Impact of UV-B radiation on photosynthetic electron transport of Wolffia arrhiza (L.) Wimm.

Wolffia arrhiza (L.) Wimm. plants precultivated under different radiation conditions were exposed to UV-B at low or strong ''white'' irradiance. Photosynthetic electron transport (Hill activity) was more damaged by UV-B under 6 W m-2 than at 15 W m-2 supplemental ''white light''(WR). The inhibitory effect was more pronounced using red radiation (RR) precultivated plants compared to precultivation at blue radiation (BR) or WR. Hill reaction in RR grown W arrhiza with a high growth rate was more affected by UV-B - in connection with DCMU and 1,5-diphenylcarbazide - than of plants with a low growth rate. No effect was observed using plants precultivated at BR or WR.