遮荫对北京山梅花光合特性和快速叶绿素荧光参数的影响

Effects of shading on photosynthetic characteristics and fast chlorophyll fluorescence induction of Philadelphus pekinensis

为了探究北京山梅花对不同光照环境的生理响应和适应性,分别以遮荫度为30%,50%,80%的黑色遮荫网进行遮荫处理。结果表明:随着遮荫度的增大,北京山梅花的净光合速率、气孔导度、蒸腾速率、Pmax、AQY、Fv/Fm、Fv/Fo呈先上升后下降的趋势;胞间CO2浓度、光补偿点、光饱和点、暗呼吸速率呈先下降后上升的趋势,均在50%遮荫度下达到极值。遮荫环境下北京山梅花叶片PSII反应中心电子传递比率上升、用于热耗散的能量比率下降。这说明遮荫使其提高了PSII光能转化效率。综合比较,北京山梅花在遮荫度为50%条件时其光合特性、荧光参数等指标要显著优于其它3个处理。遮荫度为50%的环境最适合北京山梅花的生长。

In order to investigate the effects of different light intensities on photosynthetic characteristics and chlorophyll fluorescence parameters,annual Philadelphus pekinensis was used as materials with three gradient shading treatments（30%,50% and 80%）,while the full sunlight was treated as a control.The results indicated：the net photosynthetic rate,the stomatal conductance,the transpiration rate,Pmax,AQY,Fv/Fm,and Fv/Fo of Philadelphus pekinensis increased significantly with the increase of shading degrees.The maximum value was reached at the 50% shading degree.The intercellular CO2 concentration,the light compensation point,the light saturation point,and dark respiration rate significantly decreased with the increase of shading degrees.And the minimum value reached at the 50%shading degree.Shading treatments increased theφPo,Ψo,φEo,ABS/RC,TRo/RC and ETo/RC and decreased theφDoand DIo/RC,indicating that shading increased the PSII light conversion efficiency of Philadelphus pekinensis.With the comprehensive consideration of the orna-mental effect,when the shading degree was 50%,the photosynthetic parameters and chlorophyll fluorescence parameters of Philadelphus pekinensis were obviously better than those of other 3 treatments.Thus,the environment with the shading degree of 50%is optimal for the growth of Philadelphus pekinensis.