Effects of salicylic acid, humic acid, and EDTA chelate on the increasing Pb concentration in the barley inoculated with PGPR

Document Type: Original Article


1 Department of Soil Science, Arak Branch, Islamic Azad University, Arak, Iran

2 Department of Chemical Engineering, Isfahan University of Technology, Isfahan, Iran


The present study aimed to investigate the effects of salicylic acid (SA), humic acid (HA), and EDTA chelate on the increasing Pb concentration in a plant inoculated with plant growth-promoting rhizobacteria (PGPR). Treatments consisted of applying two levels of EDTA (0 (EDTA0) and 3 (EDTA3) mmol/kg soil) and soil application of HA (0 (HA0) and 200 (HA200) mg/kg soil). In addition, foliar application of SA at the rates of 0 (SA0) and 1.5 (SA1.5) mmol/lit was also sprayed on the inoculated plant with and without PGPR cultivated in the Pb-polluted soil. After 9 weeks, barley plants were harvested and plant Pb concentration was measured using atomic absorption spectroscopy (AAS). The soil Pb concentration and plant Pb biomass was also measured. The least significant difference (LSD) test was used to determine the differences between the means (P=0.05). The results indicated that application of HA or EDTA had significantly (P=0.05) increased the Pb phytoremediation efficiency, as, applying 3 mmol EDTA/kg soil increased the Pb phytoremediation efficiency by 14.1%. In addition, a significant increasing (P=0.05) in plant biomass and Pb phytoremediation efficiency was observed by 12.2 and 13.6%, respectively, in the inoculated plant cultivated in the soil that received the greatest rates of EDTA and HA together with the highest rate of SA foliar application. Plant growth regulators such as SA or humic acid can increase plant resistance to Pb toxicity and help to increase Pb phytoremediation efficiency that is important in environmental studies.


1. Eslami H, Sedighi Khavidak S, Salehi F, Khosravi R, Fallahzadeh RA, Peirovi R, et al. Biodegradation of methylene blue from aqueous solution by bacteria isolated from contaminated soil. J Adv Environ Health Res 2017; 5(1): 10-15.

2. Eslami H, Ehrampoush MH, Esmaeili A, Ebrahimi AA, Salmani MH, Ghaneian MT, et al. Efficient photocatalytic oxidation of arsenite from contaminated water by Fe2O3-Mn2O3 nanocomposite under UVA radiation and process optimization with experimental design. Chemosphere 2018; 207: 303-312.

3. Zhou X-Y, Wang X-R. Impact of industrial activities on heavy metal contamination in soils in three major urban agglomerations of China. J Clean Prod 2019; 230: 1-10.

4. Ahmad I, Khan B, Khan S, Rahman ZU, Khan MA, Gul N. Airborne PM10 and lead concentrations at selected traffic junctions in Khyber Pakhtunkhwa, Pakistan: Implications for human health. Atmos Pollut Res 2019; 10(4): 1320-1325.

5. Esmaeili A, Mobini M, Eslami H. Removal of heavy metals from acid mine drainage by native natural clay minerals, batch and continuous studies. Appl Water Sci 2019; 9(4): 97.

6. Boskabady M, Marefati N, Farkhondeh T, Shakeri F, Farshbaf A, Boskabady MH. The effect of environmental lead exposure on human health and the contribution of inflammatory mechanisms, a review. Environ Int 2018; 120: 404-420.

7. Odoh CK, Zabbey N, Sam K, Eze CN. Status, progress and challenges of phytoremediation - An African scenario. J Environ Manage 2019; 237: 365-378.

8. Ashraf S, Ali Q, Zahir ZA, Ashraf S, Asghar HN. Phytoremediation: Environmentally sustainable way for reclamation of heavy metal polluted soils. Ecotoxicol Environ Saf 2019; 174: 714-727.

9. Rostami S, Azhdarpoor A. The application of plant growth regulators to improve phytoremediation of contaminated soils: A review. Chemosphere 2019; 220: 818-827.

10. Qiao J, Sun H, Luo X, Zhang W, Mathews S, Yin X. EDTA-assisted leaching of Pb and Cd from contaminated soil. Chemosphere 2017; 167: 422-428.

11. Jiang M, Liu S, Li Y, Li X, Luo Z, Song H, et al. EDTA-facilitated toxic tolerance, absorption and translocation and phytoremediation of lead by dwarf bamboos. Ecotoxicol Environ Saf 2019; 170: 502-512.

12. Luo J, Cai L, Qi S, Wu J, Gu XWS. Improvement effects of cytokinin on EDTA assisted phytoremediation and the associated environmental risks. Chemosphere 2017; 185: 386-393.

13. Liu Z, Nan Z, Zhao C, Yang Y. Potato absorption and phytoavailability of Cd, Ni, Cu, Zn and Pb in sierozem soils amended with municipal sludge compost. J Arid Land 2018; 10(4): 638-652.

14. Wang H-Q, Lu S-J, Li H, Yao Z-H. EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana. J Environ Sci 2007; 19(12): 1496-1499.

15. Piri M, Sepehr E, Rengel Z. Citric acid decreased and humic acid increased Zn sorption in soils. Geoderma 2019; 341: 39-45.

16. Yang T, Hodson ME. Investigating the use of synthetic humic-like acid as a soil washing treatment for metal contaminated soil. Sci Total Environ 2019; 647: 290-300.

17. Houshyar P, Baghaei A. Effectiveness of DTPA chelate on Cd availability in soils treated with sewage sludge. J Water Wastewater 2017; 28(4): 103-111.

18. Liu L, Li W, Song W, Guo M. Remediation techniques for heavy metal-contaminated soils: Principles and applicability. Sci Total Environ 2018; 633: 206-219.

19. Cheng S-F, Huang C-Y, Lin Y-C, Lin S-C, Chen K-L. Phytoremediation of lead using corn in contaminated agricultural land—An in situ study and benefit assessment. Ecotoxicol Environ Saf 2015; 111: 72-77.

20. Ma Y, Rajkumar M, Zhang C, Freitas H. Beneficial role of bacterial endophytes in heavy metal phytoremediation. J Environ Manage 2016; 174: 14-25.

21. Rajkumar M, Sandhya S, Prasad MNV, Freitas H. Perspectives of plant-associated microbes in heavy metal phytoremediation. Biotechnol Adv 2012; 30(6): 1562-1574.

22. Janmohammadi M, Bihamta M, Ghasemzadeh F. Influence of rhizobacteria inoculation and lead stress on the physiological and biochemical attributes of wheat genotypes. Cercetari Agronom Moldova 2013; 46(1): 49-67.

23. He S, Guo H, He Z, Wang L. Effects of a New-Type Cleaning Agent and a Plant Growth Regulator on Phytoextraction of Cadmium from a Contaminated Soil. Pedosphere 2019; 29(2): 161-169.

24. Aghili F, Gamper HA, Eikenberg J, Khoshgoftarmanesh AH, Afyuni M, Schulin R, et al. Green manure addition to soil increases grain zinc concentration in bread wheat. PloS one 2014; 9(7): e101487.

25. Baghaie AH, Daliri A. Effect of applying sunflower residues as a green manure on increasing Zn concentration of two Iranian wheat cultivars in a Pb and Cd polluted soil. J Human Environ Health Promot 2019; 5(1): 9-14.

26. Sakizadeh M, Mirzaei R, Ghorbani H. Accumulation and soil-to-plant transfer factor of lead and manganese in some plant species in Semnan province, central Iran. Iran J Toxicol 2016; 10(3): 29-33.

27. Gabos MB, Abreu CaD, Coscione AR. EDTA assisted phytorremediation of a Pb contamined soil: Metal leaching and uptake by jack beans. Scientia Agricola 2009; 66(4): 506-514.

28. Rasouli-Sadaghiani MH, Karimi H, Ashrafi Saeidlou S, Khodaverdiloo H. The effect of humic acid on the phytoremediation efficiency of Pb in the contaminated soils by wormwood plant (Artemicia absantium). J Water Soil Sci 2019; 22(4): 261-278.

29. Kausar R, Choudhary MI, Akram MI, Rashid M. Response of groundnut (Arachis hypogaea L.) to plant growth promoting Rhizobacteria in degraded soils. Afric J Agric Res 2018; 13(17): 904-910.

30. Adamczyk-Szabela D, Markiewicz J, Wolf WM. Heavy metal uptake by herbs. IV. Influence of soil pH on the content of heavy metals in Valeriana officinalis L. Water Air Soil Pollut 2015; 226(4): 106.

31. Yun S-W, Yu C. Immobilization of Cd, Zn, and Pb from soil treated by limestone with variation of pH using a column test. J Chem 2015; 2015.

32. Karami M, Afyuni M, Rezainejad Y, Schulin R. Heavy metal uptake by wheat from a sewage sludge-amended calcareous soil. Nutr Cycl Agroecosyst 2009; 83(1): 51-61.

33. Halim M, Conte P, Piccolo A. Potential availability of heavy metals to phytoextraction from contaminated soils induced by exogenous humic substances. Chemosphere 2003; 52(1): 265-275.

34. Guo X, Zhang G, Wei Z, Zhang L, He Q, Wu Q, et al. Mixed chelators of EDTA, GLDA, and citric acid as washing agent effectively remove Cd, Zn, Pb, and Cu from soils. J Soils Sediments 2018; 18(3): 835-844.

35. Shafigh M, Ghasemi-Fasaei R, Ronaghi A. Influence of plant growth regulators and humic acid on the phytoremediation of lead by maize in a Pb-polluted calcareous soil. Arch Agron Soil Sci 2016; 62(12): 1733-1740.

36. Hadi F, Bano A, Fuller MP. Augmented phytoextraction of lead (Pb2+)-polluted soils: A comparative study of the effectiveness of plant growth regulators, EDTA, and plant growth–promoting rhizobacteria. Bioremed J 2013; 17(2): 124-130.

37. Htwe WM, Kyawt YY, Thaikua S, Imai Y, Mizumachi S, Kawamoto Y. Effects of lead contamination in soils on dry biomass, concentration and amounts of lead accumulated in three tropical pasture grasses. Grassl Sci 2016; 62(3): 167-173.

38. Li Q, Wang G, Wang Y, Yang D, Guan C, Ji J. Foliar application of salicylic acid alleviate the cadmium toxicity by modulation the reactive oxygen species in potato. Ecotox Environ Safe 2019; 172:317-25.

39. Elhassan HE, Elkheir EMS, Diab EE, Osman GA. Salicylic acid enhanced phytoremediation of lead by maize (Zea mays) plant. Int J Eng Res Sci 2016; 2(1): 4-10.

40. Afrousheh M, Shoor M, Tehranifar A, Safari VR. Phytoremediation potential of copper contaminated soils in Calendula officinalis and effect of salicylic acid on the growth and copper toxicity. Int Lett Chem Phy Astronomy 2015;50: 159-168.

41. Erkovan HI, Gullap MK, Dasci M, Ali K. Effects of phosphorus fertilizer and phosphorus solubilizing bacteria applications on clover dominant meadow: I. hay yıeld and botanıcal composition. Turk  J Field Crops 2010; 15(1): 12-17.