铜胁迫对芥菜光合特性及叶绿素荧光参数的影响

通过水培试验研究了铜胁迫对芥菜叶片光合特性与叶绿素荧光参数的影响。结果表明，所有铜浓度处理均能降低芥菜胞间CO2浓度（Ci）和光化学淬灭系数（qP）。低浓度的Cu^2＋（≤1μmol·L^-1）能提高芥菜叶片叶绿素、类胡萝卜素含量以及净光合速率（Pn）、气孔导度（Cs）和蒸腾速率（Tr）；高浓度的Cu^2＋（≥10μmol·L^-1）使得芥菜叶片叶绿素（Chl）、类胡萝卜素（Car）含量以及净光合速率（Pn）、气孔导度（Cs）和蒸腾速率（Tr）下降。叶绿素荧光分析表明，当铜浓度低于1μmol·L。时，PSⅡ的最大光化学效率（Fv／Fm）和子叶产量（Yield）升高，当铜浓度高于10μmol·L^-1时降低，而最小荧光（Fo）和非光化学淬灭系数（qN）变化趋势与之相反。叶绿素a／b值在铜浓度低于10μmol·L。时升高，但比值随胁迫继续加剧而下降，两者间呈显著负相关（P〈0．05）；Car／Chl值在铜浓度小于50μmol·L-。时随浓度的增加而增大，之后则随铜浓度的增加而下降，两者呈极显著负相关（P〈0．01）。铜浓度与叶绿素、类胡萝卜素含量、Fv／Fm、qP和Yield均呈极显著负相关（P〈0．01），与Pn、Cs、Tr呈显著负相关（P〈0．05），而铜浓度与Fo和qN分别呈显著和极显著正相关。

Effects of Copper Stress on Photosynthesis and Chlorophyll Fluorescence Parameters of Chinese Mustard

The hydroponic experiment was carried out to understand the mechanism of the effects of copper stress on photosynthesis and chlorophyll fluorescence parameters of Chinese mustard. Compounds of copper sulphate （CuSO4·5H2O） were mixed into Hoagland nutrient solution with different concentration of 0, 1, 10, 50, 100, 200 μmol.L^-1 to form 6 treatments, each with 3 replicates and arranged randomly in growth chamber. The results indicated that intercellular COs concentration （Ci） and chemical quenching coefficient （qP） of mustard declined with Cu^2＋ concentration increased. When Cu^2＋ concentration was less than 1 μmol. L^-1, pigment content, leaf net photosynthetic rate （Pn）, stomatal conductance（ Cs ） and transpiration rate （Tr） of mustard all raised, whereas those all decreased when Cu^2＋ concentration was bigger than 10 μmol.L^-1. The maximal PS I] light energy transformation efficiency （Fv/Fm） and leaf output （Yield） increased when Cu^2＋ concentration was less than 1 μmol.L^-1, but they all decreased when Cu2. concentration was bigger than 10 μmol.L^-1. On the contrast, the fixed fluorescence （Fo） and non-photochemical quenching coefficient （qN） appeared opposite trend to Fv/Fm and Yield. The ratio of chlorophyll a to b increased with copper concentration when Cu^2＋ concentration was smaller than 10 μmol.L^-1, while it diminished when Cu2~ concentration was bigger than 10 μmol.L^-1. The ratio of carotenoids to chlorophyll raised with Cu^2＋ concentrations when copper concentration was smaller than 50 μmol.L^-1, and it decreased thereafter. There was a significant negative correlation between Cu^2＋ concentration and the ratio of carotenoids to chlorophyll （P〈0.01）. In addition, pigment content, Fv/Fm, qP, Pn, Cs, Tr and Yield all had a remarkable positive correlation with copper concentration （P〈0.01 ）, while Fo and qN of mustard had a negative correlation with Cu^2＋ concentration.