【作者】 方学智；

【导师】 朱祝军；

【作者基本信息】 浙江大学 ， 蔬菜学， 2004， 硕士

【摘要】 在重金属污染中，镉是毒性最大的元素之一，WHO确定镉为优先研究的食品污染物，联合国环境规划署提出12种具有全球性意义的危险化学物质，镉被列为首位。本试验以我国人民日常生活中最常食用的小白菜（Brassica.chinensis L.）为研究材料，探讨了不同浓度镉对小白菜生长与抗氧化系统的影响，以及镉胁迫下加入不同浓度锌对小白菜生长和细胞内抗氧化酶系统的影响，试验结果如下： 1)不同镉浓度对小白菜生长与抗氧化系统的影响：分别用0.01、0.1、1、10 mg·L^-1镉处理小白菜，结果显示，当镉浓度为0.01 mg·L^-1时促进小白菜生长，镉浓度为10 mg·L^-1时，抑制小白菜生长；与对照相比，0.01、0.1 mg L^-1镉处理后，叶绿素a与叶绿素b的含量增加，镉浓度为1 mg·L^-1时，叶绿素a与叶绿素b的含量显著下降（p＜0.05）。超氧化物岐化酶（SOD）活性随镉处理浓度增加而下降；愈创木酚过氧化物酶（GPOD）、抗坏血酸过氧化物酶（APX）在镉浓度为0.1 mg·L^-1时活性最高；过氧化氢酶（CAT）在镉浓度为1 mg·L^-1时活性达到最高；脱氢抗坏血酸还原酶（DHAR）、谷胱甘肽还原酶（GR）的活性和抗坏血酸（AsA）、还原型谷胱甘肽（GSH）含量在10 mg·L-1镉处理最高。 2)锌对镉胁迫下不同基因型小白菜生长与镉含量的影响：试验研究了不同浓度锌（Zn）(0.1 mg·L^-1、1 mg·L^-1、10 mg·L^-1)处理对5 mg·L^-1镉（Cd）胁迫下不同基因型小白菜生长与镉吸收的影响。结果表明：5 mg·L^-1镉处理后，两品种沪青一号与杭州油冬儿生长，叶绿素a与叶绿素b含量与对照相比均下降，过氧化氢（H₂O₂）与丙二醛（MDA）含量增加。外加1 mg·L^-1锌处理使沪青一号小白菜地上部镉含量增加，地上部与地下部干、鲜重降低，H₂O₂与MDA含量上升；10 mg·L^-1锌处理使沪青一号地上部镉含量下降，地上部与地下部干、鲜重上升，同时H₂O₂与MDA含量下降。但外加锌对杭州油冬儿地上部镉含量、生物产量无显著影响，H₂O₂与MDA含量随着加入锌浓摘要度升高而增加。3)锌对锅胁迫下小白菜抗氧化系统的影响:本试验用1、10 mg·L一‘锌处理受5 mg’L一，镐胁迫的小白菜，试验结果表明:5mg’L一，cd使小白菜叶片细胞 内过氧化氢（HZoZ）含量上升，1 mg·L一‘锌加入使其含量进一步上升，加入 10mg’L，锌处理后，细胞内H20:含量下降。5mg’L一’福处理使soD，cAT 活性下降，GPoD上升，加入锌后，SOD，CAT活性继续下降;1mg’L一，锌 处理使GPOD活性下降，10 mg·L一，锌处理使GPOD活性恢复到对照水平。 锅胁迫使”x，GR，DHAR活性都下降，加入1 mg·L‘，锌处理后使三者活 性继续下降，加入10mg’L一‘锌处理后则使它们的活性上升。更多还原

【Abstract】 This study was carried out to investigate the effects of cadmium on the growth and antioxidative system, and the influences of zinc on the growth and antioxidative enzymes under cadmium stress in Brassica chinensis L. The major results were summarezed as follows:1) Effects of different concentrations of cadmium on growth and antioxidative system in Brassica chinensis L: The growth and chlorophyll content were enhanced by low concentrations of Cd (below 0.1 mg L-1), whereas the growth was seriously inhibited by 10 mg L-1 Cd. SOD activity decreased with increasing Cd concentration in growth medium. The activities of GPOD and CAT increased at the treatment of 0.01 and 0.1 mg L-1, but decreased dramatically at 10 mg L-1 treatment. Cd increased the activities of APX, DHAR and GR. AsA and GSH contents increased at 10 mg L-1 Cd level.2) Effects of zinc on growth and absorbtion of Cd in different type of Brassica chinensis L. Two varieties of Brassica chinensis L. (Hu and You) were grown in nutrient solution containing Cd 5 rng L-1’+Zn 0.1 mg L-1, Cd 5 mg L-1+Zn 1 mg L-1, Cd 5 mg L-1+Zn 10 mg L-1 to investigate the effects of zinc on the growth and absorption of cadmium. The results showed that 5 mg L-1 Cd decreased the freshweight and dry weight of both shoot and root, increased the content of H2O2 and MDA in both of cultivars. This indicated that Cd affected the growth of Brassica chinensis L, but this effect was zinc concentration and cultivar dependent. The concentration of Cd in shoot of Hu increased with the increasing of zinc concentrations in culture solution, however, adition zinc to culture solution had no significant effect on the shoot Cd concentration of You.3) Effects of zinc on antioxidant enzymes in Brassica chinensis L, under cadmium stress: Brassica chinensis L. were grown in nutrient solution containing 5 mg L-1 Cd(Cd5), Cd5+Znl, Cd5+ZnlO to study the effects of zinc on the growth and antioxidant enzymes. 5 mg L-1 Cd decreased the content of H2O2 and the activities of SOD, CAT, DHAR, APX and GR, but the activity of GPOD was increased. The treatment of Cd5+Znl decreased the activities of SOD, POD, CAT, DHAR and GR, and increased the content of H2O2. Under the Cd5+ZnlO treatment, the activities of SOD, CAT declined continuously, but the activity of GPOD recovered to the normal level. There are no distinct changes in DHAR activity. The activities of APX and GR increased along with the decline of H2O2.更多还原