Green alga Zygnema was exposed to three concentrations of selenium (Se) and two levels of UV-B radiation. Se does not diminish the effects of UV-B radiation; on the contrary, the combined action of UV-B radiation and traces of Se leads to pronounced negative effects on photochemical quantum yield and the respiratory potential. The importance of Se for activity of the mitochondria is possibly an evolutionary recollection from an endosymbiotic bacterium.
COBISS.SI-ID: 5844089
St. John’s wort (Hypericum perforatum L.), was grown under different levels of UV-B radiation. A high level of UV-B radiation increased leaf concentrations of flavonoids and of tannins. The concentration of hypericin in leaves exposed to enhanced UV-B radiation was lower than that of leaves exposed to reduced UV-B radiation. The concentrations of bioactive substances in St. John’s wort herb can be altered by regulating the environment during plant growth.
COBISS.SI-ID: 6251897