锰和镉单独及联合染毒对豇豆生长及叶片脂质过氧化的影响

Effect of Manganese,Cadmium and Manganese-Cadmium Combined Exposure on Cowpea Growth and Leaf Physiological Parameters

目的研究锰和镉单独及联合染毒对豇豆生长和叶片脂质过氧化的影响。方法通过盆栽试验，测定Mn^2＋（150—900mg／L）、Cd^2＋（10～60mg／L）单独及联合染毒对豇豆的生态、生理毒性效应[株高、根长、整株干重、根、茎、叶鲜重、叶绿素a、b、类胡萝卜素、超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）]。结果豇豆生物量随着染毒浓度增加而显著降低，以叶鲜重受影响最明显。叶绿素a、b含量与染毒浓度呈负相关，其中叶绿素b对Cd^2＋染毒最敏感；不同染毒剂量组类胡萝卜素含量差异无统计学意义。豇豆叶MDA含量随染毒浓度增加总体呈递增趋势，显示膜结构受损伤程度加剧。三种保护酶对Mn^2＋,Cd^2＋独及联合染毒敏感性表现为POD〉CAD〉SOD。结论Mn^2＋．Cd^2＋单独及联合染毒对豇豆生长有明显抑制作用，以单独Cd^2＋染毒抑制效应最强，单独Mn^2＋染毒的抑制作用最小；生理指标表明Mn^2＋,Cd^2＋在植物体内存在拮抗作用。

Objective To study the effect of Mn, Cd and combined treatment on cowpea growth performance and leaf physiological indicators. Methods Cowpea （Vigna unguiculata） was used in pot-growth experiment and Mn^2＋ （150-900mg/L） and Cd （10-60 mg/L） alone and combined treatment were employed. Results Cowpea biomass declined significantly as the Mn, Cd and Mn-Cd concentrations increased, especially for the fresh leaf weight. A negative correlation existed between the treatment concentration and leaf chlorophyll a and b contents, however, leaf carotenoid content showed no significant variation under different treatment. Overall, leaf MDA content increased as the metal treatment increased, reflecting severe cell membrane damage. The sensibility of cell protective enzymes to Mn, Cd and Mn-Cd combined treatment was POD〉CAT〉SOD. Conclusion Mn, Cd and Mn-Cd combined exposure has a significant inhabitation on cowpea growth with Cd alone being heaviest and Mn lowest. The physiological indicators show that when combined pollution occurs, an antagonistic effect between Mn and Cd is exhibited.