EFFECT OF INDOLE-3-ACETIC ACID, KINETIN, AND ETHYLENEDIAMINETETRAACETIC ACID ON PLANT GROWTH AND UPTAKE AND TRANSLOCATION OF LEAD, MICRONUTRIENTS, AND MACRONUTRIENTS IN ALFALFA PLANTS

Abstract

Alfalfa plants germinated and grown for 15 d in soil containing 80 mg Pb kg⁻¹ were treated with ethylenediaminetetraacetic acid (EDTA) at 0.8 mM and indole-3-acetic acid-kinetin (IAA-KN) at 100 μM. Fifteen days after the treatment application, the concentration of lead (Pb), macronutrients, and micronutrients was determined using inductively coupled plasma/optical emission spectroscopy. The chlorophyll content and plant growth were also measured. Roots of plants exposed to Pb alone, Pb–EDTA, and Pb–EDTA-IAA-KN had 160, 140, and 150 mg Pb kg⁻¹ DW, respectively. Pb was not detected in the stems of plants exposed to Pb alone; however, stems of plants treated with EDTA and EDTA–IAA-KN had 78 and 142 mg Pb kg⁻¹ DW, respectively. While the Pb concentration in leaves of plants treated with EDTA and EDTA–IAA-KN was 92 and 127 mg kg⁻¹ DW, respectively. In addition, EDTA and EDTA–IAA-KN significantly increased the translocation of zinc and manganese to leaves. The x-ray absorption spectroscopic studies demonstrated that Pb(II) was transported from roots to leaves without a change in the oxidation state.

KEY WORDS:

• lead (Pb)
• ethylenediaminetetraacetic acid (EDTA)
• indole-3-acetic acid
• kinetin
• macronutrients
• micronutrients
• uptake

ACKNOWLEDGEMENTS

The authors acknowledge the Historically Black Colleges and Universities/Minority Institutions Environmental Technology Consortium that is funded by the Department of Energy. They also acknowledge the University of Texas at El Paso's Center for Environmental Resource Management through funding from the Environmental Protection Agency. Portions of this research were carried out at the Stanford Synchrotron Radiation Laboratory, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences. The SSRL Structural Molecular Biology Program is supported by the Department of Energy, Office of Biological and Environmental Research, and by the National Institutes of Health, National Center for Research Resources, Biomedical Technology Program. Jorge Gardea-Torresdey acknowledges the Dudley family for the Endowed Research Professorship in Chemistry and the University of Texas System LERR and STARs Programs. He also acknowledges the funding from the NSF–EPA funded UC Center for Environmental Implications of Nanotechnology (Grant # EF-0830117). Martha L. Lopez acknowledges the Consejo Nacional de Ciencia y Tecnologia of Mexico (CONACyT) for its financial support under grant 178763. The authors also acknowledge to three anonymous reviewers that greatly contributed to the improvement of this article.