The effect of cadmium on growth and composition of essential oils of Mentha piperita L.

Cadmium is a non-essential element that induces various toxic responses in plants when accumulated above the threshold level. The aim of the present research was to study the effect of cadmium on growth factors, concentration of cadmium in the rhizomes and leaves, and quality and quantity of essential oils in the leaves of Mentha piperita L. The experiment was carried out in a completely randomized design with three replications. Rhizomes with uniform weight were planted in pots 30 × 50 × 35 cm. After foliation of all rhizomes, plants were irrigated every other day, for 2 months by different concentrations of CdCl2 (0, 100, 500, and 1000 µM). Results demonstrated that the minimum stem length and fresh and dry weight of leaves were achieved in the plants treated with CdCl2 (500 µM). With increasing the cadmium in treatments, the amount of cadmium in the rhizomes and leaves were also increased. In treatment of CdCl2 (1000 µM) the accumulation of cadmium in the leaves was more than the rhizomes. There were not significant differences in the essential oils contents between treatments. Analysis of the chemical composition of essential oils indicated that the main constituents of all treated plants were 1, 8 Cineole, Dihydrocarvon, Pulegone, and Carvone. Limonene oxide was observed only in the leaves of control plants.