盐胁迫对16种幼苗渗透调节物质的影响

采用盆栽的方法,对16种2年生幼苗盐(NaCl)胁迫40 d,并进行耐盐性研究。结果表明:随盐浓度的升高,各树种的脯氨酸、可溶性糖和甜菜碱含量均呈上升趋势,在400 mmol·L-1盐浓度下,沙枣和水蜡的脯氨酸含量比对照分别增加了662.0%和562.8%,而可溶性蛋白含量在各树种间差异较大;Na+和Cl-含量在不同部位(根、茎和叶)均随盐浓度增加而增加,鞑靼忍冬、药鼠李、风箱树和醉鱼草叶片中Na+含量增加了5 20倍。K+和Ca2+含量随树种不同表现各异。综合各树种盐害症状和渗透调节物质变化特性,认为柽柳、唐古特白刺、西伯利亚白刺、卫矛和沙柳具有高度耐盐性,水蜡、沙枣、糖朴、美国皂荚和药鼠李具有中高度耐盐性,杜梨、竹柳、鞑靼忍冬、醉鱼草、风箱树和美国白蜡具有中度耐盐性。脯氨酸、可溶性糖和矿质元素含量(尤其是Na+、K+和Cl-)的变化对植物耐盐能力的影响较普遍也较大。     

盐胁迫对柳树无性系SH31离子含量及光合作用的影响

以柳树无性系SH31为试材,研究了NaCl溶液半抑制浓度胁迫下根、茎、叶中Na⁺、K⁺、Ca²⁺ 的分布规律及叶片光合特性的变化。结果表明:在NaCl溶液半抑制浓度(0.6%)下,SH31耐盐性较强;在0.6% NaCl溶液胁迫下,根部在前16 d积累大量Na⁺并拦截部分Na⁺向地上部运输;盐胁迫降低了根、茎部对 K⁺ 的吸收,而叶部却保持较高的K⁺ 含量来维持离子平衡;Ca²⁺含量在根、茎、叶中与对照的相当。在NaCl溶液半抑制浓度盐胁迫下,SH31 的净光合速率前7 d降低之后保持稳定,而气孔导度、蒸腾速率、胞间CO₂先降后升,表明前7 d的蒸腾速率下降的主要原因在于气孔限制。SH31根部对Na⁺ 选择性吸收并维持K⁺、Ca²⁺的高含量及维持较高光合作用是其重要的耐盐机制。     

盐胁迫下沙枣生物固氮能力及氮素分配研究

[目的]应用15N自然丰度法研究盐胁迫条件下沙枣的生物固氮能力,并探讨几个耐盐树种的氮素分配情况。[方法]通过耐盐树种的室内砂培试验,确定盐渍生境条件下以空气氮为唯一氮源的沙枣15N相对丰度B值及其适宜的参比植物;估测室内和野外盐渍生境中沙枣的生物固氮能力;并通过测定碳、氮、磷元素含量探讨了几种耐盐树种的氮素分配情况。[结果]室内盐胁迫砂培试验条件下,沙枣的B值为-1.41‰;柽柳和白蜡可作为沙枣的参比植物;沙枣的生物固氮百分率为55.03%。野外中度盐渍环境中,沙枣生物固氮百分率为69.69%。试验条件下,沙枣、柽柳和白蜡3个耐盐树种中,沙枣植株及其叶、茎、根含氮量最高,且与其它树种差异显著(P0.05);沙枣植株氮/碳含量比以及氮/磷含量比最高;沙枣叶、茎和根的氮/磷含量比最高。野外中度盐渍环境中,沙枣叶的氮/碳含量比以及氮/磷含量比均为最高。[结论]15N自然丰度法可用于研究盐胁迫条件下沙枣的生物固氮能力,柽柳和白蜡可作为参比植物;沙枣在盐胁迫下的固氮能力较强,是可应用于盐渍土生物改良的优良树种。本文为盐胁迫条件下利用15N自然丰度法研究生物固氮作用提供方法参考,对于盐碱地生物治理中植物材料的选择和耐盐树种资源的综合开发利用具有重要意义。     

植物盐害机理及其应对盐胁迫的策略

综述了植物盐害的机理即离子胁迫、渗透胁迫、氧化胁迫、呼吸受阻、营养亏缺、光合作用下降,又阐述了植物应对盐胁迫的策略即重建体内离子平衡、合成和积累渗透保护物质、清除活性氧、增加合成抗胁迫蛋白质和多胺类物质、调节激素种类及改变基因表达模式。     

植物体内渗透调节物质及组织结构与耐盐性的关系

文章从有机渗透调节物质、无机离子和激素等角度综述了植物耐盐的生理生化基础;对植物组织结构与耐盐性的关系作一概述。     

唐古特白刺悬浮细胞对盐胁迫的生长与生理响应

以唐古特白刺悬浮细胞为研究对象,对比分析了不同盐(Na Cl)浓度(0、100、150、200、250 mmol·L-1)胁迫下细胞生长状态和可溶性蛋白、可溶性糖、脯氨酸、过氧化物酶(POD)、超氧化物歧化酶(SOD)、丙二醛(MDA)等生理生化指标随培养时间的动态变化及其相关性。结果表明:(1)盐胁迫对白刺悬浮细胞生长状态影响明显,细胞生长符合Logistic生长曲线模型,其中,盐浓度100 mmol·L-1胁迫下白刺悬浮细胞生长速度最快,之后随着盐浓度的增加细胞生长逐渐受抑。(2)盐胁迫对白刺细胞生理生化指标影响明显,在培养初期,各指标随盐浓度的增加而增加,但随着培养时间的延长这种趋势逐渐减弱,其中,脯氨酸、SOD、MDA含量在培养过程中逐渐表现为随盐浓度的增加呈先增高后降低的趋势;在相同盐浓度胁迫下,渗透调节指标中,可溶性糖含量随培养时间的延长最先达到最大值,抗氧化酶中的SOD较POD更早达到最大值,分别是渗透调节和抗氧化酶调节的第一道防线。(3)白刺细胞鲜质量分别与可溶性糖、丙二醛含量呈极显著和显著负相关,各生理指标之间的相关性均达极显著正相关,表明盐胁迫下白刺细胞内生理生化的平衡是通过多种物质的协同作用来调节的。     

盐胁迫对灌木柳2个无性系渗透调节物质含量的影响

以灌木柳2个无性系(盐敏感型JW9-6和耐盐型JW2372)为试验材料,研究其在水培盐胁迫(0,3,6 g/L)条件下渗透调节物质的动态(2 h,1,3,7,10 d)变化情况。结果表明:灌木柳2个无性系渗透调节物质含量受盐胁迫影响的变化趋势相似,在3,6 g/L盐处理下脯氨酸含量与对照相比均显著增加,并随着盐质量浓度的升高和处理时间的延长逐渐增大;可溶性糖含量在盐处理3 d时显著高于对照并随处理时间的延长先增大后减小;可溶性蛋白含量在3 g/L盐处理下未出现明显变化,6 g/L盐处理下显著高于对照并随处理时间延长先增大后减小;相同盐质量浓度处理条件下,JW2373的脯氨酸、可溶性糖和可溶性蛋白相对含量均高于JW9-6,表现出更强的渗透调节能力。     

盐胁迫下3种海滨植物形态和生理响应特征及耐盐性差异

[目的] 研究盐胁迫条件下3种海滨植物的生理生态动态响应特征及其耐盐性差异,为盐碱地绿化树种筛选提供科学依据。[方法] 以2年生中山杉、小叶榕和海滨木槿幼苗为材料进行为期56 d的盆栽试验,设置3个盐分梯度对其生长和形态、抗氧化酶系统以及渗透调节系统等指标的动态变化特征进行比较,并通过主成分分析来明确3种植物在耐盐性上的差异。[结果] 短期盐胁迫（14 d）对3种植物存活率、叶形和叶色影响较小,但长期盐胁迫（56 d）对小叶榕产生较大影响,盐胁迫下3种植物固定枝条相对生长率动态特征差异明显。3种植物叶片超氧化物歧化酶（SOD）活性随着盐处理时间增加而呈现降低趋势,过氧化物酶（POD）和抗坏血酸过氧化物酶（APX）活性先增加后降低,丙二醛（MDA）含量呈现总体降低趋势。盐胁迫下3种植物叶片可溶性糖和可溶性蛋白含量均呈现先减少后增加的趋势,叶片相对电导率则随着盐浓度增加而显著提高。盐处理时间和物种的交互作用对SOD和POD活性以及MDA含量有显著影响,3种植物耐盐性主成分有明显差异,表明它们不同的耐盐响应特征。[结论] 3种植物的生态生理响应特征表明盐处理对小叶榕影响最大,中山杉次之,对海滨木槿影响最小,因此海滨木槿和中山杉有优先作为我国东部沿海地区盐碱地绿化树种的潜力。     

盐胁迫对尖果沙枣和大果沙枣膜脂过氧化和渗透调节的影响

用0％、0.4％、0.8％、1.2％4种浓度NaCl溶液处理大果沙枣(Elaeagnus moorcroftii)和尖果沙(E.oxycarpa)枣幼苗,盐胁迫7、14、21、35d后分别测定4种处理条件下大果沙枣幼苗和尖果沙枣幼苗叶片中可溶性糖和丙二醛的含量,研究盐胁迫对沙枣膜脂过氧化和渗透调节的影响.结果表明:①0.4％NaCl溶液处理和0.8％NaCl溶液处理的两种沙枣幼苗叶片中MDA浓度前期(尖果沙枣21d内,大果沙枣7d内)增幅较小,但随着胁迫时间的延长,MDA浓度增幅变大,1.2％NaCl溶液处理的两种沙枣幼苗叶片中MDA含量最高;②两种沙枣幼苗0.4％、08％、1.2％三个NaCl溶液处理叶片中可溶性糖含量都高于对照水平.     

盐胁迫草坪草的研究进展

盐胁迫下,草坪草的覆盖度、种子发芽率、根生长等都会受影响,草坪草通常改变自身的外部形态、调节渗透能力、采取脱水保护、改变膜透性、增加酶活性等来适应环境。文章综述了盐胁迫对草坪草种子萌发,外部形态和生理生化特性(膜透性、SOD、体内离子含量、脯氨酸等渗透调节物质)的影响;草坪草对盐胁迫的适应机制,耐盐性指标的确定以及耐盐草坪草的应用。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.