Effects of exogenous ethylene and ethylene inhibitor on longevity and petal senescence of Sweet Osmanthus

Sweet Osmanthus (Osmanthus fragrans), an evergreen tree of the Oleaceae family, is of great ornamental and economic value because its flowers emit a very strong, but pleasant fragrance. Flowers were harvested and treated with combinations of ethephon (ETP) and silver thiosulphate (STS), to test whether ethylene inhibitors at the initial stage of blooming affected vase life. Longevity of petals treated by STS was prolonged, whereas ETP treatments at concentrations above 50 mg/L significantly accelerated petal senescence. Vase life of cut Osmanthus flowers treated with STS was 7 d while that of the control was 5 d. Longevity of flowers treated with ETP was reduced by 3 d compared to the untreated control. Moreover, treatment with high concentrations of ETP (400 mg/L) significantly restrained petal expansion and rapidly caused wilting. Pre-treatment with 1 mM STS for 6h, followed by treatment with 200 mg/L ETP for 24h reduced the vase life of the cut flowers. ETP treatment caused a dramatic decrease of protein content and superoxide dismutase (SOD) activity, and an increase of peroxidase (POD) activity. However, all these physiological parameters were maintained by STS treatment indicating that flowers of Sweet Osmanthus are ethylene-sensitive and that ethylene inhibitors can contribute to prolonging their vase life.