COOLSTORAGE ENHANCES ETHYLENE PRODUCTION AND REDUCES VASE LIFE OF CARNATION FLOWERS

Cut flowers are typically coolstored for varying periods following harvest and subsequently may be exposed to large temperature fluctuations, particularly during transit. This investigation determined the influence of low temperature coolstorage and silver thiosulphate (STS) on subsequent ethylene production and vase life duration of carnation (Dianthus caryophyllus L. cv. Scania) flowers. Carnations were coolstored for 1, 2, or 5 days at 2-degrees-C and then transferred to 20-degrees-C. Coolstorage for 5 days accelerated the onset of ethylene production by 1.9 days and the onset of peak ethylene production, which occurred 1.5 days earlier than control flowers. The total number of days of ethylene production was c. 4 days for all treatments. Peak ethylene production from flowers coolstored for 5 days was 150 nlitre/flower per h greater than control flowers. A linear relationship was established between total ethylene production and the duration of coolstorage. The increased ethylene production induced in flowers coolstored for 5 days reduced the vase life by 14%. Silver thiosulphate was applied before and after 5 days of coolstorage at 20-degrees-C. The application of STS prevented overshoot ethylene production and resulted in an approximate three-fold increase in vase life for flowers treated with STS before coolstorage and an approximate two-fold increase for flowers treated after coolstorage. This study has established that coolstorage and subsequent warming of carnations results in a surge of ethylene which is earlier and greater than normally associated with senescence. This overshoot ethylene reduces the vase life of cut carnation; flowers but can be overcome by the application of STS.