UV-B effect on photomorphogenesis and essential oil composition in peppermint (Mentha piperita L.)

UV-B radiation affects the oil chemical composition as a ell as morphology, total protein and total phenol content of peppermint (Mentha piperita). Th e essential oil content was slightly increased by UV-B radiation, find the menthol content was significantly decreased because of increased synthesis of menthone, menthofuran and menthyl acetate. The effect on plant morpholog y was a significant inhibition of stem elongation, accompanied by changes i n leaf area. Protein content and total phenols were increased when plants w ere irradiated with UV-B, whereas no significant effects were observed for chlorophyll content. The economic and ecological importance of UV-B effect on peppermint essential oil is also discussed.