Institute of Biology, University of Campinas - Unicamp, PO Box 6109, 13083-970 Campinas, SP, Brazil.
J Environ Manage. 2012 Nov 15;110:299-307. doi: 10.1016/j.jenvman.2012.06.015. Epub 2012 Jul 23.
A greenhouse pot experiment was conducted to evaluate the potential of three Brazilian leguminous woody species, Mimosa caesalpiniaefolia, Erythrina speciosa and Schizolobium parahyba, for the revegetation of lead- (Pb-) contaminated areas. The response of seedlings to increasing Pb concentrations (0, 250, 500 and 1000 mg kg(-1)) in the soil was studied. In addition to Pb accumulation and translocation, the following parameters were assessed: chlorophyll, nitrate, ammonia, lipid peroxidation (MDA) and free amino acid content; seedling growth; and nitrogenase activity. No differences were observed in the germination of woody species seeds sown in soils with or without Pb addition. M. caesalpiniaefolia did not show visual symptoms of Pb toxicity, while the other two species demonstrated stress symptoms, including reduced shoot biomass yield, leaf area and height. Biochemical analyses of plant tissues revealed markedly different responses to increasing Pb concentrations, such as changes in foliar soluble amino acid composition in S. parahyba; changes in ammonia and nitrate content in E. speciosa, M. caesalpiniaefolia and S. parahyba; and changes in MDA content in S. parahyba. The levels of chlorophyll a and b and carotenoid were affected in the species studied. For the Nitrogen-fixing (N(2)-fixing) species E. speciosa, an increase of Pb in the soil affected nodule formation and growth, which led to reduced nitrogenase activity in seedlings. The concentration of Pb in shoots and roots increased with the Pb concentration in soil. However, most of the Pb absorbed accumulated in the roots, and only a small fraction was translocated to aboveground parts. These findings were confirmed by the low bioconcentration factor (BCF) and translocation factor (TF) values for the three species. The tolerance index (TI) values suggested that M. caesalpiniaefolia, a N(2)-fixing tree, was the species that was most tolerant to high Pb concentrations in soil, while E. speciosa and S. parahyba showed moderate tolerance. Of the three Brazilian native woody species studied, M. caesalpiniaefolia was found to have the highest Pb tolerance and phytostabilisation potential in Pb-contaminated soils.
进行了温室盆栽实验，以评估三种巴西豆科木本植物（金合欢属 Caesalpinia 种、巴西刺桐 Erythrina speciosa 和巴西苏木 Schizolobium parahyba）对铅（Pb）污染地区植被恢复的潜力。研究了幼苗对土壤中 Pb 浓度（0、250、500 和 1000mgkg(-1))的增加的反应。除了 Pb 积累和转运外，还评估了以下参数：叶绿素、硝酸盐、氨、脂质过氧化（MDA）和游离氨基酸含量；幼苗生长；以及固氮酶活性。在添加或不添加 Pb 的土壤中播种的木本植物种子的发芽没有差异。金合欢属 Caesalpinia 种没有表现出 Pb 毒性的肉眼可见症状，而其他两种树种则表现出应激症状，包括减少地上生物量产量、叶面积和高度。植物组织的生化分析表明，随着 Pb 浓度的增加，植物有明显不同的反应，例如巴西苏木叶片中游离氨基酸组成的变化；巴西刺桐、金合欢属 Caesalpinia 种和巴西苏木中氨和硝酸盐含量的变化；以及巴西苏木中 MDA 含量的变化。研究中受影响的物种的叶绿素 a、b 和类胡萝卜素水平。对于固氮（N(2)-fixing）物种巴西刺桐，土壤中 Pb 的增加影响了根瘤的形成和生长，导致幼苗固氮酶活性降低。地上部分和根部分别吸收和积累了一定量的 Pb。这些发现得到了三种植物生物浓缩系数（BCF）和转移系数（TF）值较低的证实。耐度指数（TI）值表明，固氮树种金合欢属 Caesalpinia 种对土壤中高 Pb 浓度最具耐受性，而巴西刺桐和巴西苏木表现出中等耐受性。在研究的三种巴西本土木本植物中，金合欢属 Caesalpinia 种被发现对 Pb 污染土壤具有最高的 Pb 耐受性和植物稳定化潜力。
