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1、第40卷第5期林业科学Vol140,No152004年9月SCIENTIASILVAESINICAESep.,2004樟树幼树光合特性及其对CO2浓度和温度升高的响应田大伦 罗 勇 项文化 闫文德(中南林学院生态教研室 株洲412006)摘 要:用Li2COR6400便携式光合作用测定系统对亚热带常绿阔叶树种樟树幼树的光合特性及其对CO2升高的响应进行了研究。结果表明:樟树叶片光合速率日变化呈双峰曲线,最高峰出现在10:00,次高峰出现在14:00,午间有明显的“午休”现象,气孔因素是导致午休的主要原因。中午光照强度大,叶片与空气
2、之间的水汽压差达到最大值,相对湿度、气孔导度、胞间CO2浓度达到最小值,诱导叶片光合午休。正常大气条件下,樟树叶片光饱和点-2-1-2-1-2-1-1为1250μmol·ms,光补偿点4016μmol·ms,在1000μmol·ms光强下CO2饱和点为1200μmol·mol,-1CO2补偿点为50μmol·mol。水分利用效率、气孔导度、蒸腾速率在不同的CO2浓度梯度下,随着光强的增加而增加。在24～35℃时,随着光合有效辐射的增加,温度升高导致樟树光合速率降低。关键词: 樟树,光合速率,CO2浓度,温度中图分类号:S71814
3、3 文献标识码:A 文章编号:1001-7488(2004)05-0088-05PhotosyntheticCharacteristicsofCinnamomumcamphoraandItsResponsetoElevationofCO2andTemperatureTianDalunLuoYongXiangWenhuaYanWende(ResearchSectionofEcology,CentralSouthForestryUniversityZhuzhou412006)Abstract:Thephotosynthetic
4、characteristicsofCinnamomumcamphoraanditsresponsetoCO2enrichmentinsubtropicalever2greenbroadleafforestareawereinvestigatedusingLi-COR6400portablephotosynthesissystem.Theresultsshowedthatthediur2nalnetphotosyntheticrateofC.camphorainsunnydayvariedwithdoublepeakcurves.T
5、hepeaksoccurredat10:00and14:00respectively.Therewasasignificantmiddaydepression.Stomatalfactors,suchasthestomatalconductance,werethemaincausesofthedepression.Atmidday,lightintensitywasthelargest,vaporpressuredeficitbetweenleavesandairreachedmaxi2mum,butairrelativehumi
6、dity,stomatalconductanceandintercellularCO2concentrationwereminimum,andhencephotosyn2theticmiddydepressionoccurred.ThelightcompensationpointandlightsaturationpointofleavesattheambientCO2concentra2-2-1-2-1-2-1tionwere4016μmol·msand1250μmol·ms,respectively.Whenlightinte
7、nsityreached1000μmol·msandam2-1-1bientCO2concentration,itsCO2compensationpointandCO2saturationpointwere50μmol·moland1200μmol·mol,re2spectively.Withtheincreasesoflightintensity,wateruseefficiency,sotmatalconductanceandtranspirationratewereimprovedatdifferentCO2concentr
8、ation.Andin24～35℃,thenetphotosyntheticrateshowedadecreasingtrendwiththetemperatureandphotosyntheticactiveradiationincreasing
