Abstract: In order to study the physiology characteristics of cold resistance of Kobresia pygmaea,the contents of malondialdehyde (MDA),free proline,soluble sugar,superoxide dismutase (SOD),peroxidase (POD) and catalase (CAT) in leaves and roots of Kobresia pygmaea in Qinghai-Tibetan Plateau were studied. The results showed that the content of malondialdehyde and soluble sugar in leaves reached the highest in the yellowing period,while the content of free proline was the highest in the greening period. The content of malondialdehyde in roots was lower in the later stages of plant growth while the contents of soluble sugar and free proline were higher in the later stages. The activities of three antioxidant enzymes in Kobresia Alpinia leaves decreased significantly at the later stage of plant growth while were higher in the later stages of plant growth in roots. The content of physiological indexes was higher in leaves than that in roots at different phenological stages. Organs,phenophase,and the interaction of organs and phenophase significantly affected the osmotic adjustment substances and antioxidant enzyme activities of Kobresia pygmaea,and the correlation of physiological indexes between different organs of Kobresia pygmaea was different in different phenological periods. In summary,the osmotic adjustment substances and antioxidant system in Kobresia pygmaea leaves and roots positively response to environmental changes in different phenological periods,which is one of the potential mechanisms for the environment adaptation of the Kobresia pygmaea.

Key words: Kobresia pygmaea, Physiological characteristics, Seasonal changes, Osmotic adjustment substances, Antioxidant systems

摘要： 为探讨青藏高原高山嵩草（Kobresia pygmaea）叶、根抗寒性生理特征，本研究对返青期、草盛中期、草盛后期和枯黄期青藏高原高山嵩草叶和根中丙二醛、脯氨酸、可溶性糖含量及超氧化物歧化酶、过氧化物酶和过氧化氢酶活性进行测定。结果显示：叶片中丙二醛和可溶性糖含量在枯黄期达到最高，而脯氨酸含量在返青期最高；根中丙二醛含量在植物生长后期较低，可溶性糖和脯氨酸含量在后期则较高；叶片中3种抗氧化酶活性在植物生长后期呈显著下降趋势（P<0.05）；而根中3种抗氧化酶活性在植物生长后期较强；不同物候期各生理指标叶片中含量均高于根；器官、物候期以及器官和物候期的交互作用能够显著影响高山嵩草的渗透调节物质和抗氧化酶活性（P<0.05），且不同物候期其不同器官生理指标的相关性不同。综上所述，高山嵩草叶片和根中的渗透调节物质和抗氧化系统对不同物候期的环境变化积极响应，这可能是其适应高寒环境的生理机制。

关键词: 高山嵩草, 生理特征, 季节变化, 渗透调节物质, 抗氧化酶活性