Improving Postharvest Quality and Vase Life of Cut Rose Flowers by Pre-harvest Foliar Co-applications of γ-aminobutyric Acid and Calcium Chloride

Rose flowers (Rosa hybrida L.) are highly perishable and have a limited vase life. This study evaluated the effects of preharvest foliar applications of γ-aminobutyric acid (GABA) and calcium chloride (CaCl), individually and combined, on antioxidant responses and vase life of cut Jumilia rose flowers. Treatments included foliar sprays of GABA at 0, 20, 40, and 60 mM and CaCl at 0, 0.75%, and 1.5%, applied in a factorial design within a completely randomized setup before harvest. Results showed GABA and CaCl interaction (especially, 60 mM GABA and 1.5% CaCl) significantly increased enzymatic antioxidants including superoxide dismutase, catalase, and peroxidase, as well as non-enzymatic antioxidants such as flavonoids, carotenoids, phenolics, and antioxidant activity in petals compared to control. SOD activity in roses, treated with CaCl (1.5%) and GABA (60 mM), peaked at 7.86 units. mg protein min, showing a nearly 2.93-fold increase over the control (2.68 units. mg protein min). A parallel trend was observed for CAT activity. These treatments also reduced petal malondialdehyde content and polyphenol oxidase activity. Protein content and vase life duration increased in all treatments. Plants treated with a combination of GABA (20 mM) and CaCl (0.75%), GABA (60 mM) and CaCl (1.5%), or GABA (40 mM) individually exhibited the longest vase life duration. The co-application of GABA and CaCl improved the antioxidant activity and postharvest quality of cut roses by reducing PPO activity and MDA contents, increasing protein content and prolonging vase life. This treatment is a potential postharvest strategy to improve antioxidant capacity and delay senescence in cut roses.