Action of abscisic and gibberellic acids on senescence of cut gladiolus flowers

The gladiolus flower is classified as insensitive to ethylene. Thus, the signals that initiate senescence are poorly understood. This study evaluated the role of abscisic and gibberellic acids on postharvest senescence of 3 cultivars of cut gladiolus flowers (Gladiolus grandiflora Hort.). Stalks were harvested and placed in test tube containing 100 mL distilled water or an aqueous solution of abscisic acid (100 and 150 mu M ABA), gibberellic acid (100 mu M GA(3)), and fluridone (1 mM) for 24 h. Subsequently, flower stalks were placed in a test tube with distilled water, and the following variables were determined: stem longevity, fresh weight change, water uptake rate and transpiration rate during the vase life, as well as membrane stability index and lipid peroxidation in 5 stages of flower development. In another experiment, the florets were removed by cutting down the pedicel. After removal, florets were placed in a beaker containing 10 mL distilled water or the following solutions: 100 or 150 mu M ABA; 100 mu M GA(3); 1 mM fluridone; and 100 mu M ABA + 100 mu M GA(3), followed by immersion in distilled water after 24 h in each treatment. Fresh weight change and transpiration rate of florets were assessed every 24 h. Abscisic acid is involved in the induction of senescence-related events in gladiolus flowers, such as high loss of membrane stability and abnormal flower opening. GA(3) regulates the action of ABA in the maintenance of cell membrane and opening of gladiolus flowers.