of gerbera is disc ussed.