Data concerned with the inhibition of ethylene (C[subscript]2H[subscript]4) biosynthesis and mode of action by pulsing carnations with silver thiosulfate (STS), (aminooxy)acetic acid (AOA), and malonate (MA) are presented. (Aminooxy)acetic acid at 12 [mu]mole/flower extended vase life to 15.1 days, STS at 1 [mu]mole/flower extended vase life to 15.3 days, and MA at 1 [mu]mole/flower shortened vase life to 8.8 days compared with 10.3 days for the water control. (Aminooxy)acetic acid and STS inhibited the activity of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase, and this resulted in a low ACC content and a low activity of the constitutive ethylene-forming-enzyme (EFE). The ultimate result of these metabolic events was that C[subscript]2H[subscript]4 biosynthesis was inhibited. Moreover, both AOA and STS decreased the respiratory rate as measured by CO[subscript]2 production. Malonate increased ACC synthase activity, and this increased the ACC content. Also, malonate increased respiration, which was unexpected. However, MA in combination with either AOA or STS reduced both C[subscript]2H[subscript]4 biosynthesis and respiration;Little ACC synthase activity existed in the upper portion of the petals, while the basal portion of the petals contained a higher ACC synthase activity. At the beginning of the vase-life cycle, ACC synthase activity was low. This was followed by a burst of activity at the climacteric, and this was followed by a decline before the death of the flowers. Ethylene-forming-enzyme activity was assayed by determining the maximum rate of C[subscript]2H[subscript]4 production. Flowers pulsed with AOA or STS showed low EFE activity related to C[subscript]2H[subscript]4 production, while the MA pulse treatment showed an increase of EFE activity at the climacteric;These results indicate that the inhibition of C[subscript]2H[subscript]4 biosynthesis and mode of action was caused by AOA and STS. Malonate pulse treatments need to be mixed with C[subscript]2H[subscript]4 biosynthesis inhibitors to inhibit C[subscript]2H[subscript]4 production and to preserve carbohydrates in the preservative solution. These results provided background information on the use of the preservatives for both inhibition of C[subscript]2H[subscript]4 biosynthesis and reduced use of carbohydrates.