低浓度Cu和Cd复合污染对小白菜生理生化特性的影响

Influence of combined pollution of Cu and Cd on the physiological and biochemical characteristics of Brassica campestris ssp. chinensis

采用盆栽试验,研究了不同质量浓度Cu(0,25,50,100,200 mg/kg)和Cd(0,1.0,10.0 mg/kg)及其复合污染对小白菜生理生化指标的影响。以不添加Cu和Cd为对照组。结果表明,小白菜外观正常,没有出现Cd中毒症状,但是Cd-Cu复合处理组小白菜的生物量、叶绿素a、叶绿素总量、叶绿素a/b值都低于对照及单一处理组,Cu、Cd复合处理对叶绿素a的影响程度大于叶绿素b;复合处理组的细胞膜透性明显低于单一处理组,硝酸还原酶(NR)活性显著高于对照及单一处理组,过氧化物酶(POD)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)活性高于相同浓度Cd单一处理组。

By pot experiment the paper studied the effects of heavy metal pollution（Cu,Cd and Cu＋Cd） on the physiological and biochemical characteristics of plant（Brassica campestris ssp.chinensis）.The test soil contains one of five levels of Cu（0,25,50,100 or 200 mg/kg） and one of three levels of Cd（0,1,10 mg/kg）.Harvest and analysis of leaf was after 40 days.During the 40-day experiment,Brassica campestris ssp.chinensis survived in the soil spiked up to 10 mg/kg Cd and 200 mg/kg Cu,showing no visual heavy metal toxictiy symptoms such as necrosis and whitish-brown chlorosis.The biomass is negatively affected by the mixture of Cu and Cd.In the absence of Cd,the relative plasmolemma permeability was stimulated with increasing Cu concentration,but it was first inhibited and then stimulated with increasing concentration of Cu by the presence of Cd.Cu or Cd strongly reduced the leaf contents of chlorophyll（Chl） a,and the ratio of Chl a and Chl b.The NR activities did not vary with increasing Cu concentration at Cd=0 mg/kg.However,the activities were first stimulated and then inhibited with increasing Cu concentration at Cd=1 or 10 mg/kg.The NR activities were particularly increased at the concentration of Cu=200 mg/kg.The sensibility of antioxidant enzymes to increasing Cd and Cu concentration are different to enzymes kinds.The SOD activity was first stimulated and then inhibited with increasing concentration of Cu without Cd,and that was stimulated with increasing concentration of Cu at Cd=1 or 10 mg/kg.There were similar responses in POD and SOD activities,and the POD activity was stimulated with increasing concentration of Cd under same concentration of Cu.Increasing Cu concentration in soil significantly increased the activity of CAT,and at the same Cu concentration the CAT activity was inhibited with increasing concentration of Cd.