【摘要】：為了適應(yīng)在不同環(huán)境下對(duì)水分的運(yùn)輸和利用,植物的一些與水分相關(guān)的結(jié)構(gòu)特征,如葉片的葉脈、氣孔以及莖干木質(zhì)部的導(dǎo)管等,可能會(huì)存在一定的功能上的關(guān)聯(lián)。而對(duì)于植物葉片水平的水分供需關(guān)系,以及葉片與枝條水力結(jié)構(gòu)和氣孔調(diào)節(jié)能力之間的關(guān)系目前并未達(dá)成廣泛的共識(shí),許多分歧有待進(jìn)一步的研究。本論文從不同的層次和角度探討了植物葉片及枝葉的水分供需關(guān)系,研究這類關(guān)聯(lián)在不同環(huán)境下以及在不同類群間的變化趨勢(shì),對(duì)了解植物維持水力系統(tǒng)功能的不同適應(yīng)策略有重要意義。本論文主要從三個(gè)方面探討了植物的水分供需關(guān)系,主要研究?jī)?nèi)容和結(jié)果如下：第一部分以分布在云南省熱帶山地森林(800 m到1400 m)和亞熱帶山地森林(2000 m到2600 m)不同海拔的105種木本被子植物葉片為材料,通過(guò)測(cè)定其葉片面積、小脈密度、氣孔密度和長(zhǎng)度等功能性狀,研究它們隨海拔梯度的變化趨勢(shì)及其相互關(guān)系。發(fā)現(xiàn)每個(gè)海拔梯度上群落水平樹(shù)種的平均氣孔密度隨著海拔的升高并未有明顯的變化趨勢(shì)。沿每個(gè)海拔梯度上樹(shù)種的平均小脈密度,分別在亞熱帶山地林和熱帶山地林的4個(gè)海拔梯度上也沒(méi)有明顯差異,但是熱帶山地林樹(shù)種的平均小脈密度要顯著高于前者。在亞熱帶山地林樹(shù)種中,小脈密度和氣孔密度存在一個(gè)顯著的正相關(guān)關(guān)系,然而從105種樹(shù)整體上來(lái)看,這一關(guān)聯(lián)表現(xiàn)較弱。氣孔性狀和葉脈性狀對(duì)隨海拔變化的環(huán)境因子的響應(yīng)并不一致。本研究結(jié)果不僅表明葉片水分供需平衡關(guān)系在被子植物樹(shù)種多科屬水平上的存在,還揭示出氣孔和小脈在應(yīng)對(duì)海拔變化時(shí)存在解偶聯(lián)的適應(yīng)性。第二部分通過(guò)測(cè)定三個(gè)光照強(qiáng)度下生長(zhǎng)的落花生(Arachis hypogaea Linn.)同一莖干上不同葉序的成熟復(fù)葉的小葉的葉面積、小脈密度和厚度(直徑)、氣孔密度和直徑等功能性狀,以及推導(dǎo)出一個(gè)更直觀的表述葉片水分供需平衡關(guān)系的指數(shù),探討氣孔與小脈隨葉序的變化趨勢(shì)及其協(xié)同性,并論證穩(wěn)定的單位長(zhǎng)度小脈對(duì)應(yīng)的氣孔個(gè)數(shù)可以表征葉片處于水分供需平衡狀態(tài)。發(fā)現(xiàn)在同一光照條件下,落花生小葉單位長(zhǎng)度小脈對(duì)應(yīng)的氣孔個(gè)數(shù)(氣孔密度與小脈密度的比值)隨著葉序的增加保持不變,也與小葉的面積無(wú)關(guān)。不同光照強(qiáng)度下生長(zhǎng)的落花生,氣孔直徑?jīng)]有顯著差異,而小脈的厚度存在顯著差異,光照越弱,其直徑越小。在每個(gè)光照條件下,小脈密度與小葉的面積之間都表現(xiàn)出正相關(guān)關(guān)系。全日照條件下的氣孔密度與小葉面積也具有顯著的正相關(guān)關(guān)系。全日照條件下,氣孔密度隨葉齡增加具有增大的趨勢(shì),在遮陰處理后,不同葉齡小葉的氣孔密度沒(méi)有差異。小脈密度和氣孔密度之間的正相關(guān)關(guān)系隨著遮陰程度的增加而減弱。三個(gè)光照強(qiáng)度下,每個(gè)小葉的小脈總長(zhǎng)度和氣孔總個(gè)數(shù)之間均存在顯著的正相關(guān)關(guān)系,并且線性回歸的斜率在不同光照之間均無(wú)明顯差異。在相同光照下,穩(wěn)定的單位長(zhǎng)度的小脈對(duì)應(yīng)的氣孔個(gè)數(shù)(孔脈比)可以作為葉片水分供應(yīng)和需求之間平衡的指標(biāo)。在應(yīng)對(duì)極低光照時(shí)(遮光率為96%),落花生葉片通過(guò)降低氣孔密度和小脈的直徑,而保持氣孔直徑和小脈密度的穩(wěn)定。這使得低光照下單位長(zhǎng)度的小脈對(duì)應(yīng)的氣孔數(shù)與高光照條件下的落花生相比較低。第三部分以豆科11個(gè)復(fù)葉樹(shù)種和6個(gè)掌狀脈的單葉樹(shù)種為研究材料,測(cè)定了其邊材導(dǎo)水率、枝條、葉軸和葉片凌晨及正午水勢(shì)與相對(duì)含水量、最大氣孔導(dǎo)度和正午氣孔導(dǎo)度等指標(biāo),來(lái)研究葉型對(duì)枝葉水分供需關(guān)系的影響。豆科復(fù)葉樹(shù)種的葉軸正午水勢(shì)更接近于枝條的正午水勢(shì),盡管二者之間存在顯著差異,但二者都與葉片正午水勢(shì)相差較大。在葉片正午水勢(shì)相近的情況下,復(fù)葉樹(shù)種枝條正午水勢(shì)顯著高于掌狀脈的單葉樹(shù)種。本試驗(yàn)中并未發(fā)現(xiàn)葉軸水勢(shì)與正午氣孔導(dǎo)度之間存在相關(guān)關(guān)系,同樣枝條正午水勢(shì)和葉片正午水勢(shì)與正午氣孔導(dǎo)度之間也不存在相關(guān)關(guān)系。而枝條正午水勢(shì)與葉片正午水勢(shì)之間存在非常高的正相關(guān)關(guān)系,在11種復(fù)葉植物中還發(fā)現(xiàn)葉軸的正午水勢(shì)與枝條的正午水勢(shì)也具有極高的正相關(guān)關(guān)系。本研究發(fā)現(xiàn)葉片的水力參數(shù)與氣孔的狀態(tài)具有更緊密的聯(lián)系,例如,正午時(shí)葉片水力導(dǎo)度與氣孔導(dǎo)度之間存在顯著的正相關(guān)關(guān)系,而與正午氣孔導(dǎo)度的降低程度具有顯著的負(fù)相關(guān)關(guān)系。除了正午枝條和葉片水勢(shì)的高度正相關(guān)外,正午葉片與葉軸水勢(shì)還與枝條相對(duì)含水量的降低具有顯著的負(fù)相關(guān)關(guān)系。植物通過(guò)這些葉片與枝條的關(guān)聯(lián)維持葉片的生理過(guò)程�？偟膩�(lái)說(shuō),本研究不僅為以小脈密度和氣孔密度的正相關(guān)來(lái)表征葉片水平的水分供需平衡的假說(shuō)提供了新的佐證,更為重要的是發(fā)現(xiàn)二者無(wú)論是隨海拔梯度,還是在不同光照強(qiáng)度下隨著葉片生長(zhǎng)次序,都表現(xiàn)出了對(duì)環(huán)境因子響應(yīng)的不一致性。將葉片水分供需平衡的視角放大到植物個(gè)體水平時(shí),本研究發(fā)現(xiàn)復(fù)葉的葉軸對(duì)于枝條和葉片間的水分關(guān)系具有明顯的影響,氣孔導(dǎo)度更多的是受到葉片水力導(dǎo)度和水分狀態(tài)的影響,而與枝條的水分狀況并無(wú)直接關(guān)聯(lián)。
[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.
【學(xué)位授予單位】：中國(guó)科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：Q945

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本文編號(hào)：2175540