刺槐种子萌发过程中的生理生化变化

用刺槐种子为材料．初步研究了刺槐种子萌发过程中可溶性糖、可溶性蛋白、丙二醛（MDA）、脯氨酸、过氧化物酶（POD）活性、多酚氧化酶（PPO）活性的变化。结果表明：刺槐种子在萌发过程中．可溶性糖和可溶性蛋白含量呈下降趋势,丙二醛和脯氨酸含量有不程度的升高,POD和PPO的活性都有大幅度升高。     

人工低温胁迫下腰果叶片生理生化指标的变化

为给选育腰果抗寒优良品种提供依据,以腰果FL30叶片为材料,进行人工低温胁迫处理,测定叶片相对电导率、丙二醛(MDA)、可溶性糖、脯氨酸和超氧化物歧化酶(SOD)5个抗寒生理生化指标。研究结果表明:随着低温胁迫时间延长,相对电导率、MDA含量先逐渐升高后趋于稳定,可溶性糖含量、脯氨酸含量和SOD活性呈现持续上升的变化规律;胁迫温度越低,相对电导率、MDA含量、可溶性糖含量、脯氨酸含量和SOD活性越高;温度低于16℃,即对腰果产生较严重伤害,且温度越低伤害程度越严重;经4℃低温胁迫4 d,可大大提高腰果的抗寒性。     

低温胁迫下5个杏树品种的抗寒性研究

以引进的‘玉杏’、‘红丰’、‘凯特’、‘红太阳’、‘大棚王’等5个杏品种1年生休眠枝为试材,经低温处理后,测定其相对电导率、可溶性糖、游离脯氨酸(Pro)含量、丙二醛(MDA)的含量,研究越冬枝条的抗寒性。结果表明:参试品种电解质渗出率、可溶性糖含量、丙二醛(MDA)含量和游离脯氨酸(Pro)含量均随着温度的降低而增高,同一低温胁迫下,不同品种间相对电解质渗出率、可溶性糖含量、丙二醛(MDA)含量和游离脯氨酸(Pro)含量不同,表明各品种间抗寒性差异显著。不同品种抗寒力排序为:‘玉杏’‘红丰’‘凯特’‘红太阳’‘大棚王’。     

外源硼酸钠对桂花幼苗抗寒性的影响

采用人工气候室模拟低温环境,研究不同浓度的外源硼酸钠对桂花幼苗抗寒性的影响。结果显示:在4℃低温胁迫下,随时间的延长,外源硼酸钠处理桂花叶片MDA含量和可溶性蛋白含量逐渐升高,游离脯氨酸、可溶性糖含量以及SOD、CAT酶活性变化趋势为先上升后下降,POD活性持续上升;外喷0.5%~1%浓度的硼酸钠可显著减少桂花叶片MDA含量,增加游离脯氨酸,促进可溶性蛋白和可溶性糖的积累,提高SOD、POD、CAT抗氧化酶活性;0.5%浓度的硼酸钠可促进植株纵向生长,1%~2%浓度的硼酸钠对低温胁迫下桂花幼苗纵向生长产生一定的抑制作用,且浓度越高抑制性越强。低温胁迫对桂花幼苗产生一定程度的伤害,适当浓度外源硼酸钠处理可以有效缓解低温胁迫对桂花叶片的伤害,提高桂花幼苗的抗寒性。     

不同海拔油橄榄对自然低温的生理响应及抗寒性差异

【目的】评价不同油橄榄品种的抗寒性,筛选出适宜不同海拔栽培的油橄榄品种,加强油橄榄引种工作的针对性和推广工作的区域性。【方法】以阿斯（Ascolana）、莱星（Leccino）、奇迹（Koroneiki）、鄂植8号（Ezhi8）和阿尔波萨纳（Arbosana）5个品种的8年生大树为研究对象,在自然低温条件下,设置1 000和1 300 m两个海拔梯度,采用随机区组试验设计,每个区组5次重复,分别测定油橄榄叶的可溶性蛋白质、可溶性糖、总叶绿素、丙二醛（MDA）、脯氨酸等物质含量及过氧化氢酶（CAT）、过氧化物酶（POD）、超氧化物歧化酶（SOD）等酶活性,结合隶属函数法评价不同品种抗寒性。【结果】自然低温下,随着海拔升高,不同品种油橄榄9个单项生理指标的变化各不相同。阿斯的总叶绿素含量、相对电导率、MDA含量、脯氨酸含量、POD活性、SOD活性均升高,可溶性蛋白质含量、可溶性糖含量降低,CAT活性不变;莱星的可溶性蛋白质含量、相对电导率、脯氨酸含量、CAT活性、POD活性、SOD活性均升高,可溶性糖含量、总叶绿素含量降低,MDA含量不变;奇迹的相对电导率、MDA含量、脯氨酸含量、CAT活...     

干旱胁迫对油橄榄幼苗的影响

以油橄榄幼苗为材料,在旱棚盆栽条件下进行苗期干旱胁迫试验。对株高、脯氨酸含量、可溶性蛋白、可溶性糖含量、丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、过氧化氢酶(CAT)活性进行了测定。结果显示:进行模拟干旱胁迫后,株高、脯氨酸、可溶性蛋白及SOD含量无明显变化;可溶性糖、CAT、MDA、POD含量逐渐升高。研究表明,在不同程度的干旱胁迫条件下,油橄榄幼苗的生长受到一定程度的抑制,但能够通过调节自身的保护酶系统活性和渗透调节物质含量来减轻干旱伤害,维持植物体的正常生理代谢功能,从而表现出一定的抗旱耐旱潜力。     

低温胁迫对5种柽柳抗寒性生理指标的影响

为了研究柽柳抗寒性,以1年生离体枝条为试材,测定不同低温处理叶片可溶性糖、可溶性蛋白质、丙二醛(MDA)、游离脯氨酸(Pro)含量,以及超氧化物歧化酶(SOD)活性.结果表明:低温胁迫下5种青海柽柳叶片下可溶性蛋白质和可溶性糖的含量随着温度的降低而上升;低温胁迫叶片内的丙二醛(MDA)含量大于对照;除刚毛柽柳的脯氨酸含量随着温度的降低先升高后降低外,而其他4种柽柳的脯氨酸含量随温度的降低均呈现升高趋势;各低温胁迫的5种青海柽柳植物的超氧物歧化酶(SOD)活性显著高于对照.根据隶属函数法,求出隶属函数值,判定5种青海柽柳扰寒性强弱的排序为:盐地柽柳>密化柽柳>刚毛柽柳>翠枝柽柳>长穗柽柳.     

低温胁迫对喜树幼苗SOD活性、MDA和脯氨酸含量的影响

本文对低温胁迫下喜树幼苗叶片内超氧化物歧化酶（SOD）活性与叶绿素、游离脯氨酸、丙二醛（MDA）含量的变化进行了研究。结果表明：喜树幼苗经低温胁迫后叶内叶绿素含量下降；SOD活性先下降、后上升、再下降，其变化规律不同于其它植物；低温造成喜树幼苗的膜脂过氧化，MDA含量明显升高，SOD活性的增强可以降低MDA的含量；脯氨酸随着胁迫的进行其含量升高，表明叶内脯氨酸的升高也有助于提高它的抗寒性，进一步可以认为叶片内脯氨酸含量的高低可作为衡量喜树抗寒性指标。     

干旱胁迫及复水对桫椤生理特性的影响

为了弄清木本蕨类植物桫椤对水分亏缺环境的适应性,选用3a生桫椤苗,通过盆栽控水进行持续干旱胁迫和复水处理,研究了干旱历时3,6,8d和复水历时3,6,9d时桫椤叶片渗透调节物质含量、丙二醛(MDA)含量以及抗氧化酶活性的变化规律。结果表明：1)随着持续干旱时间的延长,桫椤叶片可溶性糖含量、脯氨酸含量、超氧化物歧化酶(SOD)活性和过氧化物酶(POD)活性均呈先增大后减小的趋势,在干旱3d时达到最大值;桫椤叶片可溶性蛋白含量和丙二醛含量呈增加的趋势,在干旱8d时达到最大值;过氧化氢酶(CAT)活性呈先减小后增大的趋势,充分供水时活性最高。2)复水9d时,桫椤叶片可溶性糖含量、脯氨酸含量、POD活性和CAT活性已恢复并降低到充分供水时以下的水平;可溶性蛋白含量、MDA含量和SOD活性高于充分供水时。可见,干旱胁迫时,可溶性蛋白含量与充分供水时相比一直呈增加趋势,其在桫椤抵御干旱胁迫中发挥了相对重要的作用;可溶性糖含量、脯氨酸含量、SOD活性和POD活性快速响应干旱胁迫并增加,但干旱3d后即开始下降,说明桫椤对干旱胁迫的耐受能力相对较差。同时,复水后,各生理指标均迅速恢复到了充分供水时的水平...     

银胶菊对不同土壤盐度的生理适应性

外来入侵物种在异质性环境下产生可塑性反应是生态入侵的重要机制之一.为了揭示银胶菊(Parthenium hysterophorus)在盐胁迫下的适应特点,通过盆栽试验,研究银胶菊在盐胁迫环境下的生理适应性特点.盐处理浓度分为5个水平,分别为0.00、0.02、0.05、0.10、0.15 mol/L NaCl.处理15天后,测定银胶菊叶片中脯氨酸、丙二醛(MDA)和可溶性糖的含量及POD、SOD和CAT活性.实验结果表明,盐胁迫下银胶菊叶片中脯氨酸、丙二醛和可溶性糖的含量在NaCl浓度为0.02 moL/L时最低,脯氨酸和可溶性糖的含量在NaCl浓度为0.15 mol/L时达到最高值.POD活性与SOD活性与对照相比均有下降,CAT活性与对照相比均有上升,在NaCl浓度为0.05 mot/L时达到最高值.     

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.