不同杨树品种对水泡型溃疡病的抗性

采用8个杨树品种枝条通过室内接种试验表明,其中中林46杨为杨树溃疡病抗病型品种;三倍体毛白杨、北抗杨以及健杨为高度感病型品种。     

河南杨树感染杨树溃疡病调查初报

通过调查分析,发现不同杨树品种间感染杨树溃疡病情况有明显差异,其中以三倍体毛白杨、小美旱杨最易感病;中林46杨、沙兰杨、毛白杨较抗病,同一杨树品种在不同生长环境、不同立地条件下种植,其感病情况有所差异,立地条件越好,感病指数越低。杨树不同生长龄级间抗病指数也有差异,1～2 a生幼树感染杨树溃疡病以后发病严重,同一品种,龄级越大,其抗病能力越强。     

欧美杨细菌性溃疡病菌的寄主范围调查及其寄主抗性物质的初步分析

目的 为明确欧美杨细菌性溃疡病菌的寄主范围、欧美杨抗性品种及其可能的抗性活性物质。 方法 通过田间接种方法开展欧美杨细菌性溃疡病菌的寄主范围、杨树品系抗性调查,并利用高效液相色谱分析杨树抗感品种树皮中活性物质含量及其染病前后含量变化情况,同时利用抑菌实验验证潜在抗性物质的活性。 结果 研究发现欧美杨细菌性溃疡病主要危害黑杨派美洲黑杨、欧美杂交杨的品系以及旱柳,而欧洲黑杨品系具有高度抗菌能力;本研究的30个美洲黑杨和欧美杂交杨品系中,中林46杨、2025杨、2001杨、313杨、中荷1号杨和16-09杨是高感病品系;16-10杨、豫抗1号杨为高抗病品系,而131杨、03-59杨、02-212杨和03-34杨为抗病杨树品种;杂交柳和垂柳抗病,金丝柳轻微感病;栎属和青杨派的种类和品系具有高度抗性。高效液相色谱分析显示,抗病和高感病品系树皮中的邻苯二酚、苯甲酸、绿原酸、儿茶素的含量较高,其中邻苯二酚和儿茶素在病菌侵染时含量明显增加。 结论 明确了欧美杨细菌性溃疡病的主要危害对象和寄主范围,明确了具有抗性、感病的杨树品系,证明了邻苯二酚和儿茶素与杨树抗病性密切相关,该研究结果为欧美杨的栽培和病害防治提供技术支持和防治建议,该研究结果对我国欧美速生杨的细菌性溃疡病的防治具有重要意义。     

山东杨树主要品种对溃疡病抗性的研究

在山东营建杨树主要品种抗溃疡病 Dothiorella gregaira Sacc试验林 ,田间测定自然发病率和感病程度 ,同时室内测定杨树树皮含水量、两种同功酶活性和主要酚类化合物含量 ,探讨上述三项指标与溃疡病发生的关系 ,明确主要杨树品种的抗病性。结果表明 ,杨树树皮含水量、过氧化物酶和酯酶同功酶活性、对羟基苯甲酸和邻苯二酚含量与杨树对溃疡病的抗性有着密切关系。田间表现抗病的品种 ,如 I-69/5 5、I-72 /5 8和毛白杨 ,其上述三项指标高 ;感病品种 80 3杨 ,三项指标低 ;中林 2 3、2 8、46杨和 2 88-3 79杨的上述指标介于两种情况之间 ,属于中抗品种。田间和室内测定结果基本吻合。     

阜新地区主要杨树品种抗寒抗病虫性研究

采用标准地调查法,对阜新地区保存面积较大的6个杨树品种的抗寒和抗病虫性(病害主要调查溃疡病和冠瘿病,虫害主要是杨干象)进行比较分析。结果显示:(1)抗寒能力,6个杨树品种只有冻害轻微,不影响树木正常生长和材质,且品种间差异不显著;(2)抗病虫能力,中荷64和中绥12抗病虫性最强,溃疡病发病率和感病指数从高到低依次为小钻杨群众杨黑林1号哲林4号;小钻杨和群众杨的冠瘿病很严重,其他品种未发现;黑林1号杨干象危害非常严重,达到了毁林的程度,小钻杨、群众杨、哲林4号发现杨干象虫株,但不影响树木正常生长和材质。     

17个杨树无性系对水泡型溃疡病的抗性

本文测定了17个杨树无性系对水泡型溃疡病的抗性,结果表明感病的无性系有大关杨、小叶杨、Ⅰ—69杨、501杨,中等感病的有80103杨、80104杨、西马杨、路易沙杨;中等抗病的有加龙杨、1—214杨、80101杨,抗病的有健杨、213杨、80105杨、80106杨、80102杨。     

杨树黑斑病发生规律调查及防治措施

对不同品种杨树一年生平茬苗黑斑病进行了调查,将叶片感病程度分为0、Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ6个不同等级,通过对叶片感病程度进行统计,分析了其感病指数及显著性差异,结果表明:不同杨树品种抵抗黑斑病能力较弱,其中感病程度为三级的叶片数量最多,最高可占每组重复叶片总数的72%,107杨表现出较强的抗病特性,与其他品种呈显著性差异。据此,提出了相应的防治措施。     

山东杨树主要品种对溃病抗性的研究

在山东营建杨树主要品种抗溃疡病Ｄｏｔｈｉｏｒｅｌｌａ ｇｒｅｇａｉｒａ Ｓａｃｃ试验外，田间测定自然发病率和感病程度，同时室内测定杨树树皮含水量、两种同功酶活性和主要酚类化合物量，探讨上述三项指标与溃疡病发生的关系，明确主要杨树品种的抗病性量、过氧化物酶和酯酶同功酶活性、对羟基苯甲酸和邻苯二酚含量与杨树对溃疡病的抗性有着密切关系。田间表现抗病的品种，如Ｉ－６９/５５、Ｉ－７２/５８和毛白杨，其上述三     

苦楝,银杏和樟树内含物对杨树溃疡病作用的研究

用苦楝、银叶、樟树与杨树抗病品种和感病品种的内含物进行杨树溃疡测试，从孢子发芽，菌丝生长及植物抗病能力的测定结果证明，苦楝，银杏和樟树内含物对溃疡病抑制作用比抗溃疡病的杨树品种作用强，特别是苦楝和银杏表现更为突出。     

利用模糊综合评判选择杨树造纸林品种

本文借助于模糊综合评判的原理，通过对８年生对树造纸试验林中的辽宁杨、Ｉ－４５／５１杨及锦县小钻杨等３个品种的产量、抗病虫害能力和木材造纸制浆性能进行分析评判，结果辽宁杨是营造杨树造纸林的最佳品种。     

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.