铯对小麦叶片光合特性影响的研究

Effects of cesium on photosynthetic characteristics of wheat seedlings

随着环境中铯(Cs)污染日益恶化,铯对生物毒害作用的研究受到越来越多的关注.为了探讨铯对植物光合作用的影响,在石英砂和Hoagland营养液培养体系下,从三叶期开始用浓度为0、0.5、1、5、10、20 mmol·L-1的133Cs+[CsCl]处理小麦(Triticum aestivum L.)幼苗.在处理后的第0、7、14、21、28 d时,检测小麦光合特性的改变.结果表明:用0.5 mmol·L-1和1 mmol·L-1低浓度133Cs+处理7 d后,小麦叶片的叶绿素含量、叶圆片放氧活性、类囊体膜电子传递活性均显著高于对照;但随133Cs+浓度的增加及处理时间的延长,这些参数的数值均显著下降.此外,光合系统II(PSII)活性的下降速率高于光合系统I(PSI)下降速率,说明PSII相对于PSI更容易受到133Cs+的胁迫伤害.这些结果表明133Cs+对小麦的毒害效应受时间和浓度的双重制约.低浓度133Cs+可以促进小麦光合作用,而高浓度133Cs+则显著抑制小麦光合作用.

With the worsening of the cesium contamination in soil and water, there has been a growing interest in the deleterious effects of cesium on organisms. In order to contribute to the understanding of the photosynthesis characteristics change induced by cesium, three- leaf stage wheat （ Triticum aestivum L. ） seedlings raised in quartz sand and Hoagland solution culture system, were provided with a nutrient solution with the supplement of different concentrations 133Cs^＋ （0, 0. 5, 1, 5, 10, 20 mmol·L^-1 133 CsC] ）. Photosynthetic characteristics of wheat seedlings were determined after 0, 7, 14, 21 and 28 d of treatment, respectively. When the wheat seedlings were exposed to both low ^33Cs^＋ concentrations （0.5 and 1 mmol·L^-1 ） for 7 d, the chlorophyll content, oxygen-evolving activities of both leaf discs and the electron transport activities of thylakoid membranes increased firstly, and along with elevated levels of applied ^133Cs^＋ as well as the duration of treatment, all the parameters then decreased significantly compared with the control. Additionally,for the electron transport activities of thylakoid membranes, PSII drop faster than PSI, and this result indicated PSII is more susceptible to the injury of ^133Cs^＋ compared with PSI. investigation showed that the deleterious effects of ^133Cs^＋ on the wheat All the results obtained from this seedlings is restricted by both ^133Cs＋ concentrations and the duration of exposure. For the wheat seedlings employed in our study, low ^133Cs^＋ concentrations promoted the photosynthesis, and high ^133Cs^＋ concentrations inhibited photosynthesis.