全光和遮阴下两种亚热带木本植物的光合作用对光的响应  

PHOTOSYNTHETIC RESPONSES OF TWO SUBTROPICAL WOODY PLANTS GROWING UNDER SUN AND SHADE ENVI RONMENTS

作　　者：温达志[1] 叶万辉[1] 林植芳[1] 孔国辉[1] 孙梓健[1] 

机构地区：[1]中国科学院华南植物研究所,广东广州510650

出　　处：《热带亚热带植物学报》2001年第3期248-255,共8页Journal of Tropical and Subtropical Botany

基　　金：中国科学院"九五"重点资助项目(KZ952J1-105);中国科学院特别支持项目(KZ95T-04-02-04)

摘　　要：以气体交换和调制叶绿素荧光测定技术测定了2年生亚热带乔木黧蒴、林下灌木九节在全自然光和17%自然光下叶片同部位的光合作用和与之相关的荧光参数的日变化。和全光照比较,遮阴下植物叶片净光合速率Pn、气孔导度gS、胞间CO2浓度与大气CO2浓度之比Ci/Ca,类胡萝卜素与叶绿素含量之比Car/Chl、光系统II原初光化学效率Fv/Fm的变化幅度相对较小,种间差异较不明显。全光照黧蒴和九节Pn的日变化图式与gS、Ci/Ca类似,与ФPSII、qP的下降吻合。全光下黧蒴叶片qN和Car/Chl的日进程表现为增加,九节则下降,低的Car/Chl可能是导致强光下九节未能提高其qN的原因。正午前后,黧蒴qN和Car/Chl增大,而qP和ФPSII降低,Fv/Fm则保持相对稳定,反映其开放的PSII反应中心数目在此期间虽有所减少,但仍然维持了较高的光化学效率,提高的Car/Chl和qN则说明其具有较强的对过剩激发能的耗散能力。此条件下九节的gS、Fv/Fm和qN下降且明显低于黧蒴,ФPSII和qP保持相对稳定但高于黧蒴的水平,表明九节的PSII反应中心活性较稳定,但强光下气孔部分关闭、较低的Fv/Fm和qN限制了CO2供应和对光能的有效利用,且未能诱导热能耗散机制的积极运行及对光合器起到保护作用。总体上说,九节对高光强反应比黧蒴敏感。Photosynthesisandfluorescenceparametersinvolvingphotosyntheticprocessin theleavesof2-year-old subtropicaltreespeciesCastanopsis fissa and understoryshrubPsychotria rubra were determinedby usinggasexchangeandfluorescencetechniques,whichweretransplantedin25plotsfor6monthsunderfullsunlightand shade(17%of fullsunlight)for eachtreatment.The dailycourse variationof netphotosynthesisrate(Pn),stomatalconductance(g S ),ratioof intercellularto ambient CO 2 concentration(Ci/Ca),ratioof carotenoidto chlorophyllcontent(Car/Chl),andtheefficiency of photochemicalreaction(Fv/Fm)forbothplantsundershadewererelativelystableandlessdifference betweenspecies.However,infullsunlight,thePn,g S andCi/Caforthetwospeciesgenerallydeclined withtime,consistentlywiththedecreaseoftheq P andФ PSII .q N andCar/ChlforCastanopsis fissa increased withtime,butdecreasedforPsychotria rubra.Thedecreaseof q P andФ PSII in leavesof Castanopsis fissa underfullsunlightaroundthe noon timeindicatedthatthe numbersof the openPSIIreaction centerwerepossiblyreduced,butitsphotochemicalefficiencystillmaintainedat a relativelystablelevel indicatedby Fv/Fm.Meanwhile,theincreasein Car/Chlandq N suggestedthattheexcessiveactivated energycouldbe safelydissipated.Whilefor Psychotria rubra,theg S ,q N and Fv/Fmdecreasedand weresignificantlylower,butФ PSII and q P maintainedrelativelystableand werehigheras compared to Castanopsis fissa,implyingthatitsPSIIreactioncentermay changea little,butCO 2 exchange,photochemicalefficiency,andheatdissipationcapacityhadbeenweakenedtoa certaindegree.Ingeneral,Psychotria rubra showedmoresensitivitytostronglightintensitythanCastanopsis fis sa.

关 键 词：森林植物 光合作用 光化学效率 黧蒴 九节 光响应 全光 遮阴 亚热带木本植物 

分 类 号：Q945.11[生物学—植物学]