Effect of Rare Earths on Plant under Supplementary Ultraviolet-B Radiation: Ⅰ Effect of Cerium on Growth and Photosynthesis in Rape Seedlings Exposed to Supplementary Ultraviolet-B Radiation
来源期刊：JOURNAL OF RARE EARTHS2005年第5期
论文作者：Liang Chanjuan Huang Xiaohua Zhou Qing
Key words：Cerium; ultraviolet-B radiation; rape seedlings; photosynthesis; rare earths;
Abstract: Effect of cerium (Ce3+) on growth and photosynthesis in rape seedlings exposed to two levels of ultraviolet-B radiation (UV-B, 280～320 nm) was studied with hydroponics under laboratory conditions. The growth of rape seedlings exposed to two levels of UV-B irradiation (0.15 and 0.35 W*m-2/T2) was both heavily restrained. The aboveground growth indices including stem (plant) height, leaf number, leaf area, leaf fresh/dry weight and stem fresh/dry weight were obviously decreased by 13.2%～44.1% (T1) and 21.4%～49.3% (T2). Compared to CK, and except active absorption area of roots, the belowground indices main root length, root volume and fresh/dry weight by 14.1%～35.6% (T1) and 20.3%～42.6% (T2), respectively. For Ce+UV-B treatments, the aboveground and belowground growth indices were decreased by 4.1%～23.6%, 5.2%～23.3% (Ce+T1) and 10.8%～28.4%, 7.0%～27.8% (Ce+T2), lower than those of UV-B treatments mentioned above. These results show that Ce has protective effect on plant against injury of UV-B radiation. Furthermore, the protective effect of Ce on seedlings exposed to T1 level of UV-B radiation is superior to T2 level. Chlorophyll content, net photosynthesis rate, transpiration rate, stomatal conductance and water use efficiency in UV-B treatments decrease dramatically, whereas intercellular CO2 concentration increases. Although these indices in Ce+UV-B treatments decrease compared with those of CK, the decrease in Ce+UV-B treatments are lower than those in UV-B treatment. This phenomenon indicates that the ecophysiological protective effect of Ce is based on improving photosynthesis in plants. The dynamic curves of photosynthesis indices show that the course of light-repair is shortened and the injury to rape seedlings by UV-B radiation stress is alleviated by Ce.
Liang Chanjuan1，Huang Xiaohua2，Zhou Qing1
(1.Key Laboratory of Industrial Biotechnology, Ministry of Education, Southern Yangtze University, Wuxi 214036, China;
2.College of Chemistry and Environmental Science, Nanjing Normal University, Nanjing 210097, China)
Abstract:Effect of cerium (Ce3+) on growth and photosynthesis in rape seedlings exposed to two levels of ultraviolet-B radiation (UV-B, 280～320 nm) was studied with hydroponics under laboratory conditions. The growth of rape seedlings exposed to two levels of UV-B irradiation (0.15 and 0.35 W*m-2/T2) was both heavily restrained. The aboveground growth indices including stem (plant) height, leaf number, leaf area, leaf fresh/dry weight and stem fresh/dry weight were obviously decreased by 13.2%～44.1% (T1) and 21.4%～49.3% (T2). Compared to CK, and except active absorption area of roots, the belowground indices main root length, root volume and fresh/dry weight by 14.1%～35.6% (T1) and 20.3%～42.6% (T2), respectively. For Ce+UV-B treatments, the aboveground and belowground growth indices were decreased by 4.1%～23.6%, 5.2%～23.3% (Ce+T1) and 10.8%～28.4%, 7.0%～27.8% (Ce+T2), lower than those of UV-B treatments mentioned above. These results show that Ce has protective effect on plant against injury of UV-B radiation. Furthermore, the protective effect of Ce on seedlings exposed to T1 level of UV-B radiation is superior to T2 level. Chlorophyll content, net photosynthesis rate, transpiration rate, stomatal conductance and water use efficiency in UV-B treatments decrease dramatically, whereas intercellular CO2 concentration increases. Although these indices in Ce+UV-B treatments decrease compared with those of CK, the decrease in Ce+UV-B treatments are lower than those in UV-B treatment. This phenomenon indicates that the ecophysiological protective effect of Ce is based on improving photosynthesis in plants. The dynamic curves of photosynthesis indices show that the course of light-repair is shortened and the injury to rape seedlings by UV-B radiation stress is alleviated by Ce.
Key words:Cerium; ultraviolet-B radiation; rape seedlings; photosynthesis; rare earths;
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