通过盆栽紫花苜蓿实验，考察EDTA和柠檬酸（CA）对供试土壤中Ni各个形态分布、紫花苜蓿生理指标和土壤酶活性变化的影响。结果表明，供试土壤中施加EDTA/CA浓度为5.0/2.5 mmol·kg-1时，对土壤中Ni的活化效果较好，其水溶态含量是对照组的48.2倍，紫花苜蓿中丙二醛（MDA）含量提高了232.0%；施加EDTA/CA浓度为2.5/5.0 mmol·kg-1时，紫花苜蓿转运系数最大，是对照组的194.3%；紫花苜蓿细胞通透性随螯合剂总添加量的增大而增大，施加EDTA/CA浓度为5.0/10.0 mmol·kg-1时最大，比对照组增大206.3%；施加EDTA/CA对土壤过氧化氢酶均有不同程度的抑制作用。土壤蔗糖酶酶的激活率与CA施加量显著相关（P＜0.01）。研究认为，将EDTA/CA适当配比后施加，既可以减少螯合剂的用量，又可以较好地提高紫花苜蓿富集土壤中重金属Ni的效果。
Pot experiments of alfalfa were conducted to study the effects of EDTA and CA on distribution of Ni, physiological indexes of alfalfa and changes of soil enzyme activities. The results showed that when the EDTA/CA content was 5.0/2.5 mmol·kg-1, the Ni in the soil was better hydrated with the solubility was 48.2 times higher than that of the control group, and the content of malondialdehyde (MDA) in alfalfa increased by 232.0% compared the control group. When the concentration of EDTA / CA was 2.5/5.0 mmol·kg-1, the transfer coefficient of alfalfa was the highest, which was 194.3% of the control group. The cell permeability of alfalfa increased with the increase of the total amount of chelating agent with the highest cell permeability observed in the group of EDTA/CA 5.0/10.0 (P <0.05), which was 206.3% higher than that of the control group. The effect of EDTA/CA on soil catalase was inhibitory in different extent and the invertase was significantly correlated with CA (P <0.01). It is suggested that the addition of EDTA/CA in an appropriate proportion can reduce the dosage of chelating agent and improve the enrichment of heavy metal Ni in alfalfa.