不同浓度铅处理对桐花树叶片生理指标的影响

以红树植物桐花树2a生龄苗为试验材料,采用淡水水培法研究了不同浓度Pb2+(0 mg/L(对照组)、10mg/L、25 mg/L、50 mg/L、100 mg/L、300mg/L、500 mg/L)对桐花树叶片的超氧负离子(O2-)、丙二醛(MDA)含量、过氧化物酶(POD)与超氧化物歧化酶(SOD)活性、蛋白质以及可溶性总糖量含量的影响.结果表明:随着Pb2+浓度的升高,桐花树叶片中O2-和MDA含量均呈上升趋势,且均显著高于对照,最高值范围是在Pb2+浓度100～500mg/L;而蛋白质含量和POD的活性则呈下降趋势,且均显著低于对照.SOD活性在铅胁迫浓度为10 mg/L时达到最大,当高于10mg/L时,则随Pb2+浓度的升高而下降.可溶性糖含量在Pb2+浓度为0～300 mg/L时,随Pb2+浓度的升高而显著增大.试验表明:桐花树叶片在浓度为10～100mg/L铅处理下,可以通过自身的内在调控抵御铅污染,即轻度的铅污染有利于桐花树的生长;在300～500mg/L高浓度铅胁迫下,各种生理指标出现衰减,显示高浓度铅胁迫的抑制效应,不利于桐花树生长.

The Effect of Lead Exposure on the Physiological Characteristics of Aegiceras Corniculatum Leaf

Two-year-old plants of Aegiceras corniculatum cultivated in fresh water were exposed to different concentrations of Pb2+(0 mg/L(CK),10mg/L,25 mg/L,50 mg/L,100 mg/L,300mg/L and 500 mg/L) to investigate the effect of lead exposure on the contents of superoxide radical(O2-),malonic dialdehyde(MDA),peroxidase(POD) and superoxide dismutase(SOD),protein and soluble sugar.Results indicated that,with the increase of Pb2+,O2-and MDA increased to significantly higher than those under control,and reached the highest values under Pb2+ 100~500mg/L;whereas protein content and POD activity declined significantly as Pb2+ increased.SOD activity reached the highest value at 10 mg/L Pb2+,and decreased with raised Pb2+concentrations.Soluble sugar content significantly increased with the increase of Pb2+within the range of 0~300 mg/L.The conclusion is that: exposure of Pb2+ at 10~100mg/L stimulated growth of Aegiceras corniculatum,indicating there existed an intrinsic adaptive mechanism to light lead stress in the plant;but as concentration of lead increased to 300~500mg/L,growth of Aegiceras corniculatum was significantly inhibited,with all physiological indexes significantly declined.