Pb胁迫对冬凌草叶片光合色素合成和生物量的影响

Effects of Pb Stress on Photosynthetic Pigment Biosynthesis and Growth of Rabdosia rubescens

目的：研究Pb胁迫对冬凌草叶片光合色素含量动态变化和生长影响,为冬凌草种植地选择和生长调控提供依据。方法：Pb浓度（135、270、540 mg/L）、胁迫时间（20、35、50 d）分株水培试验,以叶绿素a、叶绿素b、类胡萝卜素、生长速率、生物量和植株Pb质量分数为指标,用分光光度计测定光合色素含量、等离子发射光谱仪测定植株Pb质量分数。结果：不同浓度Pb胁迫20~35 d冬凌草叶绿素和类胡萝卜素含量震荡变化;50 d时,叶绿素含量在中低浓度Pb胁迫下高于对照,高浓度下显著低于对照,类胡萝卜素含量无显著差异。结论：中低浓度Pb促进冬凌草叶绿素合成,高浓度Pb通过生物富集抑制叶绿素合成,使生长受限。

Objective：To study the impacts of lead （Pb） stress on the leaf photosynthetic pigment and the growth of Rabdosia rubescens,in order to provide a basis for planting area selection and growth regulation. Methods：Taking chlorophyll a, chlorophyll b, ea- rotenoids, growth rate, biomass and Pb content as the indexes, the Ramets hydroponic experiments at Pb concentration levels （135,270 and 540 mg/L） in the time （20, 35 and 50 d）were carried out. Photosynthetic pigment content was determined by spectrophotometer, and Pb mass fraction was detected with plasma emission spectrometer. Results ：There was uncertain effect on chlorophyll and carotenoid synthesis in different Pb concentrations in early period（20 and 35 d）. At the time of 50 d, the chlorophyll content was higher in the low-mid Pb concentrations, significantly lower in the high Pb concentration compared with the control group, and there were no signifi- cant differences on carotenoid contents in different Pb concentrations. Conclusion：Low-mid Pb concentrations can promote chlorophyll synthesis, and the bioaccumulation of high Pb concentration can inhibit the chlorophyll synthesis, and then restrict the growth of Rab- dosia rubescens.