exogenous putrescine delays senescence of lisianthus cut flowers

the anti-senescence biogenic polyamines (pas) putrescine (put), spermidine (spd) and spermine (spm) are involved in plant growth processes and responses to stress. the physiological mechanism of exogenous put to affect the senescence of cut lisianthus flowers during vase life was investigated. fresh cut lisianthus flowers were treated with distilled water (control), 0.5, 1 and 2 mm put and then held at 25 ◦c up to 12 days. exogenous put supply at 2 mm extended vase life, which was associated with reduced electrolyte leakage and mda content. put treatment also reduced activity of lipoxygenase (lox), is responsible for membrane lipid peroxidation. put treatment also enhanced activities of catalase (cat) and ascorbate peroxidase (apx) and decreased h2o2 accumulation during vase life. thus, exogenous put supplycould maintain membrane integrity by increasing antioxidant system activity, thereby retarding the senescence of cut lisianthus flower during vase life.