竹材霉菌生理特性及防霉研究

中南林学院环境与资源系冉隆贤等人，为了探明霉菌对竹材的致霉机理并有效阻止霉菌在竹材上繁殖生长，对竹材上5种主要霉菌，即黑曲霉、黄曲霉、黑根霉、指状青霉及枯青霉的生物学特性，竹材可溶性总糖和淀粉含量对霉菌生长的影响，以及5种霉菌淀粉酶、纤维素酶活性与霉烂竹材的顺纹抗压强度的相关性进行了研究，在此基础上进行了防霉剂毒性测定和竹林防霉试验。结果表明：在温度为25～30℃，相对湿度93％以上，霉菌孢子萌发和生长最快，而在5℃以下，或相对湿度低于65％时，5种霉菌孢子均不萌发，菌落不生长；最适生长PH值在4～6之间；5种…     

竹材霉菌的鉴定及防霉剂的筛选

经鉴定竹材霉菌有２５种。本文描述２０种霉菌的形态，其中常发霉菌有青霉、曲霉、毛霉、黑根霉、镰刀菌、粉红单端孢霉。经测定，青霉菌等的生长适温为１５～３０℃；相对温度为６０％时孢子开始萌发，９３％时萌发率最高。这为选择防霉时期提供了依据。在防霉剂毒性测定的基础上，配成的ＰＣＢ和ＣＢＷ防霉剂效力达９１．７％～１００％。     

淀粉酶处理对竹材防霉性能的影响

毛竹竹材由于富含淀粉和糖,在适宜的条件下极易受到以此为食的各种霉菌的侵害,给竹材加工业造成重大的损失,因此必须进行竹材的防霉保护。传统的化学药剂浸渍竹材,虽然防霉效果优异,但因其含有对人体有害的化学物质或重金属成分,长期使用会影响人类的身体健康。而利用生物酶进行竹材的防霉处理,不但简便高效,而且绿色无毒。在研究过程中采用7种不同酶量的淀粉酶溶液来处理竹材样品,同时对比了最适加酶量下3种不同处理时间和3种不同处理温度对竹材样品防霉的效果。试验结果表明:随着淀粉酶处理液中酶量的增加,竹材样品的淀粉和还原糖含量下降明显;淀粉酶处理液的处理时间对降低竹材淀粉和还原糖含量起到关键作用,适当延长竹材的酶处理时间有益于降低竹材的淀粉和还原糖含量;适合的淀粉酶处理温度能提高淀粉酶水解效率,降低竹材淀粉和还原糖含量。在竹材的防霉试验中,经淀粉酶溶液处理过的竹材,对3种霉菌(黑曲霉、桔青霉和绿色木霉)均有很好的抗霉效果;随着淀粉酶处理液酶量和处理时间的增加,竹材的防霉性能有了明显的提高。结果表明,最佳淀粉酶处理工艺为:酶量120 U/mL,酶处理时间36 h,酶处理温度95℃。研究结果可为竹材的防霉研究提供参考。     

山杏种子后熟生理及萌发条件的研究

测定了去除内果皮的山杏种子不同温度浸水处理的吸水性、温度对去除胚尖处种皮和不去种皮种子萌发的影响；萌发过程中种子内可溶性糖含量的动态变化；激素对种子萌发的影响及萌发期间种子内ａ-淀粉酶活性和过氧化氢酶活性的变化。结果表明，５０℃低温浸种２４ｈ可达山杏萌发所需水分条件及活力指数；层积处理以２～５℃效果最好；ＧＡ３在适宜浓度下能打破休眠，促进种子发芽、茎根伸长和幼苗生长；种子萌发期间可溶性糖含量呈不断增加趋势，ａ-淀粉酶活性不断增强；层积后种子内ａ-淀粉酶活性显著增强。     

高温热处理对毛竹防霉性能的影响

以毛竹为原料,在160,180,200,220℃下分别进行2,4,6,8 h的热处理,重点分析总糖、还原糖、游离糖,pH、吸湿性的变化,结合黑曲霉的霉变测试,揭示高温热处理竹材的霉变机理。研究显示：竹材中总糖和还原糖的质量浓度总体呈现出下降的趋势,总糖与还原糖的最低质量浓度分别为0.83和0.05 g/L,相比未处理竹材分别降低了68.7%和95.3%。同时,游离糖中的葡萄糖相比未处理竹材降低了13.5%;木糖与阿拉伯糖分别下降了73.1%和77.9%。而且,竹材的pH呈现出逐渐上升的趋势,维持在5.07～6.13,呈现出有利于霉菌生长的弱酸性环境。但是,高温热处理增大了竹材的接触角,润湿性降低,能阻碍霉菌生长的水分供应。黑曲霉测试显示：热处理能在一定程度上延缓竹材的霉变速率,但在160,180,200℃时竹材的感染面积占比均超过了75%,防治效力为0。即使在220℃时,霉菌感染面积仍接近50%,防治效力仅为50.0%。研究表明,尽管高温热处理降低了竹材的润湿性,糖分也明显减少,在一定程度上抑制了霉菌生长的营养物质和水分供给,延缓了霉菌的生长速率,但是竹材中保留的葡萄糖、木糖及阿拉伯糖...     

木霉菌株T95生物学特性的研究

木霉菌株Ｔ９５在ＰＤＡ培养基、麦芽糖培养基、查彼培养基、苹果树皮煎汁和基本培养基上均能生长。其中在ＰＤＡ、查彼和基本培养基上,菌丝生长较快,产孢量也较多。在ＰＤＡ培养基上,菌丝生长的温度范围是１５～３５℃,产孢的温度范围是１０～３７℃,菌丝生长和产孢的最适温度为２５℃;菌丝生长和产孢的ｐＨ值范围是２～１１,最适ｐＨ值为４。在基本培养基上,葡萄糖为菌丝生长的最佳碳源,木糖为产孢的最佳碳源;蛋白胨和牛肉浸膏是菌丝生长的最佳氮源,天门冬素是产孢的最佳氮源;维生素Ｂ１和Ｂ２对产孢作用较大。菌丝生长和产孢的最佳微量元素是Ｍｇ。分生孢子萌发需要一定的营养,ＰＤＡ膜好于２％琼脂膜。孢子萌发的温度范围是１５～３５℃,最适温度为２５℃;ｐＨ值范围是２～１１,ｐＨ值为３～５时萌发率较高;接种后８ｈ开始萌发,时间集中在１６～２４ｈ内。在２５℃时,孢子萌发的最适相对湿度为７０～８０％,最低相对湿度为５０％。     

大叶黄杨褐斑病病原菌生物学特性的研究

大叶黄杨褐斑病ＣｅｒｃｏｓｐｏｒａｄｅｓｔｒｕｃｔｉｖａＲａｖ．病原菌生长最适温度为２５℃，低于５℃或高于３８℃均不能生长；偏酸环境有利于其生长，ｐＨ４．５生长最好。分生孢子在２５℃下萌发率最高，相对湿度１００％最利于萌发，ｐＨ值适应萌发范围较广，萌发率最高为ｐＨ４．０。菌落生长和分生孢子萌发对营养要求不严格，在ＰＤＡ、ＰＭＡ、ＰＳＡ培养基上生长较好，在蒸馏水中孢子萌发率亦达９０．４％；光照条件对其影响不大     

大叶黄杨褐斑病病原菌生物学特性的研究

大叶黄杨褐斑病Ｃｅｒｃｏｓｐｏｒａ ｄｅｓｔｒｕｃｔｉｖａ Ｒａｖ．病原菌生长最适温度为２５℃，低于５℃或高于３８℃匀不能生长；偏酸环境有利于其生长，ｐＨ４．５生长最好。分生孢子在２５℃下萌发率最高，相对湿度１００％最利于萌发，ｐＨ值适应萌发范围较广，萌发率最高为ｐＨ４．０。菌落生长和分生孢子萌发对营养要求不严格，在ＰＤＡ，ＰＭＡ，ＰＳＡ培养基上生长较好，在蒸馏水中孢子萌发率亦达９０．４％；光照条     

温度对薄壳山核桃种子萌发的影响及其机制初探

将薄壳山核桃的完整种子与去壳种子在不同温度条件下进行发芽试验,并测定了温度对淀粉酶活性的影响,菜豆素(淀粉酶抑制剂)对完整种子萌发的影响,以及不同温度对种子萌发初期中,淀粉、可溶性糖、粗脂肪、可溶性蛋白和游离氨基酸变化的影响。结果表明:薄壳山核桃种子在30、35℃条件下,种子萌发率分别为84%、82%,显著高于15、25和40℃3个温度下的情况,且所需的萌发时间较15、25℃条件下更短;因此薄壳山核桃种子适宜的萌发温度为30~35℃的高温条件,而超过该温度区间容易对种子造成伤害。同时,生理研究的结果显示,15~30℃时,温度越高,薄壳山核桃种子淀粉酶活力也越高,而淀粉酶活性抑制剂能够显著降低薄壳山核桃种子在30℃中的萌发率,这表明在一定温度范围内,温度变化可改变淀粉酶活性,从而调控薄壳山核桃种子萌发;同时,其它生理指标测定表明,糖类的代谢与蛋白质的代谢在种仁响应温度变化的过程中具有重要的作用。     

CMC系列防霉剂抑菌效果研究

壳聚糖金属配合物(以下简称CMC系列)是一种对环境友好的木材防腐剂,通过抑菌试验将其用于竹材防霉,结果表明:(1)CCC和CZC两种抑菌剂对于青霉、黑曲霉和木霉的抑制效果都明显高于H3BO3,且这两种抑菌剂对霉菌的抑制持续性都比较好.(2)浓度为1.8%的CCC和CZC对青霉具有较好的抑菌效果;浓度为1.0%的CCC和1.8%的CZC对黑曲霉具有较好的抑菌效果;浓度为2.2%的CCC和0.6%的CZC对木霉具有较好的抑菌效果.     

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.