用半导体激光(3.97 mW/mm2)和相干光及非相干光转换器(专利:CN2555523Y)将半导体激光转换为同功率、同波长和同光斑大小的非相干红光辐照小麦种子。通过分析幼苗期叶片DNA及生理变化,考察低剂量激光防护紫外线-B(UV-B)辐射损伤小麦幼苗的光效应。半导体激光预处理使10.08 kJ/m2UV-B辐射损伤小麦幼苗超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性,紫外吸收物含量、可溶性蛋白质含量、叶绿素a和叶绿素b含量及根长显著增加,丙二醛(MDA)含量显著降低。而非相干红光则不能。用酶联免疫(ELISA)方法检测小麦叶片DNA受UV-B辐射损伤产生的环丁烷嘧啶二聚体(CPD)含量,发现半导体激光能显著降低UV-B辐射损伤小麦细胞DNA中环丁烷嘧啶二聚体的含量,而非相干红光却不能使其降低。说明半导体激光防护UV-B辐射损伤小麦幼苗中光效应不起作用。

The optical effect of laser on protecting wheat from ultraviolet-B (UV-B) damage was tested. A patented instrument, coherent-to-incoherent optical converter, was employed to transform semiconductor laser into incoherent red light. The wavelength, power and spot diameter of incoherent red light are the same as that of semiconductor laser. A semiconductor laser and incoherent red light with wavelength of 650 nm and power density of 3.97 mW/mm2 directly irradiated the embryo of wheat seed for 3 min respectively, and when the seedlings were 12 days old they were irradiated by 10.08 kJ/m2 UV-B radiation for 12 h in darkness. Changes in the concentration of malondialdehyde (MDA), UV-B absorbance compounds, soluble protein, chla, chlb, the activities of peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), and the growth parameters of seedlings (root length, root dry weight) were measured to test the optical effect of laser. The results showed that semiconductor laser pretreatment could enhance the SOD, POD and CAT activity, UV-B absorbance compounds, soluble protein, chla and chlb concentration, and root length, while incoherent red light pretreatment could not. When the cells of plant were irradiated by UV-B, concentration of cyclobutane pyrimidine dimers (CPDs) in wheats leaves was detected by enzyme-linked immunosorbent assay (ELISA) method, incoherent red light treatment could not eliminate active oxygen and prevent lipid peroxidation in wheat. The results also demonstrate that the plant DNA was injured by UV-B radiation and the semiconductor laser irradiance has the capability to protect plant from UV-B-induced DNA damage, while the incoherent red light could not. It is suggested that the potential mechanism is not the optical effect of laser treatment.