不同桉树品种在低温胁迫下的生理反应

Physiological reactions of different Eucalyptus cultivars under low temperature stress

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 explore the adaptability of cold resistance of introduced eucalyptus, their annual shoots in vitro were used as material to investigate the effects of low temperature （0℃、-5℃、-10℃、-15℃ and -20℃） on electrolyte leakage, soluble sugars, free proline and chlorophyll fluorescence parameters of 4 kinds of eucalyptus; simultaneously, chlorophyll fluorescence parameters of 4 kinds of eucalyptus were further studied under low temperature stress （0℃） for different treatment time （2 d, 4 d and 6 d）. The results indicated that the electrolyte leakage rates of 4 kinds of eucalyptus shoots were rising with a fall in temperature, meanwhile, the fitting of Logistic equation to LTso derived 4 kinds of eucalyptus showed that LT50 of Hehongan was minimum; the content of soluble sugar increased at first and then decreased with the fall in temperature, and the difference between the contents of soluble sugar in 4 kinds of eucalyptus was significant. Pro （proline） of 4 kinds of eucalyptus shoots was rising with a fall in temperature; the fall in temperature along with the prolong of time under 0℃ stress, Fo was up gradually, Fv/Fm,ФPSⅡ and qP were declined. Integrated indicator value of cold resistance of each provenance was obtained based on the function value. The cold resistance order of different provenances was Hehongan 〉 DH-32 〉 U-6 〉 GuangLin 9.