土壤铅和镉胁迫对红花檵木叶片光合特性及色素含量的影响

Effects of Pb and Cd Stress on Photosynthetic Characteristics and Contents of Pigments in the Leaves of Loropetalum chinense var.rubrum

采用土壤盆栽试验,研究了土壤中Pb2+、Cd2+胁迫对红花檵木光合特性及叶片色素含量的影响。结果表明:(1)Pb2+浓度为100 mg/kg时,红花檵木叶片的光合特性指标和色素含量与对照相比均明显上升,当Pb2+浓度为500 mg/kg以上时,净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)随Pb2+浓度的增加而下降,而叶绿素含量则在Pb2+浓度为1000 mg/kg以上时才出现显著下降趋势;(2)Cd2+处理降低了红花檵木叶片Pn、Tr和Gs,叶绿素含量在Cd2+浓度为100 mg/kg以上时显著下降;(3)Pb2+浓度为100mg/kg,Cd2+浓度为100 mg/kg时,红花檵木叶片中的花色素苷、可溶性糖含量和苯丙氨酸解氨酶(PAL)活性均明显高于对照,即促进了红花檵木叶片的着色。

A pot experiment was conducted to study the effects of Pb^2＋ and Cd^2＋ stress on photosynthetic characteristics and contents of pigments in the leaves of Loropetalum chinense var. rubrum. The results showed that： （1） 100 mg/kg of Pb^2＋ treatment induced a significant increase in photosynthetic characteristics and contents of pigments in the leaves of Loropetalum chinense var. rubrum compared with control; when Pb2＋ concentration was more than 500 mg/ kg, net photosynthetic rate （Pn）, stomatal conductance （Gs） and transpiration rate （Tr） all decreased with increasing Pb2＋ concentration, but chlorophyll content showed a significant decreasing trend when Pb2＋ concentration was over 1 000 mg/kg. （2） Under each treatment of Cd^2＋, Pn, Tr and Gs all declined significantly, but chlorophyll content decreased significantly when Cd^2＋ concentration was over 100 rag/rag. （3） When the concentrations of Pb^2＋ and Cd^2＋ all were 100 mg/kg, the contents of anthocyanin and soluble sugar and the activities of PAL in leaves of Loropetalum chinense var. rubrum were higher than those in the control, which meaning these treatments can promote the coloration of leaves of Loropetalum chinense var. rubrum.