乙草胺对葡萄叶片光合和叶绿素荧光特性及叶绿体结构的影响

以沙培1年生巨峰葡萄为材料,研究土施乙草胺对葡萄叶片光合、叶绿素荧光特性和叶绿体结构的影响.结果表明:喷施初期(处理后第13天),上部叶片净光合速率和气孔导度显著下降,PSⅡ最大光化学效率和实际光化学效率显著低于对照,快速叶绿素荧光诱导动力学曲线中J点和K点荧光显著上升,性能指数PⅠABs显著下降,其PSⅡ反应中心和放氧复合体受损伤程度显著高于中部叶片,但随着处理时间的延长,受损伤的程度减轻.在喷施后期(处理后第60天),上部叶片与中部叶片各指标之间的差距变小；下部叶片对除草剂的响应滞后,PSⅡ反应中心和放氧复合体受到较大损伤,J点和K点荧光上升及PⅠABs下降的幅度高于中、上部叶片.乙草胺处理后第60天,葡萄叶片可溶性糖和淀粉含量增加,中、上部叶片色素含量显著下降,叶绿体膜受损,叶绿体变小,片层结构模糊或间隙增大.表明土施乙草胺可传导至葡萄地上部,导致叶片光合机构损伤、PSⅡ活性下降和光合速率降低.

Effects of acetochlor on the photosynthetic and fluorescence characteristics and chloroplast structure of grape leaves

Taking one-year old sand-cultured Kyoho(Vitis vinifera×Vitis labrusca) grapevines as test materials,this paper studied the effects of spraying acetochlor on the grape leaves photosynthetic and fluorescence characteristics and chloroplast ultra-structure.On the 13th day after spraying acetochlor,the net photosynthesis rate and stomatal conductance of upper-node leaves decreased significantly,so as the maximal photochemistry of PSII and the quantum yield of PSII electron transport.The relative variable fluorescence in the J step and K step of the chlorophyll fluorescence transients had an obvious increase,while the performance index(PIABS) had a marked decrease.The damages to the PSII reaction center and oxygen-evolving complex of upper-node leaves were more severe,as compared to middle-node leaves,but the damage degree was alleviated along with treatment time.On the 60th day after spraying acetochlor,the differences in the photosynthetic and chlorophyll fluorescence parameters between upper-and middle-node leaves diminished.The responses of bottom-node leaves appeared later than those of the upper-and middle-node leaves.The damage of PSII reaction center and oxygen-evolving complex,the rise of relative variable fluorescence in the J step and K step,and the decline of PIABS of bottom-node leaves were much greater than those of the upper-and middle-node leaves.On the 60th day after spraying acetochlor,the leaf sugar and starch contents increased,but the pigments in the upper-and middle-node leaves decreased significantly,the chloroplast membrane was impaired,the size of chloroplasts decreased,and the lamellae became fuzzy or the gap between lamellae increased.As a whole,acetochlor could be transmitted to the aboveground part of grapevine,and result in the damage of leaf photosynthetic apparatus and the decrease of PSII activity and photosynthetic rate.