根瘤菌、菌根菌对厚荚相思苗期生长的影响

对厚荚相思苗期进行接种根瘤菌、菌根菌、根瘤菌＋菌根菌的比较试验,结果表明：接种菌根菌的促生效果显著。幼苗高生长、地上部分干重、地下部分干重、根瘤个数、根瘤重量平均数比对照分别提高了53．36％。73．30％,89．69％,224．01％和186．96％。接种各菌种对幼苗的促生效果排序为：菌根菌＋根瘤菌〉根瘤菌〉菌根菌〉对照。苗木根部菌根菌感染强度排序为：菌根菌〉菌根菌＋根瘤菌〉对照。     

根瘤菌拌种培育马占相思苗木试验

采用根瘤菌拌种培育马占相思苗木效果显著。接种苗平均每株结根瘤80.5个，与无菌对照比较增加191％－455％。接种苗根瘤生物量平均每株0.5794g，与无菌对照比较增加125％－313％。但接种苗平均高无显著差异。该试验为培育马占相思苗木早期形成根瘤固氮体系提供了一套简便易操作的新方法。     

石灰岩山地根瘤菌对台湾相思苗木生长效应

从石灰岩山地不同立地条件的台湾相思林分中采集根瘤并分离获得12株根瘤菌,将其接种到台湾相思盆栽苗木中,5个月后测量苗木的株高、地径、生物量及根瘤结瘤情况。试验结果表明:①在石灰岩山地的台湾相思林分中,根瘤数量较多的是中、下坡,最少的是下坡;单个根瘤平均质量最重的是中坡,上坡和下坡次之,表明石灰岩山地的中坡最适合根瘤菌生长。②供试的12株菌株回接到台湾相思苗木后能全部侵染苗木根部并结成有效根瘤;与对照比较,菌株回接都不同程度地促进台湾相思苗木的株高、地径、生物量的增长,增长幅度分别为1.7%~39.0%、1.7%~18.1%和21.4%~135.7%;根瘤生物量也比对照增长3.04~12.94倍。综合分析结果表明,台4、台10菌株为优良菌株。     

几种豆科树种苗木结瘤及对其生长的影响研究

以实验室条件下分离培养得到的山毛豆、台湾相思、银合欢、圣诞树和刺槐根瘤菌分别接种山合欢、台湾相思、滇合欢、香须树等树种幼苗,结果表明,被接种苗木都形成了有效根瘤,其苗高、单株重量、生长状况明显高于对照,但同一树种对不同菌株的响应不同．     

根瘤菌浸根处理对相思苗木接种的效应初报

采用根瘤菌液体菌剂对马占相思、大叶相思和杂交相思苗木进行浸根处理接种试验。结果表明：根瘤菌浸根处理能明显提高相思苗木根系结瘤；苗木生长差异因育苗基质不同而表现不同，河沙基质无施肥条件下接种苗木的苗高、地径和长势均优于无接种苗木；黄心土加草皮灰基质中接种苗木的苗高、地径比无接种苗木略有增加，但不显著；杂交相思和大叶相思比马占相思容易人工接种形成根瘤。     

厚荚相思盆栽苗接种根瘤菌对其苗木生长的影响

厚荚相思盆栽苗接种9种根瘤菌菌株对其苗木生长影响的实验结果表明:在接种不同根瘤菌菌株后的20天至6个月中,其厚荚相思苗木的生长存在差异.此期间各根瘤菌菌株对厚荚相思苗木的苗高、地径、生物量的影响程度不同,接种厚荚6号、厚荚7号和厚荚5号3个菌株对厚荚相思苗木的生长影响较大,可初步评选为促进厚荚相思苗木生长的根瘤菌菌株.     

木麻黄根瘤内生菌纯培养接种效果试验*

用Ｆｒａｎｋｉａ纯培养接种木麻黄苗木试验，获得了明显效果，苗高、地径、根瘤数、根瘤鲜重及生物量均比对照高。在４个供试菌株中，接种Ｂｒ的效果最好，苗高、地径分别为对照的３．５倍和２．７倍，其次是Ｐ１。接种效果随着苗龄增加越来越明显。苗木的高度、地径、生物量与根瘤数量、根瘤重呈极显著的直线正相关。     

接种根瘤菌对厚荚相思水分胁迫的响应

以不同浓度的聚乙二醇(PEG-600)溶液模拟水分胁迫条件,比较了不同程度水分胁迫下接种根瘤菌与不接种根瘤菌对厚荚相思苗木的生理生化响应,分析了接种根瘤菌对厚荚相思的促进生长与结瘤效应.结果表明:根瘤菌同厚荚相思具有良好的共生固氮效应,接种根瘤菌使厚荚相思苗木生物量增加,促进结瘤,接种根瘤菌能够提高厚英相思的抗旱能力.     

相思菌根的菌种筛选及其接种效应研究

ＶＡ菌根、外生菌根主菌根菌剂对马占相思和厚荚相思幼苗的接种结果表明：ＶＡ菌根和外生菌根都可对两种相思幼苗形成侵染,菌根感染率达４９．５％～７３．３３％;５个月后的马占相思苗木高比对照增加５３．９％～１４８．９９％,厚荚相思苗高增加３１．７％～９５．３９％;马占相思生物量比对照增加２０８％～３９６％,厚荚相思生物量增加２９４％～４４１．５％;对ＶＡ菌的菌根依赖性（ＭＤ）测定结果表明,除厚荚相思对Ｂ９     

接种内生菌根菌对尖叶杜英高生长的影响

在不同栽培模式下应用内生菌根菌接种尖叶杜英幼苗试验证明,接种苗木高生长均明显高于对照。其中,营养袋苗接种高生长速度比对照高26.85%;盆苗接种比对照高8.14%;地栽苗接种苗比对照高12.88%。     

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.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

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。     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.