ClO2 Prolongs the Vase Life of Paeonia lactiflora ‘Hushui Dangxia’ Cut Flowers by Inhibiting Bacterial Growth at the Stem Base

Rapid wilting after harvest greatly decreases the ornamental and economic value of fresh-cut flowers. To determine how chlorine dioxide (ClO2) affects postharvest flower quality, Paeonia lactiflora ‘Hushui Dangxia’ cut flowers in bottles were treated with different concentrations of ClO2 (0, 25, 50, 75, and 100 mg L−1). Among the treatments, ClO2 75 (i.e., 75 mg L−1) decreased the bacterial growth and lignin content at the P. lactiflora flower stem base, while also decreasing the degree of flower stem vessel blockage. Additionally, the ClO2 75 treatment increased the relative fresh weight, water balance, soluble sugar content, soluble protein content, and antioxidant enzyme activities (superoxide dismutase, peroxidase, and catalase), but decreased the malondialdehyde content and ethylene release rate of P. lactiflora cut flowers. Thus, the aging of P. lactiflora flowers was delayed, thereby maintaining the cut flower quality. Furthermore, the vase life (i.e., ornamental period) increased by three days.