Physiological and biochemical responses of sugar beet (Beta vulgaris L) to ultraviolet-B radiation

Ultraviolet radiation can cause many serious problems for all living organisms. With a growing population, the UV sensitivity of crop plants presents a particular problem. To evaluate the suitability of growing in areas under UV irradiance, the influence of different doses of UV-B (3.042, 6.084 and 9.126 kJm(−2)d(−1)) on the sugar beet (Beta vulgaris L) plants was studied. UV-B induced a significant decrease in growth displayed as reduced height and fresh and dry weight. This reduction is not dose dependent and was associated with diminishing photosynthetic O(2) evolution, relative chlorophyll content, photosynthetic pigments and chlorophyll fluorescence. On the other hand, antioxidant enzyme activities, total protein content, compatible solutes, total free amino acids and total betalain content were increased under 9.126 kJm(−2)d(−1) UV-B treatments, representing mechanisms by which the plants coped with the stress. The oxidative stress upon UV-B treatment was evident by increased malondialdehyde (MDA) content, however, hydrogen peroxide (H(2)O(2)) was not affected in UV-B exposed plants. Thus, the studied sugar beet variety BR1seems to be suitable particularly for areas with high doses of UV-B irradiation.