Silver thiosulfate or water pretreatment, the former very effective in preventing ethylene effects in carnations, was applied to cut 'Sonia' roses, and followed by water or ethephon uptake, the latter to simulate ethylene effects.
Depending on quantities taken up (concentration times volume absorbed in light or dark), effects with either chemical alone or in combination were the following:
Ethephon alone. Very high conc (4000 ppm short, to 1000 ppm long duration): leaf desiccation, very rapid petal shedding.
High conc (1000 ppm short): rapid leaf and petal shedding, no desiccation.
Medium conc (250 ppm short): slower but complete shedding.
Low conc (60 ppm short): still slower, yet distinctly accelerated petal drop, no foliage shedding.
Very low conc (15 ppm short): slightly accelerated petal drop, compared with water controls.
Silver thiosulfate alone. Uptake rates in the light being too high, resulting in leaf damage, STS had to be applied in darkness, for a few hours; 0.2 mM silver nitrate + 0.8 mM sodium thiosulfate were safer to work with than 5 to 10-fold higher concentrations.
Combination. Silver-complex uptake low enough not to cause leaf damage, was sufficient to prevent all of the above ethephon effects (except at the very highest conc). Compared with water controls, silver pretreatment did not extend vase life, however.