UV-B辐射与酸雨胁迫对生菜生理特性及品质的影响

The Effect of UV-B radiation and acid rain on physiological property and quality of lettuce

酸雨和紫外辐射的增强是全球环境问题之一，也是日前研究的热点。以生菜（lactuea）为实验材料，在大田条件下，研究了UV-B（280-320nm）辐射与模拟酸雨（AR）的胁迫对生菜生理特性和品质的影响。实验结果表明：UV-B辐射的增加降低了生菜植株的蒸腾速率、叶片中叶绿素a、叶绿素b、叶绿素a＋b的质量分数，且下降幅度随紫外辐射的增强而增大。UV-B辐射的增加提高了生菜叶片中类黄酮的含量，其增加幅度随紫外辐射的增强而增大。酸雨对生菜的蒸腾速率、叶绿素的质量分数也均有不同程度的影响，酸雨对类黄酮含量的影响不大．品质研究结果表明，随着UV-B辐射的增加，叶片中的水的质量分数持续降低，而抗坏血酸、可溶性糖、可溶性蛋白质的质量分数均先增加后减小，说明存在一个使品质发生突变的阈值范围．酸雨使得生菜中抗坏血酸的质量分数增加，并且增加幅度随pH值的减小而增大；随着酸雨酸度增强，植株中水质量分数持续降低；酸雨使生菜中可溶性糖、可溶性蛋白质的质量分数先减小后增加。在UV-B和酸雨的共同作用下，只有对类黄酮的影响具有明显的协同作用，其他指标表现不明显，但是可以看出复合作用下指标含量下降幅度明显大于单一因子的胁迫．并且下降幅度受UV-B辐射强度和酸雨pH的影响。

Acid rain and UV-B increasing is respectively one of global environment problem, which is the warm topic at present. The paper studied the effect of UV-B radiation and acid rain on physiological property and quality of lettuce under field condition. The results of physiologic index showed that UV-B radiation increasing resulted in reduction of chlorophyll-a, chlorophyU-b, chlorophyll-a＋b, and transpiration in leaf. The more ultraviolet radiation increased, the more the decreasing degrees were influenced. At the same time, the content of flavonoid in leaf was increased with UV-B increasing. Acid rain also had different influence on chlorophyll and transpiration in leaf. While acid rain had little effect on the content of flavonoid in leaves. The results about quality showed that enhanced ultraviolet radiation increased the content of ascorbic acid, dissolve sugar and dissolve protein, but the more ultraviolet radiation increased, the more the content of dissolve sugar and ascorbic acid decreased, which there exists a limit of quality content. Acid rain increased the content of ascorbic acid, and the smaller pH was, the more the content of ascorbic acid; Acid rain increased the content of dissolve sugar and dissolve protein, and the smaller pH was, the more the content of dissolve sugar and dissolve protein decreased, but they became higher when exceeded to certain extent ;with PH decreasing the water content decreased. The effect of UV-B radiation was cooperated with acid rain on the only index of the content of flavonoid in leaf. The result showed that the effects under combined stress were significantly higher than single stress.