氧化乐果对不结球白菜光系统Ⅱ的毒理效应

Toxicological effects of omethoate on leaf photosystem Ⅱ of cole.

采用不同品牌、不同浓度的氧化乐果杀虫剂对不结球白菜进行叶面喷洒处理,利用植物效率仪(PEA)测试不结球白菜叶片的快速叶绿素荧光动力学曲线,并根据JIP-test参数分析光系统Ⅱ(PSⅡ)的变化,研究氧化乐果对不结球白菜PSⅡ的毒理效应及残效动态.结果表明:除0.50%浓度氧化乐果外,其他浓度处理对不结球白菜叶片PSⅡ的最大光化学效率Fv/Fm影响不显著.但随着处理浓度的增大,初始荧光Fo、最大荧光产量Fm、J相的相对可变荧光VJ和PSⅡ单位反应中心用于电子传递的能量ETo/RC呈显著增加趋势;而被PSⅡ反应中心捕获的激发能将电子从还原态质体醌QA-送入电子传递链的效率ψo却呈显著降低趋势.两个品牌的氧化乐果杀虫剂对不结球白菜PSⅡ的影响具有较好的一致性.氧化乐果叶面喷洒处理对不结球白菜PSⅡ的影响残效均在第3天达到最大,在第9天至第12天逐渐消失.表明氧化乐果杀虫剂对不结球白菜PSⅡ的作用目标靶促进了QA向QA-的还原过程(VJ升高)以及QA-向QB的电子传递过程(ETo/RC增加).

After spraying different concentrations of two brands pesticide omethoate on cole （Brassica campestris L. ） leaves, the leaf chlorophyll a fluorescence transients were measured by a Plant Efficiency Analyzer （PEA）, and the toxicological effects and rudimental dynamic courses of omethoate on the leaf photosystem Ⅱ （ PS Ⅱ ） were investigated by JIP-test. The results showed that after spraying omethoate except at the concentration of 0.50%, the maximal efficiency of photochemistry （Fv/Fm） did not have a remarkable change. However, with increasing omethoate concentration, the minimal fluorescence Fo, maximal fluorescence Fm, relative variable fluorescence at the J-step （VJ）, and electron transport flux perreaetive center in PS Ⅱ （ETo/RC） increased remarkably, but ψo, the efficiency that a trapped exciton in PS Ⅱ moved an electron into the electron transport chain beyond QA ^-, decreased remarkably. The test two brands of pesticide omethoate had almost alike effects on the PS Ⅱ of cole, and the residual effect of the pesticide was the strongest at the third day after spraying and petered out from the ninth to twelfth day. The main targets of omethoate on the PS Ⅱ of cole could be listed as promoting the reduction from QA to QA - （ increasing of VJ ） and the electron transmission from QA^- to QB （increasing of ETo/RC）.