【作者】 张君玮；

【导师】 周青；

【作者基本信息】 江南大学 ， 环境工程， 2008， 硕士

【摘要】 采用水培法研究了稀土元素Ce(Ш)对人工模拟紫外辐射(UV-B,280-320nm)下大豆(Glycine max)幼苗叶片含水量(RWC)、水分利用效率(WUE)、气孔行为的影响,旨在揭示稀土对紫外胁迫下大豆幼苗水分代谢的保护作用,为拓展稀土农用方向提供实验依据。实验结果如下:1. 20mg·L-1CeCl3处理提高了大豆幼苗叶片自由水含量,Ce(Ш)+UV-B组自由水/束缚水值高于UV-B组。动态曲线显示Ce(Ш)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(Ш)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(Ш)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。2. 20mg·L-1CeCl3处理减轻了UV-B辐射引起的大豆幼苗根系活力、根长和根冠比下降。较之CK,UV-B辐射处理使净光合速率(Pn)、蒸腾速率(Tr)下降,Ce(Ш)+UV-B组Pn、Tr的下降趋势得到缓解,且最终达到较好的恢复效果。低剂量UV-B(0.15W·m-2)辐射胁迫使得大豆幼苗水分利用效率(WUE)高于CK(1-4天),但恢复期(7-9天)WUE急剧下降;高剂量UV-B(0.45W·m-2)辐射下WUE低于CK,降幅明显。Ce(Ш)+UV-B组大豆幼苗WUE下降幅度小于UV-B组,且恢复期(7-9天)迅速提升。3. 20mg·L-1CeCl3处理显著提高了大豆幼苗叶片背面近轴气孔密度,高剂量UV-B(T2 0.45W·m-2)辐射降低了气孔密度,与CK差异显著;Ce(Ш)+UV-B处理减轻了UV-B胁迫引起的气孔密度下降。动态结果显示,较之CK,UV-B辐射使气孔导度(Gs)下降,Ce(Ш)+UV-B处理下Gs的下降趋势得到缓解,且最终达到较好的恢复效果。ABA、H2O2、CAT活性的变化趋势与Gs不同,与CK相比,UV-B辐射导致ABA、H2O2积累,CAT活性提高,Ce(Ш)处理降低了UV-B辐射造成的ABA和H2O2的积累,进一步提高了CAT活性。实验结果表明Ce(Ш)处理缓解了UV-B辐射对大豆幼苗水分代谢的胁迫伤害作用。更多还原

【Abstract】 Effect of Ce(III) on water content (RWC), water use efficiency(WUE) and stomatal behaviour in leaves of soybean seedlings exposed to two dosages of ultraviolet-B radiation (0.15, 0.45W·m-2) was studied detaily with hydroponics under laboratory conditions.The aim was to reveal protective effect of Ce(Ш) on water metabolism in soybean seedlings under UV-B radiation which would provide experimental gist for rare earths applied in agriculture. The main results were as follows:1. Static experimental results showed that 20mg·L-1 CeCl3 increased free water content in soybean leaves. For Ce(Ш)+UV-B treatments, the ratio of free water content and irreducible water content was higher than that of UV-B treatments. Dynamic results showed that Ce(Ш) 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 oppositively which promated accumulation of free proline, but caused soluble sugar content dropping sharply. Ce(Ш) demonstrated an tagonistic effect on UV-B radiation which weakened free accumulation of proline, while increased the content of soluble sugar. Correlation analysis showed that Ce(Ш) improved the role of free proline and soluble sugar in regulating water content in soybean leaves under UV-B radiation.2. Static experiment results showed that 20mg·L-1 CeCl3 reduced decreasement of root activity, root length and root/shoot ratio induced by UV-B radiation. UV-B radiation caused the decline of Photosynthesis rate(Pn), Transpiration rate(Tr), while for Ce(III)+UV-B treatment the decline was eased. Water use efficiency (WUE) of soybean seedlings increased under low dosage of UV-B radiation(0.15W·m-2) stress(1st to 4th), then decreased sharply during the recovery periods(7th to 9th). Compared to CK, high dosage of UV-B radiation(0.45W·m-2) made WUE decreasing obviously. For Ce(Ш)+UV-B treatment, the decline rate of WUE was less than that of UV-B treatment, and WUE increased more rapidly during the recovery periods (7th to 9th).3. Static experiment showed that 20mg·L-1 CeCl3 improved stomatal density and high dosage of UV-B radiation(T2 0.45W·m-2) caused its’decline obviously compared to CK. For Ce(Ш)+UV-B treatments, the decline of stomatal density was lower than the corresponding UV-B treatments. UV-B radiation caused the decreasing of stamotal conductance(Gs), while under Ce(Ш)+UV-B treatments the Gs was larger than UV-B radiation, but smaller than CK. Diferent changes happened between ABA、H2O2、CAT and Gs. UV-B radiation caused accumulations of ABA, H2O2 and improvement of CAT’s activity. Ce(Ш) reduced contents of ABA and H2O2 induced by UV-B radiation stress in leaves of soybean seedlings, improved CAT’s activity.The experiment showed that Ce(III) played an effective role in defensing damage induc- ed by UV-B radiation stress on water metabolism of soybean seedlings.更多还原