花生对 UV-B 辐射增强的光合生理响应

On Response of Arachis hypogaea photosynthetic physiology to Enhanced Ultraviolet-B Radiation

该文研究了在接受增强强度为54μW/cm2的UV-B辐射处理3d后(每天处理8h),花生幼苗光合作用相关参数和叶绿体超微结构的变化.结果表明:在UV-B处理3d结束后,叶绿素a和叶绿素(a+b)均显著下降,同时气体交换参数也受到显著影响,表现出净光合速率(Pn)降低了35.42%,气孔导度(Gs)和气孔限制值(Ls)分别下降了28.12%和20.25%,而胞间CO2摩尔分数(Ci)却上升了16.22%,较对照有显著性差异.同样,荧光参数Fv/Fm和Fv/F0均显著降低.但UV-B处理1d和2d后,以上各指标的变化与对照差异不显著.透射电子显微镜(TEM)图像显示,叶绿体膜肿胀、基质类囊体解体,光合化产物淀粉粒数目和大小减少.叶绿体超微结构的变化可能是叶绿素体积质量分数和光合速率降低的重要原因.

The impact of UV-B radiation on photosynthetic related parameters and chloroplast ultrastruc-ture have been studied in A rachis hypogaea ,after an enhanced UV-B irradiation performed 8 h per day for 3 days with a ultraviolet light （280 -320 nm ） that maintained about 54 μW/cm2 radiation .Contents of chlorophyll a and chlorophyll （a＋b） have significantly declined after radiation for 3 days ,concomitantly , gas exchange parameters were significantly affected ,showing a 35 .42% reduction in net photosynthesis （Pn） ,28 .12% in stomatal conductance（Gs） and 20 .25% in stomata limitation（Ls） .However ,intercellu-lar CO2 concentration（Ci） is increased by 16 .22% ,showing significant difference with that in control ,at the end of the 3 days UV-B treatment .Similarly ,the fluorescence parameters of Fv/Fm and Fv/F0 have also been significantly reduced .However ,the differences of above indexes are not significant compared with the control treated with UV-B after 1 and 2 days .Transmission electron microscope （TEM ） images have revealed that chloroplast membranes is swelled and disintegrated ,and stromal thylakoids are relaxed and parallel to each other ,which might be responsible for worse performance of the photosynthesis ,as a result ,the size and number of starch grains decreased .The change of chloroplast ultrastructure may be the important cause of the decrease of chlorophyll content and photosynthetic rate .