On the possible influence of short-term ultraviolet-B (285-325 nm) radiation on growth, pigment composition and photosynthetic activity in aquatic higher plant Lemna gibba L.

The impact of short-term UV-B radiation on growth, pigment composition and photosynthetic activities was studied in intact Lemna gibba L. fronds. A daily UV-B exposure for 30 min at 5 W.m-2 resulted in significant changes on the morphology as well as physiological characteristics. Besides changes in biomass and relative growth rate, photosynthetic pigments such as Chl a, b and carotenoids decreased significantly. The level of non-photosynthetic pigments such as anthocyanin and flavonoids increased under UV-B treatment playing a defensive role. The photosynthetic activity measured in terms of O2 evolution and Chl a fluorescence induction confirmed the vulnerability of aquatic species to UV-B radiation. Thus, the impact of short-term UV-B treatment was found to have pronounced effects in aquatic plants than that of terrestrial plants