Effects of Cd, Pb, and Cu on growth and essential oil contents in dill, peppermint, and basil

The hypothesis tested in this study was that some essential oil crops could be to grown as alternatives to edible crops in heavy metal enriched soils. Experiments were conducted to evaluate the effect of Cd, Pb, and Cu on yields and essential oils of peppermint, basil, and dill. The accumulation of Cd, Pb, and Cu in plant parts, in plant material and water after distillation, and in the essential oils, was also determined. Metal treatments of peppermint and basil consisted of Cd, Pb, Cu, Cd + Pb, Cd + Cu, Pb + Cu, Cd + Pb + Cu, and unamended control. Metal treatments of dill consisted of (in mg L-1): Cd at 2, 6, and 10; Pb at 50, 100, and 500; Cu at 20, 60, and 150 and an unamended control. Peppermint and basil yields were not affected by the treatments. Copper at 60 and Cu 150 mg L-1 reduced both yields and height of dill, Cu 150 mg L-1 resulted in Cu phytotoxicity symptoms and retarded growth. High Pb and Cu reduced Cd uptake by peppermint and basil. At elevated Cd concentrations in the growth medium, Cd transport from roots to shoots of the three species was impaired. The tested treatments slightly altered chemical composition of the essential oils of basil and dill, and reduced the menthol content in the peppermint oil. Oil content in basil from the CdPbCu treatment was lower that in the control. Copper application at 150 mg L-1 reduced oil content in dill relative to the control. No detectable amount of Cd, Cu, or Pb in the oils of any of the three species was found. Peppermint, basil, and dill can be grown in soils enriched with Cd, Pb, and Cu medium without risk for metal transfer into the oils, and without significant alteration of essential oil composition that may impair marketability. Our results support the use of aromatic plants as alternative crops for Cd, Pb, and Cu enriched soils. (c) 2005 Elsevier B.V. All rights reserved.