The effects of exogenous plant growth regulators in the phytoextraction of heavy metals

• Published in: Chemosphere (Oxford) Vol. 71; no. 1; pp. 66 - 73
• Main Authors: Tassi, Eliana, Pouget, Joël, Petruzzelli, Gianniantonio, Barbafieri, Meri
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.03.2008; Elsevier
• Subjects: Applied sciences; auxins; Biological and medical sciences; Biomass; Biotechnology; Cytokinins; Decontamination. Miscellaneous; dry matter accumulation; Earth sciences; Earth, ocean, space; EDTA (chelating agent); Engineering and environment geology. Geothermics; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; heavy metals; Helianthus annuus; Industrial applications and implications. Economical aspects; lead; Metals, Heavy - isolation & purification; Miscellaneous; Pb and Zn contaminated soil; Phytoextraction; phytoremediation; Plant growth hormones; Plant Growth Regulators - pharmacology; Plants - metabolism; Pollution; Pollution, environment geology; Soil and sediments pollution; Soil Pollutants - isolation & purification; soil pollution; solubility; transpiration; zinc; Cytokinins; Helianthus annuus; Pb and Zn contaminated soil; Phytoextraction; Plant growth hormones; In situ; Gas industry; Compositae; Soil pollution; Cytokinin; Heavy metal; Phytoremediation; Decontamination; Industrial wasteland; Dicotyledones; Angiospermae; Plant growth substance; Spermatophyta; Bioremediation; Phytohormone
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2007.10.027

The term “assisted phytoextraction” usually refers to the process of applying a chemical additive to contaminated soil in order to increase the metal uptake by crop plants. In this study three commercially available plant growth regulators (PGRs) based on cytokinins (CKs) were used to boost the assisted phytoextraction of Pb and Zn in contaminated soil collected from a former manufactured gas-plant site. The effects of EDTA treatment in soil and PGR treatment in leaves of Helianthus annuus were investigated in terms of dry weight biomass, Pb and Zn accumulation in the upper parts of the plants, Pb and Zn phytoextraction efficiency and transpiration rate. Metal solubility in soil and its subsequent accumulation in shoots were markedly enhanced by EDTA. The combined effects of EDTA and cytokine resulted in an increase in the Pb and Zn phytoextraction efficiency (up to 890% and 330%, respectively, compared to untreated plants) and up to a 50% increase in foliar transpiration. Our results indicate that exogenous PGRs based on CKs can positively assist the phytoextraction increasing the biomass production, the metal accumulation in shoots and the plant transpiration. The observed increase in biomass could be related to its action in stimulation of cell division and shoot initiation. On the other hand, the increase in metal accumulation in upper parts of plant could be related to both the role of PGRs in the enhancement of plant resistance to stress (as toxic metals) and the increase in transpiration rate, i.e. flux of water-soluble soil components and contaminants by the regulation of stomatal opening.