中草7号扁蓿豆种子硬实的破除方法研究

目的]探究中草7号扁蓿豆（Melilotoides ruthenica cv. Zhongcao No.7）种子硬实的有效破除方法。方法]利用KNO₃溶液、赤霉素（GA）溶液、98%的浓H₂SO₄、热水、液氮和机械擦破种皮方法对中草7号扁蓿豆种子进行处理,以不做任何处理的种子为对照（CK）,用发芽第14天统计获得的正常发芽种子数和硬实种子数,计算发芽率、硬实率、发芽势、发芽指数、死苗率,对不同处理方法破除种子硬实的效果进行评价。结果]机械方法擦破种皮处理能使中草7号扁蓿豆种子的硬实率降低至4%,发芽率提高至96%;98%的浓H₂SO₄处理种子25~30 min,能使种子硬实率下降至5%,发芽率提高至95%;2种处理方式下种子的发芽率、发芽势、发芽指数均显著（P<0.05）高于CK,死苗率较低,两者均能有效破除中草7号扁蓿豆的种子硬实。在其他处理中,与CK相比,只有75 ℃热水处理、400 mg/L的GA溶液36~48 h处理、0.1%的KNO₃溶液浸种发芽处理,对降低中草7号扁蓿豆种子硬实率有显著（P<0.05）影响,但由于降低幅度较小,不宜采用。液氮处理使死苗率大幅增加,也不宜采用。结论]考虑到98%的浓H₂SO₄处理安全风险较高,建议在中草7号扁蓿豆批量种子的硬实处理中,优先采用擦破种皮的机械处理。

Efficacy Comparison of Different Methods for Breaking Seed Hardness of Melilotoides ruthenica cv. Zhongcao No.7

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.