Action of UV-B on Crepis capillaris (L.) Wallr. plants in controlled environmental conditions

Abstract

30-day-old Crepis capillaris plants were irradiated with physiologically realistic UV-B doses in the range of 0–9 kJ m–2 d–1 for 5 days in growth chambers of two different places. Unexpectedly, a significant effect on plant growth (expressed in fresh and dry plant weight, leaf area), superoxide dismutase (SOD) activity and protein content in the leaves was exerted by irradiation with even the lowest (1 kJ m–2 d–1) UV-B dose, but there was no effect on plant pigments (carotinoids, chlorophyll a and b). The higher doses, 5 kJ m–2 d–1 and more, showed an inhibitory effect on plant growth, protein content in leaves, but increased SOD activity per protein mass unit. The observed effects depended to various extent on the conditions in the growth chambers in which the plants were irradiated. Conclusion: even realistic physiological UV-B doses act not on a single but on many quantitative genes, and UV-B effects depend on the conditions of irradiation in the growth chambers. Keywords: UV-B, realistic physiological doses, different conditions, SOD activity, effect on growth, protein content, plant pigments