关键词: 中草7号扁蓿豆, 种子硬实, 破除方法

Abstract: [Objective] To determine the most effective method for breaking seed hardness of Melilotoides ruthenica cv. Zhongcao No.7. [Method] KNO₃ solution, gibberellic acid （GA） solution, 98% H₂SO₄, hot water, liquid nitrogen, and mechanical abrasion of the seed coat were used to treat the seeds of Melilotoides ruthenica cv. Zhongcao No.7, respectively. With untreated seeds as control （CK）, the seed germination rate, hardness rate, germination potential and germination index, as well as dead seedling rate were calculated using the number of normal germinated seeds and hardness seeds acquired on the 14^th day of germination. The efficacy of various treatment methods on breaking seed hardness was statistically compared. [Result] The hardness rate of the seeds treated with mechanical abrasion reduced to 4% and the germination rate rose to 96%. When the seeds were treated with 98% H₂SO₄ for 25-30 min, the hardness rate decreased to 5% and the germination rate increased to 95%. The germination rate, germination potential, and germination index of the seeds treated with the above two methods were significantly （P<0.05） higher than those of CK , and the dead seedling rate was lower. Both treatments were capable of successfully breaking the seed hardness of Melilotoides ruthenica cv. Zhongcao No.7. In comparison to CK, significant （P<0.05） effects on reducing the seed hardness rate were observed in the treatments of 75 ℃ hot water, 400 mg/L GA solution for 36-48 h, and seed soaking in 0.1% KNO₃ solution, but the decrease range was too little to be useful. The treatment of liquid nitrogen, which substantially elevated the dead seedling rate, was not recommended either. [Conclusion] Considering the high risk of 98% H₂SO₄ treatment, it is recommended that mechanical abrasion of the seed coat be prioritized in breaking hardness of batch seeds of Melilotoides ruthenica cv. Zhongcao No. 7.

Key words: Melilotoides ruthenica cv. Zhongcao No.7, seed hardness, breaking method