Effects of pre-cooling and chlorine on post-harvest quality ofcut roses (Rosa hybrida L.)

ABSTRACT: The aim of this study was to quantify the vase-life and water relations of cut roses in response to pre-cooling and different concentrations of chlorine in the hydration solution. Cut ‘Valentine’ roses were stored dry at 4oC or 25oC for 24h immediately after harvest and then placed in vase-solutions containing 0, 50, 100 or 150 µl l-1chlorine provided as sodium hypochlorite. The results showed significantly higher water loss in cut flowers dry stored at 25°C in the first 24 h after harvest compared with that in cut flowers dry stored at 4°C. Acombination of dry storage at 4oCand inclusion of 50µl l-1chlorine in the vase-solutionextended vase-life by 6.1 d over the control (25oC and 0 µl l-1chlorine). Vase-solutions containing chlorine showed reduced microbial counts compared with control. Results suggest that vase-life improvements are achieved through (1) a reduction in water loss from cut stems and leaves during pre-cooling and (2) a reduction in bacterial populations present in the vase-solution. This was associated with an increase in water uptake and relative fresh weight of cut stems without any toxicity to leaves. The results also revealed that only two of eight rose cultivars showed toxicity to leaves in response to 50 µl l-1chlorine, suggesting that toxicity in response to effective chlorine concentration is cultivar dependent.