[Effects of enhanced UV-B radiation on photosynthetic physiology and chloroplast ultrastructure of Phragmites australis].

The effects of different intensities of UV-B radiation on photosynthetic characteristics, photosynthetic pigment content and chloroplast ultrastructure of Phragmites australis were studied in this paper. The results showed that enhanced UV-B radiation significantly reduced the net photosynthetic rate, stomatal conductance and transpiration rate, and the degree of degradation increased with the increasing irradiation intensity. The intercellular CO2 content increased and the photosynthetic efficiency decreased significantly compared with the control. Enhanced UV-B radiation decreased photosynthetic pigment contents, including chlorophyll a, chlorophyll b, total chlorophyll and carotenoid, and the decrement increased with the increasing irradiation intensity. Under the enhanced UV-B radiation treatment, chloroplast structure was damaged, and thylakoid lamellae was disorde-red, swelling and even blurred. The effect of high intensity of radiation on chloroplast ultrastructure was greater than that of lower intensity of radiation.