芽变毛白杨组织培养初步研究

以芽变毛白杨幼嫩枝条为外植体进行愈伤组织和茎段组织培养试验研究。结果表明:芽变毛白杨诱导愈伤组织培养基为:MS 6-BA 2.0~4.0 mg/L 2,4-D 1.5~2.0 mg/L NAA 0.25 mg/L KT 2.0~4.0 mg/L 3%蔗糖,愈伤组织分化芽培养基为MS 6-BA 0.5 mg/L NAA 0.5 mg/L KT 2.0 mg/L 3%蔗糖时,培养效果好。茎段培养时,适宜无根苗生长的培养基为MS 6-BA 0.5 mg/L NAA 0.1 mg/L 3%蔗糖,生根诱导适宜的培养基为1/2MS IBA 0.5~1.0 mg/L 1.5%蔗糖。     

不同激素对红豆杉愈伤组织诱导及增殖的影响

以南方红豆杉(T.chinensis varmairei)的嫩茎为外植体,探讨了不同激素对愈伤组织诱导及继代增殖的影响。结果表明:以嫩茎为外植体,愈伤组织诱导的最佳培养基为:B5+2,4-D2.0mg/L+6-BA0.5mg/L+蔗糖20g/L+琼脂8g/L+AC1g/L+酪蛋白1g/L,但高浓度的2,4-D易使愈伤组织褐化。为了减缓愈伤组织褐化和使细胞持续增殖,继代时选用NAA替代2,4-D,继代培养的最佳培养基为:B,5(去掉Cu2+的B5培养基)+NAA 4.0mg/L+KT0.5mg/L+蔗糖20g/L+琼脂8g/L+AC0.5g/L+酪蛋白1g/L。     

曼地亚红豆杉愈伤组织诱导试验

以5年生曼地亚红豆杉当年生枝条的茎段、芽苞、叶片和幼嫩根为外植体,以MS添加不同质量浓度的2,4-D,NAA,KT为培养基进行愈伤组织诱导试验。结果表明:曼地亚红豆杉愈伤组织诱导培养基中生长素与细胞分裂素的比例应在10∶1左右;2,4-D与NAA的比例应在2∶1左右。当年生茎段是进行曼地亚红豆杉愈伤组织诱导的较好外植体,诱导率高,愈伤组织生长也较好。暗培养条件更有利于愈伤组织的诱导,诱导率高,且诱导出的愈伤组织质量好。35℃温水浸泡30 min的处理对抑制褐化有理想的效果,外植体褐化现象得到了极大抑制。     

南方红豆杉组织培养育苗试验

以南方红豆杉(Taxes chinensisvar.mairei Cheng et L.K.Fu)的幼叶、幼嫩茎段、花蕾为外植体进行组织培养育苗试验,结果表明:①外植体诱导愈伤组织的容易程度为幼嫩茎段>幼叶>花蕾;②诱导南方红豆杉产生愈伤组织的最佳培养基配方是:MS+6-BA 0.5 mg.L-1+2,4-D 1.0 mg.L-1;③BA、ZT和KT均能诱导愈伤组织分化不定芽,其中以0.1 mg.L-1ZT效果最佳,诱导率达58%;④生根培养阶段,以附加NAA1.0 mg.L-1+0.1%活性碳的1/2 MS培养基效果最好,生根率达96%;⑤试管苗移栽在河沙+泥炭的基质上,成活率可达95%。     

喜马拉雅红豆杉愈伤组织的诱导

采用喜马拉雅红豆杉的幼叶、幼嫩茎段、幼根为材料,比较不同外植体、基本培养基、植物生长调节剂的配比、抗氧化剂以及培养条件对愈伤组织诱导的影响。结果表明,幼叶做为外植体时,其诱导率高于幼嫩茎段和幼根,愈伤组织量大;MS、1/2MS、B5和WPM基本培养基上均能诱导出愈伤组织,其中MS基本培养基上诱导效果最好,显著高于其他的基本培养基;MS培养基上添加1 mg/L 6-BA和0.5 mg/L 2,4-D配合使用时,诱导率达到93.6%,愈伤组织生长也最旺盛;基本培养基MS中添加1 mg/L Vc时褐变现象得到极大抑制,愈伤组织生长较好;暗培养有利于愈伤组织的诱导,且诱导出的愈伤组织质量好。     

珙桐组织培养研究

分别以MS、N6和B5为基本培养基,添加NAA与6-BA不同浓度组合于培养基中,以珙桐的叶片、茎、芽为外植体,诱导愈伤组织。结果表明:N6培养基的诱导愈伤效果略好于MS培养基和B5培养基,但效果不显著。同时使用NAA和6-BA时,以NAA2.0 mg/L加6-BA1.0 mg/L时效果较好。叶片、茎、芽3种外植体以芽诱导愈伤组织效果最明显。     

优系欧李茎叶愈伤组织诱导与植株再生

以欧李春季萌发的幼茎、叶片为外植体诱导愈伤组织的产生,结果表明:叶片愈伤组织培养以改良MS为基本培养基,附加NAA 1.0 mg/L IBA 0.5 mg/L BA 0.2 mg/L效果较好;茎段愈伤组织培养以改良MS附加2,4-D0.5 mg/L NAA 0.3 mg/L BA 0.15 mg/L诱导愈伤组织效果好;愈伤组织再诱导不定芽以1/3 MS附加BA2.0 mg/L IBA 0.01 mg/L培养基效果佳。     

朱樱花组培快繁技术研究

研究对朱樱花籽苗、幼苗茎段和叶片,成年植株茎段和嫩叶等不同外植体和不同生长调节剂对朱樱花愈伤组织诱导的影响,结果表明:不同外植体诱导愈伤组织的能力是:籽苗茎段带节茎段叶片,籽苗茎段和带节茎段是愈伤组织诱导的最佳外植体。用种子播种一个月后的籽苗作为外植体,愈伤组织诱导率高且不会褐化,其诱导最佳培养基配方为BA1.0mg/L+NAA2.0mg/L,诱导率为100%;多年生嫩茎产生的愈伤组织丛生芽诱导率为0%,以幼苗产生的愈伤组织进行丛生芽诱导,最佳培养基配方为BA2.0mg/L+NAA1.5mg/L,诱导率为100%。通过对1%升汞对外植体消毒时间的不同实验,得出1%升汞消毒外植体6min褐化率、污染率明显减少。     

珍稀濒危植物异形玉叶金花组织培养初步研究

以异形玉叶金花幼嫩茎段为外植体,研究不同组合的激素组合及外源物对异形玉叶金花愈伤组织诱导及分化的影响。结果表明:诱导愈伤组织的最佳培养基组合为MS+6-BA 0.2 mg/L+2,4-D 1.5 mg/L;愈伤组织分化的最佳培养基组合为MS+6-BA 2.0 mg/L+NAA 0.5 mg/L+5 g/L椰乳,诱导生根的最佳培养基组合为1/4 MS+0.5mg/L NAA+0.2 mg/L IBA。     

针叶十大功劳愈伤组织诱导研究

针叶十大功劳Mahonia fortunei生长期长、市场需求量大、野生资源日益匮乏的现状,首次以针叶十大功劳Folium Mahoniae茎、叶为外植体诱导愈伤组织生长.实验结果表明选用B5及MS培养基,温度24±1℃,暗培养条件下均可诱导出愈伤组织,但B5培养基更适宜于针对十大功劳愈伤组织诱导.培养基中添加植物激素2,4-D0.5 mg/L、KT0.5 mg/L时,愈伤组织诱导率最大,且外植体污染率最低.相同培养条件下,选用茎为外植体较选用叶片为外植体可获得更高的愈伤组织诱导率.培养基中添加3%蔗糖有利于愈伤组织的诱导,但添加NH4NO3则可明显降低愈伤组织诱导率.研究结果对开展十大功劳的人工繁殖研究具有一定的参考价值.     

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.     

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.     

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.     

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。