应用PV技术对北方4种阔叶树抗旱性的研究

在温室内用盆栽法研究茶条碱（Acer ginnala)。山荆子（Malus baccata)，山桃（Prunus davidiana)和山梨（Pyrus ussuriensis)的抗旱能力。设置4种土壤水分处理（土壤相对含水量75%，61%，46%，35%）。应用压力室和PV技术测定4个树种多项水分参数，并对4树种耐旱能力进行综合评定。结果表明，在干旱胁迫条件下，山梨吸收水分能力最强；4树种均有一定的渗透调节和保持膨压能力。茶条槭，山梨，山桃能通过增加束缚水含量来实现渗透调节，但其依靠改变束缚水含量来实现渗透调节作用有限，山桃，茶条槭在土壤相对含水量降至61%时，山梨在土壤相对含水量降至46%时，由束缚水含量所引起的渗透调节作用消失；在干旱胁迫条件下，山桃，茶条槭通过改变细胞壁弹性来保持膨压，山梨，山荆孔子主要靠渗透调节来维持膨压，干旱胁迫能增强山桃，山荆子，茶条槭保持最大膨压的能力。而降低山梨维持最大膨压的能力；茶条槭能通过提高原生质忍耐脱水能力来适应干旱，山荆子，山桃原生质耐脱水能力对干旱胁迫的适应性差。在干旱胁迫条件下其耐脱水能力减弱。通过对4树种渗透调节和维持膨压能力进行综合比较。4种种抗旱能力由强至弱依次为山荆子，山梨，山桃和茶条槭。     

Effects of Repeated Cycles of Dehydration Rehydration on Drought Tolerance of Jack Pine and Black Spruce Seedlings

应用根系喷雾箱（ＲｏｏｔＭｉｓｔｉｎｇＣｈａｍｂｅｒ,ＲＭＣ）形成的５次干旱循环,通过ＰＶ曲线的水分参数研究了多重复干旱循环对１年生北美短叶松ＰｉｎｕｓｂａｎｋｓｉａｎａＬａｍｂ．和黑云杉Ｐｉｃｅａｍａｒｉａｎａ［Ｍｉｌ］Ｂ．Ｓ．Ｄ．苗木耐旱特性的影响．结果表明,生长在干旱沙地的深根性树种北美短叶松,其丧失膨压的相对含水量（８０７６％～８１４１％）和水势（（－１７４±０１０）ＭＰａ）都比较低,细胞弹性模量（５７３～６５２ＭＰａ）比较小,而束缚水含量（５２７２％～５４２６％）比较高,显示出它固有的强有力的忍耐脱水能力;但是在多重复干旱循环下它却不能进一步调节其渗透势和细胞弹性,而且其束缚水含量和吸水能力也有所下降．生长在湿润地区的浅根性树种黑云杉,虽然其丧失膨压的相对含水量（８３５３％～８５５０％）和水势（（－１６８±００３）ＭＰａ）比较高,细胞弹性模量（８６２～９６４ＭＰａ）比较大,束缚水含量（３６４４％～４６０５％）比较低,显示出较弱的耐旱能力,但是它在多重复干旱循环下却能提高其束缚水含量以改善原生质耐旱程度,降低细胞弹性以提高其吸水能力,调节其渗透势以保持较高的膨压．这表     

不同桉树无性系幼苗叶片形态、生理特征的差异性比较

以8个无性系桉树幼苗为试验材料,对其叶片形态、生理特征的差异性进行比较.结果表明:叶片形态特征、叶绿素含量和PSII电子传递最大潜力差异显著;PSII反应中心最大光能转换效率及实际光化学转换效率差异极显著.DH32-26、DH32-28幼苗叶片保水力和维持水分平衡能力中等,原生质耐脱水能力较好;DH33-27、GL-UG9叶片的保水力和维持水分平衡能力强,原生质忍耐脱水能力较差;DH184-1、GL-U4、GL-WC3幼苗叶片的保水力、维持水分平衡能力以及原生质耐脱水能力均为中等;DH201-2的保水力和维持水分平衡能力较差,原生质耐脱水能力中等.从叶片形态和生理特征方面综合评定DH184-1、GL-U4、GL-WC3为较优无性系.     

6个树种1年生枝木质部的水力特征及与栓塞修复能力的关系

【目的】植物木质部栓塞修复能力已成为植物抗旱性研究的热点。本研究探讨6个耐旱树种木质部水力特征及与栓塞修复能力之间的关系,以及决定栓塞修复能力的主要影响因子,为筛选抗旱树种提供理论依据。【方法】以西北农林科技大学博览园内生长良好的6个耐旱树种(刺槐、沙棘、榆树、元宝枫、旱柳、榛)的1年生枝为研究对象,采用Cochard Cavitron离心机诱导木质部栓塞,构建6个树种的木质部栓塞脆弱曲线,得到其栓塞脆弱性(P50)值,同时测定枝条的木质部水力直径(Dh)、黎明前木质部水势及自然状态下栓塞程度(NPLC),利用低压液流计及染色法测定已栓塞枝条不同时段(20,40,60,80,100 min)的栓塞修复程度(1-PLC),进而探究不同树种木质部栓塞修复能力与栓塞脆弱性、水力直径、黎明前水势和NPLC间的关系。【结果】1)6个树种栓塞脆弱性大小依次为刺槐榆树沙棘旱柳榛元宝枫,其中元宝枫的抗栓塞能力最强;水力直径依次为刺槐榆树榛沙棘旱柳元宝枫。2)用染色法测得的木质部栓塞修复程度与低压液流计测得的木质部栓塞修复程度相一致(回归方程是y=1.047x-7.567,R~2=0.863);低压液流计法测定的值完全可以反映在不同时间段栓塞枝条的修复状况。3)6个树种1年生枝木质部栓塞修复能力依次为刺槐榆树沙棘旱柳榛元宝枫,植物重新供水后,木质部栓塞修复能力强的树种能迅速恢复栓塞导管的输水功能;栓塞修复能力与栓塞脆弱性大小顺序完全一致,呈显著的正相关(R~2=0.980),即木质部栓塞脆弱性大的树种,其栓塞修复能力也越强;回归分析表明,6个树种木质部水力直径、黎明前水势和NPLC与栓塞修复能力有很强的相关性(R~2分别为0.868,0.740,0.741)。【结论】植物木质部水力特征与栓塞修复能力密切相关,特别是木质部栓塞脆弱性(P50)和水力直径与栓塞修复能力有很强烈的正相关,是决定栓塞修复能力的主要影响因子。     

4种柳树苗木叶的PV水分参数对水分胁迫的响应

在温室内研究了瑞典能源柳C号、2号柳、4号柳和陕北红皮柳苗木的抗旱能力。对其盆栽苗木施行水分轻度胁迫、中度胁迫、重度胁迫及正常(供水)生长4种处理,应用压力室和PV技术测定4种柳树苗木在不同处理状态下的叶组织多项水分参数,以此对其苗木的耐旱能力作综合评定。结果表明,在水分胁迫条件下,2号柳苗木叶吸收水分的能力最强;4种柳树的苗木均有一定的渗透调节和保持膨压能力,4号柳、2号柳、红柳的苗木能通过增加叶束缚水的含量来实现渗透调节,但其依靠改变苗木叶束缚水的含量来实现渗透调节的作用有限,红柳、4号柳苗木在土壤相对含水量降至61%时,2号柳苗木在土壤相对含水量降至46%时,其叶由束缚水含量所引起的渗透调节作用消失;在水分胁迫条件下,红柳、4号柳苗木通过改变叶组织细胞壁的弹性来保持其的膨压,2号柳、能源柳C号的苗木主要靠叶渗透调节来维持其的膨压。水分胁迫能增强红柳、能源柳C号、4号柳苗木保持最大膨压的能力,而降低2号柳苗木维持最大膨压的能力;4号柳能通过提高苗木叶细胞原生质忍耐脱水的能力来适应干旱,能源柳C号、红柳苗木叶细胞原生质耐脱水能力对水分胁迫的适应性差,在水分胁迫条件下其耐脱水能力减弱。通过对4种柳树苗木叶组织渗透调节和维持膨压能力的综合比较,其抗旱能力由强至弱依次为能源柳C号、2号柳、红柳和4号柳。     

信息传真

＠南方主要造林树种耐旱、耐盐碱能力的研究通过鉴定由南京林业大学森林资源与环境学院曹福亮教授承担的林业部重点指南课题《南方主要造林树种耐旱、耐盐碱能力的研究》于1997年12月31日在南京通过了由林业部科技司组织的会议鉴定。该课题的主要研究内容：（l）南方主要造林树种耐盐能力评价；（2）10个杨树无性系耐盐能力评定；（3）5个银杏品种耐盐能力研究；（4）南方主要造林树种耐旱能力评价；（5）野外林分调查和田间试验；（6）提高树木抗逆性研究。鉴定意见认为，该课题首次较系统、全面地对我国南方主要造林树种进行了耐旱、耐盐…     

晋西常见造林树种叶水势变化研究

2005年在山西方山,采用PSYPRO露点水势仪于6月中旬、7月下旬、9月底3个典型晴天测定了3个不同土壤水分条件下紫穗槐、刺槐、仁用杏、臭椿2年生盆栽苗木的叶水势,分析了4种苗木叶水势的日进程及其随季节变化的规律。结果表明,紫穗槐与仁用杏在3个水分处理下随季节变动表现了一致的规律:9月份的叶水势都明显低于6月份与7月份的,且两种苗木在7月份水势变幅都很小,3个处理全天变幅都不过0.5 Mpa;仁用杏在每个月份还表现了各自特定的“水势阈”。刺槐各水分条件下各月水势日进程均呈不对称的单谷曲线,波谷出现在上午10点左右,早晚水势较高,且3个水分处理各月日变化曲线无太大差异;臭椿6月份时各水分条件下都呈不规则“W”形,7月份时水分胁迫者水势严重下降,傍晚也难以恢复。比较各树种严重水分胁迫时叶水势,发现紫穗槐、刺槐与仁用杏有高水势延迟脱水的抗旱机理表现;而臭椿则显示出低水势忍耐脱水的耐旱机理,即其叶组织抗脱水能力较强。     

铅笔柏、侧柏幼树抗旱指标综合评价

通过对盆栽2年生铅笔柏(Sabina virginiana)、侧柏(Platycladus orientalis)的叶片(枝条)的保水力、根冠比、根系活力、叶绿素、蛋白质、SOD超氧化物歧化酶、饱和吸水时总体原初渗透势π_0、初始质壁分离时的总体渗透势π_p、零膨压时的相对渗透水含量ROC、质外体相对含水量RWC等11项生理生化指标的测定,对铅笔柏、侧柏的抗旱性强弱进行对比,结果表明:叶片保水力:铅笔柏侧柏;根冠比:铅笔柏侧柏;根系活力:侧柏铅笔柏;叶绿素含量:铅笔柏侧柏;蛋白质含量:侧柏铅笔柏;SOD超氧化物歧化酶含量:铅笔柏侧柏;饱和吸水时总体原初渗透势π_0:铅笔柏侧柏;初始质壁分离时的总体渗透势π_p:铅笔柏侧柏;零膨压时的相对渗透水含量ROC:侧柏铅笔柏;质外体相对含水量AWC:侧柏铅笔柏;失膨点渗透水和饱和渗透水比值V_p/V_0:铅笔柏侧柏。运用模糊数学的隶属函数法对2个树种的抗旱能力做综合评价,铅笔柏在抗旱能力方面强于国内乡土树种侧柏。     

四种常见针叶树种种子发芽对水分胁迫的响应

本文通过用PEG(聚乙二醇)配制不同浓度溶液,模拟不同土壤水势梯度,达到不同水分胁迫水平,进行柳杉、杉木、马尾松、侧柏等树种种子发芽水分胁迫实验。研究结果表明;水势在0～-0.6Mpa,除马尾松外,其余三种树种随水势下降,种子发芽率、发芽指数、苗长、活力指数均呈下降趋势。水势降至-0.86 Mpa时,各树种种子发芽均受完全抑制。其中侧柏在水势降至-0.6Mpa时,种子发芽已受完全抑制。综合比较,各树种种子的耐旱能力大小依次为:马尾松>杉木>柳杉>侧柏。     

侧柏不同种源对水分胁迫反应的初步研究：水分状况,电导率和叶萎…

模拟土壤干旱条件，从苗木水分状况，细胞相对透性和叶萎蔫表现等３个方面，研究了侧柏５个种源３年生盆栽苗的抗旱性及其差异。试验结果表明，在干旱胁迫下，北方种源苗木较高方种源的水势下降较慢，叶细胞膨压为零时的土壤含量及土壤水势临界值较低，叶细胞相对透性增大较慢，耐旱性较强；生理指标所反映的种源耐旱笥强弱与对叶萎蔫表现的观察结果基本一致；供试种源抗旱能力可排列为：密云〉志丹〉徐州〉黎平。     

Contrasting physiological responses of two co-occurring eucalypts to seasonal drought at restored bauxite mine sites

This study describes the physiological response of two co-occurring tree species (Eucalyptus marginata and Corymbia calophylla) to seasonal drought at low- and high-quality restored bauxite mine sites in south-western Australia. Seasonal changes in photosynthesis (A), stomatal conductance (g(s)), leaf water potential (ψ), leaf osmotic potential (ψ), leaf relative water content (RWC) and pressure-volume analysis were captured over an 18-month field study to (i) determine the nature and severity of physiological stress in relation to site quality and (ii) identify any physiological differences between the two species. Root system restriction at the low-quality site reduced maximum rates of gas exchange (g(s) and A) and increased water stress (midday ψ and daily RWC) in both species during drought. Both species showed high stomatal sensitivity during drought; however, E. marginata demonstrated a higher dehydration tolerance where ψ and RWC fell to -3.2 MPa and 73% compared with -2.4 MPa and 80% for C. calophylla. Corymbia calophylla showed lower g(s) and higher ψ and RWC during drought, indicating higher drought tolerance. Pressure-volume curves showed that cell-wall elasticity of E. marginata leaves increased in response to drought, while C. calophylla leaves showed lower osmotic potential at zero turgor in summer than in winter, indicating osmotic adjustment. Both species are clearly able to tolerate seasonal drought at hostile sites; however, by C. calophylla closing stomata earlier in the drought cycle, maintaining a higher water status during drought and having the additional mechanism of osmotic adjustment, it may have a greater capacity to survive extended periods of drought.     

Water relations of seedlings of three Quercus species: variations across and within species grown in contrasting light and water regimes

We compared seedling water relations of three Mediterranean Quercus species (the evergreen shrub Q. coccifera L., the evergreen tree Q. ilex L. subsp. ballota (Desf.) Samp. and the deciduous or marcescent tree Q. faginea L.). We also explored seedling potential for acclimation to contrasting growing conditions. In March, 1-year-old seedlings of the three species were planted in pots and grown outdoors in a factorial combination of two irrigation regimes (daily (HW) and alternate day watering (LW)) and two irradiances (43 and 100% of full sunlight). At the end of July, predawn and midday water potentials (Psi(pd), Psi(md)) were measured, and pressure-volume (P-V) curves were obtained for mature current-year shoots. Species exhibited similar Psi(pd) and Psi(md) values, but differed in leaf morphology and water relations. The evergreens possessed larger leaf mass per area (LMA) and were able to maintain positive turgor pressure at lower water potentials than the deciduous species because of their lower osmotic potential at full turgor. However, the three species had similar relative water contents at the turgor loss point because Q. faginea compensated for its higher osmotic potential with greater cell wall elasticity. Values of Psi(pd) had a mean of -1.12 MPa in LW and -0.63 MPa in HW, and Psi(md) had a mean of -1.13 MPa in full sunlight and -1.64 MPa in shade, where seedlings exhibited lower LMA. However, the P-V curve traits were unaffected by the treatments. Our results suggest that Q. faginea seedlings combine the water-use characteristics of mesic deciduous oak and the drought-tolerance of xeric evergreen oak. The ability of Q. coccifera to colonize drier sites than Q. ilex was not a result of higher drought tolerance, but rather may be associated with other dehydration postponement mechanisms including drought-induced leaf shedding. The lack of treatment effects may reflect a relatively low contrast between treatment regimes, or a low inherent responsiveness of these traits in the study species, or both.     

Osmotic potential of several hardwood species as affected by manipulation of throughfall precipitation in an upland oak forest during a dry year

Components of dehydration tolerance, including osmotic potential at full turgor (Psi(pio)) and osmotic adjustment (lowering of Psi(pio)), of several deciduous species were investigated in a mature, upland oak forest in eastern Tennessee. Beginning July 1993, the trees were subjected to one of three throughfall precipitation treatments: ambient, ambient minus 33% (dry treatment), and ambient plus 33% (wet treatment). During the dry 1995 growing season, leaf water potentials of all species declined to between -2.5 and -3.1 MPa in the dry treatment. There was considerable variation in Psi(pio) among species (-1.0 to -2.0 MPa). Based on Psi(pio) values, American beech (Fagus grandifolia Ehrh.), dogwood (Cornus florida L.), and sugar maple (Acer saccharum Marsh.) were least dehydration tolerant, red maple (A. rubrum L.) was intermediate in tolerance, and white oak (Quercus alba L.) and chestnut oak (Quercus prinus L.) were most tolerant. During severe drought, overstory chestnut oak and understory dogwood, red maple and chestnut oak displayed osmotic adjustment (-0.12 to -0.20 MPa) in the dry treatment relative to the wet treatment. (No osmotic adjustment was evident in understory red maple and chestnut oak during the previous wet year.) Osmotic potential at full turgor was generally correlated with leaf water potential, with both declining over the growing season, especially in species that displayed osmotic adjustment. However, osmotic adjustment was not restricted to species considered dehydration tolerant; for example, dogwood typically maintained high Psi(pio) and displayed osmotic adjustment to drought, but had the highest mortality rates of the species studied. Understory saplings tended to have higher Psi(pio) than overstory trees when water availability was high, but Psi(pio) of understory trees declined to values observed for overstory trees during severe drought. We conclude that Psi(pio) varies among deciduous hardwood species and is dependent on canopy position and soil water potential in the rooting zone.     

额济纳绿洲不同树龄胡杨狭叶和阔叶耐旱特征

应用压力室技术对胡杨幼苗、幼树和成熟胡杨的狭叶和阔叶测定,绘制PV曲线并利用相关公式计算不同树龄胡杨狭叶和阔叶的水分参数,同时结合角质层蒸腾和气孔蒸腾测定结果研究胡杨狭叶和阔叶耐旱特征。研究结果表明：胡杨阔叶的耐早性强于狭叶,二者的耐旱方式存在差异,阔叶渗透物质含量高,忍耐低渗透势的能力强;狭叶主要通过高弹性的细胞壁维持膨压,其忍耐低渗透势的能力不及阔叶。成熟胡杨无论狭叶还是阔叶主要的水分散失形式是气孔蒸腾,体内的水分平衡主要通过气孔进行调节。     

Reduction in turgid water volume in jack pine,white spruce and black spruce in response to drought and paclobutrazol

Significant reductions in needle water content were observed in white spruce (Picea glauca (Moench) Voss), black spruce (Picea mariana (Mill) B.S.P.), and jack pine (Pinus banksiana Lamb.) seedlings in response to a 10-day drought, although turgor was apparently maintained. When the seedlings were re-watered after the drought, jack pine needles regained their original saturated volume, whereas white spruce and black spruce needles did not. Significant drought-induced reductions in turgor-loss volume (i.e., tissue volume at the point of turgor loss) were observed in shoots of all three species, especially jack pine. Repeated exposure to 7 days of drought or treatment with the cytochrome P(450) inhibitor, paclobutrazol ((2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-pentan-3-ol), reduced seedling height relative to that of untreated controls in all three species. The reductions in saturated and turgor-loss needle volumes in the paclobutrazol-treated seedlings were comparable with those of seedlings subjected to a 10-day drought. The treatment-induced reductions in shoot and needle water contents enabled seedlings to maintain turgor with tissue volumes close to, or below, the turgor-loss volume of untreated seedlings. Paclobutrazol-treated seedlings subsequently survived drought treatments that were lethal to untreated seedlings.     

Seasonal variability of photosynthetic characteristics influences growth of eight tropical tree species at two sites with contrasting precipitation in Panama

Relative to closed-canopy tropical forests, tree seedlings planted in open grown areas are exposed to higher light intensity, air temperatures, vapor pressure deficit, and greater seasonal fluxes of plant available water than mature tropical forests. The species-specific adaptive capacity to respond to variable precipitation and seasonality in open grown conditions, therefore, is likely to affect species performance in large-scale reforestation efforts. In the present study, we compared the photosynthetic characteristics of eight tropical tree species within and between seasons at two study sites with contrasting dry season intensities. All species except Pseudosamanea guachapele reduced leaf physiological function between the wet and dry seasons. The contrasting severity of seasonal drought stress at the study sites constrained growth rates and photosynthetic characteristics differently. Variation of photosynthetic characteristics at the species level was high, particularly in the dry season. Faster growing species at the less seasonal site, Terminalia amazonia, Inga punctata, Colubrina glandulosa, and Acacia mangium, exhibited a greater adaptive capacity than the other species to down-regulate leaf photosynthesis between seasons. As the dry season was more severe at the more seasonal site, most species strongly reduced physiological function regardless of relative growth rates, except two species (Tectona grandis and P. guachapele) with widespread distributions and relatively high drought tolerance. Our results underscore the need to consider seasonal drought tolerance when selecting tree species for specific reforestation sites.     

桉树的抗旱性研究进展

在干旱和半干旱地区,为了成功地栽培桉树,许多学者从不同角度对桉树种群的抗旱性机理和它们对不同干旱环境的反应进行了研究和探讨。结果认为,桉树种群的遗传基因能适应于干旱的环境。生长在水分短缺条件下的植株,是通过各种途径保持组织水含量在细胞免受伤害的临界值以上而达到其适应。一般来说,具有旱生植物特征的桉树种群对干旱的适应能力较强,它们能够生存在较干旱的环境条件下,但不可能从湿润的气候环境中取得生长优势。     

Physiological and morphological adaptations of the fruit tree Ziziphus rotundifolia in response to progressive drought stress

The physiological basis of drought resistance in Ziziphus rotundifolia Lamk., which is an important, multipurpose fruit tree of the northwest Indian arid zone, was investigated in a greenhouse experiment. Three irrigation regimes were imposed over a 34-day period: an irrigation treatment, a gradual drought stress treatment (50% of water supplied in the irrigation treatment) and a rapid drought stress treatment (no irrigation). Changes in gas exchange, water relations, carbon isotope composition and solute concentrations of leaves, stems and roots were determined. The differential rate of stress development in the two drought treatments did not result in markedly different physiological responses, but merely affected the time at which they were expressed. The initial response to decreasing soil water content was reduced stomatal conductance, effectively maintaining predawn leaf water potential (Psi(leaf)), controlling water loss and increasing intrinsic water-use efficiency, while optimizing carbon gain during drought. Carbon isotope composition (delta13C) of leaf tissue sap provided a more sensitive indicator of changes in short-term water-use efficiency than delta13C of bulk leaf tissue. As drought developed, osmotic potential at full turgor decreased and total solute concentrations increased in leaves, indicating osmotic adjustment. Decreases in leaf starch concentrations and concomitant increases in hexose sugars and sucrose suggested a shift in carbon partitioning in favor of soluble carbohydrates. In severely drought-stressed leaves, high leaf nitrate reductase activities were paralleled by increases in proline concentration, suggesting an osmoprotective role for proline. As water deficit increased, carbon was remobilized from leaves and preferentially redistributed to stems and roots, and leaves were shed, resulting in reduced whole-plant transpiration and enforced dormancy. Thus, Z. rotundifolia showed a range of responses to different drought intensities indicating a high degree of plasticity in response to water deficits.     

干旱河谷10种生态恢复树种的光合和水分生理特征研究

通过对岷江上游干旱河谷10种生态恢复树种盆栽苗木的光合、荧光以及水分生理特征等的比较,分析了不同植物在干旱地区的光合运作情况以及光合生理特征和水分生理特征,及其间的相关关系,揭示了各类植物的抗旱特征,以期为干旱河谷区植被恢复树种材料的选择提供理论依据。