镉对姜叶片活性氧代谢影响的时间和剂量效应

为探讨姜对镉（Cd）胁迫的生理响应特性，通过外施CdCl2 ? 2.5H2O溶液，研究不同Cd水平对姜叶片活性氧代谢的影响。结果表明，Cd胁迫下，姜叶片中  生成速率和H2O2含量显著升高，且呈剂量和时间效应，同时丙二醛（MDA）含量和电导率持续增加。姜幼苗期，超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）、谷胱甘肽还原酶（GR）、抗坏血酸过氧化物酶（APX）、单脱氢抗坏血酸还原酶（MDHAR）、脱氢抗坏血酸还原酶（DHAR）、抗坏血酸氧化酶（AAO）等抗氧化酶活性均被Cd胁迫所诱导增强，还原型抗坏血酸（AsA）、总抗坏血酸（AsA + DHA）、酸溶性SH、还原型谷胱甘肽（GSH）、植物络合素等抗氧化物质含量显著升高，AsA/DHA、GSH/GSSG比值显著增加；随Cd胁迫浓度和时间的增加，相关保护酶活性及抗氧化物质含量均显著降低，表明姜对Cd较短期（40 d）胁迫或较低浓度Cd胁迫具有适应性，但胁迫120 d或过高浓度的Cd胁迫严重损伤了姜叶片抗氧化系统，使活性氧代谢失调，叶片膜系统遭到严重伤害。

Time and Does Effects of Cadmium on Active Oxygen Metabolism in Ginger Leaves

To investigate the physiological response characteristics of ginger under Cd stress，the effects of the different Cd levels on active oxygen metabolism of ginger leaves with applying CdCl2 ? 2.5H2O solution were studied. The results showed that under Cd stress，with MDA content and electrolyte leakage rate increasing continuously， productivity rate and H2O2 content increased significantly in a dose and time dependent manner. At the seedling stage，the activities of superoxide dismutase（SOD），peroxidase（POD），catalase（CAT），glutathione reductase（GR），ascorbate acid（APX），monodehydroascorbate reductase（MDHAR），dehydroascorbate reductase（DHAR）and ascorbic acid oxidase（AAO）were enhanced markedly，and the contents of reduced ascorbic acid（AsA），total ascorbic acid（AsA + DHA），acid soluble SH，reduced glutathione（GSH）and phytochelatins were induced remarkably，and the ratios of AsA/DHA and GSH/GSSG also increased significantly. With the increase of Cd stress level and exposure duration，the activities of protective enzymes related and the content of antioxidants decreased significantly. The results suggested that ginger has the adaptability to Cd stress at short term（40 days）or lower Cd concentration stress. But under 120 days or higher Cd concentration stress，the antioxidant system in ginger leaves was damaged seriously and the balance of active oxygen metabolism was destroyed，and then the leaf membrane systems was damaged.