Thidiazuron—a potent inhibitor of leaf senescence in Alstroemeria

The time to flower senescence and leaf yellowing in 20 cut flower cultivars of Alstroemeria was studied. In deionized water (DI), the time to abscission of the first petal ranged from 9 to 16 days. Time to leaf yellowing ranged from 5 to 18 days. These two processes proceeded independently so that in some cultivars leaf yellowing occurred long before flower senescence, and in others, much later. Thidiazuron (TDZ, N-phenyl-N′-1,2,3-thiadiazol-5-ylurea), a substituted phenylurea with cytokinin-like activity, markedly extended leaf longevity. TDZ was much more effective than two other substituted phenyl-urea compounds tested, in delaying leaf yellowing. A single 24-h pulse treatment with 10 μM TDZ prevented yellowing of isolated leaves for more than 2 months.