百菌清对杨树烂皮病的抑制机理初步分析

为了更科学有效的防治杨树烂皮病，文章初步分析了百菌清对杨树烂皮病的抑菌机理，采用固、液体培养法，测定百菌清对杨树烂皮病菌丝生长、生物量、菌丝体内丙二醛和可溶性蛋白质含量的影响。结果显示，百菌清对杨树烂皮病菌丝生长及生物量有显著的抑制作用；能增大细胞膜脂质过氧化程度，导致丙二醛含量增多；并能抑制菌丝体内可溶性蛋白质合成，使体内蛋白质含量降低。     

中生菌素对杨树烂皮病的抑菌机制初报

为了研究中生菌素对杨树烂皮病的抑菌机制,采用固、液体培养法,测定中生菌素对杨树烂皮病菌丝生长及生物量的影响,并测定其对菌丝体内可溶性蛋白质和丙二醛含量的影响。结果表明:中生菌素对杨树烂皮病菌丝生长及生物量有明显的抑制作用,并抑制菌丝体内可溶性蛋白质合成,增大细胞膜脂质过氧化程度,导致丙二醛含量增大。证实中生菌素作为一种广谱杀菌剂,可应用于林业病害的防治,为杨树烂皮病科学防治提供一定理论基础。     

几种拮抗菌对杨树烂皮病菌的影响

Trichoderma3个菌株及Chaetomium sp.与杨树烂皮病菌(Cytospora chrysosperma)的对峙培养试验的结果表明:试验中采用的Trichoderma viride1,Trichoderma viride2,Trichoderma harzianum及Chaetomium sp.对杨树烂皮病菌都有一定的抑制效果,其中Trichoderma viride1对病原菌的相对抑制效果最好,且其相对抑制效果随着时间的增加而增长,在74h时达到最高,抑制率可达到64.55%;其相对抑制效果也达到最大,为11.49;其它3个菌株的相对抑制效果在对峙培养74 h时也达到最大,介于1.77~4.15之间。     

杨树枝枯病病原菌的初步研究 Ⅰ.病原菌形态和致病性

杨树烂皮病为害杨属各个种,分布普遍。是苗圃和幼林的重要病害之一,也是成年树枝枯的主要原因。我国杨树烂皮病病原菌过去的报导是Valsa sordida Nit.北京地区引起杨树烂皮和枝枯的病原菌,除Cytos-     

7种杀菌剂对杨树烂皮病、溃疡病病菌的室内毒力测定

室内测定了7种杀菌剂对杨树烂皮病病原菌金黄壳囊孢菌Cytospora chrysosperma (Pers.)Fr.、溃疡病病原菌Dothiorella gregaria Sacc.的毒力.72 h含药平板对抑制金黄壳囊孢菌的菌丝生长毒力最强的有10％苯醚甲环唑水分散剂、250 g/L嘧菌酯悬浮剂,EC50值依次为0.0006,0.020 2μg/mL;其次为70％甲基托布津可湿性粉剂,EC50为0.195 8μg/mL;最弱的是树乐粉剂,EC50为319.658 0μg/mL.48 h对杨树溃疡病病原菌的毒力最强的有250 g/L嘧菌酯悬浮剂、10％苯醚甲环唑水分散剂,EC50依次为0.072 2,0.090 4μg/mL;其次为70％甲基托布津和50％多菌灵可湿性粉剂,EC50依次为2.5603,19.0454 μg/mL;树乐最弱,EC50为366.415 7μg/mL.同一药剂对杨树烂皮病菌的毒力强于溃疡病菌.     

走马芹提取物对杨树烂皮病的抑制作用研究

对走马芹的80%乙醇超声波提取物对杨树烂皮病原菌的抑制作用进行了研究,实验结果表明:不同浓度的走马芹提取物均对杨树烂皮病的病原菌产生了较强的抑制作用并呈对数增长趋势。     

绿木霉菌株T43对松烂皮病菌的抑制效果及其抑菌机理

通过对峙培养和非挥发性代谢产物对病原菌生长的抑制]作用,对引进绿木霉(Trichoderma virene)菌株T43及其抑菌活性物质对松树烂皮病菌(Cenangium ferruginosum)的抑制效果进行了研究;从菌株T43发酵液乙酸乙酯提取物对松树烂皮病菌的3种保护酶(SOD、CAT和POD)活力影响的角度,初步探讨了提取物对病原菌的抑菌机理.研究结果表明:对峙培养48 h后,菌株T43对松烂皮病菌相对抑制效果为1.00,72 h后菌株T43与病原菌形成明显的拮抗线,并抑制病原菌的生长.菌株T43乙酸乙酯提取物对病原菌株的室内生长抑制率为60.50％.菌株T43发酵液乙酸乙酯提取物对病原菌的3种保护酶具有明显的抑制作用.     

两种抑菌剂对杨树烂皮病的抑制作用研究

选用广谱抑菌剂百菌清和生物抑菌剂中生菌素,研究它们对杨树烂皮病的抑制作用.结果 表明采用生长速率法,通过室内抑菌试验,确定百菌清600倍稀释液和中生菌素800倍稀释液对杨树烂皮病的抑制率均达到85％以上,证实中生菌素对杨树烂皮病的抑菌效果高于百菌清.期待为杨树烂皮病病害防治提供一定的理论基础,为杨树烂皮病生物防治提供一...     

江苏杨树烂皮病发生状况调查及化学防治试验

通过对江苏省杨树烂皮病发生状况调查发现,在新沂,六合和仪征3个地区有杨树烂皮病发生。在调查的4 417株杨树中,平均发病率占11.32%;杨树烂皮病的发生与树种、树龄、地形、土壤、坡向以及虫害的关系均较密切。苗圃内不同药剂、配比度对杨树苗刮皮后的涂药试验发现,吡唑醚菌酯500,1 000,1 500倍液3种配比度的防治效果均在88%以上,嘧菌酯500倍液的防治效果高于80%。说明在苗圃用吡唑醚菌酯1 000倍和1 500倍液防治杨树烂皮病,可以取得良好的防治效果。     

百菌清对两种杨树病害病原菌的抑制作用初探

选取保护性杀菌剂百菌清,研究其对杨树水泡型溃疡病和烂皮病的抑制作用,采用生长速率法和数据统计分析。通过室内抑菌试验结果表明,百菌清600倍稀释液对杨树水泡型溃疡病抑制率达到90%以上,百菌清400倍稀释液对杨树烂皮病的抑制率达到88%以上,证实百菌清对两种杨树病害有较好的抑制效果。期待本研究为百菌清在杨树病害防治中的应用提供理论支持,为杨树病害防治提供科学依据。     

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.