7种紫花苜蓿对云南某铅锌矿区土壤镉铅的累积特征及品种差异

摘要

以云南某铅锌矿周边的农田为试验地,以7个紫花苜蓿(Medicago Sativa L)品种为植物材料开展田间大棚试验,研究各品种的株高、生物量、镉铅含量及累积量、富集系数和转移系数等指标,探讨不同紫花苜蓿对镉、铅的吸收累积特征及存在的品种差异.结果表明,从富集系数看,至开花期时(120 d),Cd富集能力最强的品种为"游客",其Cd富集系数为0.054,地上部Cd含量为0.22 mg·kg-1,地上部Cd累积量为40.58 μg·m-2,分别为Cd富集能力最弱品种"WL525HQ"的245%、200%和245%.Pb富集能力最强的品种为"国产",其Pb富集系数为0.035,地上部Pb含量为2.67 mg·kg-1,地上部Pb累积量为282.2 μg·m-2,分别为Pb富集能力最弱品种"WL525HQ"的152%、153%和110%.多数受试品种对Cd、Pb具有较强的转运能力,其中对Cd转运能力最强的品种为"三得利",其转运系数为1.545,是最弱品种"国产"的172%;对Pb转运能力最强的品种为"国产",其转运系数为2.048,是最弱品种"多叶"的171%.综上,受试紫花苜蓿品种对Cd、Pb的吸收累积存在一定品种差异,若以地上部金属含量为指标,"游客"为Cd高累积品种,"国产"为Pb高累积品种,"四季旺"为Cd低累积品种,"WL525HQ"为Pb低累积品种.%For studying the interspecific differences and accumulation features of cadmium(Cd)and lead(Pb)about different alfalfa (Medicago Sativa L)varieties, greenhouse experiments were carried out in a lead-zinc mine of Yunnan and the indexes including plant height,biomass,content and accumulation of Cd and Pb,enrichment coefficient and transfer coefficient were measured.The results showed that from the enrichment coefficient,the variety having the strongest Cd accumulation capacity was"Youke",its Cd enrichment coefficient, Cd content of shoot, Cd accumulation of shoot were respectively 0.054, 0.22 mg·kg-1and 40.58 μg·m-2and were higher respectively by 145%,100%and 145%than that of the weakest varieties"WL525HQ"in anthesis(120 day). The svariety having the strongest Pb accumulation capacity was"Guochan",its Pb enrichment coefficient,Pb content of shoot,Pb accumulation of shoot were respctively 0.035, 2.67 mg·kg-1and 282.2 μg·m-2and were higher respectively by 52%, 53% and 10% than that of the weakest varieties "WL525HQ" in anthesis(120 day).From transfer coefficient,most of cultivars used in experiments had a certain capacity for transfering Cd and Pb from root to shoot.The variety having the strongest Cd transfer capacity was"Sandeli",its Cd transfer coefficient was 1.545 and was higher by 72%than that of the weakest varieties"Guochan"in anthesis(120 day).The variety having the strongest Pb transfer capacity was"Guochan",its Pb transfer coefficient was 2.048 and was higher by 71%than that of the weakest varieties"Duoye"in anthesis(120 day).In conclusions the inerspecific differences of Cd and Pb accumulative characteristics were existed among alfalfa cultivars used in the experiments, Based on metal content in shoot "Youke" and "Guochan" could be considered as Cd and Pb high accumulation cultivar respectively, whereas"Sijiwang"and"WL525HQ"could be considered as Cd and Pb low accumulation cultivar respectively.