The effect of UV‐B and UV‐C radiation onHibiscusleaves determined by ultraweak luminescence and fluorescence induction

Abstract
The effects of UV‐C (254 nm) and UV‐B (280‐320 nm) on chlorophyll fluorescence induction and ultraweak luminescence (UL) in detached leaves ofHibiscus rosa‐sinensisL. were investigated. UL from leaves exposed to UV‐B and UV‐C radiation reached a maximum 72 h after irradiation. In both cases most of the light was of a wavelength over 600 nm. An increase in the percentage of long wavelength light with time was detected. UV radiation increased peroxidase activity, which also reached a maximum 72 h after irradiation. UV‐B and UV‐C both reduced variable chlorophyll fluorescence. No effect on the amount of chlorophyll or UV screening pigments was observed with the short‐term irradiation used in this investigation.