叶片叶肉结构对环境光强的适应及对光合作用的影响

本文利用Kubelka-Munk理论描述了平行光在叶片内的吸收和散射,同时利用叶片分层光合作用非直角双曲线光反应模型,给出了整张叶片光合作用计算式。最后利用优化理论阐明了叶片叶肉分化成光合特性具有明显差异的栅栏组织和海绵组织可能是对叶片内光梯度的一种适应;同时证明了叶片叶肉在一定环境光强下存在一个最佳的栅栏组织和海绵组织比例,并且这个比例随环境光强增大而增大,这最佳比例也受叶肉组织光合特性差异的影响。

Adaptation of leaf mesophyll structure to environmental light condition and its effect on leaf photosynthesis.

In this paper the hypothesis that most structural features of leaf can be explained as the adaptation to maximise leaf photosynthesis capacity has been explored. The light envi ronment within leaf is described by the application of the K-M theory and a leaf photo synthesis model incorporating it was presented.Finally,the adaptation of mesophyll stru cture to environmental light condition to maximise leaf photosynthesis was demonstrated by applying optimization theory. Comparing the leaf photosynthesis with different ratios of palisade to spongy tissue showed that there is an optimal ratio (e. g.Kp = depth of pa lisade layer/depth of spongy layer = 0.6), which is very close to actual leaf structure (Table 2). It has been demonstrated by further analysis that the optimal ratio (Kopt) of leaf mesophyll varies with environmental light condition. The fraction of palisade tis sue which makes up the total leaf thickness increases with environmental light intensity, and the optimal ratio (Kopt) depends on the photosynthesis properties of palisade and spongy tissues (Table 3).