【摘要】 对胡杨大树典型多态叶--锯齿卵圆形和披针形叶的光合特性、气孔特性及水分生理进行了系统研究。结果表明,锯齿卵圆形叶的Pn高于披针形叶。自然条件下,锯齿卵圆形叶的光补偿点为60μmol/(m2.s),披针形叶为75μmol/(m2.s),两种叶的光饱和点都在1800μmol/(m2.s)以上,在自然状态下都达不到光饱和点。锯齿卵圆形叶的Tr、气孔密度及大小均大于披针形叶,气孔开放率略小于披针形叶,Ψ100、Ψ0以及二者的差值均小于披针形叶。锯齿卵圆形叶的体积弹性模量(ε)为8.4324,披针形叶为2.3597。锯齿卵圆形叶枝条的平均导水率为6.61×10-5kg/(s.MPa),披针形叶为5.19×10-5kg/(s.MPa);失水胁迫后锯齿卵圆形叶枝条的导水率降低了0.06×10-5kg/(s.MPa),披针形叶降低了1.88×10-5kg/(s.MPa),表明锯齿卵圆形叶枝条的导水力在干旱环境下比较稳定。胡杨两种形态的叶光合能力和保水能力存在明显不同,锯齿卵圆形叶具有相对较强的耐高光强和水分亏缺胁迫的能力。正是有多态叶的这种个体发育形式,胡杨才具有更强的适应恶劣多变生态环境的能力。更多还原

【Abstract】 The photosynthetic characteristics,stomatal characteristics and water physiology of dentate broad-ovate leaves and lanceolate leaves from Populus euphratica were studied in this paper.The results showed that Pn of dentate broad-ovate leaves was higher than that of lanceolate leaves.Under normal conditions,the light compensation points of dentate broad-ovate leaves and lanceolate leaves were 60 and 75 μmol/(m2·s) respectively,the light saturation point of both was above 1 800 μmol/(m2·s).Both of them could not reach the light saturation point under normal conditions.Tr,stomatal density and size of dentate broad-ovate leaves were higher than that of lanceolate leaves,while the stomatal opening rate was lower than that of lanceolate leaves.Ψ100,Ψ0 and the difference of the two values of dentate broad-ovate leaves were lower than that of lanceolate leaves.The ε values of dentate broad-ovate leaves and lanceolate leaves were 8.432 4 and 2.359 7 respectively.The average hydraulic conductivity of branches with dentate broad-ovate leaves and lanceolate leaves was 6.61×10-5 and 5.19×10-5 kg/(s·MPa);and the reduction of hydraulic conductivity of dentate broad-ovate leaves and lanceolate leaves was 0.06×10-5 and 1.88×10-5 kg/(s·MPa) respectively after drought stress,this indicated that the hydraulic conductivity of branches with dentate broad-ovate leaves was relatively stable in dry environments.The study shows that,the light energy efficiency and water stress tolerance ability of dentate broad-ovate leaves are higher than that of lanceolate leaves,maybe these changes are the results of leaves of P.euphratica to adapt to the environmental stress during their development.更多还原