Abstract: The toxic effects of different concentrations of Cr³⁺ and Cr⁶⁺ on the physiological and biochemical characteristics of tea plant were studied in Hoagland solution culture. The results indicated that: with the increasing of Cr³⁺, Cr⁶⁺ concentrations, the symptoms of tea plant became obviously; the contents of chlorophyll and the ratio of chlorophyll a and chlorophyll b reduced obviously, and there were obviously negative effects to net photosynthesis rate, intercellular CO₂ concentration, transpiration rate and stoma conductivity. Under the Cr³⁺ stress, the activities of SOD, POD and CAT increased at first and then decreased, under the Cr⁶⁺ stress, the activities of SOD and POD increased at first and then decreased too, but the activity of CAT decreased all the time. At the same time, the contents of MDA and proline (Pro), cytomembrane permeability increased obviously with the increasing of Cr³⁺, Cr⁶⁺ concentrations. Therefore, it highlighted that the Cr³⁺ and Cr⁶⁺ stresses could mangle the cytomembrane system, the structures and functions of the major organelles of tea plant, and the toxic effects of Cr⁶⁺ on tea plant was stronger than that of Cr³⁺.

Key words: Cr³⁺, Cr⁶⁺, tea plant, stress, physiological and biochemical characteristics