红掌组织培养快繁技术研究

分别采用红掌叶片和茎尖作为外植体，建立了组织培养快繁技术体系，结果表明：以0．1％ HgCl2作为消毒剂最佳的消毒时间均为8min ，叶片愈伤组织诱导、不定芽分化和增殖最佳培养基分别为 M S＋IAA2．0mg／L＋6－BA 0．2mg／L、MS＋NAA0．5mg／L ＋6－BA2．0mg／L ，茎尖不定芽诱导与增殖最佳培养基为MS＋IAA0．2mg／L ＋KT2．0mg／L ，最佳的生根培养基为1／2MS＋IAA0．5mg／L＋6－BA 0．2mg／L。     

霍山石斛组培丛生芽诱导增殖及生根技术

以霍山石斛无根试管苗为试材,研究了丛生芽诱导增殖和生根技术.丛生芽诱导增殖通过4因素3水平正交试验,筛选出的最适培养基为1/2MS 0.2 mg/LKT 0.2 mg/L NAA 0.3 mg/L 6-BA.4个因子对霍山石斛丛生芽诱导的影响顺序依次为:KT＞基本培养基＞6-BA＞NAA,其中,KT对霍山石斛丛生芽的诱导效果极为显著.添加不同浓度的生长素及香蕉泥进行生根诱导,其生根效果排序为:香蕉泥＞IBA＞NAA,最佳的生根培养基是MS基本培养基添加20%香蕉泥,生根率可达94.3%.     

激素在红掌叶片再生体系建立中的应用

以红掌嫩叶为外植体,研究了激素在不定芽的诱导、增殖、生根过程中的作用。结果表明:叶片外植体不定芽诱导的最适培养基为MS+NAA0.50+BA2.00,最佳增殖培养基为MS+NAA0.10+BA1.50,最适合生根的培养基为1/2MS+NAA0.2。     

不同因素组织培养对山苍子茎段腋芽生长发育的影响

以山苍予带腋芽的茎段为外植体。研究了影响茎段诱导分化丛生芽、增殖与生根的主要影响因素。结果表明：山苍子通过茎段外植体直接分化丛芽进行离体培养的途径。最佳丛生芽诱导分化的培养基是1／2MS＋6-BA2.0mg／L＋NAA0.1mg／L，＋AC0.5g／L；最佳增殖培养基为WPM-6-BAl．0mg／L十IBA0．1mg／L＋Vclmg／L，以不定芽形式增殖，增殖系数为5．6，增殖周期为30d左右；生根培养基为改良1／2MS＋NAA0.3mg/L＋IBA0.2mg／L＋AC0.5g／L，生根率91％。     

不同因素组织培养对山苍子茎段腋芽生长发育的影响

以山苍子带腋芽的茎段为外植体，研究了影响茎段诱导分化丛生芽、增殖与生根的主要影响因素。结果表明：山苍子通过茎段外植体直接分化丛芽进行离体培养的途径。最佳丛生芽诱导分化的培养基是1／2MS＋6-BA2．0mg·L^-1＋NAA0．1mg·L^-1＋ACO．5g·L^-1；最佳增殖培养基为WPM＋6-BA1．0mg·L^-...     

花叶菖蒲组织培养与快繁技术试验

取花叶菖蒲的茎尖作外植体，培养于附加不同激索配比的MS培养基匕进行不定芽诱导、增殖及试管苗生根等试验，结果表明，6种配比培养基中，最适合花叶菖蒲不定芽诱导的培养基为MS＋6-BA5mg／L；增殖培养基为MS＋6-BA5Mg／L＋NAA0．5mg／L；试管苗生根诱导前在空白Ms培养基先壮苗培养一代，生根培养基为MS＋NAA0．5mg／L。试管苗不经炼苗可直接出瓶，移栽于蛭石：珍珠岩为1：1的混合基质中，成活率可达98％以上。     

赛黑桦组织培养技术研究

以赛黑桦休眠枝萌发的腋芽为外植体,研究了不同种类和不同浓度植物激素对赛黑桦外植体诱导、愈伤组织诱导、不定芽增殖和生根等环节的影响。结果表明:(1)外植体芽的诱导培养以WPM+6-BA0.5 mg·L~(-1)+NAA0.1 mg·L~(-1)为最佳培养基;(2)愈伤组织诱导以WPM+6-BA1.0 mg·L~(-1)+NAA0.02 mg·L~(-1)为最佳培养基;(3)在芽增殖培养中以WPM+6-BA0.1 mg·L~(-1)+NAA0.02 mg·L~(-1)增殖效果最好,增殖系数达4.0;(4)生根培养以WPM+NAA0.05 mg·L~(-1)效果最佳,生根率91.7%;(5)生根苗移栽成活率达90%以上。     

钟花樱组织培养再生体系的建立

对钟花樱组织培养再生体系进行研究,结果表明,BA／NAA约为10时,即取BA 0．8-1．0mg／L,NAA0．08- 0．1mg/L(单位下同),对芽的诱导有较好的效果,培养基组合为MS BA 1．0 NAA0．1。在芽的增殖与伸长方面,筛选出较优的培养基组合为1／2MS 6-BA 1．0 NAA0．1 GA30．5 肌醇25,芽的增殖系数为4．7,芽均高1．314 cm。在此基础上通过5次连续继代培养,芽的增殖系数达到了7．31,丛生芽诱导率81．0％。钟花樱根的诱导试验表明, 通过暗培养3 d,以1／2MS NAA 0．2 IBA 0．8 6-BA 0．01的培养成份组合最适宜根的诱导,生根率达90％。试验中低浓度的细胞分裂素6-BA对提高生根率是必要的。     

新几内亚凤仙组织培养及试管内开花试验

以新几内亚凤仙花种子无菌萌发的试管苗为材料,探讨了激素对芽增殖、生根以及试管内开花的影响。结果表明：芽增殖最适培养基为Ms＋0．5mg／L6-BA＋0．5mg／LNAA,35d顸芽增殖倍数为3．0,侧芽增殖倍数为5．3,生根率同步达100％;试管内诱导开花的最适培养基为Ms＋2．0mg／L6-BA-＋-0．2mg／LNAA,其开花率达90％,平均每颗苗开花数为2．2朵,花期长达60d。     

西伯利亚花楸组织培养技术研究

以西伯利亚花楸的半木质化茎段为外植体,对其进行了组织培养研究。结果表明：以o．1％HgCl2表面灭菌8min效果最好。在丛生芽诱导增殖培养阶段,Ms＋6-BA1．0mg／L＋IBA0.1mg／L丛生芽诱导率和增殖率最高,分别为1。0％和13．6±2．3。在1／2MS＋IBA0．5mg／L培养基中的生根效果最好,生根率为82．6％。移栽时,选择蛭石＋草炭土（体积比为1：1）较好,有利于试管苗的成活及生长。     

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.     

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.     

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 Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.