Effect of ultraviolet A (UV-A) radiation on Crepis capillaris (L.) Wallr. plants was investigated. The UV-A (365 nm) doses were 0, 2, 4, 6, 8, 10 kJ·m-²·d-¹. The duration of radiation was 7 days. Effects of UV-A radiation on fresh and dry biomass, leaf area and quantities of plant pigments (chlorophylls a and b, carotenoids) was determined. Superoxide dismutase (SOD) activity in leaves was estimated by native 10 % polyacrylamide gel electrophoresis (PAGE) method. The obtained results demonstrated harmful effect of UV-A radiation on the growth of plant: as little as 4 kJ·m-²·d-¹ UV-A reduces fresh and dry biomass of C. capillaris, the amount of chlorophylls a and b as well as carotenoids. Only higher doses of UV-A had negative effect on the leaf area. UV-A dose of 8 kJ·m-2 induces a new isoform of SOD. This induction should be evaluated as a response to UV-A irradiation. It shows SOD involvement in the mechanism of antioxidant protection.
Keywords: ultraviolet A, irradiation, Crepis capillaris, leaf pigments, superoxide dismutase.