桃儿七组织培养苗炼苗移栽技术

从炼苗时间、移栽基质、移栽季节等方面对桃儿七组培苗炼苗移栽技术进行了研究。结果表明,一定范围内,炼苗时间越长组培苗移栽成活率越高,开瓶炼苗5d最适宜出瓶移栽;移栽基质选用草炭土与珍珠岩按2∶1比例混合,成活率最高,25～30d均有新叶和新根长出。在兰州地区,10—11月和3—4月适宜进行桃儿七组培苗的移栽,成活率最高达98.1%。移栽后10个月,植株生长健壮,根系发达。本研究结果为利用组织培养技术进行桃儿七的快速繁殖提供技术支撑。     

美国红栌组培苗温室移栽技术

以美国红栌组培苗为材料,初步研究了炼苗时间、移栽基质等因素对组培苗移栽成活率及苗生长质量的影响.结果表明,在温室自然光照条件下,瓶内闭盖炼苗最适宜的时间为8～12 d,然后开盖炼苗2 d;移栽基质以芬兰进口草炭土与珍珠岩按体积比3:2混合或国产草炭土与珍珠岩等体积混合较适宜,移栽成活率及苗高分别达90%和12 cm.     

刺五加组培苗移栽炼苗技术研究

在日光温室中,对刺五加组培苗进行移栽炼苗试验的研究结果表明:自然光照射4天,打开瓶口并敷上一层纱布后,再经3天充分的炼苗可以提高成活率;组培苗移栽的适宜时期为11月～翌年3月;移栽基质为腐叶土:园田土=1∶1的复合土,移栽成活率可达80％以上.     

千层金组培瓶苗移栽试验

运用正交试验的方法研究不同基质、不同炼苗时间以及不同遮阳网遮光率对千层金组培瓶苗的移栽效果,结果表明:基质为木屑:泥炭土(1:1),炼苗时间为15 d,遮阳网遮光率为50%对于千层金组培瓶苗移栽效果最好,成活率达到97.9%.     

蕨类植物组培苗炼苗及移栽技术

我国拥有丰富的蕨类植物资源,其在药用、食用和观赏方面具有较高的利用和经济开发价值。移栽作为影响蕨类植物组培苗出瓶后成活率的关键环节,决定了组培苗能否顺利从室内培养应用到大田生产中。文章在前人工作的基础上,对蕨类植物组培苗的出瓶时间、炼苗方式以及移栽的基质、温度、光照、湿度、肥料等影响因子进行了阐述。     

文心兰组培苗繁育技术规程

为了规范文心兰组培苗的生产、保证种苗质量,从组培苗繁育中的母株选择、外植体选取、外植体消毒、诱导培养、增殖培养、分化培养、生根培养、炼苗、试管苗质量,组培苗移栽中的环境条件、洗苗与消毒、基质、移栽、栽培管理、移栽苗质量等方面,总结出文心兰组培苗繁育技术规程,为文心兰组培苗标准化生产提供依据。     

紫叶稠李组培苗生根及移栽研究

以紫叶稠李组培瓶苗为实验材料,研究了不同苗高、基部茎粗和不同植物生长调节剂以及不同基质对组培苗生根、移栽成活的影响,结果表明,组培瓶苗的苗高、基部茎粗和植物生长调节剂以及不同基质对组培苗生根、移栽成活有显著影响,选用瓶苗高为2.5～3.0cm,基茎粗0.06～0.1cm的苗接种到添加生长素IBA0.2mg/L和NAA0.5mg/L的基本培养基中生根,生根率可达86.13%,将生长健壮的生根苗移栽在细河沙、熟表土和草炭土基质上炼苗,成活率达93.3%。     

龙头竹组培快繁技术研究

试验研究了龙头竹不同外植体类型、不同消毒药剂及消毒时间对组培效果的影响,以及不同炼苗时间、不同育苗基质、不同肥料种类及施肥方式对组培苗移栽成活率和发笋率的影响。结果表明:龙头竹播种苗秆芽是最适合的组培外植体,外植体消毒以0.1%氯化汞、消毒7 min效果最好;组培苗移栽后炼苗9 d,育苗基质宜采用20%蛭石和80%珍珠岩混合基质,移栽15 d后叶面施用0.3%氮磷钾复合肥组培苗生长状况最好。     

美国红枫组培苗生根移栽试验

以美国红枫微茎段为试验材料,研究生根基质、炼苗时间、育苗基质、育苗穴盘类型等因素对美国红枫组培苗生根移栽影响。结果表明:用以草炭土为基质的培养基代替琼脂培养基对美国红枫生根率影响差异不大;生根后炼苗3d时的移栽成活率最高;以1号基质(进口草炭土∶珍珠岩=2∶1)为育苗基质的美国红枫组培苗移栽成活率最高且长势最好;以32孔的穴盘成活率较高,且便于后期养护管理。     

矾根种苗组织培养工厂化生产技术研究

经过多年的研究和实践表明:矾根的顶芽或腋芽均可作为组织培养的外植体。在其培养过程中加入适量浓度的6-BA和NAA有助于调节和促进外植体的生长和生根。研究发现:以30~40d为一继代培养周期为好,若超出此期限,易诱发玻璃苗;控制空气中尘埃粒子的大小和浓度可减少组培苗的污染率;由组培苗转变成生产用苗的炼苗过程,其温度、光照和温度的控制是十分重要的。并十分强调:组培苗一旦脱离试管(或瓶)切不可用净水泡洗,否则将严重降低组培苗的移栽成活率;矾根组培苗移出后的移栽基质以2∶1或3∶4(体积比)的泥炭和珍珠岩为好。     

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。