风信子组培快繁技术的研究

采用不同诱导、继代和生根培养基进行风信子组培快繁技术研究，结果表明：鳞片不定芽诱导的最佳培养基为MS 6-BA1．0—1．5mg／L NAA0．2—0．4mg／L；不定芽继代培养的最佳培养基为MS 6-BA1．0mg／L NAA0．2mg／L；最佳生根培养基为1／2MS NAA0．3mg／L；蛭石1份 珍珠岩1份 园土1份是风信子试管苗最佳的驯化移栽基质，在该基质中生根苗移栽成活率达90％。     

喜树茎段不定芽的诱导及再生系统的建立

选用1年生喜树带芽茎段为外植体，筛选出了喜树最佳诱导培养基为MS NAA0．05mg／L 6-BA1．0mg／L．诱导率为92％；芽增殖的最佳培养基是MS NAA0．1～0．5mg／L BA1．0mg／L．分化频率为82%～87％；壮茁培养基为MS NAA0．05mg／L BA0.3mg／L；最佳生根培养基为1／2MS NAA0．1mg／L IBA1．0mg／L．生根率为95％。初步建立了喜树无性微繁再生系统，并对喜树外植体选择及最佳生根条件进行了讨论。     

丽格海棠叶片的组织培养研究

取丽格海棠叶片作外植体,通过试验,分析不同激素配比对芽的诱导、增殖及生根的影响,筛选出丽格海棠叶片组织培养的适宜培养基及试管苗最佳移栽基质。结果表明：其最佳诱导培养基为MS＋6-BA1．5mg／L＋NAA0．8mg／L,不定芽诱导率达100％;最佳继代培养基是MS＋6-BA1．0mg／L＋NAA0．5mg／L,增殖倍数达6．5倍;最佳生根培养基是1／2MS＋NAA0．4mg／L,生根率达100％;试管苗最佳移栽基质为用1／2MS大量元素浇透的草炭,移栽成活率为85％。     

红金银花离体快繁技术

采用不同诱导、增殖和生根等培养基进行的红金银花离体快繁技术的研究结果表明：丛生芽诱导以MS 6-BA2．0～3．0mg，L NAA0．2mg/L培养基为好；以MS 6-BA2．0mg／L NAA0．2mg／L CW10％为增殖培养基可以获得理想的效果，增殖倍数达4．9倍；在不舍任何激素的1／2MS 0．15％活性炭培养基上即可形成较发达的根系，生根率达100％；试管苗移栽对基质要求不严，移栽到疏松透气的蛭石 珍珠岩 园土(1：1：1)混合基质中，成活率可达92％。     

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％。     

红蝉花的组织培养及快速繁殖技术

以红蝉花(Mandevilla sanderi)带腋芽的成熟茎段、幼嫩茎段和茎尖作为外植体进行试管培养的结果表明：茎尖是初代培养最适合的外植体，MS BA2．0～4．0mg／L NAA0．1mg／L有利于外植体腋芽的萌生；最有效的芽增殖培养基为MS BA4．0mg／L NAA0．01mg／L，增殖系数达到4．3；最有效的生根培养基为MS NAA2．0mg／L C0．2％，生根率可达76．7％。     

4个芦荟品种离体快繁技术研究

该文对库拉索、中华、木立和高尚4个芦荟品种离体快繁技术进行了研究。结果表明，库拉索和木立芦荟不定芽间接分化，库拉索主要是丛生芽＋愈伤组织方式，木立芦荟主要是愈伤组织的形式；中华芦荟和高尚芦荟主要是丛生芽方式直接分化。4个芦荟品种的最适继代增殖培养基库拉索为MS＋6-BA2．0mg／L＋NAA0．1mg／L，繁殖系数为7．29；中华芦荟为MS＋6-BA1．0mg／L＋NAA1．5mg／L，繁殖系数达6．64；木立芦荟为MS＋6-BA2．0mg／L＋NAA0．1mg／L，繁殖系数达14．0；高尚芦荟为MS＋6-BA1．0mg／L＋NAA0．1mg／L，繁殖系数达8．10。库拉索和中华芦荟的最适生根培养基为MS＋NAA0．5mg／L，生根率分别为86．5％和100％；木立和高尚芦荟为MS，生根率分别为99％和79％。最适移栽基质为珍珠岩：河沙：草炭土=1：1：1，成活率达92％。     

颐和园古西府海棠的组织培养与快速繁殖

以北京颐和园古西府海棠嫩枝为外植体进行组织培养研究,结果表明：取西府海棠当年新生嫩茎务切段为外植体进行组织培养,其中最适不定芽启动培养基为1／2MS＋IBA0．3mg／L＋NAA0．05mg／L;将无菌苗接种到分化培养基MS＋6－BA1．5mg／L＋NAA0．4mg／L上,组培苗生长健壮且分化率高,增殖系数可达4．16;不定根最适诱导培养基为1／2MS＋IBA0．6mg／L和1／2MS＋NAA1．0mg／L,生根率分别达100％、98％。炼苗基质为蛭石：珍珠岩体积比：1：1。试管苗移栽成活率达92％。     

罗扶木瓜组培快繁技术

以罗扶木瓜茎尖为试材进行离体组培快繁技术的研究结果表明：最佳诱导产生不定芽的培养基为MS 6-BA1．0mg／L NAA0．2mg／L，增殖培养基为MS 6-BA2．5mg／L NAA0．1mg／L，生根培养基1／2MS IBA0．2mg／L ABT1．0mg／L。试管苗经适宜条件练苗驯化的移植大田，成活率可达82％以上，而且生长良好。     

杏李种间杂交新品种“味王”胚培养与植株再生

以杏李品种“味王”幼胚为实验材料，探讨了幼胚愈伤组织诱导、丛生芽分化、生根的最佳实验条件，并成功地培育出了再生植株．结果表明：MS＋BA2．0mg／L＋NAA0．5mg／L为愈伤组织诱导的最佳培养基；MS＋BA1．5mg／L＋NAA0．5mg／L为丛生芽分化的最适培养基；MS＋NAA0．8mg／L为最理想的生根培养基；练苗在80％遮阳网下进行，移栽25d后成活率可达85％．     

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.