Responses of leaves and shoots to environmental variables and tree growth

1.通过同时测量气体交换和碳同位素，我们确定了树木叶片中厚的叶肉细胞壁，特别是常绿树木的叶肉细胞壁，对光合作用下CO_2的扩散是一个相当大的障碍。我们阐明了为什么阳光下的叶子应该比阴影下的叶子厚。厚度对于增加CO_2溶解的表面积很重要。我们还发现栅栏组织细胞响应成熟叶片的信号进行周状分裂。当成熟叶片暴露在强光下时，发育叶片中的栅栏组织细胞不论发育叶片的光照条件如何，都呈周状分裂。我们描述了常绿树种叶片光合活性的发展。叶片完全扩张后，光合速率达到最大值。我们分析了成熟树叶的体积弹性模量的行为，这是确定水关系的一个重要参数。体弹性模量对水应力的响应减小，从而维持细胞的膨胀。这些变化是可逆的，而且比渗透势的变化快。我们应用管道模型理论的导数形式来描述树木的生长。截光和长、短枝分化是决定树木厚度生长的重要因素。

1.By concurrent measurements of gas exchange and carbon isotope, we established that thick mesophyll cell walls in tree leaves, in particular those of evergreen trees, is a considerable barrier to photosynthetic CO_2 diffusion.2.We clarified why sun leaves should be thicker than shade leaves. Thickness if important for increasing the surface area for CO_2 dissolution. We also found that palisade tissue cells divide periclinally in response to signal from the mature leaves. When mature leaves are exposed to high light, palisade tissue cells in developing leaves divide periclinally irrespective of the light conditions of the developing leaves.3.We described development of photosynthetic activity in the leaves of evergreen tree species. The maximum photosynthetic rate was observed well after the full leaf expansion.4.We analyzed behavior of the bulk elastic modules, an important parameter for determining water relations, in mature tree leaves. Bulk elastic modules decreased in response to water stress so that cell turgor was maintained. These changes were reversible and quicker than changes in osmotic potential.5.We applied the pipe model theory in the derivative form to describe tree growth. Light interception and long and short shoot differentiation are important determinants of thickness growth of the trees.