采用盆栽法研究了15 mg·kg^-1Cd胁迫条件下0.05～0.30 mmol·L^-1硝普钠（SNP）与0.50和1.50 mmol·L^-1［s,s］-乙二胺二琥珀酸（EDDS）单一或复合处理对紫苜蓿（Medicago sativa Linn.）幼苗生长、生理和Cd积累的影响，并分析了生长和Cd积累指标间及其与SNP和EDDS浓度的相关性。结果显示：在土壤Cd胁迫条件下，与对照（不施用SNP和EDDS）相比，不同浓度SNP单一处理总体上可提高紫苜蓿幼苗的株高、主根长、地上部的鲜质量和干质量、地下部的鲜质量和干质量、根系活力及光合色素含量，也可提高地上部和地下部的Cd含量、Cd转运系数、地上部和地下部的Cd富集系数、Cd修复效率、地上部各亚细胞组分的Cd含量及地下部细胞器和可溶部分的Cd含量；经不同浓度EDDS单一处理后，上述多数指标显著升高，仅部分指标显著降低；而经不同浓度SNP与EDDS复合处理后，部分生长、生理和Cd积累指标高于对照或同浓度SNP单一处理，其中，经不同浓度SNP与0.50 mmol·L^-1EDDS复合处理后，部分指标还高于同浓度SNP与1.50 mmol·L^-1EDDS复合处理。总体上看，0.10～0.20 mmol·L^-1SNP与0.50 mmol·L^-1EDDS复合处理对紫苜蓿幼苗的生长、生理和Cd积累的促进作用更明显；地下部的Cd含量和Cd富集系数大幅度高于地上部，地上部和地下部的细胞壁和可溶部分的Cd含量大幅度高于细胞器和线粒体。在SNP单一处理下，紫苜蓿幼苗地上部的Cd含量和Cd富集系数以及地下部的鲜质量、干质量、Cd含量和Cd富集系数与SNP浓度显著正相关；在不同浓度SNP与1.50 mmol·L^-1EDDS复合处理下，地上部Cd含量和Cd富集系数与SNP浓度显著负相关；而在其他处理条件下，生长和Cd积累指标与SNP和EDDS浓度无显著相关性。综合分析结果表明：在土壤Cd胁迫条件下，施用适宜浓度的SNP和EDDS有利于紫苜蓿幼苗的生长及对Cd的吸收积累，有助于细胞壁中Cd向可溶部分转移及降低细胞器和线粒体中Cd含量。综合考虑认为，0.10～0.20 mmol·L^-1SNP与0.50 mmol·L^-1EDDS联用可强化紫苜蓿对Cd污染土壤的修复效应。

Effects of single or combined treatments of 0.05-0.30 mmol·L^-1sodium nitroprusside (SNP) and 0.50 and 1.50 mmol·L^-1 ［s,s］-ethylenediamine disuccinic acid (EDDS) on growth, physiology, and Cd accumulation of Medicago sativa Linn. seedlings under 15 mg·kg^-1 Cd stress condition were studied by using pot-culture method, and the correlations among growth and Cd accumulation indexes and their correlations with SNP and EDDS concentrations were analyzed. The results show that under soil Cd stress condition, compared with the control (not applying SNP and EDDS), single treatment of different concentrations of SNP can increase height, main root length, fresh mass and dry mass of above-ground part, fresh mass and dry mass of under-ground part, root activity, and contents of photosynthetic pigments of M. sativa seedlings in general, and can also increase Cd content in above- and under-ground part, Cd translocation coefficient, Cd concentration coefficient of above- and under-ground part, Cd remediation efficiency, Cd content in each subcellular component of above-ground part, and Cd content in organelles and soluble fraction of underground part; most above-mentioned indexes increase significantly after single treatment of different concentrations of EDDS, while only some indexes decrease significantly; meanwhile, after combined treatment of different concentrations of SNP and EDDS, some growth, physiological, and Cd accumulation indexes are higher than those of the control or single treatment of the same concentration of SNP, in which, after combined treatment of different concentrations of SNP and 0.50 mmol·L^-1 EDDS, some indexes are even higher than those of combined treatment of the same concentration of SNP and 1.50 mmol·L^-1 EDDS. In general, combined treatment of 0.10-0.20 mmol·L^-1 SNP and 0.50 mmol·L^-1 EDDS have more evident promotion effect on growth, physiology, and Cd accumulation of M. sativa seedlings; Cd content and Cd concentration coefficient of under-ground part are greatly higher than those of above-ground part, and Cd content in cell wall and soluble fraction of above- and under-ground part is greatly higher than that in organelle and mitochondria. Under SNP single treatment, Cd content and Cd concentration coefficient of above-ground part, and fresh mass, dry mass, Cd content, and Cd concentration coefficient of under-ground part of M. sativa seedlings show significant positive correlations with SNP concentration; under combined treatment of different concentrations of SNP and 1.50 mmol·L^-1 EDDS, Cd content and Cd concentration coefficient of above-ground part show significant negative correlations with SNP concentration; while under the other treatment conditions, growth and Cd accumulation indexes have no significant correlations with SNP and EDDS concentrations. The comprehensive analysis result shows that under soil Cd stress condition, application of suitable concentrations of SNP and EDDS are beneficial to the growth and absorption and accumulation of Cd of M. sativa seedlings, and can help Cd translocation from cell wall to soluble fraction and decrease Cd content in organelles and mitochondria. It is comprehensively considered that the combined application of 0.10-0.20 mmol·L^-1 SNP and 0.50 mmol·L^-1 EDDS can strengthen the remediation effect of M. sativa on Cd contaminated soil.