Abstract: Taking the biological soil crust (Bryum argenteum) broadly existed in the Tengger Desert of China as test object, this paper studied the effects of UV-B radiation on the photosynthesis, cell membrane integrality, water-soluble protein content, and antioxidant enzymes activities of B. argenteum under laboratory condition. UV-B radiation decreased the chlorophyll content, chlorophyll fluorescence parameters, water-soluble protein content, and antioxidant enzymes activities of B. argenteum significantly, with the decrements positively proportional to the radiation intensity, while increased the malondiadehyde and carotenoid contents, with the increments increased with increasing radiation intensity. These results indicated that enhanced UV-B radiation intensity caused a significant reduction in the photosynthetic rate, cell membrane damage, and disorder of antioxidant enzyme system, but the increase of the carotenoid content with increasing radiation intensity could be one of the self-protection mechanisms of B. argenteum in resisting UV-B stress.

Key words: rice, P accumulation, P use efficiency for grain, P harvest index.