用膜透性、SOD酶活性和膜脂肪酸成分探讨林木抗寒性

通过对邓恩桉不同优良个体膜透性、SOD酶活性与膜脂肪酸组成成分的分析，研究林木的抗寒性。结果表明：不饱和脂肪酸指数（IUFA）是个体抗寒性指标，不同优良个体IUFA的变化为187．02～231．68。不同低温胁迫处理下，个体SOD酶活性的变化在拐点前，随着胁迫加剧而上升，拐点后急剧下降。膜透性表现为电导率变化，在拐点前随着胁迫加剧而迅速加大，出现拐点后缓慢上升，个体抗寒性越差，出现拐点越早。应用上述3种方法探讨林木抗寒性发现，林木在低温胁迫过程中，SOD酶活性与电导率变化有基本一致的拐点值，SOD酶活性变化的拐点最低温度可确定为个体低温临界点。

Cold-Resistance Assessment of Eucalyptus dunnii by SOD Enzyme Activity, Membrane Permeability and Membrane-Fat Acid Content

The composition of membrane-fat acid, the activity of SOD enzyme and membrane permeability in the leaves of different elite Eucalyptus dunnii were analyzed to study the cold resistance characteristics of the differ- ent elite individuals. The results indicated that the index of unsaturated fatty acid （IUFA） could be adopted to eval- uate the cold resistance of the individuals, whose IUFA index varied between 187.02 - 231.68 among the different elite Eucalyptus dunnii plants. Treated by the low temperature stress, the activity of SOD enzyme rose with the in- creasing stress of low-temperature before the inflexion and then dropped sharply after the inflexion. The membrane permeability increased quickly along with the low-temperature stress intensified before the inflexion and increased slowly after the inflexion. The weaker the cold-resistance was, the earlier the inflexion occurred. The study with different physiological indexes showed that the inflexion value of the SOD enzyme activity was in accordance with the membrane permeability. It was proposed that the lowest temperature with which the inflexion occurred for SOD enzyme activity could be taken as the threshold of cold-resistance for different elite Eucalyptus dunnii individuals.