Antimicrobial Effect of Slightly Acidic Electrolyzed (HOCl) Water on Botrytis cinerea of Cut Rose Flowers

Abstract

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 × 105 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.