Effect of exogenous hydrogen peroxide or ascorbic acid on senescence in cut flowers of tree peony (Paeonia suffruticosa Andr.)

Tree peony (Paeonia suffruticosa Andr.) 'Luoyang Red' cut flowers were placed in separate vases filled with distilled water after pre-treatment with distilled water, 0.01 M H2O2, or 0.01 M ascorbic acid (ASA) for 12 h. We measured several morphological indices and physiological changes in the branches of flowers in each vase. H2O2 treatment accelerated the flowering and wilting of cut flowers of tree peony. The average vase-life was 3.0 d, which was 1.0 d shorter than that of the untreated control group (4.0 d; P <= 0.05). The maximum flower diameter was 14.0 cm, which was 0.7 cm larger on average than that of the control group (13.3 cm). Exogenous H2O2 also significantly increased superoxide dismutase (SOD) activity, catalase (CAT) activity, and malondialdehyde (MDA) concentrations in petals by 12.2%, 14.4%, and 11.5%, respectively. Exogenous ASA treatment extended the average vase-life of cut flowers of tree peony to 4.8 d, which was 0.8 d longer than that of the control group. This treatment also improved the uptake of water by flower branches and increased the maximum flower diameter (15.0 cm), which was 1.7 cm larger than that of the control group. Exogenous ASA reduced average SOD activities and MDA concentrations in petals by 7.9% and 6.7%, respectively. These findings showed that senescence in cut flowers of tree peony was closely related to membrane lipid peroxidation in the petals, and that exogenous anti-oxidants such as ASA could delay senescence in cut flowers of tree peony and improve their quality.