【摘要】 以人工低温处理尾叶桉和邓恩桉幼苗,研究其对两种桉树光合和叶绿素荧光参数的影响。结果表明:低温处理后两种桉树叶绿素含量下降,光合和叶绿素荧光参数光合速率、气孔导度、蒸腾速率、表观量子效率、光饱和点、羧化效率、Fv/Fm和Fv/Fo下降,Fo值和CO2补偿点上升,而Ci则先上升后下降。进一步的分析表明,在持续低温胁迫的初始阶段,羧化酶活性的下降是导致两种桉树Pn降低的主要因素为非气孔因素,而随着低温处理持续时间延长至48h时,叶绿素含量出现显著下降,羧化酶效率继续下降,此时气孔限制因素也逐渐成为Pn的降低的主要因素之一。两种桉树叶绿素荧光参数的变化差异表明,非损伤的叶绿素荧光技术有望用来快速筛选不同抗寒能力的桉树品种。从各个参数的变化可以看出,低温胁迫处理对尾叶桉的影响明显要大于对邓恩桉的影响。更多还原

【Abstract】 Photosynthetic and chlorophyll fluorescence parameters of E.urophylla and E.dunnii to low temperature stress were measured in this paper.The results showed that net photosynthetic rate(Pn),stomata conductance(Gs),transpiration rate(Tr),apparent quantum efficiency(F),light saturated point(LSP),carboxylation efficiency(CE),Fv/Fm,Fv/Fo and the content of chlorophyll of E.urophylla and E.dunnii seedling leaves decreased by low temperature treatments,but Fo and CO2 compensation points(CCP)increased,and Ci increased first and then decreased.The decreasing of net photosynthetic rate was mostly caused by non-stomatal limitation at the beginning of low-temperature stress,subsequently by stomatal limitation and non-stomatal limitation simultaneity.The changes of chlorophyll fluorescence parameters showed it was possible to use chlorophyll fluorescence to select for different cold-hardness eucalypts.The resultssuggested that there was a better resistance in E.dunnii than in E.urophylla to low-temperature stress.更多还原