Hard seed (fruit) is called hard seed because its epidermis structure is compact and solid, or it has cuticle and waxy layer, which is impermeable to water or air, so it can't germinate. The dormancy of many leguminous grass species belongs to this type. In production practice, it is necessary to comprehensively consider whether to take measures such as mechanical damage, low temperature treatment, high temperature treatment, variable temperature seed soaking and chemical treatment to break dormancy. Mechanical damage is usually crushed with a stone mill or milled with a rice mill, and the shell is removed, resulting in cracking of the seed coat. Low temperature treatment: the seeds were treated at the low temperature of 0 ~ 10℃ for 7 days. High temperature treatment: the seeds are dried at a high temperature of about 100℃ and treated for 4 ~ 10 minutes. Soaking seeds at variable temperature means soaking seeds in hot water at 50 ~ 98℃ 10 ~ 30 minutes, or cooling to soak for one day and night, then taking them out to dry, and moving them to a cool place at night to be watered and kept moist. After 2 ~ 3 days, the seed coat will crack, so you can sow while the water is wet. Chemical treatment can be used to corrode seeds with concentrated sulfuric acid or concentrated hydrochloric acid for several minutes to one hour, and the treatment time varies from species to species until there is a hole in the seed coat, and then it is fully washed in flowing water. Seeds can also be treated with 25% hydrogen peroxide for 5 ~ 15 minutes, and the treatment time varies with varieties. Good results can also be obtained by treatment with alkaline substances such as sodium hydroxide. Pay attention to protection during handling to avoid acid and alkali burns.