环境梯度和叶型对叶片水分供需关系的影响
发布时间：2018-08-10 16:43
【摘要】：为了适应在不同环境下对水分的运输和利用,植物的一些与水分相关的结构特征,如叶片的叶脉、气孔以及茎干木质部的导管等,可能会存在一定的功能上的关联。而对于植物叶片水平的水分供需关系,以及叶片与枝条水力结构和气孔调节能力之间的关系目前并未达成广泛的共识,许多分歧有待进一步的研究。本论文从不同的层次和角度探讨了植物叶片及枝叶的水分供需关系,研究这类关联在不同环境下以及在不同类群间的变化趋势,对了解植物维持水力系统功能的不同适应策略有重要意义。本论文主要从三个方面探讨了植物的水分供需关系,主要研究内容和结果如下：第一部分以分布在云南省热带山地森林(800 m到1400 m)和亚热带山地森林(2000 m到2600 m)不同海拔的105种木本被子植物叶片为材料,通过测定其叶片面积、小脉密度、气孔密度和长度等功能性状,研究它们随海拔梯度的变化趋势及其相互关系。发现每个海拔梯度上群落水平树种的平均气孔密度随着海拔的升高并未有明显的变化趋势。沿每个海拔梯度上树种的平均小脉密度,分别在亚热带山地林和热带山地林的4个海拔梯度上也没有明显差异,但是热带山地林树种的平均小脉密度要显著高于前者。在亚热带山地林树种中,小脉密度和气孔密度存在一个显著的正相关关系,然而从105种树整体上来看,这一关联表现较弱。气孔性状和叶脉性状对随海拔变化的环境因子的响应并不一致。本研究结果不仅表明叶片水分供需平衡关系在被子植物树种多科属水平上的存在,还揭示出气孔和小脉在应对海拔变化时存在解偶联的适应性。第二部分通过测定三个光照强度下生长的落花生(Arachis hypogaea Linn.)同一茎干上不同叶序的成熟复叶的小叶的叶面积、小脉密度和厚度(直径)、气孔密度和直径等功能性状,以及推导出一个更直观的表述叶片水分供需平衡关系的指数,探讨气孔与小脉随叶序的变化趋势及其协同性,并论证稳定的单位长度小脉对应的气孔个数可以表征叶片处于水分供需平衡状态。发现在同一光照条件下,落花生小叶单位长度小脉对应的气孔个数(气孔密度与小脉密度的比值)随着叶序的增加保持不变,也与小叶的面积无关。不同光照强度下生长的落花生,气孔直径没有显著差异,而小脉的厚度存在显著差异,光照越弱,其直径越小。在每个光照条件下,小脉密度与小叶的面积之间都表现出正相关关系。全日照条件下的气孔密度与小叶面积也具有显著的正相关关系。全日照条件下,气孔密度随叶龄增加具有增大的趋势,在遮阴处理后,不同叶龄小叶的气孔密度没有差异。小脉密度和气孔密度之间的正相关关系随着遮阴程度的增加而减弱。三个光照强度下,每个小叶的小脉总长度和气孔总个数之间均存在显著的正相关关系,并且线性回归的斜率在不同光照之间均无明显差异。在相同光照下,稳定的单位长度的小脉对应的气孔个数(孔脉比)可以作为叶片水分供应和需求之间平衡的指标。在应对极低光照时(遮光率为96%),落花生叶片通过降低气孔密度和小脉的直径,而保持气孔直径和小脉密度的稳定。这使得低光照下单位长度的小脉对应的气孔数与高光照条件下的落花生相比较低。第三部分以豆科11个复叶树种和6个掌状脉的单叶树种为研究材料,测定了其边材导水率、枝条、叶轴和叶片凌晨及正午水势与相对含水量、最大气孔导度和正午气孔导度等指标,来研究叶型对枝叶水分供需关系的影响。豆科复叶树种的叶轴正午水势更接近于枝条的正午水势,尽管二者之间存在显著差异,但二者都与叶片正午水势相差较大。在叶片正午水势相近的情况下,复叶树种枝条正午水势显著高于掌状脉的单叶树种。本试验中并未发现叶轴水势与正午气孔导度之间存在相关关系,同样枝条正午水势和叶片正午水势与正午气孔导度之间也不存在相关关系。而枝条正午水势与叶片正午水势之间存在非常高的正相关关系,在11种复叶植物中还发现叶轴的正午水势与枝条的正午水势也具有极高的正相关关系。本研究发现叶片的水力参数与气孔的状态具有更紧密的联系,例如,正午时叶片水力导度与气孔导度之间存在显著的正相关关系,而与正午气孔导度的降低程度具有显著的负相关关系。除了正午枝条和叶片水势的高度正相关外,正午叶片与叶轴水势还与枝条相对含水量的降低具有显著的负相关关系。植物通过这些叶片与枝条的关联维持叶片的生理过程。总的来说,本研究不仅为以小脉密度和气孔密度的正相关来表征叶片水平的水分供需平衡的假说提供了新的佐证,更为重要的是发现二者无论是随海拔梯度,还是在不同光照强度下随着叶片生长次序,都表现出了对环境因子响应的不一致性。将叶片水分供需平衡的视角放大到植物个体水平时,本研究发现复叶的叶轴对于枝条和叶片间的水分关系具有明显的影响,气孔导度更多的是受到叶片水力导度和水分状态的影响,而与枝条的水分状况并无直接关联。
[Abstract]:In order to adapt to water transport and utilization in different environments, some water-related structural characteristics of plants, such as leaf veins, stomata, and vessel of stem xylem, may have some functional relationships. For water supply and demand at the leaf level, as well as the hydraulic structure and stomata of leaves and branches There is no general consensus on the relationship between regulatory capacity, and many divergences need to be further studied. In this paper, the relationship between water supply and demand of plant leaves and branches and leaves is discussed from different levels and perspectives, and the changing trends of these relationships in different environments and between different groups are studied. The main contents and results are as follows: In the first part, the leaves of 105 species of woody angiosperms distributed in tropical mountain forests (800 m to 1400 m) and subtropical mountain forests (2000 m to 2600 m) of Yunnan Province at different altitudes were taken as the samples. Material, leaf area, veinlet density, stomatal density and length were measured to study their variation trend with altitude gradient and their relationship. It was found that the average stomatal density of community-level tree species on each altitude gradient did not change significantly with altitude. There was no significant difference in mean veinlet density between subtropical mountain forest and tropical mountain forest, but the mean veinlet density of tropical mountain forest species was significantly higher than that of the former. The results of this study not only show that the balance of leaf water supply and demand exists at the level of angiosperm species and genera, but also reveal that stomata and veins have uncoupling adaptation to altitude changes. In the second part, the leaf area, veinlet density and thickness (diameter), stomatal density and diameter of mature compound leaves of Arachis hypogaea Linn. grown under three different light intensities on the same stem were measured, and a more intuitive index was deduced to describe the balance between leaf water supply and demand. The number of stomata and veins per unit length of a peanut leaf was found to vary with the number of veins per unit length (the ratio of stomatal density to vein density) under the same illumination condition. There was no significant difference in stomatal diameter, but significant difference in the thickness of the veins. The weaker the light, the smaller the diameter of the veins. Under each light condition, there was a positive correlation between the density of the veins and the area of the leaves. There was a significant positive correlation between stomatal density and leaf area. The stomatal density increased with leaf age under full sunshine. There was no difference in stomatal density among different leaf ages after shading treatment. There was a significant positive correlation between the total length of veins and the total number of stomata in each lobule under light intensity, and the slope of linear regression had no significant difference between different light intensity. Balance index. When dealing with extremely low light (shading rate 96%), the leaves of peanut drop maintained the stability of stomatal diameter and vein density by reducing stomatal density and veinlet diameter. This made the stomatal number per unit length of veins under low light condition lower than that under high light condition. The sapwood water conductivity, branch water potential, leaf axis and leaf water potential, relative water content, maximum stomatal conductance and midday stomatal conductance of leaf species and six single leaf species with palm veins were measured to study the effect of leaf type on water supply and demand of branches and leaves. The midday water potential of the branch was significantly higher than that of the single-leaf species with palm vein when the midday water potential of the leaf was similar. There was no correlation between the noon water potential of the branch and the noon water potential of the leaf and the noon stomatal conductance of the branch, but there was a very high positive correlation between the noon water potential of the branch and the noon water potential of the leaf. For example, there is a significant positive correlation between blade hydraulic conductivity and stomatal conductance at noon, but a significant negative correlation between blade hydraulic parameters and stomatal conductance at noon. In general, this study not only provides new evidence for the hypothesis that the positive correlation between venule density and stomatal density is used to characterize the water supply-demand balance at leaf level, but also provides more weight. It was found that both of them showed inconsistency in response to environmental factors, either with altitude gradient or with leaf growth order under different light intensity. The stomatal conductance was more affected by leaf hydraulic conductance and water status than by branch water status.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：Q945
[Abstract]:In order to adapt to water transport and utilization in different environments, some water-related structural characteristics of plants, such as leaf veins, stomata, and vessel of stem xylem, may have some functional relationships. For water supply and demand at the leaf level, as well as the hydraulic structure and stomata of leaves and branches There is no general consensus on the relationship between regulatory capacity, and many divergences need to be further studied. In this paper, the relationship between water supply and demand of plant leaves and branches and leaves is discussed from different levels and perspectives, and the changing trends of these relationships in different environments and between different groups are studied. The main contents and results are as follows: In the first part, the leaves of 105 species of woody angiosperms distributed in tropical mountain forests (800 m to 1400 m) and subtropical mountain forests (2000 m to 2600 m) of Yunnan Province at different altitudes were taken as the samples. Material, leaf area, veinlet density, stomatal density and length were measured to study their variation trend with altitude gradient and their relationship. It was found that the average stomatal density of community-level tree species on each altitude gradient did not change significantly with altitude. There was no significant difference in mean veinlet density between subtropical mountain forest and tropical mountain forest, but the mean veinlet density of tropical mountain forest species was significantly higher than that of the former. The results of this study not only show that the balance of leaf water supply and demand exists at the level of angiosperm species and genera, but also reveal that stomata and veins have uncoupling adaptation to altitude changes. In the second part, the leaf area, veinlet density and thickness (diameter), stomatal density and diameter of mature compound leaves of Arachis hypogaea Linn. grown under three different light intensities on the same stem were measured, and a more intuitive index was deduced to describe the balance between leaf water supply and demand. The number of stomata and veins per unit length of a peanut leaf was found to vary with the number of veins per unit length (the ratio of stomatal density to vein density) under the same illumination condition. There was no significant difference in stomatal diameter, but significant difference in the thickness of the veins. The weaker the light, the smaller the diameter of the veins. Under each light condition, there was a positive correlation between the density of the veins and the area of the leaves. There was a significant positive correlation between stomatal density and leaf area. The stomatal density increased with leaf age under full sunshine. There was no difference in stomatal density among different leaf ages after shading treatment. There was a significant positive correlation between the total length of veins and the total number of stomata in each lobule under light intensity, and the slope of linear regression had no significant difference between different light intensity. Balance index. When dealing with extremely low light (shading rate 96%), the leaves of peanut drop maintained the stability of stomatal diameter and vein density by reducing stomatal density and veinlet diameter. This made the stomatal number per unit length of veins under low light condition lower than that under high light condition. The sapwood water conductivity, branch water potential, leaf axis and leaf water potential, relative water content, maximum stomatal conductance and midday stomatal conductance of leaf species and six single leaf species with palm veins were measured to study the effect of leaf type on water supply and demand of branches and leaves. The midday water potential of the branch was significantly higher than that of the single-leaf species with palm vein when the midday water potential of the leaf was similar. There was no correlation between the noon water potential of the branch and the noon water potential of the leaf and the noon stomatal conductance of the branch, but there was a very high positive correlation between the noon water potential of the branch and the noon water potential of the leaf. For example, there is a significant positive correlation between blade hydraulic conductivity and stomatal conductance at noon, but a significant negative correlation between blade hydraulic parameters and stomatal conductance at noon. In general, this study not only provides new evidence for the hypothesis that the positive correlation between venule density and stomatal density is used to characterize the water supply-demand balance at leaf level, but also provides more weight. It was found that both of them showed inconsistency in response to environmental factors, either with altitude gradient or with leaf growth order under different light intensity. The stomatal conductance was more affected by leaf hydraulic conductance and water status than by branch water status.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：Q945
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