昆明56个桂花品种ISSR分析

本研究基于ISSR分子标记,以华东木犀和云南木犀为对照种,研究昆明市区56个桂花品种(含10个待定品种)间的亲缘关系。从102条引物中筛选出24条,共扩增出251个位点,多态性位点数243个,多态性比率达96.81%。根据聚类分析树状图,以遗传相似系数0.726为截值,可将材料分为4类,此时将桂花56个品种与木犀属两个对照种区分开。再以0.760和0.790为截值,可将剩下的品种划分为由1至7个品种组成的聚类小组,此时同一品种群内的品种、各品种群之间花色相近的品种大多聚类,但没有严格按照品种群聚类。10个待定品种根据其形态特征和聚类结果,可推测均为银桂品种群的品种。银桂品种群的Nei’s遗传多样性指数(0.188 5)和Shannon多样性指数(0.300 9)在4个品种群中最高。4个品种群群间遗传多样性比率为54.49%,桂花品种群之间的变异大于品种群之内的变异。遗传距离最远的在四季桂品种群与丹桂品种群之间(0.093 9);遗传距离最近的在银桂品种群与金桂品种群之间(0.014 0)。     

咸宁市桂花品种调查

通过对湖北省咸宁市桂花品种资源的调查,共记载37个品种,分属4个品种群,其中四季桂品种群4个品种、金桂品种群14个品种、银桂品种群15个品种、丹桂品种群4个品种。编制了各品种群品种分类检索表,并对各品种特征进行了描述。     

四川四季桂品种群品种调查与分类

对四川省几个栽培桂花的主要城市四季桂品种进行了调查和整理,共记载了6个四季桂品种.编制了四季桂品种群各品种分类检索表并对各品种进行了特征描述.     

桂花走向世界迈出的关键一步——我国专家喜获木犀属(桂花属)植物国际登录权威

向其柏获得木犀属(桂花属)植物国际登录权威日前,国际园艺学会命名与登录委员会及国际园艺学会执行委员会与理事会致函南京林业大学向其柏教授,正式授权向其柏和中国花卉协会桂花分会为木犀属(俗称桂花属)植物国际登录权威。这意味着,今后全球范围内木犀属植物的命名,都要由我国南京林业大学的专家进行权威认证。同时,向其柏教授也成为继陈俊愉院士获得梅花品种国际登录权威以来第二位获得此项资格的中国专家,而且是获得整个属植物品种国际登录权威的专家。我国是木犀属植物的分布中心,全世界有记载、并为大多数研究者承认的32种木犀属植物…     

桂花品种资源及其分类研究

在多年来实地调查研究的基础上 ,提出桂花品种性状记载的标准和方法 ,按照 4个品种群 :金桂品种群、银桂品种群、丹桂品种群、四季桂品种群 ,编制了现已初步查清的 35个桂花品种的检索表。并就如何进一步开展桂花的研究提出了建议。     

昆明市桂花品种资源调查

昆明气候特殊,近几年城市扩展迅猛,新增绿地较多,因此,重新调查昆明市区的桂花品种,发掘具有本土特色品种工作尤为重要。依据向其柏、臧德奎的桂花品种分类检索表,对昆明市五城区的桂花品种资源进行调查,共鉴定出59个桂花品种,其中四季桂品种群7个,银桂品种群29个,金桂品种群16个,丹桂品种群7个,包括疑似新品种10个(新记载8个,翟丽丽记载2个,均为银桂品种)。编制了各品种群的分类检索表,描述了8个疑似新品种形态特征,并总结了昆明市区桂花品种资源特点。     

河南省南阳市桂花品种资源调查研究

通过连续3年的系统调查,查清了河南省南阳市桂花品种资源有4个品种群,其中金桂品种群4个,银桂品种群6个,丹桂品种群4个,四季桂品种群6个共20个品种,并对生产中存在的问题提出了意见建议。     

浅谈桂花的繁殖育苗技术

2004年11月,我国成功取得木犀属植物品种国际登录权,这是中国花卉产业的一大盛事,它必将推动桂花产业的蓬勃发展。桂花是具有极高观赏价值的优良园林树种,深受世界人民的喜爱。我国人民通过漫长的2500多年人工引种和训化,由天然野生至人工栽培;由山野进入宫苑、百姓居室。时至今日,桂花的实用价值已得     

桂花嫩枝短穗扦插技术

桂花为木犀科木犀属,常绿小乔木。桂花品种较多,我市常见有四季桂、金桂与银桂。桂花是园林绿化常用树种,深受人们喜爱。桂花繁殖方式较多,籽播、嫁接、扦插、压条均可。但籽播桂花普遍存在开花迟、开花少甚至不开花的问题;嫁接与压条繁殖费工费时,成本高,不适宜大...     

陕西关中地区木兰属植物品种分类研究

采用实地调查、对比分析、专家咨询等手段,对关中地区木兰属植物集中的植物园及城市园林绿地,从花、果、叶、枝干等方面对木兰属植物的生物学特性及形态特征进行调查统计。采用二元分类法,按属—亚属—组—种—品种群—品种6个分类等级对关中地区木兰属种及品种进行分类整理。结果显示:木兰属植物有41个种及品种,其中本地种5个,本地区外分布种15个,本地自育品种10个,本地与外地合育品种3个,外地培育品种4个,外来杂交种(品种)4个;可分为2个亚属,7个组,21个种,5个品种群,20个品种;木兰属品种的最初来源基本是玉兰和紫玉兰,品种的育种工作,从自然芽变,种间杂交,开始转向属间杂交品种选育。初步明确了关中地区木兰属种及品种的数量与来源,并进行归类整理。     

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.     

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.     

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.     

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.     

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.