铅胁迫对狗牙根生理特性和铅积累的影响

摘要

为阐明铅胁迫对植物的毒害机制和重金属污染土壤、水体的植物修复模式，采用水培的方法，模拟三峡库区长江水体 Pb2＋污染环境，研究不同浓度 Pb2＋胁迫对三峡库区库岸适生植物狗牙根中超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）活性、叶绿素含量和铅积累的影响。结果表明：在铅胁迫初期（Pb2＋＜20 mg／L），植株 SOD、CAT 活性和叶绿素含量明显升高，最高点分别是361．78 U／g FW、215．16 U／（g·min）和2．99 mg／L；随着 Pb2＋浓度的增加及胁迫时间的延长，SOD、CAT 活性和叶绿素含量呈下降趋势，最低点分别是152．87 U／g FW、162．12 U／（g·min）和1．44 mg／L；而狗牙根叶片中 POD整体呈上升趋势，最高点是291．12 U／g FW；同时，狗牙根对 Pb2＋的积累主要分布于根，其次为茎。结论：狗牙根能明显降低江水中的 Pb2＋含量，可作为植物修复重金属污染水体的优良物种。%In order to elucidate the toxic mechanism of C.dactylon under lead (Pb2+ )stress and the underlying mechanism involved in phytoremediation of heavy metal contaminated soil and water,Pb (NO3 )2 was added into Hoagland solution to imitate Pb2+ polluted water environment and the effects on antioxidant system,chlorophyll content and the capacity for Pb2+ accumulation in resisting Pb2+ stress in C.dactylon were studied by water culture method.The results showed that the activities of SOD,CAT and chlorophyll content went obviously up at the beginning of lead stress(Pb2+ <20 mg/L),the maximum were 361.78 U/g FW,215.16 U/(g · min)and 2.99 mg/L respectively;but they decreased as the quantity of lead increasing and the stress time extending.The minimum were 152.87 U/g FW,162.12 U/(g·min)and 1.44 mg/L respectively;The activity of POD of C.dactylon showed an up trend with increasing Pb2+ concentration,the maximum was 291.12 U/g FW.Pb2+ was mainly distributed in the roots of C.dactylon,followed by the stems.This investigation also showed that C.dactylon could decrease the content of Pb2+ in polluted water,and the C.dactylon was a good plant species for the water ecosystem restoration.