铅胁迫对紫穗槐光合作用及生理生化特征的影响

以紫穗槐幼苗为材料，通过盆栽试验，研究不同浓度（0、100、300、600 mg·kg^-1）铅（Pb）胁迫条件下，紫穗槐叶片中的丙二醛（MDA）含量、抗氧化酶（SOD、POD、CAT）活性等生理指标和光合作用参数以及叶绿素荧光参数对 Pb 胁迫的响应。结果表明：紫穗槐叶片中 MDA 含量和电解质外渗率随着 Pb 胁迫程度的增加呈升高趋势，Pb 胁迫提高了紫穗槐叶片中抗氧化酶 SOD、POD 的活性；100 mg·kg^-1 Pb 胁迫处理下，紫穗槐净光合速率（Pn）显著高于对照组；Pb 胁迫浓度达到 300 mg·kg^-1 时，紫穗槐抗氧化酶活性、相对叶绿素含量（SPAD 值）显著升高；600 mg·kg^-1 Pb 胁迫下 CAT 活性开始有所降低，光合作用降低主要受非气孔限制因素的影响，对紫穗槐叶绿素荧光特性未造成严重损伤。说明紫穗槐对环境中 Pb（600 mg·kg^-1）污染的耐受能力较强。

Effects of Lead Stress on Photosynthesis and Physiological and Biochemical Characteristics of Amorpha fruticosa

The seedlings of Amorpha fruticosa were cultured at lead concentration of 0(control), 100, 300, 600 mg·kg^-1 respectively, under pot experiment to observe and analyze the response of physiological indicators such as malonaldehyde(MDA) content, activities of antioxidant enzymes (SOD, POD, CAT), photosynthesis and chlorophyll fluorescence parameters in leaves of Amorpha fruticosa to Pb stress. The results showed that with the increase of Pb concentration, the contents of MDA and activities of SOD and POD in leaves of Amorpha fruticosa increased. The net photosynthetic rate(Pn) was significantly higher than that of the control at 100 mg·kg^-1 Pb stress treatment. When the Pb concentration reached 300 mg·kg^-1, the activity of antioxidant enzymes and relative content of chlorophyll(SPAD) of Amorpha fruticosa increased significantly. The activities of catalases(CAT) began to decrease, the decrease of photosynthesis was mainly affected by nonstomatal limitation, and the chlorophyll fluorescence characteristics of Amorpha fruticosa were not seriously damaged when Amorpha fruticosa was under Pb stress of 600 mg·kg^-1. It indicated that Amorpha fruticosa could resist Pb pollution (600 mg·kg^-1)in the environment.