Effects of Different Hormone Pretreatments on the Germination of Mentha arvensis (Peppermint) Seeds

[Objective] To study the effects of different hormone pretreatments on the germination of Mentha arvensis (peppermint) seeds. [Method] Effects of different hormones on the germination of peppermint seeds were studied, including GA3, ethephon, NAA, and 2, 4-D. [Result] The germination rate and germination potential of peppermint seeds were gradually increased with GA3 concentration increasing from 40 to 160 mg/ml, but from then on, they began to decline apparently. And its optimum concentration was between 160 and 200 mg/ml. Ethephon could effectively promote the germination of peppermint seeds and improve the germination rate when being used in concentrations between 40 and 100 mg/ml, but that used in concentrations above 100 mg/ml evidently inhibit germination. When the NAA concentration was increased from 0.08 to 0.1 mg/ml, the germination rate and germination potential were gradually increased, that is to say, NAA in appropriate concentrations could significantly promote the germination of peppermint seeds and improve the germination rate. If NAA concentration continued to rise, there would be a significant reduction in germination rate and germination potential (P<0.05), confirming the presence of inhibitory effects for NAA in higher concentration above 0.5 mg/ml. Similarly, 2, 4-D used in concentrations between 10 and 30 mg/ml could promote the seeds germination and improve the germination rate, while that in higher concentration above 50 mg/ml inhibited germination. The germination rate and germination potential were gradually increased with 2, 4-D concentration increasing from 10 to 30 mg/ml, but they began to significantly decline if concentration continued to rise (P<0.05). [Conclusion] GA3, ethephon, NAA, and 2,4-D have different effects on the germination of peppermint seeds.