Abstract: Influence of cerium(Ce3+) on photorespiration rate,photosynthesis rate and chlorophyll content of soybean seedlings exposed to two levels of ultraviolet-B radiation(UV-B,280-320 nm) was studied with hydroponics under laboratory conditions.The results showed that the photorespiration rate effectively increased without UV-B stress;the photosynthesis rate and chlorophyll content decreased caused by UV-B radiation;and all of the indexes with Ce+UV-B treatment were better than those with UV-B treatment,compared with the check as the soybean seedling was pretreated by 20mgL-1CeCl3.The photorespiration rate,photosynthesis rate and chlorophyll content of the soybean seedlings increased by 20mgL-1CeCl3 treatment as stressed under UV-B treatment.By increasing the photorespiration rate,the overplus phoenergy was exhausted.The damage to photosynthetic organs of the soybean seedlings was alleviated,the net photosynthesis rate under UV-B stress decreased,the degradation of chlorophyll was catabolic.Therefore,the resistance of plant to the adversity increased.

Key words: Cerium(Ⅲ), Cerium(Ⅲ), UV-B radiation, Photorespiration rate, Chlorophyll content