高山杜鹃叶片再生植株的研究

研究高山杜鹃叶片再生植株无菌培养物建立、初代培养、继代培养和生根培养4个技术环节,最终建立高山杜鹃组培快速繁殖技术体系。结果表明:适宜的叶片诱导不定芽再生的培养基为WPM+TDZ0.2mg/L+NAA0.4mg/L;继代增殖培养基为WPM+KT2mg/L+NAA0.2mg/L;生根培养基为1/2MS+IBA5g/L+糖20g/L+活性碳0.5%。     

灯台树组培快繁技术研究

以灯台树带顶芽的茎段为外植体,进行了组培快繁研究。结果表明,启动培养基采用WPM BA0.5 mg/L IBA 0.2 mg/L GA31 mg/L为宜;继代增殖培养基采用M BA 1 mg/L IBA 0.2 mg/L GA32 mg/L为宜,增殖系数达4.4;生根培养则以1/2M IBA 3 mg/L配合10 d暗培养效果最好,生根率达60.0%。     

钙果6号组织培养技术研究

以钙果6号幼嫩的茎尖和茎段为外植体,对初代培养、继代培养和生根培养阶段的培养基进行筛选的结果表明,适合钙果的初代培养基配方为BA1.0mg/L+NAA0.05mg/L、继代培养基为MS+BA0.5mg/L+NAA0.05mg/L、生根培养基为1/2MS+IBA0.05mg/L。     

橡皮树的离体快繁技术研究

用MS为基本培养基,以6-BA、NAA、IBA、LH不同含量配制成培养基,在温度、光照时间和强度相同的情况下试验。其结果表明,诱导阶段可选MS+6BA0.2mg/L+NAA0.1mg/L;继代培养基可选择1/2MS+IBA0.2mg/L+NAA0.2mg/L+LH1.0mg/L;生根培养可选1/2MS+IBA0.2mg/L+NAA0.2mg/L。     

野百合组织培养的研究

以野百合鳞茎、叶片为外植体通过继代培养和生根培养,诱导不定芽的发生,进而获到再生植株。试验结果表明:用MS培养基培养野百合鳞茎、叶片组织,均能够诱导不定芽产生;在培养基中附加BA2.5mg/L和NAA0.2mg/L有利于鳞茎不定芽的诱导且芽苗长势好,而叶片则在培养基中附加BA1.5mg/L、NAA0.2mg/L的培养效果最佳;从不定芽诱导出根以1/2MS效果最好。     

华富苹果离体叶片再生的主要影响因素研究

以花药培养选育的富士品种"华富"组培苗的叶片为试材,研究了离体叶片诱导再生不定芽过程中不同激素种类与组合、暗处理时间等因素对不定芽再生率的影响。结果表明:试管苗继代培养3～4代,取顶部嫩叶3～4片,剪除叶片边缘,叶片以近轴面接种到最佳诱导再生培养基MS+TDZ 2.0mg/L+IAA 0.75mg/L+蔗糖30g/L,pH值5.8,黑暗培养10～15d后,转入光照培养条件下,再生率达83.3%～86.7%。再生不定芽分化15～20d后转接到增殖培养基MS+BA 0.5mg/L+IBA 0.1mg/L上,当不定芽长度约2cm时再转接到生根培养基1/2MS+IAA 1.0mg/L+蔗糖2%,15d后,生根率可达95.0%以上。     

重瓣大岩桐茎尖培养与快速繁殖

以重瓣大岩桐茎尖为外殖体,进行组织培养,结果表明,茎尖可诱导形成愈伤组织及再生小植株。经试验筛选出各培养阶段最适宜的培养基为;①愈伤组织诱导培养基:MS BA1.5mg/L NAA0.2mg/L;②分化继代培养基:MS BA1.0mg/L NAA0.1mg/L;③生根培养基:l/2MS IBA0.2mg/L。     

葡萄不定芽离体诱导再生植株的研究

进行了紫苑、魏可和砧木 99R几个葡萄品种不定芽离体诱导再生植株的研究。实验通过对其叶片、叶柄、茎段外植体的诱导再分化 ,以器官发生途径实现植株再生。结果表明 :不同品种间存在差异 :(1)紫苑不定芽诱导再生效果最好 ,其中用IBA与TDZ组合诱导最好 ,叶柄在MS +IBA0 .2 0mg/L +TDZ0 .75mg/L培养基中再生率高达 4 2 .9% ;用IBA与BA组合效果也较好 ,叶柄和茎段在MS +IBA0 .0 5mg/L +BA2 .0mg/L中再生率达 30 .8%。 (2 )魏可叶柄不定芽诱导再生在MS +IBA0 .2 0mg/L +BA2 .0mg/L培养基再生率 2 0 .0 %。 (3)砧木品种 99R不定芽诱导再生率较低 ,叶片在MS +IBA0 .0 1mg/L +BA1.5mg/L培养基中再生率 2 0 .8%。(4)栽培品种比砧木易于诱导再生不定芽     

洋丁香组织培养的研究

以植物园洋丁香茎段为试验材料,利用组织培养技术,筛选出诱导分化、继代增殖和生根的最佳培养基。结果表明:芽继代增殖培养基为:1/3MS+2,4D0.05(mg/L)+IBA2.0(mg/L)+NAA0.2(mg/L),最佳壮苗培养基为1/3MS+6-BA0.2(mg/L)+IBA1.0(mg/L)。最适合的生根培养基为MS+NAA0.2(mg/L)+IBA2.0(mg/L)+GA0.5(mg/L)。     

双色茉莉茎段离体培养再生植株的研究

以双色茉莉茎段为外植体,探讨外植体取材季节和部位、基本培养基种类、植物生长调节剂组合、活性炭等对茎段器官发生和植株再生的影响.结果表明:在4月和10月取材最好,其诱导率分别达到了92.780/和84%,污染率最低;1/2MS 0.01 mg/L NAA 3.0 mg/L BA 2.0 mg/L KT培养基最适合不定芽的诱导分化,不定芽分化率达到了88.34%;在继代增殖培养中,继代次数最好在6代以内,否则增殖率下降,MS 0.5mg/L IBA 3.0mg/LBA 0.2%活性炭培养基最适合不定芽的增殖(5.92)和大于2cm芽的分化(47.16%).不定芽可在1/2MS培养基中有效伸长,适宜的生根培养基为1/2MS 1.0 mg/L IBA 0.2 mg/L BA,生根率达到100%.     

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.     

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.     

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。