What are the methods for treating licorice seeds?
I. Sulfuric acid treatment method. For every 1 kg of clean seeds, use 20-30 ml of 80% sulfuric acid and stir evenly. Once uniform sulfuric acid etching marks are visible on the seed coat, rinse with clean water and dry in the sun for later use. The treatment time depends on temperature and the amount of acid added. With the same amount of acid, the treatment time is shorter when the temperature is high and longer when the temperature is low. With more acid added, the treatment time is shorter; conversely, the treatment time is longer.
II. Seed coat crushing method. Place the seeds on a grinding pan at a thickness of 3 cm, turning them as you grind. When the seed coat is ground to a yellowish-white color, it is ready. Then place the ground seeds in warm water at 40°C and soak for 2-4 hours. Remove them and rinse off the mucilage with clean water, and they are ready for sowing.
III. Wet sand stratification method: First soak the seeds in warm water at 70°C for 8-10 hours, then remove them and bury them in moist sandy soil. Cover with a wet cloth or straw curtain, sprinkle water frequently to keep them moist. When the temperature rises back to 18-20°C, take them out and sow. This method must be started 50-60 days in advance.
Warming and repeated soaking method
IV. Place the seeds in warm water at 60°C and soak for 6-8 hours. At this point, most of the seeds have absorbed water and are plump (about 2/3), and they separate from the seeds that have not absorbed water (the hard, unswollen seeds) into two layers. The unswollen seeds are at the bottom, and the swollen seeds are on top, but they do not float on the water surface. You can pour off the water while floating out the swollen seeds, repeating several times until all the swollen seeds have been floated out for later use. Then place the unswollen seeds in boiling water at 100°C and soak for 2-3 seconds, remove them, and immediately place them in cold water to shock them, so that the seed coat is stimulated by the cold and heat. Then place them in warm water at 60°C and soak for 2-4 hours. At this point the seeds are properly treated. Combine them with the floated-out seeds, rinse off the mucilage with clean water, and they can be used as sowing seeds. Licorice seeds treated with the warming and repeated soaking method have a germination rate of 91.3% and a seedling emergence rate of 90%.