PHYTOTOXIC EFFECTS OF TRIVALENT CHROMIUM ON RAPESEED PLANTS

The response of hydroponically cultivated rapeseed (Brassica napus L.; c.v. Verona) plants to Cr(III)-nitrate was investigated. The applied metal concentration varied in the range from 6 to 480 mu mol L super(-1) (i.e. 0.312-12.480 mg L super(-1)). Cr(III) application resulted in reduced length, fresh mass as well as dry mass of rapeseed plant organs and the inhibitory effect of Cr(III) increased with increasing metal concentration in the external solution. The roots were more sensitive to Cr(ITJ) treatment than the shoots. Due to Cr(III) application significant decrease in the concentration of assimilation pigments (chlorophyll alpha , chlorophyll b, caro-tenoids), proteins and reduced thiol groups in rapeseed leaves was observed. As an indicator of lipid peroxida-tion, malondialdehyde contents were used, expressed as thiobarbituric acid reactive substances (TBARS). The concentration of TBARS rose with the increasing Cr(III) concentration. Accumulated Cr concentration in roots of rapeseed cultivar Verona showed linear increase with increasing external Cr(III) concentration reaching 22810 mg Cr kg super(-1) at treatment with 480 umol L super(-1) Cr(III), however translocation of Cr into the shoots was low, what was reflected in small values of translocation factors (0.0015-0.0330).