Abstract

DE LA ROSA, G. et al. Effect of the plant stage and presence of a chelating agent on the tolerance and absorption of Cr(III) by Helianthus annuus. Rev. Mex. Ing. Quím [online]. 2008, vol.7, n.3, pp.243-251. ISSN 1665-2738.

Experiments were performed in hydroponics to determine the effect of Cr(III) on H. annuus germination, tolerance, and absorption in the presence and absence of the chelating agent SS-ethylene diamine tetraacetate (SS-EDDS). The presence of 40 mg kg^-1 Cr(III) had no significant effect on seed germination. In addition, seeds and seedlings at different growth stages were treated with 40 mg kg^-1 Cr(III) to determine the effect of plant age on the tolerance to these treatments. It was found that the younger the plant, the higher the resistance to Cr(III). Consequently, H. annuus seeds were sown on (a) nutrient solution without Cr(III) (Control I); (b) nutrient solution without Cr(III) + 0.8 mM EDDS (Control II); (c) nutrient solution with 40 mg L^-1 Cr(III); (d) nutrient solution with 40 mg L^-1 Cr(III) + 0.8 mM EDDS. It was found that, after 15 days following germination, roots were able to accumulate 7,400 y 710 mg Cr kg^-1, whereas shoots accumulated 200 y 32 mg Cr kg^-1 (dry weigth), for Cr y Cr- SS-EDDS treatments, respectively. Therefore, the presence of SS-EDDS reduced Cr(III) absorption and traslocation. These results indicated that H. annuus does not need the presence of SS-EDDS to absorb significant amounts of Cr(III); this might reduced the costs associated to the phytoremediation of Cr(III) contaminated media using this plant species.

Keywords : phytoremediation; Cr(III); EEDS; plant age; traslocation.

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