两种优良巴西杂交桉树的组织培养和快速繁殖

本研究以巴西尾巨桉和巨赤桉两种优良杂交桉树的带芽茎段为外植体进行离体培养和快速繁殖研究.结果表明:尾巨桉和巨赤桉再生芽诱导的最佳培养基为改良MS+6-BA 0.5 mg·L-1+NAA 0.2 mg·L-1,继代增殖的最适培养基为改良MS+6-BA 0.5 mg·L-1+NAA 0.15 mg·L-1.芽诱导和继代增殖中6-BA的浓度对两种杂交桉树有显著影响.生根培养中,尾巨桉和巨赤桉生根情况差异显著,尾巨桉茎芽最适生根培养基为1/2MS+NAA0.2 mg·L-1+IBA 1.0 mg·L-1,巨赤桉茎芽最适生根培养基为1/2MS+NAA 0.15 mg·L-1+IBA 1.0 mg·L-1.两种杂交桉树组织培养体系的建立,为桉树良种选育和遗传转化体系的研究提供技术参考.     

银莓离体快繁技术研究

以银莓当年生枝的顶芽和腋芽为外植体,以MS为基本培养基,添加不同配比的植物生长调节剂进行离体培养.结果表明:芽诱导最适宜的培养基为MS+6-BA3.0 mg·L-1+NAA3.0 mg·L-1+蔗糖30 g·L-1+琼脂4.5 g·L-1,增殖培养基为MS+6-BA1.0 mg·L-1+NAA1.0 mg·L-1+蔗糖...     

金合欢组织培养技术研究

以金合欢2a生优树的带芽茎段为材料,着重研究不同激素浓度及其配比对金合欢组织培养各环节的影响,探索适宜的启动、增殖、生根培养基配方.结果表明:适宜的启动培养基配方为:3/4MS+6-BA1.0 mg· L-1+IBA0.5 mg·L-1;适宜的增殖培养基配方为:MS +6-BA0.5 mg·L-1+ NAA0.3 mg·L-1+ NaH2PO440 mg·L-1,月增殖系数可达3.83;适宜的生根培养基配方为:1/2MS+ IBA0.6 mg·L-1+ NAA0.2 mg·L-1,生根率可达86％,生根效果较理想.     

文冠果组织培养研究

以文冠果茎段为外植体,进行组织培养,试验结果表明:MS+6-BA 0.5mg·L-1+IBA 1.0mg·L-1最适宜不定芽诱导;MS+KT 1.0mg·L-1+IBA 0.5mg·L-1最适宜芽分化培养;生根最佳培养基为1/2MS+IBA 0.5mg·L-1+NAA 0.1mg·L-1。     

红丝线组织培养技术研究

选用红丝线当年生枝条为外植体,开展红丝线组培快繁技术研究.结果表明,在红丝线组织培养过程中,基本培养基以MS较佳;初代诱导的最适培养基为:MS +6-BA 2.0 mg·L-1,诱导率80％;芽增殖的最适培养基为:MS+ 6-BA 0.5 mg·L-+ NAA 0.05 mg·L-1,增殖系数达5.9;最适生根培养基为:MS+ IBA 0.1 mg·L-1+ NAA 0.3mg·L-1,生根率100％;移栽存活率高达98.6％.     

油茶优良无性系组织培养与植株再生

以油茶优良无性系的腋芽为外植体,分别采用附加不同种类激素的MS培养基对其进行组织培养试验,结果表明:不定芽的最佳继代增殖培养基为MS+6-BA0.8 mg.L-1+NAA0.1 mg.L-1,诱导生根最适培养基为1/2MS+IBA0.5 mg.L-1+NAA0.2 mg.L-1,生根率达87.5%。     

黑果腺肋花楸的组织培养快繁技术

为建立黑果腺肋花楸高效的离体再生体系,对其组织培养快繁技术进行系统研究。结果表明:以茎尖和幼嫩茎段为外植体,最佳诱导培养基为MS+6-BA 1 mg·L-1+NAA 0.5 mg·L-1,诱导率均在90%以上;最佳增殖培养基MS+6-BA 1 mg·L-1+NAA 0.2 mg·L-1,增殖系数达9.0;最佳生根培养基为1/2MS+ABT 6.0 mg·L-1,生根率达100%。     

钟花樱组织培养繁殖研究

以钟花樱(Cerasus campanulata)的嫩枝作外植体进行组织培养技术研究。结果表明：适合不定芽诱导的培养基为 MS+6-BA 1.0 mg · L-1+NAA 0.1 mg · L-1+蔗糖30 g · L-1+卡拉胶6.5 g · L-1,诱导率为44.44%,适合增殖培养的培养基为 MS+6-BA 1.0 mg · L-1+NAA 0.05 mg · L-1+GA30.5 mg · L-1+蔗糖30 g · L-1+卡拉胶6.5 g · L-1,增殖倍数为3.70,适合生根培养的培养基为1/2 MS+IBA 1.5 mg · L-1+NAA 0.1 mg · L-1+蔗糖30 g · L-1+卡拉胶6.5 g · L-1+活性碳0.5 g · L-1,生根率为82.23%。     

高精油互叶白千层组培快繁技术

以高精油含量的互叶白千层优良单株(H21、H35、H38)为试验材料,通过茎段离体培养,开展不同单株的组培快繁技术研究。结果表明,3个单株在诱导培养基MS+1.0mg·L-16-BA+0.05mg·L-1NAA上均取得较高的诱导率,但单株间诱导率存在极显著差异;H21、H35、H38在最佳增殖培养基(B1+1.5mg·L-16-BA+0.01mg·L-1NAA)上增殖培养40d,其增殖倍率分别为4.1、5.3、5.6,有效芽苗率高达90%以上;H21、H35、H38在培养基1/2B1+0.5mg·L-1ABT+0.5mg·L-1NAA诱导生根,生根率分别为65%、96%、93%,最佳生根培养基为1/2MS+0.5mg·L-1ABT+0.5mg·L-1NAA;以纯黄心土为移栽基质,炼苗30d,3个无性系平均移栽成活率高达84.8%。     

五叶地锦离体培养及植株再生

以五叶地锦(Parthenocissus quinquefolia)子叶柄、下胚轴、叶片为外植体进行离体培养,以1/2 MS、B5和Heller为基本培养基,附加不同浓度的细胞分裂素(6-BA,KT, TDZ)及生长素(NAA)诱导下胚轴直接再生不定芽.实验结果表明,暗处理30 d,靠近下胚轴的子叶柄接种在1/2 MS 0.3 mg·L-16-BA培养基上,其不定芽分化率最高达64.67%;下胚轴接种在1/2 MS 2.0 mg·L-1KT 0.05 mg·L-1NAA和Heller 0.5 mg·L-1BA 0.1 mg·L-1NAA培养基上,其不定芽分化率接近,达到24%左右;无菌苗的叶片接种在B5 0.5 mg·L-1TDZ 0.05 mg·L-1NAA培养基上,其不定芽分化率达17.7%.芽增殖培养基为1/2 MS 0.5 mg·L-16-BA 0.1 mg·L-1NAA增殖系数为3～5, 1/2 MS 0.5 mg·L-1IBA 500 mg·L-1活性炭适于再生幼苗的生根,生根苗经移栽全部成活.     

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.     

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.     

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.     

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。