新疆7种城市园林绿化树种叶绿素荧光特征比较

Comparison of Chlorophyll Fluorescence Characters in Seven Garden Tree Species in Xinjiang

测定比较了新疆7种城市园林绿化树种的初始荧光(Fo)、最大荧光(Fm)、PSⅡ最大光能转化效率(Fv/Fm)和PSⅡ最大光能转化潜力(Fv/Fo)4个叶绿素荧光参数随太阳总辐射、空气温度和空气相对湿度变化的日变化以及不同作用光强下从初始荧光上升到最大荧光一半所需时间(T1/2)的变化特征。结果表明:随太阳辐射的增强、空气温度的升高和空气相对湿度的降低,7种测试树木的叶绿素荧光参数Fv/Fm逐渐降低,均在中午光照较强时段维持在较低水平;7种测试树木叶绿素荧光参数Fv/Fm,Fv/Fo的种间差异达到了显著水平(P<0.05),Fo,Fm的种间差异达到了极显著水平(P<0.001),在时间序列上Fv/Fm,Fv/Fo,Fo和Fm均表现为差异极显著(P<0.001);圆冠榆、倒榆的Fv/Fm值全天保持较高水平;黄太平、榆叶梅、黄果山楂的Fv/Fm日均值处于较低状态;除黄太平的叶绿素荧光参数T1/2下午相比上午变化不是很明显外,其他树种均有不同程度的降低,表明下午的强光、高温和低空气湿度使得PSⅡ活性下调,PSⅡ光合电子传递链受阻,从而发生了光抑制。测试树种耐光抑制能力的强弱为:榆科的圆冠榆、倒榆耐光抑制能力最强,木犀科的紫丁香、大叶白蜡其次,蔷薇科的黄太平、榆叶梅、黄果山楂耐光抑制能力最弱。

Diurnal variation （Fo）, maximal fluorescence （Fv/Fm）, maximal potential of four chlorophyll fluorescence parameters including initial fluorescence （Fm）, maximal efficiency of primary conversion of light energy of PS Ⅱ of primary conversion of light energy of PS Ⅱ （Fv/Fo） along with variation of three environmental factors including solar radiation, air temperature, air relative humidity and character of T1/2 under different actinic intensity in seven tree species were determined and compared. The results were shown as follows： Fv/Fm gradually decreased with the increase of solar radiation, rise of air temperature and decrease of air relative humidity, Fv/Fm of all species were at low level at noon when the light is strong. There were extremely significant differences in Fo and Fm（ P 〈0. 001）among the seven tree species, and the differences in Fv/Fm and Fv/Fo were significant（ P 〈0.05）on the level of species series. The differences in Fv/Fm, Fv/Fo , Fo and Fm were extremelysignificant（ P 〈0. 001）on the level of time series. The value of Fv/Frn of Ulmus densa and U. pumila var. pendula kept on a higher level. The value of Fv/Fm of Malus robusta, Amygdalus triloba and Crataegus chlorocarpa retained on a lower level during the whole diurnal variation process. Except that T1/2 of Malus robusta was not evidently varied at p.m. compared with the same value at a. m. , T1/2 of the other tree species decreased to some certain extent,it indicated that photosynthetic activity decreased and PS Ⅱ electron transport was inhibited after strong irradiance,high air temperature and low air relative humidity, which led to light inhibition. The extent of ability to resist light inhibition of experimented tree species was： Ulmus dens and U. pumila var. pendula were the strongest, Syringa oblata and Fraxinus chinensis were the middle, Malus pruni folia, Amygdalus triloba and Crataegus chlorocarpa were the weakest.