中文摘要：

为了研究外源重金属胁迫下小麦叶片细胞膜的电特性，应用电阻抗图谱的方法测定了不同浓度的Cu^2＋、Zn^2＋、Pb^2＋、Ni^2＋和Cr^3＋胁迫下两种小麦叶片的胞外电阻、胞内电阻、弛豫时间以及弛豫时间分布系数。结果表明．当重金属离子浓度在0．200mg·kg^-1的范围内增加时．两种小麦叶片的胞外电阻和弛豫时间均表现为先增加后减小，胞内电阻和弛豫时间分布系数减小，与最小值相比．晋麦的胞外电阻减小49．7％-126．1％，弛豫时间减小120．2％-561．2％，弛豫时间分布系数减小13．3％～37．1％，小偃的胞外电阻减小32．7％-61．5％，弛豫时间减小38．9％-210．3％，弛豫时间分布系数减小8．5％-31．2％；与对照相比，晋麦的胞内电阻减小27．5％-59．5％，小偃的胞内电阻减小44．9％～72．9％。与其他两种离子相比，Cu^2＋、Zn^2＋和Pb^2＋更能显著地改变电阻抗参数的值，因此，4个电阻抗参数对Cu^2＋、Zn^2＋和Pb^2＋更敏感。可以分别应用渐进回归函数、一元线性函数对Cu^2＋、Zn^2＋、Pb^2＋和Ni^2＋、Cr^3＋胁迫下小麦叶片的胞内电阻进行预测，Zn^2＋和Pb^2＋胁迫下小麦叶片的弛豫时间分布系数可分别用一元线性和负指数函数进行预测。电阻抗参数对不同重金属离子浓度的响应显示出这种方法在土壤重金属污染程度的诊断方面具有一定的应用前景。

英文摘要：

To study the electrical properties of cell membrane in leaves of wheat under the stress of exogenous heavy metals Cu^2＋, Zn^2＋, Pb^2＋, Ni^2＋ and Cr^3＋ the extracellular resistance, intracellular resistance, relaxation time and distribution coefficient of relaxation time in leaves of two wheat species under different concentrations of above heavy metals were measured by means of the electrical impedance spectroscopy. When heavy metal ions increased from 0 to 200 mg·kg^-1, the extracellular resistance and relaxation time in leaves of both wheat species enhanced first and then decreased, whereas the interstellar resistance and distribution coefficient of relaxation time diminished. Compared with the minimum levels of each parameter, extracellular resistance in Jin-mai and Xiao-yan wheat decreased by 49.7%- 126.1% and 32.7%-61.5%, relaxation time by 120.2%-561.2% and 38.9%-210.3%, and distribution coefficient of relaxation time by 13.3%-37.1% and 8.5%-31.2%, respectively. While compared with the control, intracellular resistance in Jin-mai and Xiao-yan wheat reduced by 27.5%-59.5% and 44.9%-72.9%, respectively. Cu2^2＋, Zn^2＋ and Pb^2＋ could significantly change the levels of electrical impedance parameters and the four parameters were more sensitive to them. Asymptotic regression and univariate linear functions might be used for predicting the intracellular resistance in leaves of wheat under Cu^2＋, Zn^2＋, Pb^2＋ stress, as well as Ni^2＋ and Cr^3＋; univariate linear and negative exponential functions could be applied to predict the distribution coefficient of relaxation time in leaves of wheat stressed by Zn^2＋ and Pb^2＋, respectively. Responses of the electrical impedance parameters to the ion concentration of heavy metals indicated that the method had the potential application in monitoring the pollution degree of heavy metal in soil.