He-Ne激光对增强UV-B辐射小麦叶片显微结构及光合特性的影响

Effects of Enhanced UV-B and He-Ne Laser on Leaf Microstructure and Photosynthesis in Wheat

采用低剂量(5 mW·mm-2)He-Ne激光辐照经增强UV-B辐射处理(10.08 kJ·m-2·d-1)后的晋麦47号小麦幼苗,用常规石蜡切片法,观察各处理组小麦幼苗叶片组织显微结构特征;同时对幼苗光合特性、水分利用及色素含量状况进行测定分析.结果显示:(1)与对照(CK)相比,UV-B辐射处理(B)与复合处理(BL)的表皮细胞及腺毛排列致密,气孔稀疏、缩小且下陷;叶肉组织细胞均明显加厚,细胞略小且排列紧密,维管束相对面积减小,BL的以上性状均介于CK与B之间.(2)B组净光合速率、气孔导度、蒸腾速率均显著降低.与B相比,BL气孔导度及光合速率偏高,蒸腾速率差异不明显.就水分利用率而言,L最大,略高于CK,B组最小,略低于BL,各组间差异显著.(3)增强UV-B辐射可使小麦幼苗叶绿素含量显著降低,经He-Ne激光辐照处理后可以使叶绿素含量得到一定程度恢复性升高,并且Chla变化的幅度大于Chlb.结果表明:低剂量He-Ne激光辐照能够对小麦幼苗组织显微结构以及光合器官的UV-B辐射损伤起到促进修复的作用.

The seedlings of wheat（‘Jinmai 47＇）were exposed to H e-Ne laser irradiation （L） with 5 mW·mm^-2 power density after enhanced UV-B radiation（10.08 kJ·m^-2·d^-1 ）. The micro-structure character- istics of wheat leave tissue were studied by the method of paraffin wax section. Meanwhile, the photosynthesis characteristics and water use conditions of wheat seedlings were studied. Here are the results. （1） Compared with CK,the epidermic cells and tentacles of UV-B treatment （B） and compound treatment（BL） arrange closely. Stomas are small, sparse and cave in,and leaf tissue cells more thicker, smaller and arrange closely. The ralative transverse areas of vascular bundles tend to minish. The previous characters in BL lies between CK and B. （2）The net photosynthetic rate, stomatal conductance and transpiration rate in B dropped notably. Compared with B,the net photosynthetic rate and stomatal conductance in BL are on the high side, but difference in transpiration rate is not evident. On water utilization efficiency, L〉CK〉BL〉 B. （3）Chlorophyll content in wheat seedlings cut down sharply under UV-B radiation,when treated with He Ne laser, the content will hoist in a certain extent,and the changeable extent of Ch1 a is wider than that of Ch1 b. In conclusion,the use of laser irradiation treatment can repair partly the damage induced by UV-B radiation in cell microstructure and photosynthetic organs in wheat seedlings.