Abstract: The electrical conductivity of different Eucalyptus dunnii plus trees was determined at normal temperature and under different low temperature stress, to discuss the relation between the change of electrical conductivity and the individual cold-resistance in different treatments. The results indicated that the electrical conductivity of different individuals existed diurnal fluctuation at normal temperature, which did not contact directly with the individual cold-resistance. The electrical conductivity of different plus trees varied with the differences of cold-resistance under different low temperature stress, the cold-resistance stronger, the low-temperature interval that the electrical conductivity changed gradually more hysteretic, and the range of variation smaller. According to the electrical conductivity in different treatments, the logistic equations and self-lethal temperature of different individuals were respectively gained by regression analysis, to quantitatively assess the cold-resistances of different individual, which would provide the scientific basis for selecting plus trees of the rapid-growth and cold-resistance.

Key words: Eucalyptus dunnii, electrical conductivity, plus tree, cold-resistance, self-lethal temperature

摘要： 本文通过测定邓恩桉不同优株在常温下电导率日变化与不同低温胁迫处理电导率的变化，探讨不同处理条件下，电导率变化与个体抗寒性的关系。结果表明，不同个体在常温下电导率存在日波动变化，但日波动性与抗寒性没有直接联系。在不同低温胁迫处理下, 不同优良个体电导率随抗寒能力不同而变化，抗寒能力越强，电导率发生骤变的低温区间越滞后，且变化幅度也较小。由不同处理下的电导率，分别求得不同个体的logistic方程, 经回归分析得出各不同个体的半致死温度,定量评价不同个体抗寒能力，为抗寒-速生优株筛选提供科学依据。

关键词: 邓恩桉, 电导率, 优株, 抗寒性, 半致死温度