光照强度对蒲公英光合特性的影响

在日光温室内，采用遮阳网遮光的方法，营造相对于自然光照的弱光条件，探讨光照强度对蒲公英光合特性的影响。试验结果表明是，蒲公英叶片光系统Ⅱ的光化学效率Fv／Fm在75％自然光照强度处理和45％自然光照强度处理间差异不显著，但均极显著地高于15％自然光照强度处理。蒲公英叶片的光合速率表现为随着光照强度的降低植株叶片光合速率显著降低，表明高光照强度有利于植株叶片光合速率的提高。45％自然光照强度处理明显促进了蒲公英叶片中叶绿素含量的增加，虽然蒲公英叶片中叶绿素a、叶绿素b和类胡萝卜素含量均增加，但叶绿素b增加幅度高于叶绿素a。

Effects of Light Intensity on Photosynthetic Characters in Taraxacum mongolicum

To explore light adaptation characteristics, Taraxacum mongolicum were cultured under three light regimes which was 75% ,45% and 15% of the full sunshine for 2 months in greenhouse of Shenyang agriculture university, Pmax,LMA,Fo, Fv/Fm, chlorophyll and yields were measured. The results showed ：Under 15% full sunshine lower growth light regimes the inhibition of photosynthesis was serious in Taraxacum mongolicum. While 45% and 75% full sunshine wasn＇t significant. With the increase of growth light intensity, photosyn- thesis was increased significantly. The maximum efficiency of photosystem Ⅱ , photochemistry （Fv/Fm） and minimal fluorescence （Fo） were not change under 45% and 75% full sunshine while Fo and Fv/F decreased under 15% full sunshine significantly, This indicated that higher light intensity can protected photosynthetic apparatus from photodamage mainly through utilizing more light energy by photosynthesis, Pmax increased with the increase of growth light intensity. While pigments content on Taraxacum mongolicum were promoted with the decreasing of light intensity,45% treatment was significant especially. The increase Chlb exceeded that of Chla and consequently decreased the ratio between Chla and Chlb.