Young Boon Lee

Low-light conditions during winter cultivation reduce the postharvest quality of cut roses, highlighting the importance of effective postharvest management. This study investigated the effects of malic acid (MA) and sucrose (Su) vase solutions on the postharvest quality and vase life of cut rose (Rosa hybrida L.) ‘Candlelight’ grown under low-light conditions. Cut flowers were maintained in distilled water (DW), tap water (TW), 1% chrysal (CR), 50 mg·L⁻¹ malic acid (MA), 1% sucrose (Su), or 50 mg·L⁻¹ malic acid + 1% sucrose (MA + Su). MA resulted in the longest vase life, extending it by 22–29% compared with DW and TW, although a significant difference was observed only between MA and DW. It also maintained relatively high vase solution uptake and RFW and prevented basal stem browning. In contrast, Su reduced vase life by 40–43% compared with DW and TW despite increasing leaf carbohydrate content, whereas MA + Su resulted in a significantly shorter vase life than MA alone. Correlation analysis revealed that vase life was positively associated with RFW and flower diameter and negatively associated with non-photochemical quenching (NPQ), fluorescence decline ratio (Rfd), and the petal color parameters L* and C*. These findings suggest that MA treatment sustained vase solution uptake and relative fresh weight, thereby contributing to the maintenance of postharvest quality and prolonged vase life.

In this study, we investigated the effects of the substrate water content on potted kalanchoe (Kalanchoe blossfeldiana) in an export distribution simulation. Potted kalanchoe plants were treated either with the optimum substrate water content (OSW, 50-60%) or a low substrate water content (LSW, ≤ 20%) and the postharvest quality and shelf life were assessed at farm or wholesale, export, auction, and consumer stages. The shelf life of the LSW flowers was shorter than that of the OSW flowers by 36%. The primary reason for the short shelf life after the LSW treatment was an increase in leaf chlorosis. The plant height was shorter with the LSW treatment at all stages, while the plant width was longer before the export stage. The fresh and dry weights of the root with the LSW treatment were lower at all stages. The chlorophyll content and the Fv/Fm of the leaves were lower during the auction stage for the LSW treatment. The Fv/Fm of the OSW treatment and LSW treatment were 0.79 and 0.77, respectively, during the auction stage. The change in the size of the stomatal pores and complexes was higher for the LSW treatment at all stages, but this difference was not significant. The difference between the air temperature and the petal or leaf surface temperature did not differ between treatments at the auction stage and consumer stage. The correlation between the shelf life and plant height was positive for all stages. There was no correlation between shelf life and the temperature of the flowers or leaves on auction stage and consumer stage. At the end of the shelf life, there was a high positive correlation between the shelf life and the substrate water content (r = 0.8**), the number of flowers (r = 0.8**) or buds (r = 0.6**), and flowering rate compared to the shipment (r = 0.5*) at the consumer stage. The findings here indicates that the substrate water content affects the postharvest quality and shelf life of potted kalanchoe.

This study investigates the antifungal effect of slightly acidic electrolyzed water on Botrytis cinerea, an agent that causes gray mold to appear on the cut rose flower of the type known as 'Bubble Gum'. Petals were inoculated by spraying a spore suspension with 3 × 10 5 spores•mL-1 (1.2 mL per flower) which was then allowed to dry in air for an hour. The petal pulsing treatments used here were as follows: no treatment (NT, control) and HOCl treatments at concentrations of 0, 5, 10, 20, and 30 µL•L-1 sprayed for three seconds. The treatment with 30 µL•L-1 HOCl (27.8%) reduced B. cinerea by 71% compared to NT (94.6%) and by 68% compared to the 0 µL•L-1 HOCl (87.9%). The vase life of cut rose flowers was lowest in the NT and highest with 30 µL•L-1 HOCl. The disease incidence rate according to the visual index of B. cinerea decreased as the HOCl concentration was increased. The petal color did not differ among the treatments in terms of the L*, a*, and b* values, except for NT compared to the corresponding value before the postharvest treatment. NT showed the highest rate of color change as measured by the ΔE* value compared to 0 days, and the petal color remained unchanged to the greatest degree in the HOCl treatments. Electrolyte leakage from the petals was highest in NT, and there was no petal tissue damage after the HOCl treatments. The flowering rate was lowest in NT, and there were few differences among the treatments. There were no differences among the treatments in terms of the chlorophyll content, Fv/Fm, and stomatal size change rate of the leaf, indicating that the quality of the leaf was not affected. Thus, an immediate petal pulsing treatment with slightly acidic electrolyzed water is recommended to inhibit gray mold on cut rose flowers at 30 µL•L-1 HOCl just before postharvest storage. This treatment did not cause any apparent damage to the petals or leaves.