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, sections 4 cm long were excised 10, 20, 30 and 40 cm (basal portion) away from the base of the inflorescence of straight and bent scapes and analyzed for ethylene evolution, ACC content, PAL (phenylalanine ammonialyase) 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 did not increase upwards. POD activity was stimulated in bent scapes and showed the same pattern as ethylene. PAL activity was significantly higher in the basal portion regardless of the curvature of the scape but bent scapes showed higher activities than straight ones. A potential senescence process involved in the ''stem break'' of gerbera is discussed.