藿香蓟(Ageratum conyzoides)对土壤铅胁迫的生理响应

Physiological Responses of Ageratum conyzoides to Lead Stress in Soil

为了解日益增加的城市土壤铅(Pb)胁迫对城市园林地被植物的影响,采用盆栽实验研究土壤Pb胁迫对藿香蓟(Ageratum conyzoides)叶片生理特性的影响.结果显示,Pb胁迫处理降低了藿香蓟叶片的叶绿素总量及叶绿素a和b含量,质膜透性增大,丙二醛(MDA)含量上升.随着Pb浓度增加,同一时期内藿香蓟叶片SOD、POD和CAT酶活性均上升,但土壤Pb浓度超过750 mg kg-1或1 000 mg kg-1后保护酶活性开始逐渐下降.随着胁迫处理时间的延长,SOD活性在d 20、d 40和d 60时都高于胁迫处理d 7时的活性,POD活性是在d 20时急剧下降,CAT活性则在胁迫处理d 60时急剧下降.研究表明,藿香蓟能在一定程度上适应土壤Pb胁迫,但Pb胁迫浓度超过750 mg kg-1后将影响其生理代谢过程.

In order to understand the effects of increasing lead（Pb） contamination in soil on understory plant in urban forest,a pot experiment was conducted to study the physio-ecological effects of Pb stress in soil on the leaves of Ageratum conyzoides.All the treatments with different Pb concentrations decreased the concentrations of total chlorophyll and chlorophyll a and b,but increased the concentrations of cytomembrane permeability and malondialdehyde（MDA） in the leaves.The activities of superoxide dismutase（SOD）,peroxidase（POD） and catalase（CAT） were higher until the Pb concentration in soil reached 750 mg kg-1 or 1 000 mg kg-1,and thereafter decreased.As the soil Pb treatments proceeded,the SOD activities on day 20,40 and 60 were higher than that on day 7,while the activities of POD and CAT decreased sharply after 20 d and 60 d,respectively.These results implied that A.conyzoides could adapt to the Pb-contaminated soil to a certain extent,but higher Pb stress in soil would damage its physiological processes.Fig 4,Ref 20