遮光处理对桐花树光合特性的影响

研究了不同光照强度全光照(Ac100)、48%光照(Ac48)、20%光照(Ac20)]对淡水种植的桐花树光合特性及叶绿素含量的影响.结果表明:Ac100的净光合速率日变化呈"双峰"型,有显著的"午休"现象,而Ac48和Ac20的净光合速率日变化呈"单峰"型,"午休"程度降低;不同月份期间,遮光处理对桐花树的净光合速率(Pn)、有效光合辐射(PAR)、气孔导度(Gs)和蒸腾速率(Tr)均存在显著影响.遮光处理的桐花树叶片最大光合速率(Pmax)、光饱和点(LSP)、光补偿点(LCP)、暗呼吸速率(RD)以及表观量子效率(AQY)与全光照处理相比均下降;随遮光度增大,叶片叶绿素a+b和叶绿素b含量显著升高,而叶绿素a/b降低,且叶面积显著增大.试验表明遮光处理通过影响环境因子和桐花树叶片生理特性等内在因素而影响其光合作用,且桐花树能适应一定程度的遮光环境.

Effects of Photosynthetic Characters on Aegiceras corniculatum under Different Shading Treatments

The Photosynthetic Characters and ChlorophyII conten of Aegiceras corniculatum were investigated under different shading treatmentsfull natural light（Ac100）,48% of full natural light（Ac48）and 20% of full natural light（Ac20）].The results showed that change of the net photosynthetic rate（Pn） of Aegiceras corniculatum in the daytime was two peak curves under full natural light and there was a point depression at noon,while there was only one peak curve under 48% and 20% of full natural light and the range of depression at noon.The net photosynthetic rate（Pn） and Photosynthetic radiation（PAR）and Stomatal conductance（Gs）and transpiration rat（Tr） had significant effects under different shading treatments in different monthly.Compared with full natural light,the Aegiceras corniculatum under shade treatment had significantly lower maximum net photosynthetic rat（Pmax）,light saturation point（LSP）,light compensation point（LCP） and dark respiration rate（Rd）,but higher Chl content per unit mass and leaf area,and the chlorophy II a/b was reduced.The results showed that the effect of shading on photosythesis was due to the influences of shading on environment factor and physiological activity in Aegiceras corniculatum,and that Aegiceras corniculatum are shade tolerant.