Assessment of the root system of Brassica juncea (L.) czern. and Bidens pilosa L. exposed to lead polluted soils using rhizobox systems

ABSTRACT

The purpose of this study was to compare the behavior of the root system of one of the most frequently cited species in phytoremediation Indian mustard [Brassica juncea (L.) Czern.] and a representative perennial herb (Bidens pilosa L.) native of Argentina, for different concentrations of lead in soils through chemical and visualization techniques of the rhizosphere. Lead polluted soils from the vicinity of a lead recycling plant in the locality of Bouwer, were used in juxtaposed rhizobox systems planted with seedlings of B. juncea and B. pilosa with homogeneous and heterogeneous soil treatments. Root development, pH changes in the rhizosphere, dry weight biomass, lead content of root and aerial parts and potential extraction of lead by rhizosphere exudates were determined. In both species lead was mainly accumulated in roots. However, although B. juncea accumulated more lead than B. pilosa at elevated concentrations in soils, the latter achieved greater root and aerial development. No changes in the pH of the rhizosphere associated to lead were observed, despite different extractive potentials of lead in the exudates of the species analyzed. Our results indicated that Indian mustard did not behave as a hyperaccumulator in the conditions of the present study.

KEYWORDS:

• rhizosphere
• Pb
• phytoremediation
• rhizobox
• B. juncea
• B. pilosa

Acknowledgments

This work was partially supported by the Agencia Nacional de Promoción Científica y Tecnológica (FONCyT) and the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). The authors M. J. Salazar and J. H. Rodriguez were supported by Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). The author M. J. Salazar is a Ph.D. student in Biological Sciences at the National University of Córdoba. We would especially like to thank the Brazilian Synchrotron Light Source (LNLS) (partially supported under proposals XAFS1-15165 and XAFS1-15981) and C. Vergara Cid and A. Blanco for field and laboratory support. We also are grateful to Internacional de Equipos Científicos, S.A. de C.V. Mexico (IECSA) for donating the Petri dishes, to Dr. P. Hobson (native speaker) for language revision and to the Bouwer smelter neighbors (M.R. Pavani, and S. Herrera) and to the land owner and mayor of Bouwer (J. Lupi).