Chlorine dioxide treatments extend the vase life of exported cut roses

This study investigated the effect of applying chlorine dioxide (ClO₂) on the vase life of exported cut roses. The roses (Rosa hybrida L. ‘Beast’) were treated in a holding solution (HS) treatment of tap water (TW, control), distilled water (DW), 2% sucrose, 4 µL·L^-1 ClO₂, 4 µL·L^-1 ClO₂ + 2% sucrose, 200 µL·L^-1 8-hydroxyquinoline-5-sulfoonic acid (8-HQS) + 2% sucrose, and a pulsing solution (PS) treatment of 50 µL·L^-1 ClO₂ for 10 seconds. An HS of 4 µL·L^-1 ClO₂ or 4 µL·L^-1 ClO₂ + 2% sucrose and PS of 50 µL·L^-1 ClO₂ extended vase life 0.3 to 2.6 days more than the control (TW and DW), and the effect was greatest in PS. Initial weight was maintained until day 6 after treatment in an HS of 8-HQS + sucrose and sucrose, and day 8 after treatment in an HS of TW, DW, a PS of 50 µL·L^-1 ClO₂, and a PS of 50 µL·L^-1 ClO₂ + an HS of 4 µL·L^-1 ClO₂ with sucrose, and day 10 after treatment in HS of 4 µL·L^-1 ClO₂ and ClO₂ + sucrose. Vase solution uptake was higher in a PS and HS of ClO₂ than in sucrose and 8-HQS, respectively, 6 days after treatment. Bacteria in the vase solution without stems were detected continuously in the HS of TW, DW, and sucrose at 1.4 × 10⁴, 3.8 × 10⁴, and 1.4 ×10⁵ CFU/L, but not in the HS of ClO₂, ClO₂ + sucrose, and 8-HQS + sucrose 6 days after treatment. Bacteria in the vase solution with stems were detected in TW, DW, and sucrose at levels of 8.0×10⁴, 1.4×10⁵, and 6.8×10⁵ CFU/L, respectively, 6 days after treatment, but the sterilization effect of ClO₂, ClO₂ + sucrose, and 8-HQS + sucrose continued until 8 days after treatment. Treatment with an HS of 4 µL·L^-1 ClO₂ + 2% sucrose or a PS of 50 µL·L^-1 ClO₂ for 10 seconds in an export container was simulated in the laboratory for 2 days to a cooperative sorting facility from a rose greenhouse and then for 4 days to an auction market in Japan from a cooperative sorting facility in Korea. The vase life of roses in HS + HS, HS + TW, PS + TW, PS + PS, and TW + HS was 18.7, 18.0, 17.7, 17.2, and 14.3 days, respectively. The relative fresh weight was the lowest in the TW + HS at 2 days after treatment. Therefore, for the export process of cut roses, HS of ClO₂ + sucrose and PS of ClO₂ were effective for 2 days after harvest, and HS + HS maintained both the sterilization effect in the vase solution and a high relative fresh weight.