采用水培法研究了不同浓度Cd²⁺、Zn²⁺单一及复合胁迫(0. 05 和0. 50 mmol·L^-1 Cd²⁺ ,0. 5 和5. 0 mmol·L^-1Zn²⁺ )对凤眼莲[Eichhornia crassipes (Mart.) Solms]幼苗根质膜3 种氧化还原酶[NADH 氧化酶、Fe(CN)₆^3-还原酶和EDTA-Fe³⁺还原酶]活性的影响。结果表明, Cd²⁺、Zn²⁺ 单一及复合胁迫对凤眼莲根质膜NADH 氧化酶、Fe(CN)₆^3-还原酶及EDTA-Fe³⁺还原酶活性的影响效应有明显的差异。0. 05 或0. 50 mmol·L^-1 Cd²⁺单一胁迫处理20 h 可使凤眼莲根质膜3种氧化还原酶活性均较对照显著降低(P≤0. 05),0. 5 或5. 0 mmol·L^-1 Zn²⁺ 单一胁迫20 h 可导致凤眼莲根质膜NADH 氧化酶和EDTA-Fe³⁺ 还原酶活性也均较对照显著降低(P≤0. 05)。随胁迫时间的延长,Cd²⁺、Zn²⁺单一及复合胁迫处理均可使凤眼莲根质膜氧化还原酶活性增强,胁迫处理20 d 时凤眼莲根质膜3 种氧化还原酶活性均高于胁迫20 h 的活性。Cd²⁺ -Zn²⁺复合胁迫对凤眼莲根质膜3 种氧化还原酶活性的影响效应因作用时间和胁迫浓度的不同而有一定的差异;在胁迫20 h 时,Cd²⁺ 与Zn²⁺ 之间对凤眼莲根质膜3 种氧化还原酶活性的作用关系较复杂,因胁迫浓度的不同表现出协同或拮抗的关系;胁迫20 d 时,Cd²⁺与Zn²⁺对凤眼莲根质膜3 种氧化还原酶活性的复合影响表现出明显的拮抗关系。研究结果显示,Cd²⁺、Zn²⁺ 对凤眼莲根质膜氧化还原酶的复合作用效应与Cd²⁺和Zn²⁺的浓度比例及胁迫时间均相关。

Effects of single and combined stresses of Cd²⁺ and Zn²⁺ with different concentrations (0. 05 and 0. 50 mmol·L^-1 Cd²⁺, 0. 5 and 5. 0 mmol·L^-1 Zn²⁺ ) on activities of three oxido-reductases [NADH oxidase, Fe(CN)₆^3- reductase and EDTA-Fe³⁺ reductase ] in root plasmalemma of Eichhornia crassipes (Mart.) Solms seedling were researched by water culture method. The results show that the effects of single and combined stresses of Cd²⁺ and Zn²⁺ on activities of NADH oxidase,  Fe(CN)₆^3-reductase and EDTA-Fe³⁺ reductase in root plasmalemma of E. crassipes are obviously various. The activities of three oxido-reductases in root plasmalemma of E. crassipes treated with 0. 05 or 0. 50 mmol·L^-1 Cd²⁺ single stress for 20 h are all significantly lower than those of the control (P≤0. 05).Also, both of NADH oxidase and EDTA-Fe³⁺ reductase activities in root plasmalemma of E. crassipes treated with 0. 5 or 5. 0 mmol·L^-1 Zn²⁺ single stress for 20 h are significantly lower than those of the control (P≤0. 05). The single and combined stresses of Cd²⁺ and Zn²⁺can lead to enhance three oxido-reductase activities with prolonging of stress time, and three oxido-reductase activities treated for 20 d are higher than those treated for 20 h. The effect of combined stress of Cd²⁺-Zn²⁺ on three oxido-reductase activities in root plasmalemma of E. crassipes has a certain difference with different stress times and different stress concentrations. When stressed for 20 h, the combined effect of Cd²⁺ and Zn²⁺ on three oxido-reductase activities is very complex, which appears synergistic or antagonistic actions with different stress concentrations, while stressed for 20 d, the combined effect is an obviously antagonistic action. It can be concluded that the combined effect of Cd²⁺ and Zn²⁺ on oxido-reductase activities in root plasmalemma of E. crassipes is relate to concentration proportion of Cd²⁺ and Zn²⁺ and stress time.