【摘要】 采用水培试验方法研究了紫外辐射(UV-B,280～320nm)与酸雨(AR)单一和复合胁迫对油菜幼苗保护酶(CAT)及光合作用的影响。结果表明,单一胁迫与复合胁迫对油菜幼苗CAT活性及光合作用有不同程度的作用效果。在单一UV-B辐射(0.45W·m-2),单一酸雨(pH3.5)胁迫及复合胁迫下,质膜透性、MDA含量及CAT活性的增幅为8%、18.1%、26.0%,11.5%、21.6%、66.7%和28.8%、85.0%、113.8%;叶绿素含量、净光合速率、蒸腾速率、水分利用效率及气孔导度降幅为16.5%、48.6%、57.2%,28.6%、42.9%、78.6%,3.9%、12.4%、14.8%,27.8%、31.0%、74.5%和35.6%、38.2%、44.7%;而胞间CO2浓度的增幅为9.3%、10.6%、26.4%。结果显示,复合胁迫的抑制效应强于单一胁迫,即UV-B+AR>UV-B>AR,且对不同指标的影响不尽一致。更多还原

【Abstract】 The response of defense enzyme and photosynthesis in rape seedling t o combined stress of elevated ultraviolet-B radiation (UV-B, 280～320nm) and a cid rain was studied under lab conditions. In the experiment, the rapes were sep arated to three groups except control group. One group was sprayed with simulate d acid rain at pH valve of 3.5. One group was exposed to UV-B radiation with le ver of 0.45 W·m-2. Another group was treated with simulated acid rain at first , and then exposed to UV-B radiation. After 5 days of UV-B treatment, membrane permeability, MDA content, CAT activity, chlorophyll content, net photosynthesi s rate, transpiration rate, water use efficiency, stomatal conductance and inter cellular CO2 concentration of rapes were mensurated. The results showed that the re were different effect on the CAT activity and photosynthesis under single str ess and combined stress. Enhanced UV-B radiation and acid rain treatment induce d rise on CAT activity with the increase in membrane permeability and MDA conten t, decrease in chlorophyll content, net photosynthesis rate, transpiration rate, water use efficiency and stomatal conductance and increase in intercellular CO2 concentration, compared to control plants. Although the change trend was the sa me under single and combined stress, the extent of change was different. Under s ingle stress and combined stress, the increase in membrane permeability was 8% ,18.1%,26.0%, in MDA was 11.5%,21.6%,66.7%and in CAT activity was 28.8 %,85.0%,113.8%, respectively. When damage happened after treated by the sin gle stress and combined stress, the decrease in chlorophyll content was 16.5%, 48.6%,57.2%, respectively, in net photosynthesis rate was 28.6%,42.9%,78. 6%, in transpiration rate was 3.9%,12.4%,14.8%, in water use efficiency wa s 27.8%,31.0%,74.5%and in stomatal conductance was 35.6%,38.2%,44.7%, Contrarily, the intercellular CO2 concentration was increase (9.3%,10.6%,26. 4%). From above results, it could be found that the inhibition of combined stre ss is stronger than that of single stress (UV-B+AR>UV-B>AR) and different str ess has different effect on each index. To CAT activity of rape, the single stre ss and combined stress showed the addictive effect, however, showed synergistic effect on the MDA, net photosynthesis rate, water use efficiency and intercellul ar CO2 concentration and independent effect on chlorophyll content, stomatal con ductance, transpiration rate and membrane permeability.更多还原