Dinora Vázquez-Luna
Universidad Veracruzana, Mexico.
Title: Biological indices of toxicity in tropical legumes grown in oil-contaminated soil
Biography
Biography: Dinora Vázquez-Luna
Abstract
This study evaluated the toxic effects of total petroleum hydrocarbons (TPH) on growth of the legumes Crotalaria incana L. and Leucaena leucocephala Lam., and on the development of soil microorganisms. The aim of this study was to generate user-friendly indicators of soil contamination to measure the toxic effects of TPH on growth of tow tropical legumes, and on the development of nitrogen-fixing soil microorganisms (rhizobial and free-living). The indices developed were the biological toxicity indices (BTI) and the toxicity potential index (TPIc) in higher plants. Growth and biomass accumulation in both plant species decreased with high pollutant concentrations. The EC50 and the NOEC were not identified for either species. The Phytotoxicity Relative Index showed that root length was most strongly affected by the oil, and the Impact Index on Nitrogen Fixer Microorganisms indicated that, despite damage to the root system, L. leucocephala rhizosphere bacteria doubled at 10,000 mg kg−1 TPH after of 240 days of exposure. Finally, the TPIc revealed that C. incana was more sensitive than L. leucocephala to chronic TPH toxicity and might strongly depend on beneficial soil bacteria.
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