不同浓度镧处理对铅胁迫下玉米生长和铅吸收的影响

采用温室盆栽试验的方法,研究不同浓度的镧处理(0、50、200和800 mg·kg~(-1))对中度铅胁迫下(200 mg·kg~(-1))玉米生长、矿质营养元素吸收、C∶N∶P生态化学计量比及Pb和La吸收的影响,探讨土壤-植物系统中稀土重金属的相互作用,旨在为稀土矿区稀土重金属复合污染土壤的治理提供基础数据和理论依据.结果表明,随着外源La浓度的增加土壤中乙酸铵-EDTA提取态La的浓度显著增加,而乙酸铵-EDTA提取态Pb的浓度显著降低;玉米地上部干重显著降低了17.90%~81.17%,根冠比显著增加了21.74%~86.96%;随着土壤中La浓度的增加根部P含量显著降低了19.16%~89.68%,La浓度为200 mg·kg~(-1)和800 mg·kg~(-1)时,地上部P和N含量分别显著降低了65.51%~91.98%和48.27%~76.58%;随着土壤中La浓度的增加,植株C∶P、N∶P和植株La浓度显著增加,地上部和根部Pb浓度分别显著增加了52.61%~99.01%和15.99%~44.34%;随着La浓度的升高显著降低了玉米植株K、Ca和Mg的含量.结果初步证明,在稀土-重金属复合污染土壤中,稀土元素的存在加剧了重金属对植物生长的毒害效应及其所引发的生态风险问题,应进一步深入研究稀土对植物吸收重金属的影响及作用机制.

Effects of Different Concentrations of Lanthanum on the Growth and Uptake of Pb by Maize Grown Under Moderate Lead Stress

A greenhouse pot experiment was conducted to investigate the effects of different concentrations of lanthanum (0 mg·kg^-1, 50 mg·kg^-1, 200 mg·kg^-1 and 800 mg·kg^-1) on growth, nutrient uptake, C:N:P stoichiometry, and La and Pb uptake by maize (Zea mays L.) under moderate lead stress (200 mg·kg^-1) and evaluate the interaction of rare earth elements and heavy metals in the soil-plant system. The aim was to provide basic data and a theoretical basis for the remediation of rare earth element and heavy metal-co-contaminated soils in a rare earths mining area. The results indicate that the concentrations of CH₃COONH₄-EDTA-extractable La and Pb significantly increase and decrease, respectively, with increasing La concentrations of the soils. The shoot dry weights of maize significantly decreases by 17.90% to 81.17% and the root to shoot ratio of maize significantly increases by 21.74% to 86.96% with increasing La concentrations of the soils. With increasing La concentrations in soils, the root P contents of maize significantly decrease by 19.16% to 89.68%. The shoot P and N contents significantly decrease by 65.51% to 91.98% and 48.27% to 76.58%, respectively, when the exogenous application of La is 200 mg·kg^-1 and 800 mg·kg^-1, respectively. The increasing La concentrations in soils significantly increase the C:P and N:P ratios and shoot and root La concentrations of maize. The shoot and root Pb concentrations of maize significantly increase by 52.61% to 99.01% and 15.99% to 44.34%, respectively, with increasing La concentrations. Overall, the increasing La concentrations in soils significantly decrease the K, Ca, and Mg contents of maize. The results demonstrate that the presence of rare earth elements aggravates the phytotoxicity of heavy metals to plant and ecological risks. Further research should focus on the effects and mechanisms of rare earth elements on the heavy metal uptake by plants.