PHYSIOLOGICAL RESPONSE OF TWO Brassica napus L. CULTIVARS TO NICKEL TREATMENT

Adverse effect of nickel on hydroponically cultivated plants of two Brasssica napus L. cultivars (Verona and Viking) was investigated. Dry mass of shoots and roots as well as some biochemical characteristics (concentration of photosynthetic pigments, TBARS and proteins) of plant leaves were determined. In addition, the content of nickel in plant organs was estimated. Visible symptoms of Ni toxicity were notable already at the lowest applied concentration (6 mu mol . dm(-3)). Higher applied Ni concentrations (24, 60 and 120 mu mol . dm(-3)) resulted in moderate to strong toxic effects on plants of both studied cultivars. After application of 6 and 12 mu mol . dm(-3) Ni shoot dry mass of cv. Viking was substantial lower than that of cv. Verona. Decrease of root dry mass after treatment with 6, 12 and 120 mu mol . dm(-3) Ni was similar for both cultivars. Strong decrease in content of photosynthetic pigments was observed after application of 120 mu mol . dm(-3). Comparing to the control, the content of these pigments in leaves of plants dropped under 50% (both cultivars). The highest applied Ni concentration 120 mu mol . dm(-3) caused that protein content in leaves dropped by 39% (cv. Verona) and 37% (cv. Viking) comparing to the control plants. After application of 120 mu mol . dm(-3) Ni the content of malondialdehyde in leaves was 2.64- (Viking) and 2.31- (Verona) times higher than that of control. Nickel amounts accumulated in roots of plants were higher than those in shoots. Accumulated Ni amounts in roots of cv. Verona plants were 1.3- (120 mu mol . dm(-3)) to 1.9- (6 mu mol . dm(-3)) times lower than those of cv. Viking plants, whereas metal amounts accumulated in shoots of cv. Verona plants were 1.2- (120 mu mol . dm(-3)) to 1.8- (6 mu mol . dm(-3)) times lower than those of cv. Viking plants.