锰胁迫对垂序商陆光合特性及叶绿素荧光参数的影响

Effects of manganese stress on photosythesis and chlorophyll fluorescence parameters of Phytolacca americana

垂序商陆(Phytolacca americana L.)是我国首次发现的锰超富集植物。通过温室营养液培养实验,研究垂序商陆锰耐性与光合特性及叶绿素荧光参数的关系。结果表明,随着生长介质中锰浓度的升高,垂序商陆叶片的叶绿素a、叶绿素b和总叶绿素含量下降,净光合速率(Pn)和气孔导度(Gs)呈下降趋势,而胞间CO2浓度(Ci)却逐渐升高;叶绿素a/b值和蒸腾速率(Tr)在1 000μmol.L-1锰供应水平时达到最大值;叶片PSⅡ的最大量子产量(Fv/Fm)、PSⅡ有效光化学量子产量(EQY)和光合电子传递速率(ETR)呈下降趋势,而光化学淬灭系数(qP)和光合有效辐射(PAR)高于239μmol photons.m-.2s-1下的非光化学淬灭系数(NPQ)在5 000μmol.L-1锰供应水平时达到最大值。因此,垂序商陆在锰胁迫下可能具有一定的光合保护机制。

Phytolacca americana L.（Phytolaccaceae） is a new manganese hyper-accumulator plant from Southern China.In order to estimate the relationships among manganese tolerance of P.americana and photosynthesis and chlorophyll fluorescence parameters,chlorophyll contents,gas exchange and chlorophyll fluorescence parameters were measured by glasshouse experiments.With the manganese concentration in the media increasing,chlorophyll a,chlorophyll b and total chlorophyll contents of P.americana decreased,and net photosynthetic rate（Pn）,stomatal conductance（Gs） also gradually declined,but intracellular CO2 concentration（Ci） gradually increased.Chlorophyll a/b ratio and transpiration rate（Tr） was the highest at a manganese supply level of 1000 μmol·L-1.The maximum quantum yield of PSⅡ photochemistry（Fv/Fm）,the effective quantum yield of PSⅡ photochemistry（EQY）,and the photosynthetic electron transport rate（ETR） were gradually decreased.At the manganese concentration of 5 000 μmol·L-1 in the solution,the photochemical quenching（qP） reached the maximum,and non-photochemical quenching（NPQ） also reached the maximum when photosynthetic active radiation（PAR）was higher than 239 μmol photons·m-2·s-1.It is indicated that P.americana has photosynthetic protection in some degree under manganese stress.