不同生活型典型荒漠植物凝结水吸收、运移分配及生理影响
The Water Absorption, Transport and Distribution and Their Physiological Effects of Typical Desert Plants in Different Life Forms

水分作为植物生存的主要限制因子,在荒漠生态系统中的重要作用不容忽视。荒漠植被在水分限制条件下,通过适应环境采取了一系列策略利用一切可以利用的水源。凝结水作为干旱区非常重要的水资源在植物水分平衡研究扮演着重要的角色,其对荒漠植被的重要性一直是生态学领域研究的热点问题。尽管与降水、径流水相比较而言凝结水量较小,但依旧可以影响甚至在某些情况下显著影响当地植物水分平衡。大多数学者探讨了植物光合器官的凝结水吸收现象及简单的光合生理的研究,但未对植物吸收凝结水以后水分在植物体内如何变化这一过程有过深入的研究。其次,已有的研究多集中于干旱区植物对吸水现象的描述,而对于不同生活型植物对凝结水利用后,水分变化情况的比较却鲜有报道。本研究从温带干旱区不同生活型荒漠植物出发,设计野外原位控制实验,通过人工模拟冠层凝结水,结合生理和光合荧光生理,利用稳定18O同位素示踪技术来探究凝结水在三种不同生活型荒漠植物体内吸收、运移和分配机制。主要研究结果如下:(1)在人工模拟冠层凝结水的情况下,三种植物:沙拐枣(Calligonum mongolicum)、梭梭(Haloxylon ammodendron)和对节刺(Horaninowia ulicina)在22:00到次日凌晨6:00的时间范围内,水势值均有变化,都出现了逆向水势梯度,即植物通过逆向水势梯度将同化枝(叶片)吸收的凝结水输送到二级枝条(枝条),此时同化枝(叶片)水势大于二级枝条(枝条),这说明三种植物均具有吸收凝结水的能力。(2)不同生活型植物体内所获得潜在水源略有不同,稳定18O同位素示踪水的结果显示:三种植物对凝结水的吸收是自上而下的,即同化枝(叶片)吸收凝结水以后会向二级枝条(枝条),甚至是根部去运输。其中,沙拐枣在ZG1(遮盖1)、ZG2(遮盖2)两种处理下,18O均在根际土位置富集,而在其余部位18O分布较为均匀;同样的,梭梭18O只在同化枝富集;对节刺在两种处理下,18O富集情况存在差异。三种不同生活型植物各器官部位都参与到了水分的吸收过程中。(3)光适应下三种植物的最小荧光(Fo’)、稳态荧光(Fs)、最大光化学量子产量(Fv/Fm)、有效光化学量子产量(Fv’/Fm’)、实际光化学效率(ΦPSⅡ)、光化学淬灭系数(qP)、非光化学淬灭系数(qN)、电子传递效率(ETR)等荧光参数的变化情况具体表现为沙拐枣分别与梭梭、对节刺呈显著差异(P<0.05),且梭梭与对节刺彼此间无显著差异(P>0.05);梭梭ZG1处理下植株的Fo和Fm较之CK植株其值降低,而ZG2植株则显著提高(P<0.05),沙拐枣ZG2植株的(ΦPSⅡ显著低于CK植株(P<0.05),对节刺光适应下各荧光参数如Fo’、Fm’、Fs差异性变化规律一致,具体表现为CK植株与ZG1和ZG2均有显著差异(P<0.05)。光合及荧光参数能直接反映植物凝结水吸收后其生理情况。三种植物的生理活动主要通过气孔进行限制,当太阳辐射增强,满足光合作用时,光合作用开始,气孔张开,同时植物通过调节气孔影响蒸腾作用,调节植物体内水势,自此,植物根部吸收水分通过木质部运输至同化枝(叶片)。而植物夜间的根系吐水可能是为了缓解根部所受到的干旱胁迫。

As a major limiting factor for plant survival,water plays an important role in desert ecosystems.Under the condition of water restriction,desert vegetation adopts a series of strategies to make use of all available water sources by adapting to the environment.As a very important water resource in arid area,dew is an important factor for plant water balance research.Its importance to desert vegetation has always been a hot issue in the field of ecology.Although the amount of dew is small compared to precipitation and runoff water,it can still affect and even in some cases significantly affect the local plant water balance.Most scholars have studied the phenomenon of dew absorption in plant photosynthetic organs and simple photosynthetic physiology,but there was no in-depth study on the process of how water changes in plants after the absorption of condensed water.Secondly,existing studies mainly focus on the description of water absorption by plants in arid areas,while few reports have been reported on the comparison of water changes after the utilization of condensed water by plants of different life forms.Based on different life types of desert plants in temperate arid regions,this study designed field in-situ control experiments.Through artificial simulation of canopy condensate water,combined with physiological and photosynthetic fluorescence physiology,stable 18O isotope tracer technology was used to explore the absorption,migration and distribution mechanism of condensate water in desert plants.The main research results are as follows:(1)Under the condition of artificial simulation of canopy condensation water,three kinds of plants:Calligonum mongolicum,Haloxylon ammodendron and Horaninowia ulicina from22:00 to 6:00 am the next day:00 time period,the water value has the change,a reverse water potential gradient in the assimilating shoots of plants through the reverse water potential gradient(leaf)absorption of the condensate to the secondary branch(branch),the assimilation branches(leaf water potential is greater than the secondary branches(branches),suggesting that three plants have the ability to absorb water.(2)Different life types of plants have different potential water sources,the results of stable18O isotope tracer water showed that the absorption of the dew by the three plants was from top to bottom,that is,the assimilation branch(leaf)absorbed the dew and then transported to the secondary branches(branches)and even the roots.Under two treatments of Calligonum mongolicum,18O was enriched in the rhizosphere soil.Under the treatment of ZG1(Cover 1)and ZG2(Cover 2),only the assimilation branch of Haloxylon ammodendron was enriched with 18O,while the content of 18O in other parts was low.There was a difference in the concentration of18O between the two treatments of Horaninowia ulicina.,and all organs of plants are involved in the process of water absorption.(3)Light adaptation for three plants under minimal fluorescence(Fo),the steady-state fluorescence(Fs),maximum quantum yield of photochemical reaction(Fv/Fm)and effective photochemical quantum yield(Fv’/Fm’),the actual photochemical efficiency((ΦPSⅡ),coefficient of photochemical quenching(qP),the coefficient of photochemical quenching(qN),electron transport efficiency(ETR)changes of the fluorescence parameters such as the manifestation of Calligonum mongolicum has significantly difference(P<0.05)between Haloxylon ammodendron and Horaninowia ulicina respectively,and Haloxylon ammodendron suffering with no significant difference between the section stab each other(P>0.05);Haloxylon ammodendron ZG1 processing plant Fo and Fm than CK plants under its value is reduced,while the ZG2 plants significantly increased(P<0.05);Calligonum mongolicum ZG2 plant(ΦPSⅡ significantly lower than that of CK plants(P<0.05),the Horaninowia ulicina parameter under the fluorescence light adaptation such as Fo’、Fm、Fs difference change law,embodied in the CK plants with ZG1 and ZG2 had significant difference(P<0.05).The photosynthetic and fluorescence parameters can directly reflect the physiological conditions of these three plants after absorption of dew.The physiological activities of plants are mainly restricted by stomata.When the solar radiation increases and photosynthesis is satisfied,stomatal opening begins.At the same time,plants affect transpiration and regulate water potential in plants by regulating stomata.At night,the root system of the plant may expel water to alleviate the stress on the root system.

生活型; 荒漠植物; 凝结水; 18O稳定同位素; Isosource模型; 光合荧光参数;

life-form; desert plants; dew; 18O stable isotope; Isosource of model; Photosynthesis fluorescence parameter;

吕光辉;

Q948

69551920K