人心果成熟胚离体培养及愈伤组织诱导

对越南人心果的成熟种胚进行离体培养诱导无菌苗．最佳培养基是MS,最佳激素配比是NAA0．2mg／L BA5．0mg／L。再以无菌苗的茎为外植体进行不定芽的诱导试验,其结果表明．不定芽诱导的最佳培养基及其激素配比为MS NAA0．2mg／L 2．4-D5．0mg／L．最佳环境条件是光照13h／d．光强2000lx．温度30℃。而以无菌苗的幼叶为外植体进行愈伤组织诱导和继代培养的最佳培养基为MS 6-BA2．5mg／L 2．4-D1．0mg／L 1AA0．5mg／L。在继代培养过程中,5mg／L或10mg／L的AgNO3和2000mg／L PVP可抑制愈伤组织褐变。     

云南萝芙木叶愈伤组织诱导与植株再生

研究了云南萝芙木叶愈伤组织的诱导及器官发生条件．结果表明：诱导愈伤组织的培养基为Ms＋2,4-D2．0mg／L＋6-BA0．5mg／L;诱导愈伤组织芽分化和增殖的培养基分别为MS＋6-BA3．0mg／L＋NAA0．05mg／L和MS＋6BA3.0mg／L＋NAA0．1mg／L;根分化的最适培养基为1／2 MS＋NAA0．8mg／L;生根苗经练苗后移栽,成活率达90N,生长良好．     

花叶木槿组织培养技术的研究

以花叶木槿叶片、茎段、芽为外植体进行的离体再生研究结果表明,叶片愈伤组织诱导最佳的培养基是MS＋6-BA2mg／L＋NAA0．2mg／L＋2,4-D0．2mg／L;茎段在MS＋6～BA3mg／L＋NAA0．4mg／L上诱导的愈伤组织有不定芽分化,分化率45％;芽在MS＋6-BA3mg／L＋NAA0．4mg／L培养基上效果较好,在MS＋6-BA1mg／L＋NAA0．2mg／L上生根效果最好,可达100％。     

毛竹愈伤组织培养研究

以毛竹春笋为培养材料进行愈伤组织诱导,分析了不同的激素组合、温度及光照对愈伤组织诱导的影响。结果表明以MS为基本培养基,在NAA与6-BA的组合中,NAA（0．5—10mg／L）＋6-BA（0．5—5mg／L）都能诱导出愈伤组织;在2,4-D与6-BA的组合中,2,4-D（0．1—5mg／L）＋6-BA（0．5—5mg／L）也都能诱导出愈伤组织;但2,4-D的组合比NAA组合的效果好一些。其中3mg／L2,4-D＋1mg／L6-BA在20℃、3％蔗糖、0．9％琼脂、暗培养条件下愈伤组织诱导率达100％,且状态最好。     

杂交榛不同外植体的培养

对佳木斯大学抗寒鉴定圃的杂交榛进行离体培养,分别以其茎段、叶片、子叶和胚为外植体进行初代培养,结果表明：（1）茎段初代培养适宜的培养基为MS＋6-BA3．0mg／L＋NAA0．1mg／L;（2）叶片初代培养适宜的培养基为Ms＋6-BA3．0mg／L＋NAA1．0mg／L;（3）适宜诱导子叶愈伤组织的培养基为MS＋6-BA3．0mg／L＋NAA0．1mg／L＋2,4-D0．1mg／L;（4）利于胚分化成苗的培养基为MS＋KT3．0mg／L＋NAA0．1mg／L＋2,4-D0．1mg／L。     

蜘蛛兰的组织培养

本试验以蜘蛛兰叶片为外植体,研究了蜘蛛兰愈伤组织诱寻和芽分化的最适NAA和6-BA的浓度组合以及诱导生根的最适NAA浓度．结果表明：①愈伤组织诱导最适培养基为MS NAA1mg／L 6-BA2mg／L：③愈伤组织诱导芽分化最适培养基为MS NAA1mg／L 6-BA2．5mg／L;③诱导生根的最适NAA浓度为1mg／L。     

野葛愈伤组织诱导与不定芽分化

采用MS为基本培养基，附加NAA、6-BA和IAA3种激素．诱导野葛不同外植体愈伤组织形成；再将愈伤组织接种在不同浓度6-BA的MS培养基上．分别在光照和黑暗条件下进行不定芽的诱导。结果表明．野葛幼叶、茎段和顶芽在适宜激素的诱导下均能形成愈伤组织，但不同激素组合其愈伤组织诱导率不同。幼叶愈伤组织诱导的最适培养基为MS NAA1．0mg／L 6-BA1．0mg/L．其诱导率为75％．茎段愈伤组织诱导的最适培养基为MS NAA1．0mg／L 6-BA3．0mg／L IAA0．2mg/L，其诱导率为70％。不同外植体形成的愈伤组织其不定芽的分化诱导率不同．茎段愈伤组织在不同浓度6-BA下均能诱导出不定芽；光照有利于芽的分化．在光培养条件下，茎段愈伤组织不定芽平均诱导率为66．7％。     

不同激素配比对油茶花药愈伤组织形成的影响

为了加快油茶品种改良,提高油茶花药愈伤组织的诱导效率,在低温预处理（4℃）的基础上,以MS为基本培养基,研究了不同浓度的2,4-D、NAA及2,4-D、6-BA配比对普通油茶花药愈伤组织诱导效率的影响。结果表明：2,4-D、NAA诱导普通油茶愈伤组织的较优组合为2,4-D0．6mg／L,NAA0．05或0．5mg／L,愈伤组织诱导率分别达到35．56％和24．65％,在油茶花药愈伤组织诱导过程中。2,4-D有利于愈伤组织的形成,是最重要的因素;2,4-D、6-BA的混合使用更有利于愈伤组织的发生,并且两种激素适当的配比是提高愈伤组织诱导率的重要因素,0．5mg／L的2,4-D与0．2mg／L6-BA组合是实验得出的较优水平,愈伤组织诱导率达到42．74％。     

木瓜海棠组织培养技术的研究

以木瓜海棠当年生嫩枝上带有腋芽的茎段为外植体，运用对比试验和正交设计等方法，对木瓜海棠试管苗的快繁、生根、叶片和茎段愈伤组织的诱导进行研究。结果表明：快繁最适培养基为：MS＋6-BA1．0mg／L＋NAA0．1mg／L＋2，4-D0．2mg／L，增殖系数可达8．7；采用一步生根法最佳培养基为：1／2MS＋IBA1mg／L＋NAA0．2mg／L；在MS＋6-BA4．0mg／L＋2，4-D0.5mg/L的培养基上愈伤组织生长的较快，结构正常。     

红姜花叶片培养及植株再生

对红姜花组织培养进行研究，试验结果表明：诱导红姜花叶片产生愈伤组织效果较好的培养基是MS 6-BA0，5mg／L 2，4-D1．0mg／L；最适于愈伤组织分化的基本培养基是N6：6-BA、ZT和KT均能诱导愈伤组织分化不定芽，其中以6-BA为最好，在所试的6-BA浓度中，以3．5mg／L的效果较佳；生根培养阶段，以附加NAA0．8mg／L或IBA0．8mg／L 0．15％活性炭的1／2MS培养基效果较好，生根率达100％；在河沙上，试管苗移栽成活率可达93．3％。     

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.     

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.     

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.     

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。     

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.