低温处理对矩镰荚苜蓿休眠态转变和生理的影响

Effects of low temperature treatment on shifts in dormancy status and physiological characteristics of wild Medicago archiducis-nicolai

摘要:

【目的】矩镰荚苜蓿（Medicago archiducis-nicolai）是青藏高原分布的一种野生优良牧草，抗寒性极强，但其越冬休眠与抗寒机理尚不清楚。本研究旨在明确矩镰荚苜蓿生理休眠发生与解除的低温条件以及低温环境下休眠提高矩镰荚苜蓿抗寒性的生理基础。【方法】以采自祁连山东段高寒草甸的野生矩镰荚苜蓿为试材，观测分析不同低温处理下矩镰荚苜蓿休眠状态的变化，测定休眠进入和破除前后的生理生化指标。【结果】2 ℃低温处理 10~15 d，矩镰荚苜蓿再生高度显著下降，在低温 15 d 降到最低（P＜0. 05），持续低温处理 6 d 后，再生高度快速增加；可溶性糖、脯氨酸含量和 CAT、SOD 酶活性随低温处理时间的延长呈先升后降的趋势，POD 酶活性变化趋势则相反，但均显著高于对照（室温）；9 ℃和 2 ℃处理下的再生高度和生理生化指标变化规律基本一致。【结论】矩镰荚苜蓿对低温敏感， 10 ℃以下持续低温处理 10~15 d 便进入生理休眠，随着处理时间的延长，休眠很快被解除；通过休眠态的转变，增强了渗透调节能力和抗氧化能力，从而提高了越冬抗寒性。

Abstract:

【Objective】Medicago archiducis - nicolai is a one of excellent wild forages distributed in QinghaiTibet Plateau，with strong cold resistance，but its winter dormancy and cold resistance mechanism is unclear. 【Method】 In this study，the shifts of dormancy status of M. archiducis-nicolai were investigated and analyzed under different low temperature treatments，and the physiological and biochemical indexes of Medicago archiducis-nicolai before and after dormancy were measured.【Result】 The results showed that the regeneration height of M. archiducis- nicolai decreased significantly at 2 ℃ for 10~15 days and reached the lowest at 15 days （P＜0. 05）. Under continu- ous low -temperature conditions，the regeneration height exhibited an upward trend. The levels of soluble sugar and proline，as well as the activities of the CAT and SOD antioxidant enzymes，initially increased and then decreased with the duration of low temperature treatment. However，POD activity showed the opposite trend，but all these values were significantly higher than the control （at room temperature）. The changes observed at 9 ℃ and 2 ℃ were essen- tially the same.【Conclusion】 Analysis of the results indicates that M. archiducis-nicolai is sensitive to low tempera- ture. Endo-dormancy is induced after 10~15 days of continuous low-temperature treatment below 10 ℃，and the dor- mancy is quickly relieved with extended treatment time. Through the modulation of dormancy，M. archiducis-nicolai enhances its osmotic regulation and antioxidant capabilities，thus improving its winter cold resistance.