Effect of sucrose at different concentrations and cold dry storage on vase-life of three ornamental Eucalyptus species

Abstract

Cut stems from the genus Eucalyptus are widely sold on World floriculture markets; however, there has been limited research into the optimal post-harvest requirements of most commercially significant species. Previous research has shown a range of responses to varying combinations of sucrose concentrations and time periods. In this study, we investigated the effects of a 2 h pulse of 20% sucrose, a 24 h pulse of 5% sucrose, 2% sucrose supplied continuously or 24 h dry storage at 3°C on vase-life of bud and flowering stems of E. lesouefii and E. yalatensis, and woody fruit stems of E. tetragona syn. E. pleurocarpa. Data indicated that 2% sucrose applied continuously was detrimental to the vase-life of all three species, significantly shortening the vase-life of E. tetragona syn. E. pleurocarpa and E. lesouefii compared to other treatments. The most successful treatment for E. tetragona syn. E. pleurocarpa was a 2 h pulse of 20% sucrose that resulted in a mean vase-life of 29 d, significantly longer than the control treatments (27 d). For E. lesouefii, a 24 h pulse of 5% sucrose resulted in a vase-life of 17 d, significantly longer than the control (15 d).The vase-life of E. yalatensis was 12- 15 d across all treatments, with none significantly better than the control. Symptoms of damage and senescence observed during the trials included "leaf blueing", bud and leaf softening, bud splitting, new growth desiccation and blackening. These symptoms could not be correlated to treatment. Differences in vase-life and leaf damage symptoms were found between plants within a species (grown from open-pollinated seed) indicating a genotype effect. This study indicates that for these three Eucalyptus species, post-harvest damage to leaves, buds, fruits and stems varies with treatment, genotype and species. The overall implications of this trial are that each species requires specific testing to determine its optimal post-harvest requirements.