Stomata are key factors in prolonging the postharvest fresh-keeping period of carnation under a high-voltage electrostatic field

The effect of a high-voltage electrostatic field on postharvest preservation of carnation (Dianthus caryophyllus L.) was studied. The morphological indexes such as cut flower morphology, colour char-acteristics, flower weight, water content, stomatal traits (including stomatal closure ratio (SCR) and stomatal size), and physiological indexes such as chlorophyll, anthocyanin, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), malondialdehyde (MDA) were recorded in the whole process by setting field intensities of 10 kV · m^–1, 30 kV · m^–1 and the control group (CK) (0 kV · m^–1). The results showed that the vase period of 10 kV · m^–1 treatment was significantly increased, which was 1.52 days longer than that of CK, with consequent effects on flower colour brightness. Also, the effect on flower colour brightness was obvious. Compared with CK, at 10 kV · m^–1, anthocyanins increased by 8.1%, which improved flower colour brightness, and SOD activity increased by 11.2%, indicating reduced oxidative stress and better maintenance of flower weight and water content. Interestingly, the SCR of 10 kV · m^–1 was 4.85 times higher than that of CK, with a decrease of 9.4% in stomatal length and 10.68% in stomatal width. To sum up, 10 kV · m^–1 can prolong the vase life of carnation significantly and may delay the flower wilting time by adjusting the stomatal opening-closing ratio. The research provides a new idea for the fresh-keeping technology of cut flowers.