Effects of postharvest application of salicylic acid and benzothiadiazole on cut rose (Rosa hybrida)

Rose (Rosa hybrida) is among the most important species sold as cut flower. Its vase life is quite short and ranges from 6 to 10 days, depending on postharvest conditions. Flower and leaf senescence is the main responsible for quality losses and strongly affects the marketability of this ornamental item. Salicylic acid is a plant hormone playing a key role in flowers senescence acting at different levels. The aim of this work was to evaluate the effects of postharvest treatments on the quality and on the vase life of cut-rose flowers. Cut roses (flowers and leaves) were treated for 24 h with salicylic acid – SA and with a commercial formulation containing benzothiadiazole – BTH, which is a functional analogue of the hormone. During vase life, chlorophyll a fluorescence was monitored non-destructively in leaves. Samples (leaves and petals) were collected at the beginning of the trial (T0) and after 4 (T4) and 7 (T7) days at 20°C and destructive determination of phenolic index was conducted. Results showed that SA treatment was effective in extending the vase life of roses but did not affect the phenolic content. On the other hand, BTH significantly increased the levels of phenols, especially in leaves, but, at the same time, it negatively affected the quality of stems, probably due to an impairment of water uptake.