THE PROTECTIVE FUNCTION OF THE EPIDERMAL LAYER OF RYE SEEDLINGS AGAINST ULTRAVIOLET‐B RADIATION

Ultraviolet‐B radiation induces the accumulation of UV‐absorbing pigments of the flavonoid type in the epidermal layer of rye seedlings. The content of pigments identified as isovitexin derivatives was about 4 times higher in leaves preirradiated for up to 24 h with long wavelength UV‐B radiation as compared to control plants without any UV‐B pretreatment. Leaves preconditioned in this way could prevent or reduce damage to photosynthetic function caused by short wavelength UV‐B radiation. Photosynthetic activity monitored by variable fluorescence was reduced in unprotected leaves compared to protected leaves when expressed as a fluorescence decrease ratio value, as quantum yield of photosystem II (Fvm/Fm) or as leaf vitality index (Fm/Fo).

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