油茶泌蜜规律及花粉活力和柱头可授性的变化

通过对云南省林科院树木园中油茶(Camellia oleifera)开花泌蜜规律的观测,结果表明,油茶秋冬开花,整体花期约110天左右,单朵花期为5～7天,散粉主要集中在第1～2天,油茶花粉活力在花开后第1天最大,为(48.56±5.42)%(n=20),随后花粉活力逐渐下降,花谢时花粉几乎没有活力。柱头可授性在第2～3天最高。移取条件下油茶单花泌蜜量在开花后逐步增加,第4天达到最大值,油茶单花的总泌蜜量平均为(103.35±11.95)μL(n=30),花蜜糖浓度在第2天最高,随后逐渐下降,花蜜的平均糖浓度为31.45%(n=30);累积条件下油茶单花累积泌蜜量在开花后逐步增加,第5天累积泌蜜量和糖浓度都达到最大值,随后累积泌蜜量和花蜜糖浓度均下降。     

广宁红花油茶花粉性状及授粉特征

为阐明广宁红花油茶授粉特性,提高其产量和效益,采取野外实地调查与实验室观测相结合的方法,研究了其花粉数量、活力、储藏条件、柱头可授性及辅助授粉效果。结果表明:(1)广宁红花油茶单枚花药花粉数在3 120~12 460粒之间,平均值为6 877粒;单花花粉数量随其花药花粉量增加而增加,在792 200~3 468 400粒之间,平均值为2 102 250粒。(2)花药多在开花第1天开始散粉,开花当天花粉活力随时间进程呈上升趋势,第2天达到最大值,前3 d花粉活力都在80%以上。而柱头可授性在花后第2天达到最大值,2~3 d是柱头可授性最强的时期,即最佳授粉时间。(3)花粉的最佳贮藏方式是-80℃处理,60 d内其活力仍保持在80%以上。(4)在自然授粉条件下,其结实率较低,自花结实率为3.26%;经过人工异株授粉后,结实率提高近2倍。     

常绿杜鹃品种‘XXL’的花粉活力及柱头可授性观察

以常绿杜鹃品种‘XXL’为研究材料,采用花粉离体培养法和联苯胺-过氧化氢法测定其开花过程中的花粉活力及柱头可授性,并对其柱头表面分泌粘液情况与其柱头可授性之间的关系进行研究。结果表明,在开花当天,常绿杜鹃品种‘XXL’的花粉活力较低(68.42±7.06%),柱头无粘液,柱头无可授性;在开花后2天,花粉活力达到最高值(80.75±9.44%);在开花后3-4天,花粉活力开始减弱,柱头仍无粘液,但柱头开始有可授性;在开花后5-7天,柱头开始分泌粘液,柱头可授性逐渐增强;在开花后8-11天,柱头分泌粘液量增多,期间的柱头可授性最强;在开花后12天,花瓣萎蔫,花粉活力降至最低(48.72±14.53%),可授性仍然很强。实验结果表明,常绿杜鹃品种‘XXL’适宜作为父本、母本开展杂交育种工作,其开花后2-6天为最佳采粉期,开花后8-12天为最佳授粉期。     

不育紫薇花粉活力及柱头可授性研究

以4年生"不育紫薇"和普通"可育紫薇"为研究对象,进行杂交育性分析,并利用液体培养法和荧光显微技术测定了两个紫薇品种的花粉活力和柱头可授性。结果表明:"不育紫薇"的花药表面较光滑湿润,难以释放花粉;花粉粒畸形,不能萌发,没有生活力;雌蕊的柱头对正常成熟的花粉有亲和力,具有可授性,但结实率仅4.0%。"不育紫薇"的不育性状由雄性不育和雌性不育共同作用所致。     

濒危植物扇脉杓兰的花部特征与繁育系统

通过野外观测,运用杂交指数(OCI),花粉萌发试验,去雄、套袋、人工授粉等方法对扇脉杓兰开花特性、花粉活力、柱头可授性、繁育系统进行研究,并对其柱头表面和花粉进行扫描电镜观察.结果表明:扇脉杓兰4-6月份开花,群体花期23天,单花花期12 ～ 16天.开花当天柱头即具有可授性,柱头可授性持续期为14天左右.花粉活力在花朵刚开放时最高(95％),至花朵凋谢之前仍保持较高的活力(70％).雌雄生殖单位在持续时间上有较长的相遇期.开花时柱头略高出花药,在花朵开放的整个过程中雌、雄蕊的相对位置始终不变.扇脉杓兰杂交指数OCI =4.自然条件下,扇脉杓兰的结实率仅为5％.人工自花授粉、异花授粉的结实率分别为90％和95％,表明扇脉杓兰是高度自交亲和的.而套袋后不采取措施和去雄的花均小结实,表明扇脉杓兰不存在自动的自花授粉、无融合生殖,因而扇脉杓兰必须通过一定的媒介传粉才能繁衍后代.     

紫玉兰(Magnolia liliflora)的繁育系统研究

从花部形态、花粉活力、柱头可授性、花粉-胚珠比(P/O)、杂交系数(OCI)、套袋实验、传粉观察等方面,对紫玉兰的繁育系统进行了研究.结果表明:(1)紫玉兰是两性花,花期为15 d左右.(2)紫玉兰散粉后9h内花粉活力达到最高,24h后花粉活力明显下降,56 h后花粉基本丧失活力;拄头可授性在开花后3d内最强,4d～6d可授性开始降低,第7d基本失去可授性.(3)传粉方式以虫媒传粉为主,是虫媒植物.(4)繁育系统检测结果为部分自交亲和、异交,需要传粉者的活动才能完成授粉过程.     

小桐子繁育系统与传粉生态学研究

在野外定位观测小桐子花朵的功能形态特征、开花动态、传粉方式,用杂交指数(OCI)、花粉/胚珠比(P/O)、去雄、套袋、人工授粉等方法分别测定小桐子的繁育系统.结果显示:(1)小桐子是单性花,雌雄同株同序.雄花单花期2 d,雌花单花期5～8 d,雌花直径略大于雄花.(2)雄花开花后9 h内花粉活力较高,24 h后花粉活力明显降低,48 h后花粉基本散失活力;雌花柱头可授性在开花后4 d内最强,5～8 d可授性开始降低,第9天基本失去可授性.(3)传粉方式以虫媒传粉为主,为虫媒植物.(4)繁育系统检测结果为部分自交亲和异交,需要传粉者活动才能完成授粉过程.     

檫木花粉活力和柱头可授性研究

通过野外观察檫木Sassafras tzumu（Hemsl.）Hemsl的开花过程,用联苯胺—过氧化氢法测定其柱头可授性,TTC的方法测定檫木花粉活力。结果表明：柱头具可授性时间为8 d,檫木的花粉活力持续时间为32 h。根据测定时间发现柱头可授期和花粉活力较强期重叠较长,通过后期观察到檫木有结实,说明檫木具有正常的传粉机制和结实能力。     

笔竹(Pseudosasa viridula)花粉活力及柱头可授性研究

通过研究不同条件下笔竹的花粉活力以及柱头可授性,为笔竹的有性繁育及杂交育种工作提供理论参考依据,并为竹类植物生殖生物学积累相关资料。采用I_2-KI染色法、花粉离体培养基法测定笔竹花粉活力变化;采用联苯胺-过氧化氢法对不同开花阶段的柱头可授性进行测定。结果显示:笔竹新鲜花粉活性最强;1 d中笔竹花粉活性在3∶00 pm左右达到最高;不同浓度的蔗糖、硼酸配比对花粉萌发具有显著影响,笔竹花粉在10%蔗糖+0.01%硼酸浓度的培养基上培养3 h,萌发率最高;不同储藏条件对笔竹花粉萌发具有显著影响,而4℃湿藏条件下保存短时间内可延长花粉活力至120 h;柱头具可授性,可授期仅2～3 h,成熟期(散粉时期)柱头可授性最强。结论:笔竹花粉在10%蔗糖+0.01%硼酸的培养基内培养3 h萌发效果最好;1 d内尽量采集3∶00 pm左右的新鲜笔竹花粉对散粉时期的柱头进行人工授粉效果最好;新鲜花粉易失活,低温不干燥的储藏处理可以短时间内延长花粉寿命。     

鸢尾属7个品种花粉活力及柱头可授性研究

为探索鸢尾属不同品种的花粉活力及柱头可授性的变化规律,从而提高其杂交效率,以鸢尾属7个品种为试验材料,对其开花过程中不同时间的花粉活力和柱头可授性进行观测,并对其结果进行UPGMA聚类分析。结果表明,7个鸢尾品种花粉活力最高期与柱头可授性最高期在时间上不吻合。‘贵格少女’开花后2h花粉即散尽,6-8h柱头可授性保持最高;蓝蝴蝶、黄菖蒲、马蔺、‘音箱’、‘紫褐’和‘平瓣粉’分别于花后2h、2h、4h、6h、6h、6h花粉活力达到最大值,4-24h、4-26h、4-24h、6-8h、6h、6-8h柱头可授性保持最高。在欧式距离D2=2.68处,7个鸢尾品种可分为两大类,第一类包括4个品种,按相似度依次为‘音箱’、‘平瓣粉’、‘贵格少女’和‘紫褐’。第二类包括3个品种,按相似度依次为黄菖蒲、马蔺、蓝蝴蝶。     

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.     

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。     

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.