Characterization of Petal Senescent Types in Cut Dahlia and Extension of Their Vase Life by Treatment with Silver Thiosulfate Complex Followed by Glucose Plus Germicides

The vase life of cut dahlia (Dahlia × hortensis Guillaumin) flowers is generally short. Petal senescence is known to be divided into petal wilting, withering, and abscission. Petals with ongoing wilting were isolated from the inflorescence and supplied with water using 10 cultivars to clarify the type of petal senescence of dahlia. Based on the recovery of fresh weight and appearance of petals, senescent types could be categorized into three types: petal senescence in two, six, and two cultivars were categorized into abscission, abscission with withering, and wilting types, respectively. The pulse treatment with silver thiosulfate complex (STS) significantly extended the vase life of 7 out of 10 cultivars. Moreover, pulse treatment with STS followed by continuous treatment with GLA, which was comprised of glucose, isothiazolinone germicide, and aluminum sulfate, increased the relative fresh weight of the five dahlia cultivars more than pulse treatment with STS. Therefore, this combined treatment is available to extend the vase life of cut dahlia, irrespective of the senescent types.