So far, more attention has been mostly paid to the effects of the chelates application to improve phytoextraction efficiency, but less information is available about their effects on the rhizosphere enzyme activities. A greenhouse study was conducted to investigate the effect of EDTA and citric acid (CA) (3 and 5 mmol/kg) on the Pb accumulation in plant organs, the dehydrogenase, urease and alkaline phosphomonoesterase activities, geometric mean of enzyme activities (GMea), total enzyme activity (TEA), and Shannon's diversity index. The application of EDTA harmed plant growth, whereas CA treatments improved plant growth. The 3 and 5 mmol/kg EDTA enhanced Pb accumulation in shoots by 2.6–6 and 1.7–3 times, respectively, in comparison with the control. Pb accumulation in roots after the CA application was significantly higher than control and EDTA treatments. The high dose of EDTA reduced the dehydrogenase and urease activities, GMea, TEA, and diversity of enzyme activities. In contrast, the low dose of EDTA increased the dehydrogenase and alkaline phosphomonoesterase activities, and enzyme-based indices compared with control treatment. In both high and low concentrations, CA significantly stimulated enzyme activities of the rhizosphere, as well as the enzyme-based indices, compared with control and EDTA treatments. CA increased Pb accumulation in the root while did not elevate Pb translocation to the shoot, and also improved the rhizosphere enzyme activities. Thus, we conclude that: i) the effect of EDTA on the Pb phytoextraction and rhizosphere enzyme activities depended on the dosage of EDTA used; ii) CA can be a more suitable choice to increase Pb phytostabilization due to enhancement of the rhizosphere microbial activities.

迄今为止，人们更多地关注了螯合剂的应用对提高植物提取效率的影响，但是关于它们对根际酶活性的影响的信息很少。进行了温室研究以研究EDTA和柠檬酸（CA）（3和5 mmol / kg）对植物器官中Pb积累，脱氢酶，脲酶和碱性磷酸单酯酶活性，酶活性几何平均值（GMea）的影响，总酶活性（TEA）和香农多样性指数。EDTA的使用损害了植物的生长，而CA处理改善了植物的生长。与对照相比，3 mmol / kg EDTA和5 mmol / kg EDTA分别使嫩芽中的Pb积累提高了2.6-6倍和1.7-3倍。施用CA后根部的Pb积累显着高于对照和EDTA处理。高剂量的EDTA降低了脱氢酶和脲酶的活性，GMea，TEA和酶活性的多样性。相反，低剂量的EDTA与对照组相比增加了脱氢酶和碱性磷酸单酯酶的活性，以及​​基于酶的指数。与对照和EDTA处理相比，在高浓度和低浓度下，CA都能显着刺激根际的酶活性以及基于酶的指数。CA可以增加根中Pb的积累，而不会提高Pb向茎上的转运，也可以改善根际酶的活性。因此，我们得出以下结论：i）EDTA对Pb植物提取物和根际酶活性的影响取决于所用EDTA的剂量；ii）由于根际微生物活性增强，CA是增加Pb植物稳定性的更合适的选择。