Salicylic acid retards petal senescence in cut lisianthus (Eustoma grandiflorum 'Miarichi Grand White') flowers

The effect of exogenous salicylic acid (SA) on the vase life of cut lisianthus flowers was investigated. 'Miarichi Grand White' flowers were obtained from a commercial grower and were pulse-treated with a 0, 50, 100, 150 or 200 mg.L-1 SA solution containing 200 mg.L-1 8-hydroxyquinoline sulphate (HQS) and 5% (w/v) sucrose for 18 hours. As compared to distilled water (DW) as the control, the greatest delay in petals senescence was obtained in cut flowers pulsed with 100 mg.L-1 SA. Vase life of flowers increased by 4.5 days in the above mentioned treatment. The characteristics such as water uptake (WUP), relative fresh weight (RFW), protein concentration, proline accumulation, and activities of lipoxygenase (LOX) and superoxide dismutase (SOD) were measured in the 0 and 100 mg.L-1 SA treatments over the period of vase life. The WUP and RFW were obviously greater in the SA-treated flowers than in the control. Degradation of protein and accumulation of proline during vase life was shown to be suppressed by 100 mg.L-1 SA. The activity of LOX was gradually increased with progressing flower senescence, while the activity of SOD was declined. The flowers which had been pulsed with 100 mg.L-1 SA exhibited lower LOX and a higher SOD activities. Overall, the results suggest that SA can increase the vase life of lisianthus cut flowers by improving the antioxidant system and reducing damages caused by oxidative stress during senescence.