Effects of Fe compounds on nutrient uptake by plants grown in sand media with different pH

The effect of soil and foliar application of different iron (Fe) compounds (FeSO₄, Fe‐EDTA, Fe‐EDDS, and Fe‐EDDHA) on nutrient concentrations in lettuce (Lactuca sativa cv. Australian gelber) and ryegrass (Lolium perenne cv. Prego) was investigated in a greenhouse pot experiment using quartz sand as growth medium. Soil application was performed in both the acidic and alkaline pH range, and foliar application to plants grown in the alkaline sand only. Lettuce growth was depressed by Fe deficiency in the alkaline sand, whereas the treatments had no effect on ryegrass growth. Soil‐applied Fe compounds raised the Fe concentrations in lettuce. This was especially true for the Fe chelates, which also increased yields. Soil‐applied Fe compounds had no statistically significant effect on Fe concentrations in ryegrass. Concentrations of manganese (Mn) in lettuce were equally decreased by all soil‐applied chelates. In the alkaline sand, soil application of Fe‐EDDHA elevated copper (Cu) and depressed zinc (Zn) concentrations in lettuce. The chelates increased Zn concentration in ryegrass. Foliar application of Fe‐EDDS increased Fe concentrations in lettuce and in ryegrass most. Fe‐EDDHA depressed Mn and Zn concentrations in lettuce more than other Fe compounds, suggesting the existence of another mechanism, in addition to Fe, that transmits a corresponding signal from shoot to roots with an impact on uptake of micronutrients.     

Impact of liming on utilization of 59Fe‐chelates by lettuce (Lactuca sativa L.)

A pot experiment was conducted to determine the utilization of iron (Fe) by lettuce (Lactuca sativa L. cv. Australian gelber). Iron was applied as ⁵⁹Fe in inorganic and chelated form, particularly biodegradable chelate, ⁵⁹Fe‐EDDS. Two stereoisomeric forms of ethylenediaminedisuccinate: [S,S]‐EDDS and a mixture of EDDS containing 25% [S,S]‐EDDS, 25% [R,R]‐EDDS, and 50% [S/R]/[R/S]‐EDDS, ethylenediaminetetraaceticacid (EDTA) and ethylenediimino bis(2‐hydroxyphenyl)acetic acid (EDDHA) were used as ligands. Lettuce was grown in unlimed and limed quartz sand with nitrate as the sole source of nitrogen. Liming decreased lettuce yields but had no effect on Fe concentrations, indicating that Fe concentrations were a poor indicator of Fe bioavailability within the plant. In unlimed sand, utilization of ⁵⁹Fe from all ⁵⁹Fe‐chelates was on the same level (2.8%–3.6%). In limed sand, only ⁵⁹Fe‐EDDHA maintained the ⁵⁹Fe utilization on a level (3%) comparable to that in unlimed sand. Although the utilization of ⁵⁹Fe from the other chelates decreased to 0.6%–1.1% after liming, Fe concentrations were not affected due to the increased uptake of indigenous Fe. The most biodegradable form of EDDS, namely ⁵⁹Fe‐EDDS(S,S), provided ⁵⁹Fe for lettuce as efficiently as the mixture of ⁵⁹Fe‐EDDS stereoisomers and the ⁵⁹Fe‐EDTA. Utilization of ⁵⁹Fe in inorganic form was 0.5% and 0.03% in unlimed and limed sand, respectively. This study shows that biodegradable ligands are able to serve as chelators to sustain Fe availability in calcareous environments. They may be of use especially in drip irrigation, where ligand accumulations may pose a threat to groundwater quality.     

Interaction of Iron with Copper,Zinc, and Manganese in Wheat as Affected by Iron and Manganese in a Calcareous Soil

Iron (Fe) availability is low in calcareous soils of southern Iran. The chelate Fe-ethylenediamine di (o-hydroxy-phenylacetic acid) (Fe-EDDHA), has been used as an effective source of Fe in correcting Fe deficiency in such soils. In some cases, however, its application might cause nutritional disorder due to the antagonistic effect of Fe with other cationic micronutrients, in particular with manganese (Mn). A greenhouse experiment was conducted to evaluate the influence of soil and foliar applications of Fe and soil application of manganese (Mn) on dry matter yield (DMY) and the uptake of cationic micronutrients in wheat (Triticum aestivum L. var. Ghods) in a calcareous soil. Results showed that neither soil application of Fe-EDDHA nor foliar application of Fe sulfate had a significant effect on wheat DMY. In general, Fe application increased Fe uptake but decreased that of Mn, zinc (Zn), and copper (Cu). Application of Mn increased only Mn uptake and had no significant effect on the uptake of the other cationic micronutrients. Iron treatments considerably increased the ratio of Fe to Mn, Zn, Cu, and (Mn + Zn + Cu). Failure to observe an increase in wheat DMY following Fe application is attributed to the antagonistic effect of Fe with Mn, Zn, and Cu and hence, imbalance in Fe to (Mn + Zn + Cu) ratio. Due to the nutritional disorder and imbalance, it appears that neither soil application of Fe-EDDHA nor foliar application of Fe-sulfate is appropriate in correcting Fe deficiency in wheat grown on calcareous soils. Hence, growing Fe-efficient wheat cultivars should be considered as an appropriate practice for Fe chlorosis-prone calcareous soils of southern Iran.     

Fate of DTPA,EDTA, and EDDS in Hydroponic Media and Effects on Plant Mineral Nutrition

Synthetic chelators are commonly used in hydroponic media to solubilize iron (Fe); however, the fate of these chelators is unknown. This study examined the persistence of three synthetic chelators, ethylenediaminetetraacetate (EDTA), diethylenetriaminepentaacetate (DTPA), and ethylenediaminedisuccinate (EDDS) in a bench-scale lettuce production system. The EDDS concentration decreased rapidly within 7d, most likely due to biodegradation. The EDTA and DTPA concentrations stayed steady throughout the experiments despite additions to maintain a constant volume and loss of chelator may have been due to either plant uptake or photodegradation of the chelator. Despite large differences in solution chemistry, the final shoot concentrations of iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) were similar among chelator treatments, whereas root concentrations of these same elements were highly variable. The concentration of DTPA in a commercial lettuce production system was measured and highly variable concentrations were found.     

Effect of Nano Fe-Chelate,Fe-Eddha and FeSO4 on Vegetative Growth,Physiological Parameters and Some Nutrient Elements Concentrations of Four Varieties of Lettuce (Lactuca sativa L.) In NFT System

In order to investigate the effects of different iron (Fe) sources (nano iron (Fe)-chelate, Fe- ethylenediamine-di(o-hydroxy phenyl acetic acid (EDDHA) and iron (II) sulfate (FeSO₄)) on lettuce (Lactuca sativa) growth in alkaline solutions, an experiment was arranged in hydroponic system. This study showed that leaf Fe content and overall plant growth was significantly increased by Fe-chelate application, and the highest values of leaf Fe, plant pigments and vegetative growth were recorded in plants treated with nano Fe-chelate. The lowest Fe, chlorophyll, carotenoids and soluble sugars in leaves were observed in FeSO₄ treatment. There were no difference in soluble sugars contents of plants between nano Fe-chelate and Fe-EDDHA treatments. Fertilization of lettuce plants with different Fe-chelate sources had a beneficial effect on the manganese (Mn) and zinc (Zn) uptake in plants. It is concluded that application of chelated form of Fe (especially nano Fe-chelate) must be performed in hydroponic system with alkaline water, to overcome Fe deficiencies and to make better nutritional status.     

Distribution and secondary effects of EDDHA in some vegetable species

Tomato (Lycopersicum esculentum), cucumber (Cucumis sativus), pepper (Capsicum annuum), and lettuce (Lactuca sativa) were grown on rockwool or perlite substrate with nutrient solution. Fe was administered as the Fe complex of the chelator ethylenediamine di-(o-hydroxyphenylacetic acid) (EDDHA) or Fe(NH₄)₂(SO₄)₂ in the nutrient solution or as inorganic iron in the substrate. Roots and leaves of plants grown on Fe-EDDHA contained EDDHA in quantities up to 0.27 × the amount of Fe, which is interpreted as an indication of the contribution of passive chelate absorption to Fe uptake. Fruits of tomato and pepper, and leaves of lettuce contained only traces of EDDHA. Breakdown of the chelator in leaves of pepper and tomato is estimated to have been between 0.5 and 2% per day. In tomato fruits, lycopene content was lowered in plants growing on Fe-EDDHA. Cucumber growing on Fe-EDDHA suffered from serious infection by the mildew Sphaerotheca fusca; the plants growing on an inorganic source of iron were resistant. These results exemplify physiological effects of EDDHA other than those directly associated with iron nutrition.     

Uptake of Zn and Fe by wheat (Triticum aestivum var. Greina) and transfer to the grains in the presence of chelating agents (ethylenediaminedisuccinic acid and ethylenediaminetetraacetic acid)

A way to decrease iron and zinc deficiency in humans is to biofortify foods by increasing the bioavailable contents in these elements. The aim of this work was to study if chelating agents could be used to increase the capture of Fe and Zn by wheat grains. Zn and/or Fe in combination with the chelating agents ethylenediaminedisuccinic acid (EDDS) or ethylenediaminetetraacetic acid (EDTA) were added at various times (i.e., at flower head formation, anthesis, and postanthesis) to spring wheat ( Triticum aestivum var. Greina) grown in nutrient solution. Treatments lasted for 2 weeks, and the plants were harvested at grain maturity. The shoots of treated plants accumulated higher Zn and/or Fe concentrations than untreated plants, depending on the treatment. The plants also accumulated significant concentrations of EDDS or EDTA in their shoots. Elevated Zn and Fe concentrations in the shoots did in most cases not lead to significantly higher Zn and Fe concentrations in the grains. The grains of plants treated with EDDS during flower head formation accumulated elevated Fe and Zn concentrations but at the cost of a reduction in yield. The control plants transferred higher percentages of Fe and Zn from the shoot into the grain than the treated plants. This indicates that EDTA and EDDS inhibited in most cases the translocation of Fe and Zn from the shoots into the grains. The amounts of EDDS and EDTA found in the grains of treated plants were very small. This indicates that there was little transfer of the chelates into the symplast and that the apoplastic pathway, which is important for the transport of chelants into the shoots, is efficiently blocked between shoots and seeds.     

Application of biosolids to soil affects Cu and Zn accumulation and antioxidant activity of lettuce (Lactuca sativa L.)

The application of biosolids to agricultural fields is becoming increasingly common. The effect of biosolids on the behavior of metals in different plants has been reported to be variable and ambiguous. A greenhouse experiment was conducted on a soil spiked with four rates of copper (Cu) (0, 50, 100, and 150 mg kg^?1) and zinc (Zn) (0, 150, 300, and 450 mg kg^?1) in lettuce culture. When Cu and Zn were spiked to anaerobically-digested biosolids, their availability in lettuce increased. Root and shoot fresh weight decreased due to a decrease in photosynthetic rate. superoxide dismutase (SOD) and peroxidases (POD) activity increased after the application of Cu and Zn. The bioavailability of Zn in lettuce was greater than that of Cu because of a higher transfer factor in plants and due to a higher endogenous Zn concentration.These results will allow for better fertilization management when biosolids are applied to tomato culture.     

EDDS对海州香薷修复重金属复合污染土壤的田间效应

两年田间小区试验研究了加入易降解络合剂EDDS后污染土壤及修复植物海州香薷地上部Cu、Zn、Pb含量及地下水水质变化。结果显示,添加EDDS能在一定程度上提高海州香薷对Cu、Zn、Pb的吸收量,但是对地下水水质影响不大,符合国家III类地下水水质标准。EDDS强化海州香薷修复复合污染土壤有一定的应用前景,且对于地下水的潜在淋滤风险较小,但是在应用期间应注意对环境因素特别是降水及地下水的影响。     

重金属胁迫对水稻不同品种超氧化物歧化酶的影响

用不同浓度的Cd2 + 、Cu2 + 和Hg2 + 处理花期的扬稻 6号 (籼稻 )、武育粳 8号 (粳稻 )和协优 81 8(杂交稻 ) ,测定各器官SOD活性 ,并进行SOD同功酶的电泳分析。结果表明 ,较高浓度重金属显著抑制各品种根系SOD活性 ,也抑制叶片SOD活性 ,但抑制程度因重金属种类和品种类型而异。各浓度均抑制武育粳穗SOD活性 ,但诱导扬稻 6号穗SOD活性增高。协优 81 8穗SOD活性受Cd2 + 抑制 ,但却受高浓度Cu2 + 和Hg2 + 诱导。≥ 2 0ppmCd2 + 、Cu2 + 和Hg2 + 均抑制水稻根系SOD同功酶表达 ,但诱导扬稻 6号和协优 81 8穗SOD同功酶表达。Mn SOD和Cu Zn SOD同功酶对重金属胁迫的敏感性不同 ,重金属对水稻根系Mn SOD的抑制程度明显高于Cu Zn SOD。     

营养液供液高度对水培生菜生长及矿质元素吸收的影响

在密闭植物工厂条件内,设置5种营养液高度（2、3、4、5、6cm）水培种植生菜,以探究霍格兰（Hoagland）配方营养液不同供液高度对生菜十种矿质元素（K、P、Ca、Mg、Na、Fe、Mn、Zn、Cu、S）吸收及积累的影响。结果表明：生菜地上部生物量以及光合色素含量均在4cm供液高度处理下最大,而地下部生物量以及根长均随着营养液供液高度的增加而升高;生菜地上部十种矿质元素的含量均在供液高度6cm处理下最大,而矿质元素在生菜中的单株累积量则表现为Fe、Mn元素在6cm供液高度下最大,Ca、Mg、Na、Zn、Cu、S元素在4cm供液高度下最大,K、P元素在5cm供液高度下最大。因此,实际生产中可以通过调节水培生菜营养液的供液高度,以达到提高生菜产量或生产功能性蔬菜的目的。     

Iron and/or acid foliar spray versus soil application of Fe-EDDHA for prevention of iron deficiency in Valencia orange grown on a calcareous soil

A two-year experiment was conducted in an iron(Fe)-deficient orchard with calcareous soil to find out an alternate method for soil application of Fe ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid) (Fe-EDDHA) in orange trees. Foliar sprays of Fe-EDDHA (5 g l^?1, pH = 7.8), sulfuric acid (pH = 3), citric acid (5 g l^?1, pH = 2.4), Fe (II) sulfate solutions (250, 500, and 750 mg Fe l^?1) with their initial pH (6.5, 6.35, and 6.12) and reduced ones to pH of 3 were compared with soil applied (75 g tree^?1) Fe-EDDHA and a control test. Although optimum chlorophyll content, leaf Fe concentration, fruit quantitative and qualitative attributes were resulted from soil application of Fe-EDDHA, repeated sprays of Fe-EDDHA or acidified Fe solutions created suitable results. Acidification of Fe solutions made them more effective in alleviation of leaf Fe concentration and Fe chlorosis, probably due to remobilization of inactive Fe within the plant and prevention of Fe oxidation and precipitation in foliar solutions.     

可降解络合剂及微生物调控对海州香薷修复污染土壤的效应

盆栽试验研究了海州香薷在Cu、Zn、Pb污染土壤上生长和对Cu、Zn、Pb的富集能力,以及调控剂EDDS、壳聚糖和微生物菌剂对海州香薷重金属吸收的影响。结果表明,Cu223mg/kg,Pb232mg/kg,Zn1068mg/kg的重金属复合污染土壤对海州香薷的生长发育没有明显影响。施用EDDS(3mmol/kg土) 微生物制剂处理组海州香薷叶片中Cu含量高达847mg/kg,Zn含量为745mg/kg;Cu吸收量高达6244μg/株,Zn吸收量为5670μg/株,叶片中Cu、Zn的含量和吸收量均极显著高于对照(p<0.01);3mmol/kg土EDDS处理海州香薷茎中Pb含量显著增加(p<0.05),茎中Pb的吸收量亦显著提高(p<0.05),茎秆中Pb的吸收量为274μg/株。微生物制剂或壳聚糖单独处理对海州香薷生长和金属元素吸收均没有明显的效果。     

X‐ray fluorescence analysis of small leaf samples mixed with cellulose or boric acid

Abstract

X‐ray fluorescence (XRF) is an effective and rapid technique for the analysis of many mineral elements in plant tissue. Plant samples sometimes are too small to make good pellets and to provide good XRF analyses. Leaf tissue was mixed with cellulose or boric acid at different ratios to assess whether pellets from these mixtures could be analyzed by XRF and to determine the effects of these inert substances on analysis of Al, Ca, Cl, Cu, Fe, K, Mg, Mn, P, S, Si, and Zn. Concentrations of all elements decreased linearly at all leaf/cellulose ratios. Concentrations of Mn, Fe, Zn, and Cu decreased linearly at all leaf/boric acid ratios, but concentrations of the other elements decreased linearly only when leaf/boric acid ratios were above about 40/60, and decreases in concentration of these other elements were more pronouned at leaf/boric acid ratios below 40/60. Concentrations of P, S, Cl, K, Mg, Ca, Si, and Al were higher in leaf/boric acid than in leaf/cellulose pellets, and similar concentrations were noted for Cu, Mn, Fe, and Zn in both kinds of pellets. Mechanically shaking cellulose with leaf tissue generally resulted in higher mineral element concentrations than if samples were mixed by hand. Cellulose would be the preferred inert substance to mix with plant samples if plant samples are below ～40 mg in size. Small samples of plant tissue can effectively be analyzed by XRF when mixed with cellulose or boric acid.     

ELEMENTAL SULFUR IMPREGNATED WITH IRON AS A FERTILIZER SOURCE FOR KENTUCKY BLUEGRASS

Elemental sulfur (S) impregnated with Fe (S-Fe) fertilizer was evaluated on Kentucky bluegrass (KBG; Poa pratensis L.) in three glasshouse studies: (1) with/without Fe as S-Fe, ferrous sulfate (FS), or iron-ethylenediamine-N,N’-bis(2-hydroxyphenylacetic acid) (Fe-EDDHA) to soil (49 kg Fe ha^?1), or foliar Fe-EDDHA (5 kg Fe ha^?1) on two cultivars; (2) 0, 49, 197, or 592 kg Fe ha^?1 of S-Fe deep mixed or surface mixed on two soils; (3) 0 or 49 kg Fe ha^?1 applied as S-Fe on four cultivars. A field study comparing 0 and 49 kg Fe ha^?1 applied as S-Fe to KBG was also conducted. Soil applied S-Fe was assimilated in shoots as efficiently as Fe-EDDHA applied to soil or foliage. Shoot Fe increased significantly with increasing S-Fe in a curvilinear response when deep mixed with soil and in a linear response when surface applied. However, no Fe source tested impacted yield or verdure in these studies.     

Copper and zinc uptake by celery plants grown on acidic soil amended with biosolids

For trace elements, such as copper (Cu) and zinc (Zn), the bioavailability of these elements, Cu and Zn, in biosolids is important because both are essential elements and both are potential contaminants when biosolids are land applied. A greenhouse study was conducted in factorial experiment based on a completely randomized design (CRD) with four replications on a soil treated with four rates of Cu (0, 50, 100, and 150 mg/kg) and four rates of Zn (0, 150, 300, and 450 mg/kg) on celery plants to investigate the distribution and mobility of these elements as well as growth and antioxidant changes of celery. The results of antioxidant changes were inconclusive due to irregular changes with Zn and Cu applications. However, generally the results show that Cu did not affect superoxide dismutase (SOD) or peroxidase (POD) activities in most of the treatments. On the other hand, Zn stimulated SOD and POD activities in most of the treatments. The photosynthesis rate decreased with the applications of Cu and Zn at the rates above 100 and 300 mg/kg and increased in low Cu concentration (50 mg/kg) compared to S (soil without biosolid).     

Fe对龙葵幼苗Zn毒害耐受性的影响

本研究以龙葵为试验材料,采用水培方法分析了补充Fe对龙葵幼苗Zn毒害耐受性的影响。结果表明,补充200μmol.L 1Fe-EDTA提高了龙葵幼苗对Zn毒害的耐受性。400μmol.L 1ZnCl2处理导致龙葵幼苗株高、根长和叶绿素含量显著减少,并引起H2O2的积累。补充Fe后,植株生长状况得到明显改善,SOD、CAT和APX基因的表达和酶的活性显著提高。同时RT-PCR结果显示,补充Fe后,FeSOD2和CAT1基因的表达明显升高。这些结果表明,Zn毒害对龙葵幼苗生长发育的影响很大程度上可能是由于Zn毒害引起的缺Fe导致的;Zn毒害条件下补充Fe可以通过提高FeSOD2和CAT1基因的表达,提高抗氧化酶的活性,降低ROS的水平,降低植株的氧化伤害。本研究为进一步研究植物响应Zn毒害的生理分子机理,以及植物修复技术的实际应用提供了理论基础。     

ALLEVIATION OF CADMIUM-TOXICITY BY APPLICATION OF ZINC AND ASCORBIC ACID IN BARLEY

ABSTRACT

Effect of cadmium (Cd) on biomass accumulation and physiological activity and alleviation of Cd-toxicity by application of zinc (Zn) and ascorbic acid in barley was studied, using semisolid medium culture including 15 treatments [four Cd concentration treatments: 0.1, 1, 5, 50?µmol?L^?1, four treatments with addition of 300?µmol?L^?1 Zn or 250?mg?L^?1 ascorbic acid (ASA) based on these four Cd concentrations, respectively, and three controls: basic nutrient medium, and with Zn or ASA, respectively]. Cadmium addition to semisolid medium, at a concentration of 1, 5, and 50?µmol?L^?1, inhibited biomass accumulation and increased malondialdehyde (MDA) content of barley plants, while the addition of 0.1?µmol?L^?1 Cd increased slightly dry mass. There was a tendency to a decrease in Zn, copper (Cu) concentrations both in shoots and roots and iron (Fe) in shoots of barley plants exposed to 1 to 50?µmol?L^?1 Cd. In addition, there were indications of a stress repose characterized by increased superoxide dismutase (SOD) and peroxidase (POD) activities relative to plants not subjected to Cd. The physiological changes caused by Cd toxicity could be alleviated to different extent by application of 300?µmol?L^?1 Zn or 250?mg?L^?1 ASA in Cd stressed plants. The most pronounced effects of adding Zn or ASA in Cd stressed medium were expressed in the decreased MDA and increased biomass accumulation, e.g., MDA contents were reduced (p≤0.01) by 4.8%–17.8% in shoots and 0.5%–19.7% in roots by adding 300?µmol?L^?1 Zn, in 50?µmol?L^?1 Cd stressed plants, and by 1.3%–7.4% in shoots and 2.6%–4.5% in roots by application of 250?µmol?L^?1 ASA, respectively. However, ASA addition may enhance Cd translation from root to shoot, accordingly, ASA would be unsuitable for the edible crops grown in Cd contaminated soils to alleviate phytotoxicity of Cd.     

Nutritional Alleviation of Zinc-Induced Iron Deficiency in Indian Mustard and the Effects on Zinc Phytoremediation

ABSTRACT

Indian mustard (Brassica juncea Czern) is a promising species for the phytoextraction of zinc (Zn), but the effectiveness of this plant can be limited by iron (Fe) deficiency under Zn-contaminated conditions. Our objectives were to determine the effects of root-applied Fe and Zn on plant growth, accumulation of Zn in plant tissues, and development of nutrient deficiencies for B. juncea. In the experiment, B. juncea was supplied 6 levels of iron ethylenediamine dihydroxyphenylacetic acid (Fe-EDDHA; 0.625 to 10.0 mg L^?1) and two levels of Zn (2.0 and 4.0 mg L^?1) for 3 weeks in a solution-culture experiment. Nutrient solution pH decreased with decreasing supply of Fe and increasing supply of Zn in solution, indicating that B. juncea may be an Fe-efficient plant. If plants were supplied 2.0 mg Zn L^?1, plant growth was stimulated by increases in Fe supply, but plant growth was not influenced by Fe treatments if plants were supplied 4.0 mg Zn L^?1. Zinc concentration in roots and shoots was suppressed by increasing levels of Fe in solution. Leaf concentrations of Cu, Mn, and P were suppressed also as Fe supply in solutions increased. Iron additions to the nutrient solution were not effective at increasing the Zn-accumulation potential of B. juncea unless plants were supplied the higher level of Zn in solution culture. Even under these conditions, Fe additions were effective only if supplied at low levels in solution culture (1.25 mg Fe L^?1). Results suggest that Fe fertility has limited potential for enhancing Zn phytoextraction by B. juncea, even if plants suffer a suppression in growth from Fe deficiency.     

Effects of Chelating Compounds on Mobilization and Phytoextraction of Copper and Lead in Contaminated Soils

Six chelating compounds: ethylenediamine-tetraacetic acid (EDTA), ethylenediamine-N, N'-disuccinic acid (EDDS), tartaric acid, citric acid, glycine and histidine, were tested as potential agents to mobilize copper (Cu) and lead (Pb) from two soils polluted with the emissions from copper smelters. Copper was mobilized with the following efficiency: EDTA > citric and tartaric acids > histidine > EDDS and glycine, while Pb extractability followed the order: EDTA > EDDS >> tartaric and citric acid >> glycine and histidine. With respect to these results, EDTA and EDDS were chosen for a pot experiment on chelate-induced phytoextraction of Cu and Pb by maize (Zea mays). Chelates were applied at the rates of 0.2, 0.5, and 1.0 mmol kg^?1, and this experiment was carried out at two different watering regimes. Both EDTA and EDDS caused significant increase of Cu uptake from soils, but its concentrations in biomass were far below those required for efficient soil remediation. Lead uptake was only slightly affected by chelate application. Losses of Cu from soil by leaching were much higher than those caused by plant uptake.