【摘要】 为揭示多形叶发育的生态适应机制,选择锯齿卵圆形、卵圆形和披针形3种典型成年胡杨叶片进行气孔及光合特性方面的研究。观察到,胡杨叶片近轴面与远轴面的气孔密度相近,气孔为非均匀开闭;3种形态叶的气孔密度不同,锯齿卵圆形的最大,披针形的最小。气孔下陷程度存在显著差异,锯齿卵圆形叶气孔下陷较深,披针形的最浅。它们的光合速率日变化规律基本一致,呈单峰曲线。光合速率日平均值存在较大差异,卵圆形叶和锯齿卵圆形叶的光合速率日平均值明显高于披针形叶。3种形态叶的光补偿点相近,但饱和点存在差异;叶片的PSⅡ原初光能转换效率以及PSⅡ潜在活性也存在明显差异,其中锯齿卵圆形叶的最高。结果表明,胡杨叶片在发育过程中从形态、解剖和光合特性上均发生了变异。更多还原

【Abstract】 The shapes of the leaves of adult Populus euphratica are varied from lanceolate to dentate broad_ovate. In order to find the ecological adaptation mechanism of the varied typical leaves, the dentate broad_ovate、broad_ovate and lanceolate leaves as the typical leaves were chosen to study their stomatal and photosynthetic characteristics. It is observed that the stomas on the adaxial and abaxial epidermis of the same leaves open unequally and their densities are similar. The stomatal densities of the three typical leaves are different, which decrease from broad_ovate to lanceolate leaves. Their stomatal sunken degree varies obviously, which is lessened from broad_ovate to lanceolate leaves. The changes of the diurnal photosynthetic rate of the three typical leaves are basically accordant with a curve of single apex. The average values of the diurnal photosynthetic rate of these leaves are different, which decrease from broad_ovate, dentate broad_ovate leaves to lanceolate. The compensation points of light are similar in the three typical leaves, while the saturation points of light are varied obviously among them. The efficiency of solar energy conversion and potential activity of the PSⅡ in the leaves are distinct, which of the dentate broad_ovate leaves is the highest. The results imply that their leaf shapes, anatomic structures and photosynthetic characteristics are varied during the leaf development.更多还原