海水处理对不同产地菊芋幼苗光合作用及叶绿素荧光特性的影响

EFFECTS OF SEAWATER ON PHOTOSYNTHESIS AND CHLOROPHYLL FLUORESCENCE IN HELIANTHUS TUBEROSUS SEEDLINGS IN DIFFERENT REGIONS

种植抗盐耐海水经济作物是合理开发利用沿海滩涂和海水资源、培育耐盐植物的有效措施之一。该研究以不同产地菊芋(Helianthustuberosus)为试验材料研究了海水处理对菊芋幼苗生长、光合作用和叶绿素荧光特性的影响。结果表明1)随着海水浓度的增加,各地菊芋幼苗根、地上部的鲜重和干重均降低,但盐城菊芋幼苗地上部和根鲜重及干重降低的幅度小于武威和烟台菊芋幼苗。2)随着海水浓度的增加,各地菊芋叶片的净光合速率(Pn)、蒸腾速率(Tr)、水分利用效率(WUE)、气孔导度(Gs)和气孔限制值(Ls)均降低,而细胞间隙CO2浓度(Ci)增大,且在各处理下盐城菊芋较武威和烟台菊芋叶片Pn和Tr大,而盐城菊芋在15%海水处理下,WUE和Ci较武威及烟台菊芋低,Gs和Ls较武威和烟台菊芋高。3)随着海水浓度的增加,各地菊芋叶片的初始荧光(Fo)、最大荧光(Fm)、可变荧光(Fv)、恒态荧光(Fs)、恒态荧光与初始荧光差值(ΔFo)、PSⅡ潜在光化学效率(Fv/Fo)和PSⅡ最大光化学效率(Fv/Fm)均降低,且在各处理下盐城菊芋较武威和烟台菊芋叶片Fm、Fv、Fs、Fv/Fo大。随着海水浓度的增加,盐城菊芋叶片电子传递速率(ETR)、光化学荧光猝灭系数(qP)和光化学速率变化幅度不大,武威和烟台菊芋在30%海水处理下显著下降,较盐城菊芋小,各处理下菊芋叶片的PSⅡ实际光化学效率(ΦPSⅡ)变化也不一致,盐城和武威菊芋叶片的ΦPSⅡ在15%海水处理较0和30%海水处理下大,而烟台菊芋叶片的ΦPSⅡ在0海水处理下最大。4)随着海水浓度的增加,各地菊芋叶片的叶绿素a(Chla)含量均降低,而叶绿素b(Chlb)含量没显著差异,且在各处理下盐城菊芋较武威和烟台菊芋叶片Chla含量大,武威和盐城菊芋叶片的Chla/Chlb比值均降低,烟台菊芋叶片的Chla/Chlb比值在0和15%海水处理下没差异。可见海水处理对菊芋幼苗生长发育、光合作用和叶绿素荧光特性均有影响,随海水浓度的增加,其效应越明显,但对各来源地菊芋幼苗的影响不一致,盐城菊芋幼苗表现为更耐海水。

Background and Aims Growing plants that are tolerant to saltwater is an option for use of coastal mudflats and application of seawater. Methods Pot experiments were carried out to study the effects of the seawater on photosynthesis and chlorophyll Ⅱ fluorescence of Helianthus tuberosus seedlings from three different regions, Yancheng （YC）, Wuwei （WW）, and Yantai （YT）. Three different concentrations of seawater were applied： 0 （CK）, 15%, and 30% seawater. Key Results Fresh and dry weights of roots and shoots of seedlings decreased with increasing seawater concentrations for all regions, but less at YC. Net photosynthetic rate （Pn）, transpiration rate （ Tr ）, water use efficiency （WUE）, stomatal conductance （Gs）, and stomatal limitation （Ls） decreased with increasing seawater concentration for all regions; however, intracellular CO2 （Ci） increased with increasing seawater concentration. The Pn and Tr were the highest for YC, whereas WUE and Gi were lower and Gs and Ls were higher than those for WW and YT with the 15% seawater treatment. Minimal fluorescence （Fo）, maximum fluorescence （Fm）, variable fluorescence （ Fv ）, stable fluorescence （ Fs ）, difference between Fs and Fo （ △Fo ）,PS Ⅱpotential fluorescence efficiency （ Fv/Fo ）, and PS Ⅱmaximum fluorescence efficiency （ Fv/Fm ） all decreased with increasing seawater concentration. Values of Fm, Fv, Fs, and Fv/Fo were the highest for YC. Electronic transfer rate （ETR）, photochemical quench （qp）, and photochemistry rate of YC leaves changed slightly. Compared to the controls, values for WW and YT all decreased markedly with 30% seawater and were lower than for YC. The PS Ⅱactual fluorescence efficiency （ φPSⅡ ） changed differently with different treatments. The φPSⅡ for YC and WW was the highest with 15% seawater than other seawater concentration, and φPSⅡ for YT was highest with CK. The Chla contents all decreased and Chlb contents changed slightly with increasing seawater concentration. The ratio of Chla and Chlb for WW and YC deceased with increasing seawater concentration, and the ratio for YT changed slightly with the 0 and 15 % seawater treatments. Conclusions Seawater suppressed the growth, photosynthesis, and chlorophyll Ⅱ fluorescence of H. tuberosus seedlings, and effects increased with increasing seawater concentration. Seedlings grown in the YC region were less affected by seawater than those in the WW and YT regions.