The stratospheric ozone depletion and enhanced solar ultraviolet-B (UV-B) irradiance may have adverse impact on living organisms. The impact of UV-B radiation (UV-B, 280~320nm) on growth, biochemical and antioxidant enzyme activity was studied in Indigofera tinctoria (L.) seedling, commonly used as a green manure. The supplementary UV-B radiation significantly decreased the growth, development and changes in UV-B absorbing compounds such as anthocyanin and flavonoids. The antioxidant enzymes were unaffected and showed an enhanced activities of peroxidase, superoxide dismutase, polyphenoloxidase and phenylalanine ammonia-lyase except catalase in UV-B irradiated seedling. Indigofera tinctoria seedling tries to counteract high level of reactive oxygen species produced under UV-B stress through the increased activities of antioxidant enzyme. The results suggest that Indigofera tinctoria is resistant to UV-B radiation damage and the possible negative effect of additional UV-B radiation on the growth of seedling may have been effectively balanced by the UV-B radiation stress through increase in UV-absorbing compound and antioxidant enzymes.
Keywords: Antioxidant, flavonoids, stress, UV-B radiation.