CULTIVAR, FLOWER STAGE, SILVER THIOSULFATE, AND BA INTERACTIONS AFFECT PERFORMANCE OF POTTED MINIATURE ROSES

Experiments were conducted to study the interaction of cultivar, flower stage, silver thiosulfate (STS), and BA on flower senescence and leaf abscission in greenhouse grown potted miniature roses. plants of Rosa L. 'Meijikatar' (Orange Sunblaze) and 'Meirutral' (Red Sunblaze) were sprayed with several concentrations of STS and BA in factorial combination. In winter, plants were sprayed with STS at 0 or 2 mM and BA at 0, 0.02, 0.04, 0.11, 0.22, or 0.44 mM. In spring, flowers at three stages of development were sprayed with STS at 0, 2, or 3 mM, and BA at 0, 0.02, 0.04, 0.22, or 0.44 mM. One day after treatment in both experiments, plants were placed in darkness at 16C for 4 days to simulate shipping, and then they were evaluated in a controlled environment at 21C. Poststorage floral longevity (PSFL) was longer far 'Meirutral' than for 'Meijikatar' plants, regardless of chemical treatment or flower stage. Flowers that were in the bud stage (stage 1) before simulated shipping lasted longer than flowers showing color (stages 2 and 3), regardless of cultivar or chemical treatment. Combinations of STS and BA did not increase PSFL compared to STS alone. Plants treated with 2 or 3 mM STS exhibited longer PSFL than nontreated plants; however, 2 and 3 mM were about equally effective. STS at 4 mM was phytotoxic in a preliminary experiment. Applying BA alone did not affect PSFL, but did improve postharvest flower opening on 'Meijikatar' plants about the same as STS applied alone. The large flowering cultivars represented by 'Meijikatar' and 'Meirutral' appear to be nonresponsive to BA. A star-shaped malformation was induced on 'Meijikatar' and 'Meirutral' plants by simulated shipping and was not prevented by STS or BA. Chemical name used: N-(phenylmethyl)-1H-purin-6-amine (BA).