何首乌茎段快速繁殖技术的研究

对何首乌茎段快繁技术进行了研究。结果表明：何首乌最佳诱导培养基为MS＋6-BA1．0mg／L＋NAA0．05mg／L或Ms＋6-BA1．0mg／L＋NAA0．02mg／L，对于芽增殖，以MS＋6-BA1．0mg／L＋NAA0．05mg／L培养基较好，培养30d后芽增殖率可达到4．02。诱导生根培养基以1／2MS＋6-BA1．0mg／L＋NAA0．1mg／L或MS＋6-BA0．5mg／L＋NAA0．05mg／L较好，培养20d后生根率分别可达91．7％和96．3％。     

铁线莲＂茱莉亚＂的组织培养研究

以铁线莲“茱莉亚”的茎段和茎节为外植体,在MS基本培养基中添加2．0、3．0mg／L6-BA,0．05、0．1mg／I。NAA和1．5、2．0mg／LKT,对其进行了初代诱导和继代增殖培养。结果表明：粗嫩茎的成活率远高于细嫩茎,可达到96．3％;MS＋2．0mg／L6-BA＋0．05mg／LNAA＋1．0mg／LKT对“莱莉亚”茎段的诱导优于茎节,达到64．4％;MS＋3．0mg／L6-BA＋0．1mg／LNAA＋1．5mg／LKT适合愈伤组织的增殖,茎段和茎节的愈伤增殖率均在90％以上。     

观赏金线莲组培快繁技术研究

以优良观赏金线莲茎段、茎尖、叶片为试材,研究其再生植株在不同外源激素配比下的适宜培养基。试验结果表明：观赏金线莲最适于启动培养基为MS＋6-BA2．0mg／L＋NAA0．2mg／L。最佳的促进侧芽增殖的组合是MS＋6-BA3．0mg／L＋NAA0．1mg／L。1／2MS＋IBAl．5mg／L＋NAA1．5mg／L＋活性炭0.5mg／L为诱导生根的最佳组合。     

花叶木槿组织培养技术的研究

以花叶木槿叶片、茎段、芽为外植体进行的离体再生研究结果表明,叶片愈伤组织诱导最佳的培养基是MS＋6-BA2mg／L＋NAA0．2mg／L＋2,4-D0．2mg／L;茎段在MS＋6～BA3mg／L＋NAA0．4mg／L上诱导的愈伤组织有不定芽分化,分化率45％;芽在MS＋6-BA3mg／L＋NAA0．4mg／L培养基上效果较好,在MS＋6-BA1mg／L＋NAA0．2mg／L上生根效果最好,可达100％。     

油茶组织培养繁殖技术初步研究

以油茶（Camellia oleifera）种子胚芽和2a生扦插苗带侧芽的嫩枝作外植体进行组织培养技术研究。结果表明：适合油茶种子胚芽诱导的培养基为MS＋6-BA2．0mg／L．4-NAA0．2mg／L＋GA31．0mg／L＋蔗糖30g／L＋卡拉胶6．5g／L,适宜的增殖培养基为MS＋6-BA1．5mg／L＋NAA0．1mg／L＋GA31．0mg／L＋蔗糖30g／L＋卡拉胶6．5g／L,增殖倍数为3．50;适合油茶不定芽诱导的培养基为MS＋6-BA1．5mg／L＋IAA2．0mg／L＋GA,1．0mg／L＋蔗糖30g／L＋卡拉胶6．5g／L,适宜的增殖培养基为MS＋6-BA2．0mg／L＋IAA1．0mg／L＋GA,1．0mg／L＋蔗糖30g／L＋卡拉胶6．5g／L,增殖倍数为3．96。木质化程度已较高的油茶组培茎芽适宜的生根基质为细沙,生根率达95％。     

大叶女贞组培快繁体系的建立

选用大叶女贞1年生木质化带芽茎段、腋芽、幼嫩新梢、萌蘖茎段和秋梢为外植体进行组织培养研究,结果表明：最适消毒处理是0．1％HgCl2 5min,最适外植体是萌蘖茎段和幼嫩新梢。萌蘖枝条适宜的起始培养基为MS＋6-BA 0．5mg／L＋NAA 0．1mg／L;幼嫩新梢适宜的起始培养基是MS＋6-BA 1．0mg／L＋NAA 0.05mg／L;最适增殖培养基是MS＋6-BA 4．0mg／L＋NAA 0．1mg／L,增殖系数为4．42。     

紫叶黄栌观赏特性及快繁技术研究

以紫叶黄栌的当年生嫩枝茎段为外植体进行簇生芽诱导,研究结果表明,诱导簇生芽时,在MS 6-BA2．0 mg／L NAA0．2 mg／L培养基上的诱导效果较好,分化率达100％;继代培养时,以MS 6-BA1．0 mg／L KT 0．5 mg／L NAA0．1 mg／L培养基增殖倍数较高,达到11．8倍;再生苗在1/2MS NAA0．1 mg／L的培养基上生长良好;在炼苗中,移栽基质以蛭石 森林土较好,可促进小苗后期生长。     

夏蜡梅组织培养试验初报

以夏蜡梅茎段为外植体，进行夏蜡梅组培试验，结果表明：外植体茎段的最佳消毒方式是先用70％酒精消毒10—15s，再用0．1％HgCl溶液浸泡3—5min；继代增殖培养的最佳培养基为MS＋6-BA2．0mg／L＋NAA0．1mg／L＋蔗糖30g/L，增殖系数4．03，茎芽生长粗壮；最佳生根培养基为I／2MS＋IBA0．4mg/L。     

巨桉组培育苗技术研究

以巨桉成龄树基部萌芽条的茎段为外植体,通过3种基本培养基和9种生长调节剂不同浓度组合的对比试验,筛选出MS＋6-BA0．4mg／L＋NAA0．2mg／L为诱导培养基,改良MS＋6-BA0．5mg／L＋NAA0．3mg／L为继代培养基,B2＋ABT1号生根粉0．8mg／L为生根培养基。应用这些配方进行巨桉组培,芽增殖数达3．26倍,瓶苗生根率达98％,移植成活率90％以上,达到了工厂化苗木生产的要求。     

菊花组培育苗试验

以菊花妃冠嫩叶及带腋芽的茎段为外植体进行组培育苗试验,确定适宜的外植体为带腋芽的茎段;适宜继代培养基为MS＋6-BA2．0mg／L＋NAA0．1mg／L;适宜生根培养基为1／2MS＋NAA0．5mg／L。以珍珠岩为移栽基质,成活率可达95％。     

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.     

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.     

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.     

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.     

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.     

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。