Effects of UV-A and UV-B Irradiation on Antioxidant Activity and Fluorescence Characteristics of Soybean (Glycine max L.) Seeds

Plant secondary metabolism, as well as the growth and development of specific photomorphogenic responses, can be induced by UV light. The effects of UV-A and UV-B irradiations on the antioxidant activity and fluorescence characteristics of Glycine max L. seeds were investigated for two different exposure periods (1, 3 h). The antioxidant activity and photoluminescent characteristics of irradiated seeds were evaluated by the DPPH (2,2'-diphenyl-1-picrylhydrazyl radical) assay and excitation-emission matrices (EEMs) fluorescence spectroscopy, respectively. The DPPH scavenging activity significantly increased with exposure time in the UV-A treated seeds, while variations were observed after UV-B treatment. EEM showed three main peaks characterized with excitation/emission 280/355 nm (Peak A), 290/400 nm (Peak B), and 370/465 nm (Peak C). The most prominent change in fluorescence intensity was observed in peak B. Obtained results indicate that the type of UV radiation, as well as period of exposure, induce biochemical and biophysical changes in the soybean seeds.