Effect of heavy metal stress on the growth and physiological characteristics of Pelargonium hortorum

The effects of different concentrations of Pb²⁺, Cd²⁺, Cu²⁺, and Zn²⁺ on the growth and physiological characteristics of Pelargonium hortorum were studied. Results showed that the growth of P. hortorum stressed by four types of heavy metals was inhibited by different degrees, with root length being the most significantly inhibited. However, despite this inhibitory effect, the plants continued to grow. With increasing concentrations of heavy metals, the plant biomass decreased, whereas leaf relative conductivity was significantly increased (P < 0.05). Chlorophyll, soluble protein, and free proline contents and catalase(CAT), superoxide dismutase(SOD), and peroxidase(POD) activities were significantly (P < 0.05) higher intreated plants than in the control plants. Plants did not show obvious withering when Pb²⁺ concentrations were less than 1 000 mg·kg^–1 and Zn²⁺ concentrations were less than 800 mg·kg^–1, whereas under other treatments, two or three basal leaves had withered and abscised. Therefore, P. hortorumshows some tolerance to four different heavy metals, and was fix potential of the types for using the heavy metal contaminated soil.