平榛离体培养技术的研究

对平榛外植体不同取材时期和外植体种类对初代培养的影响及增殖培养阶段不同激素对增殖生长的影响进行研究.结果表明:外植体种类与取材时间是平榛离体培养的关键,最佳外植体为休眠过后室内萌发的嫩梢顶芽,其污染率低,萌芽率可达83.33%;适宜平榛离体培养的基本培养基为DKW培养基;芽分化阶段较好的培养基为DKW+TDZ 1.0mg/L+IBA 0.01mg/L+GA0.2mg/L;继代增殖培养阶段,细胞分裂素TDZ和生长素IBA的组合最有利于芽的增殖生长,其最适浓度分别为0.5mg/L和0.1mg/L,增殖倍数为3.2.     

卷荚相思优树无性系快速繁殖技术

采用卷英相思优树半木质化的带腋芽茎段为外植体,进行外植体消毒、不定芽分化、继代增殖和壮苗生根适宜条件的研究.结果表明:卷英相思不定芽增殖适宜的细胞分裂素为6-BA0.4mg/L,生长素为NAA 0.01 mg/L或IBA 0.05 mg/L;生根壮苗适宜的生长素为IAA 0.16 mg/L,添加1.0 mg/L活性炭可完全抑制不定根的发生.     

大花、重瓣型非洲紫罗兰组织培养技术研究

对大花、重瓣型非洲紫罗兰(Saintpaulia ionantha)的组织培养研究表明,外植体消毒以0.1%的升汞溶液浸泡5~6 min为宜;不同激素浓度对其愈伤组织诱导、愈伤组织分化、芽丛形成及根的形成有不同的影响;生长素与细胞分裂素的比例决定着愈伤及芽丛的形成;小苗在1/2MS培养基上生根最好。各培养阶段的最适培养基分别为:愈伤组织诱导MS+6-BA1.0 mg/L+NAA 0.5mg/L,芽分化及增殖培养MS+6-BA 2.0 mg/L+NAA0.5 mg/L,生根培养1/2MS+NAA0.1 mg/L或1/2MS+IBA0.1 mg/L。     

红星梨叶片不定梢诱导及增殖培养

为了找到红星梨叶片离体培养的最佳条件,从取材时间、暗培养、植物生长调节物质、不同继代次数等方面研究其对红星梨叶片再生的影响。结果表明:外植体取4月初的茎段较好,选用继代2次植株的叶片,细胞分裂素BA比TDZ效果好,生长素IBA比NAA效果好,暗培养30d,适合叶片再生的培养基为NN69+BA 5.0mg/L+IBA 0.3 mg/L,适合再生苗增殖的培养基为MS+BA 1.0mg/L+IBA 0.2mg/L+GA 0.2mg/L。     

植物激素对光叶楮试管苗生长的影响

通过BA、NAA、IBA、IAA对光叶楮试管苗生长的影响研究结果表明,光叶楮增殖时用细胞分裂素BA和生长素NAA为好,其适宜的浓度分别为1.0~1.5 mg/L和0.5 mg/L,培养21 d增殖系数为3.6~4.5。     

彩叶朱蕉组织培养育苗技术研究

以彩叶朱蕉优株顶芽和茎段为外植体,设计不同浓度细胞分裂素、生长素以及培养基组合,诱导芽分化、增殖和生根.MS+6-BA 3.0 mg/L+NAA 0.01 mg/L+蔗糖30g/L培养基适用于诱导芽的形成,3/4MS+6-BA 2.0 mg/L+NAA 0.01 mg/L+蔗糖30g/L培养基适用于芽的增殖,3/4MS...     

大花蕙兰的嫩根与根兜组织快繁技术研究

取大花蕙兰的的嫩根和根兜为外植体在MS培养基上用不同浓度的细胞分裂素BA和生长素NAA进行了研究。结果表明：根兜的分化率比嫩根高,而最适合的培养基配方为MS＋BA1.5 mg/L＋NAA0.5 mg/L＋蔗糖30 g/L＋琼脂8 g/L。可直接分化成小苗,增殖的同时可获得健壮的再生植株。最适的生根培养基为：MS＋NAA0.3 mg/L＋活性碳1.0/L＋蔗糖25 g/L＋琼脂7 g/L。     

香花槐生物学特性及其芽分化影响因素研究

研究了影响香花槐组织培养芽分化的主要因素,包括:外植体取材时期、消毒处理、基本培养基、细胞分裂素种类与浓度配比、细胞分裂素与生长素配比等。结果表明:M是最佳基本培养基;适合香花槐增殖分化的细胞分类素为浓度0.5mg L-1的6-BA;香花槐增殖培养的最佳组合为6-BA0.5mg L-1+IBA0.05mg L-1+2%蔗糖。     

扁桃茎尖组织培养的研究

为快速繁殖扁桃,以从美国引种的5个品种为试材,从取材、材料的处理、外植体的诱导分化、芽的增殖、生根以及影响试管苗形成的重要因子等方面探讨了扁桃组织培养的技术和方法。经研究得出生长素与细胞分裂素对芽的诱导分化及芽的增殖最佳配比浓度为：在改良MS基本培养基上添加0.5mg/L的NAA,0.5mg/L的KT,0.1mg/L的BA,此配比浓度产生的扁桃有效苗最多;而添加1.5～2.0mg/L的IBA生长素有利于扁桃组培苗生根。     

樟树组织培养快繁育苗技术研究

文章报道了应用组织培养育苗技术对樟树家系进行快速繁殖的初步结果.试验表明:带腋芽的茎段外植体在添加细胞分裂素和生长素的MS培养基上可分化形成不定芽,但芽增殖和继代培养过程并不需要添加生长素.在DCR BA 3.0 mg/L的培养基上增殖培养时,平均每个外植体增殖4.7个不定芽,高度小于1.5 cm的不定芽的比例为74.1%;而在DCR BA 4.0 mg/L的培养基上培养时,平均每个外植体增殖2.4个不定芽,高度大于1.5 cm的枝芽比例可提高至58.1%.枝芽接种在DCR IBA 1.5 mg/L的培养基上诱导生根培养28 d的生根率为98%,移植的再生植株95%以上存活.     

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。