Response of Seed Germination and Seedling Growth of Licorice to Chemical Scarification and Gibberellic Acid Levels

Natural habitats of licorice have decreased dramatically while the demand for this plant rises. Licorice seeds exhibit a low germination rate due to secondary dormancy imposed by the hard seed coat. In this study, conducted in the spring of 2021 at Shahid Bahonar University of Kerman, Iran, the interaction effect of sulfuric acid (95-97%, 60 min) scarification with gibberellic acid (GA) concentrations (0, 100, 250, 500, and 1000 mgL-1) has been studied in a factorial experiment based on a completely randomized design with four replications. Results show that although there has been no difference in germination between GA levels for scarified seeds, GA at 250 mg L-1 improves germination by 36%, compared to the control in non-chemically scarified ones. In contrast, increasing in GA concentrations increased seedling length, plant height, number of leaves and compound leaves, leaf area, fresh and dry weight of shoot and root, while decreased chlorophyll index (SPAD). As a result, chemical scarification, application of GA at 1000 mg L-1, and germination at room temperature can effectively increase the germination rate and uniformity as well as early growth of licorice plant.