Clo2 Treatment Delays Petal Senescence and Extends the Vase Life of Paeonia Suffruticosa ‘Luoyang Hong’ Cut Flowers

Mechanical damage and bacterial contamination of fresh cut flowers after harvesting can negatively affect the quality and longevity of cut flowers. In this study, the effect of different concentrations of the bactericide ClO2 (0, 0.025, 0.05, 0.075, and 0.1 g·L-1) on the quality and longevity of Paeonia suffruticosa ‘Luoyang Hong’ cut flowers was investigated. All treatments except for the 0.025 g·L-1 ClO2 treatment increased water uptake, membrane stability indices, and the activity of antioxidant enzymes such as superoxide dismutase and peroxidase, and inhibited stem-end bacterial growth in the cut flowers. Among all the treatments, the 0.1 g·L-1 ClO2 treatment showed the strongest effect to delay the senescence of cut flowers, increasing their vase life by up to 3 d more than that of the control. Bacterial isolation, scanning electron microscopy, and enzyme activity analyses confirmed that the 0.1 g·L-1 ClO2 treatment not only strongly inhibited bacterial growth, but also reduced the activities of lignin synthesis-related enzymes such as polyphenol oxidase, phenylalanine ammonia lyase, and peroxidase at the stem end of cut flowers. In addition, the 0.1 g·L-1 ClO2 treatment reduced the release of ethylene by regulating the expression of PsACO1, and affected ethylene transduction in cut flowers through regulating the expression of PsEIL3 and PsERF1. Therefore, the 0.1 g·L-1 ClO2 treatment might be used as a bactericide to enhance the vase life of P. suffruticosa ‘Luoyang Hong’ cut flowers.