Ce(Ⅲ)对UV-B辐射下大豆幼苗叶片含水量的影响

Effect of Cerium on Water Content in Leaves of Soybean Seedlings Under Supplementary UV-B Radiation Stress

采用水培法研究Ce(Ⅲ)对紫外辐射(UV-B,280～320nm)胁迫下大豆"台湾292"幼苗叶片含水量的影响。静态实验结果显示,20mg·L-1CeCl3处理提高了大豆幼苗叶片自由水含量,Ce(Ⅲ)+UV-B组自由水/束缚水值高于UV-B组。动态曲线显示Ce(Ⅲ)缓解了UV-B辐射胁迫期大豆幼苗叶片含水量的下降,促进恢复期含水量的提升。UV-B辐射对大豆幼苗叶片两种渗透调节物质(游离脯氨酸、可溶性糖)含量的影响不同,使得游离脯氨酸大量积累,而可溶性糖含量急剧下降。Ce(Ⅲ)处理对UV-B辐射表现出拮抗效应,即减弱了游离脯氨酸的积累,同时促进可溶性糖含量的增加。相关性分析结果显示,Ce(Ⅲ)改善了游离脯氨酸及可溶性糖调节大豆幼苗叶片含水量的作用。试验结果表明,20mg·L-1CeCl3处理有效防御了UV-B辐射对大豆幼苗水分代谢的胁迫作用。

In order to understand effect of rare earth on water metabolism in soybean seedlings under UV-B radiation stress. Effect of cerium（ Ⅲ）on water content in leaves of soybean seedlings exposed to ultraviolet-B radiation（UV-B, 280-320 nm）was studied with hydroponics under laboratory conditions. The levels of UV-B irradiation were 0.15 Wm^-2（T1 ）and 0.45 Wm^-2（T2 ）, which were determined by ultraviolet radiac （made by photo-electricity instrument factory of Beijing Normal university）, Irradiated six hours every day （9：00- 15：00）, lasted for five days, then enterred recovery periods, totally ten days. There were 6 sample sets（CK, Ce, T1, Ce＋T1, T2, Ce＋T2）in the experiment. Static experimental results show that 20 mg·L^-1 CeCl3 increased free water content in soybean leaves. The value of free water content/irreducible water content of Ce （ Ⅲ ）＋UV-B treatments was higher than that of UV-B treatments. Dynamic curve showed Ce （ Ⅲ）eased UV-B radiation stress on water content in soybean leaves, accelerated the recovery pace. UV-B radiation affected two osmolytes （proline, soluble sugar）in soybean leaves differently, promated accumulation of free proline, and caused soluble sugar content dropping sharply. Ce （Ⅲ）demonstrated an tagonistic effect on UV-B radiation, weakened free proline＇ accumulation, while increas- ing the content of soluble sugar. Correlation analysis showed that Ce（ Ⅲ ）improved the role of free proline and soluble sugar in regulating water content in soybean leaves under UV-B radiation. The experimental results showed that Ce （Ⅲ ）played an effective way to ease UV-B radiation stress on water metabolism of soybean seedlings.