Morphological and metabolic alterations in duckweed (Spirodela polyrhiza) on long-term low-level chronic UV-B exposure.

Laboratory grown duckweed (Spirodela polyrhiza) plants were exposed to 0.72 and 1.44J of UV-B radiation daily for 7 days at 0.4mW/cm(2) intensity. Chlorosis and necrosis were observed along with depletion in protein, pigments (chlorophyll, pheophytin, carotenoids, phycoerythrin, phycocyanin, and flavoxanthin), biomass, root length, and frond size in UV-B-exposed plants. The study confirms morphological and metabolic alterations leading to reduction in the productivity of duckweed following long-term exposure to UV-B radiation.