Leaf yellowing or petal senescence is the main postharvest disorder for many cut flowers. Plant hormones such as cytokinins are able to inhibit leaf yellowing in some cut flowers and potted plants. In our experiments, we applied thidiazuron aiming to delay leaf yellowing and 1-methylciclopropene (1-MCP) for inhibiting flower senescence of cut stock flowers during vase life. Cut flowers were pulse treated with water (control), 5 µM TDZ, 500 nL L-1 1-MCP or combinations 5 µM TDZ+500 nL L-1 1-MCP, 5 µM TDZ+500 nL L-1 1-MCP+10 µL L-1 ethylene or 10 µL L-1 ethylene. All treatments were applied for 24 h (pulse), except for the 1-MCP that was applied for 6 h. The effect of treatments was evaluated by chlorophyll determination, petal fall, leaf yellowing appearance, vase life and ethylene production.
Pulse treatment with TDZ was able to delay leaf yellowing in light during whole experimental period (30 days). During the first days after TDZ treatment, the chlorophyll b biosynthesis was strongly induced, after 5 days were the initial values, 3-fold higher while the total chlorophyll did not change. The TDZ stimulated ethylene production such as 1-MCP as soon as after 24 h. The ethylene production was found in cut flowers treated with ethylene, reaching 9 nl g-1 h-1 in leaves and 6.5 nl g-1 h-1 in detached flowers. The 1-MCP dramatically reduced the efficiency of TDZ even if the vase life of cut flowers was extended compared with controls.