红树林植物叶片形态和解剖特征对叶肉导度、叶片导水率的影响

叶肉导度和叶片导水率是影响光合作用的两个重要过程,叶肉导度通过影响从气孔下腔到Rubisco酶位点的二氧化碳浓度梯度直接影响光合作用,而叶片导水率则通过影响水分供应或气孔行为来影响光合作用,然而对这两个生理过程之间的协同性研究较少。本研究选择9种红树林植物为研究对象,探讨盐生环境下植物叶肉导度和叶片导水率的协同性及其与叶片解剖结构特征之间的相关性。结果表明,9种红树林植物叶片导水率(0.78~5.83 mmol·m~(-2)·s~(-1)·MPa-1)、叶肉导度(0.06~0.36 mol·m~(-2)·s~(-1))、最大光合速率(7.23~23.71μmol·m~(-2)·s~(-1))等特征的差别较大;叶肉导度与最大光合速率呈显著正相关,而与比叶重无显著相关性,其原因是由于比叶重与叶片厚度、叶片密度不存在相关性;叶脉密度与气孔密度呈较强的相关性,说明红树林植物叶片水分运输与散失相关的叶片结构之间存在协同关系;叶片导水率不受叶脉密度影响,并且与叶肉导度、最大光合速率也不存在相关性,这很可能与红树林植物叶片的肉质化、有发达的储水组织有关,体现了红树林植物叶片结构和功能的特殊性。

Impact of Leaf Morphological and Anatomical Traits on Mesophyll Conductance and Leaf Hydraulic Conductance in Mangrove Plants

Mesophyll conductance (g_m) and leaf hydraulic conductance (K_leaf) are two important physiological processes that control photosynthesis. However, few studies have investigated the correlations between them. We measured the morphological and anatomical traits of the leaves and the maximum photosynthetic rate (A_max), g_m and K_leaf in nine mangrove forest species to explore the correlation between the structural and functional traits of the leaves in these species. Our results showed that there were large variations in K_leaf (0.78-5.50 mmol·m^-2·s^-1·MPa^-1), g_m (0.06-0.36 mol·m^-2·s^-1) and A_max (7.23-23.71 μmol·m^-2·s^-1) across the nine species. Mesophyll conductance was significantly correlated with A_max, but not with leaf mass per area. Among the nine species, stomatal density was correlated with vein density, indicating a balance between leaf-level water transpiration and supply. There was no significant relationship between K_leaf and vein density, nor between A_max and g_m. Decoupled coordination between leaf economic and hydraulic traits for plants growing in mangrove forests indicates additional leaf trait such as water storage tissues assisting their leaf carbon assimilation, This study showed the special leaf structural and physiological adaptation of mangrove plants to the stressful habitats.