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为探讨引种桉树抗寒适应性,以1年生离体枝条为试材,研究不同低温(0℃、-5℃、-10℃、-15℃和-20℃)处理对4种桉树电解质外渗率、可溶性糖、游离脯氨酸(Pro)及叶绿素荧光参数的影响,以及在0℃(CK)低温胁迫下不同处理时间(2 d、4 d、6 d)对4种桉树叶绿素荧光参数的影响。结果表明,随着处理温度降低4种桉树叶片的电解质外渗率呈上升趋势,拟合Logistic方程得出4种桉树的半致死温度(LT50),表明河红桉LT50最低;可溶性糖含量随着温度的降低先升高后降低,各品系间可溶性糖含量表现显著差异;游离脯氨酸(Pro)含量随着温度的降低而上升;叶绿素荧光参数分析显示,随着处理温度下降及0℃下胁迫时间延长,初始荧光(Fo)逐渐上升,PSⅡ最大光化学效率(Fv/Fm)、实际光化学效率(ФPSⅡ)、光化学猝灭系数(qP)逐渐下降。根据隶属函数法,求出隶属函数值,综合各指标,得出4种桉树抗低温胁迫能力强弱的排序为:河红桉﹥DH-32﹥U-6﹥广林9。
In order to investigate the cold tolerance of introduced Eucalyptus, 1-year-old detached shoots were used to study the effects of different low temperature treatments (0 ℃, -5 ℃, -10 ℃, -15 ℃ and -20 ℃) , Soluble sugar, free proline (Pro) and chlorophyll fluorescence parameters, and the effects of chlorophyll fluorescence parameters on the chlorophyll fluorescence parameters of Eucalyptus under different treatment time (2 d, 4 d, 6 d) at 0 ℃ influences. The results showed that the electrolyte leakage rate of four eucalyptus leaves tended to increase with the decrease of treatment temperature. Logistic equation was fitted to calculate the lethal temperature (LT50) of four eucalyptus trees, indicating that LT50 was the lowest. The content of soluble sugar The decrease of temperature firstly increased and then decreased, and the content of soluble sugar in each strain showed significant difference. The content of free proline increased with the decrease of temperature. The analysis of chlorophyll fluorescence parameters showed that with the decrease of treatment temperature and 0 ℃ The initial fluorescence (Fo) increased gradually with the prolonging of stress time. The maximum photochemical efficiency (Fv / Fm), the actual photochemical efficiency (ФPSⅡ) and the photochemical quenching coefficient (qP) decreased gradually. According to the membership function method, the subordinate function values were obtained. According to the indexes, the order of the ability of four kinds of Eucalyptus under cold stress was: Eucalyptus urophylla> DH-32> U-6> Guanglin9.