The effect of the supplemental UVB radiation in forest species was studied in Sophora microphylla, a native tree that grow at low latitudes in the Central-South of Chile and important by their association with soil bacteria and mycorhizal fungi. Seeds of sun and shade variety growing at different light intensities were collected. Using indoor supplemental UVB radiation germination and seedling grow were examined. As response to UVB radiation, seeds and young emerging seedling from high irradiance habitat (PPF ± 2200 m molm-2s-1), sun variety plants show more tolerance than plants from habitat with less irradiance (PPF ± 1400 m molm-2s-1), shade variety plants. Germination and growing of sunny plants was faster than shady plants. Photosynthetic pigments (chlorophyll a and chlorophyll b) content increased in shady plants and was almost invariable for sunny plants. Total protein content decreased in both cases. Biosynthesis of flavonoids and epicuticular waxes was induced by UVB, especially in sun variety seedling. UVB screening total flavonoids were determined with UV spectroscopy. Epicuticular wax analysis was performed with FT IR technique. All this results suggest that an increment of UVB radiation is more harmful for plants accustomed to low radiation intensity, than for those growing at high light intensity.