Pre-Harvest Chemical Compounds Influence Lily (Lilium × elegans) Leaf and Flower Indigenous Phenols, Flavonoids and Gibberellic Acid Levels

Abstract

The global cut flower industry, including lilies, represents a highly promising investment. Therefore, improving the quantity and quality of these commercially significant flower species is crucial. The objectives of this study were to (1) evaluate the influence of different pre-harvest chemical compounds on endogenous GA3, phenol, flavonoids and total antioxidants levels on the leaf and petals parts of Longiflorum-Asiatic (Lilium × elegans cv. Cevennes, yellow) lily and to (2) assess the effect of these compound on the flower quality component. The study was conducted over two cycles in both greenhouse and laboratory settings. Lily bulbs were transplanted into 10 L pots and grown for 70 days. Treatments were applied by spraying twice with a five-day interval on the flowers still on the plants and not yet fully opened. The treatments included 8-hydroxyquinoline sulfate (8HQS) at 100, 200, and 400 mg L−1; salicylic acid (SA) at 100 and 200 mg L−1; SmartFresh™ at 1 and 2 mg L−1; Harvista™ at 150 mg L−1; GA₃ at 50 mg L−1; and a control (water). The lily stems were harvested when one of the flowering buds began to open but was not fully opened. A post-harvest assessment was conducted in the laboratory at room temperature (20 ± 2 °C). The results showed that the lily leaf had a much higher endogenous concentration of GA3 (256%) and lower concentrations of total phenols (22%), flavonoids (28%), and antioxidant activity (14%) when compared to flower petals. In addition, the foliar application of flower preservative compounds one week before harvesting significantly improved the endogenous levels of GA3, total phenols, flavonoids, and antioxidants activity, especially SmartFresh™ at rate of 1 mg L−1. In terms of flower quality, SmartFresh™, at rate of 1 mg L−1, and 8-HQS, at rate of 200, had consistently higher vase lives compared to the control treatment across the two experimental cycles. Compared to the control, SmartFresh™ (the post-harvest ethylene control) increased the vase life of lily flowers by 35% at cycle 1 and 31% at cycle 2 while 8-HQS, at rate of 200 mg L−1, increased the vase life by 21% and 15% at cycles 1 and 2, respectively. However, no significant effect was found in the petal flower color coordinates (L*, a* and b*) across the treatments. Overall, the foliar application of preservative compounds (such as SmartFresh™) at the pre-harvest stage potentially stimulates the endogenous levels of GA3, total phenols, flavonoids, and antioxidants activity, leading to better improvements in post-harvest flower quality, specifically vase life.