外源物质对盐胁迫下麻黄幼苗根系生长的影响

为了研究硝普钠(SNP)、亚精胺(Spd)和水杨酸(SA)对盐胁迫下麻黄幼苗根系生长和氧化损伤的影响。采用营养液水培的方式,分析3种外源物质处理对麻黄根系生长的影响。结果表明:在200 mmol/L的NaCL胁迫下,麻黄幼苗中质膜过氧化指标丙二醛(MDA)含量增加,代谢产物可溶性蛋白、可溶性糖、脯氨酸的含量降低,根系活力也呈下降趋势。经不同浓度的SNP、Spd、SA处理后,一定浓度的硝普钠(SNP)、亚精胺(Spd)和水杨酸(SA)能够提高麻黄幼苗的抗盐能力。3种外源物质缓解效果为:SA(50 mg/L)SNP(0.1 mmol/L)Spd(0.25 mmol/L)。施用水杨酸(SA)50 mg/L后,可溶性蛋白含量增加14.30%,可溶性糖含量增加35.58%,脯氨酸含量增加65.5%,MDA含量降低42.11%,根系活力增加18.17%。     

吲哚丁酸对一串红种子萌发及幼苗生长的影响

不同浓度吲哚丁酸(IBA)对一串红种子萌发及幼苗生长影响的研究结果表明:10-6 mg/L的IBA可以增加一串红种子的发芽率、侧根数、叶绿素含量和根系活力。     

水杨酸和吲哚丁酸对冬季山椒子幼苗生长及抗逆生理的影响

【目的】探讨植物生长调节剂水杨酸(SA)和吲哚丁酸(IBA)对山椒子Uvaria grandiflora幼苗生长及生理特性的影响,为山椒子的人工栽培及壮苗生长提供理论基础。【方法】以山椒子1年生实生苗为供试材料,采用盆栽试验方法,叶面分别喷施不同质量浓度(0、50、100、150、200 mg/L)的SA和IBA,研究SA和IBA对其生长指标、叶片叶绿素含量、叶片MDA含量、叶片抗氧化酶活性和叶片渗透调节物质含量的影响。【结果】与对照相比,各质量浓度的SA、IBA溶液处理均使山椒子幼苗高和地径显著增加,且除MDA含量以外,叶绿素含量、抗氧化酶活性、渗透调节物质含量均显著增加,其中分别以150 mg/L的SA溶液处理和100 mg/L的IBA溶液处理的效果最佳。150 mg/L的SA溶液处理和100 mg/L的IBA溶液处理下,山椒子苗高和地径显著高于对照组,苗高分别达到对照的143%和153%,地径分别达到对照的144%和138%;叶片叶绿素含量分别提高至对照的150%和108%;叶片抗氧化酶(SOD、CAT、POD、APX)活性显著增强,SOD活性分别为对照的164%和125%,CAT活性分别为对照的129%和127%,POD活性分别为对照的317%和347%,APX活性分别为对照的125%和106%;叶片渗透调节物质游离脯氨酸、可溶性蛋白含量显著升高,游离脯氨酸含量分别高出对照37%和42%,可溶性蛋白含量分别高出对照113%和19%;叶片MDA含量分别下降至对照的61%和48%。【结论】叶面喷施SA和IBA溶液可明显促进山椒子幼苗生长并诱导其抗逆性增强,其中分别以150 mg/L的SA溶液处理和100 mg/L的IBA溶液处理时效果最佳,且SA处理效果略优于IBA处理。     

水杨酸浸种处理对干旱胁迫下云南蓝果树种子萌发和早期幼苗生长的影响

利用不同浓度的水杨酸(0g/L、0.25g/L、0.5g/L、0.75g/L、1g/L)对云南蓝果树种子进行浸种处理和不同浓度的PEG-6000溶液(0、5%、10%、15%)模拟不同强度的干旱胁迫,研究水杨酸浸种处理对干旱胁迫下云南蓝果树种子萌发和早期幼苗生长的影响。结果表明,未经SA浸种处理时,轻度干旱胁迫就显著抑制了云南蓝果树种子的萌发,且随着PEG-6000胁迫浓度的增加,云南蓝果树种子的萌发率、发芽势、发芽指数、活力指数、幼苗根长、根冠比以及根干重、根鲜重、子叶鲜重和子叶干重都显著下降。SA溶液浸种后(SA溶液浓度范围为0.25~1.0g/L),在不同程度干旱胁迫条件下(PEG-6000浓度为5%~15%),云南蓝果树种子萌发率、发芽势、发芽指数、活力指数、根长、根干重、根鲜重、子叶鲜重和子叶干重都显著高于对照,并随着SA浓度的增加而显著增加,在SA浓度为0.75g/L时,增加幅度最显著。因此,云南蓝果树对干旱环境具有非常差的耐受性,但是SA的浸种处理可以缓解干旱胁迫对云南蓝果树种子萌发和早期幼苗生长的影响。建议育苗前对云南蓝果树种子进行SA预处理,最适浓度为0.75g/L。本研究为水杨酸在云南蓝果树保育中的应用提供了科学依据。     

叶面喷施不同浓度的氯化镧对毛豆幼苗生长的影响

采用不同浓度氯化镧对毛豆幼苗进行叶面喷施处理,测定稀土元素镧对毛豆营养生长和生理特性的影响。试验结果表明:采用适宜浓度的氯化镧对毛豆进行喷施处理,可以增加根茎粗度、有效促进幼苗增高、增加叶绿素的含量、提高光合作用、增加干物质的积累、促进根系的生长、增加根系活力等。从叶面喷施几种不同浓度的氯化镧对毛豆的营养指标及生理指标的影响进行综合判断可知:在试验范围内,以5mg/L的氯化镧处理效果为最佳,建议在生产上合理的应用。     

水杨酸对盐胁迫下大豆生长和渗透调节能力的影响

砂基培养大豆,盐胁迫下进行水杨酸处理,NaCl和SA处理的预定浓度分别为0 0(对照)、100 0、100 0.3、200 0、200 0.3mmol/L。结果表明:SA处理后提高盐胁迫下大豆Pro、SS、AA和叶绿素含量;增强根系活力、硝酸还原酶(NR)活性。综合各项生长和生理指标表明,SA处理有利于增加渗透调节能力,减缓水分胁迫,缓解盐害;且SA对NaCl 100mmol/L处理的大豆生长缓解效应优于NaCl200mmol/L胁迫的。     

弱光条件下光质对喜树生理生化指标的影响

为给喜树栽培提供理论依据,对弱光环境下红、黄、蓝、绿等光质对喜树幼苗叶绿素含量、超氧化物歧化酶活性、丙二醛、游离脯氨酸和喜树碱含量的影响进行了研究。结果表明:绿光使叶绿素含量增加,而其它单色光使叶绿素含量降低,减少部分主要是叶绿素b,叶绿素(a/b)比值升高;与白光相比黄光使叶片中的超氧化物歧化酶活性升高,而其它3种光条件下的超氧化物歧化酶活性降低;红光使丙二醛含量升高,同时使叶内游离脯氨酸含量持续上升,其它3种光对游离脯氨酸和丙二醛含量影响不大;与白光相比,绿光和红光可使叶片中喜树碱含量增加,而黄光和蓝光不能引起喜树碱含量的增加。弱光条件下不同光质对喜树幼苗生长形成了胁迫,光质对其初生和次生代谢均产生了一定的影响。     

不同施磷水平对喜树幼苗生长及喜树碱积累的影响

采用盆栽施肥的方法,研究了不同施磷水平(对照0 kg P·hm-2、低磷42 kg P·hm-2、中磷84 kg P·hm-2、高磷168 kg P·hm-2)对喜树当年实生幼苗生长及次生代谢物喜树碱积累的影响。结果表明:随着施磷水平的增加,喜树幼苗的苗高及叶、茎、根的干物质量均增加,且各施磷水平幼苗叶、茎、根的干物质量差异显著(p<0.05)。在不同磷素水平下,幼苗叶、根、茎中的喜树碱含量均在低磷水平时出现最大值,并且低磷水平与对照间喜树碱含量差异显著(p<0.05)。随着磷用量的增加,喜树全株及叶、茎的喜树碱总量持续增加,但喜树全株和叶在高磷与中磷水平间差异不显著。根中喜树碱总量在不同磷素水平差异显著,在中磷水平最高。由结果可知:磷可以促进喜树幼苗中喜树碱的合成,适当的低磷胁迫可以增加喜树幼苗中喜树碱含量。培育喜树碱原料林时,适宜的施磷水平应为中磷水平,幼苗喜树碱总量主要取决于喜树生物量的积累。     

水分胁迫下绿风95对毛豆幼苗生长及其抗渍性的影响

在水分胁迫下采用不同浓度的绿风95对毛豆幼苗进行叶面喷施处理,测定其对毛豆幼苗生长及其抗渍性的影响。试验结果表明:采用一定浓度的绿风95处理可以促进苗生长、提高根系活力、叶绿素含量、脯氨酸含量和抑制丙二醛增生、降低细胞膜透性,增强了毛豆幼苗对渍水环境的抵抗能力。从叶面喷施对毛豆的营养指标和生理指标进行综合判断可知:在试验的范围内,以2ml/L绿风95的处理效果为最佳。     

外源ABA对渗透胁迫下喜树幼苗生理生化指标的影响

为给喜树栽培和利用提供理论依据,研究了外源ABA对渗透胁迫下喜树幼苗几项生理生化指标的影响。结果表明:渗透胁迫导致喜树幼苗内脯氨酸(Pro)含量增高,增施外源ABA其脯氨酸含量较渗透胁迫下低;渗透胁迫下,喜树幼苗内丙二醛(MDA)含量持续上升,外源ABA处理的喜树幼苗内丙二醛含量呈现先上升后下降的趋势;渗透胁迫使喜树幼苗的超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性持续下降,外源ABA的使用可以减缓这种下降趋势;渗透胁迫使喜树幼苗内过氧化物酶(POD)活性呈现先上升后下降的趋势,外源ABA可以提高过氧化物酶活性;渗透胁迫使喜树幼苗内喜树碱(CPT)含量上升,外源ABA处理不能显著提高喜树幼苗内喜树碱含量,而渗透胁迫导致喜树幼苗内10-羟基喜树碱(10-OH CPT)含量下降,外源ABA的使用加剧了下降趋势。     

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.