六个圆柏品种(系)抗旱性分析

以圆柏6个品种(系)为试验材料,在干旱胁迫条件下时各品种(系)的生理生化指标进行测定与分析.结果表明,干旱胁迫对叶夹角、叶片水分饱和亏缺、细胞膜相对透性、叶绿素含量、游离脯氨酸含量、可溶性糖含量、过氧化物酶活性等指标均产生影响.方差分析可知,各品种(系)间有极显著差异.用模糊数学隶属度公式对各品种(系)的抗旱性进行综合评定,其抗旱能力从大到小依次为:'兰塔桧'＞京桧10-3＞京桧6-2＞京桧13-1＞京桧22-1＞'金花桧'.     

切花百合寒地引种及其鳞片扦插技术探讨

以荷兰引进的6个切花百合品种为试材,在黑龙江哈尔滨和宾县东部山区林地,进行温室和露地栽培、鳞片扦插繁殖和种球越冬栽培试验.结果表明,露地栽培和温室栽培交替进行可有效复壮种球,提高产花质量;多数百合品种春季低温处理后的鳞片扦插繁殖率和成苗率远高于夏季休眠鳞片,22℃恒温繁殖率高于变温;椰糠和草碳水藓混合基质(1∶1)为鳞片扦插的最佳基质,将鳞片二等分分割可有效提高扦插繁殖率和成苗率;亚洲杂种百合可在高寒引种地露地越冬栽培,黑龙江省东部山区林地的特殊生态条件适于亚洲百合种球的繁育.     

“兰州百合”等4个百合品种在邢台山区的引种表现

为了掌握百合优质品种在露地条件下的生育规律和种球繁殖栽培技术措施,引进兰州百合、百合‘京橙812’、‘京橙906’‘、京黄804’‘、京白1号’等新品种,对其进行连续3a的物候期及形态发育的观测,并设置摘蕾、栽植密度等技术措施研究对种球生长发育的影响。调查结果显示:春植的4种百合生长周期为175～182d,最佳采收期为10月中下旬。株行距20cm×20cm时,‘京白一号’产量最高为17259.6kg/hm2。百合鳞茎营养丰富,富含糖、蛋白质、粗纤维等。以‘京黄804’为例进行栽植密度试验发现:密植虽不利于鳞茎发育,但适度密植有利于提高总产量,最佳种植密度15cm×15cm,商品球(单个重量在50g以上)率达72.4%。花蕾4cm时摘蕾去顶后地下鳞茎可增产14.2%。百合0～1℃冷冻贮藏采用真空封口可贮藏180～200d。     

桂花品种切花瓶插衰老生理研究

研究了不同桂花品种切花在开花和衰老过程中花朵的保护酶活性、丙二醛(MDA)、细胞质膜透性及可溶性蛋白质等的变化规律.结果表明:3个桂花品种花朵的可溶性蛋白质的含量均呈下降趋势,细胞质膜透性和丙二醛含量随花朵的衰老而增大;超氧化物歧化酶(SOD)活性前期上升后期下降,呈现出明显的峰值;过氧化物酶(POD)表现为上升趋势.综合比较各项指标测定结果,3个品种的瓶插寿命长短为:'晚籽银'桂＞'多芽金'桂＞'四季桂'.保鲜液对延长桂花花期有一定的效果.     

百合的叶烧生理现象研究

在工厂化栽培条件下，通过对4个种系15个百合品种不同种球规格和种植季节叶烧指数的测定，分析了种系间、品种间的生长差异，初步揭示了百合种系、各个品种、以及不同种球规格和种植季节与发生百合叶烧生理现象的关系及控制叶烧现象的基本要素，为百合切花的良种选育和栽培管理提供了依据。     

东方百合种球冷藏技术研究初探

以东方百合品种西伯利亚16～18cm开花种球为材料,探讨了不同温度和冷藏时间对东方百合种球品质、种球萌发能力和开花的影响,结果表明：1．5～2．0℃的冷藏温度非常适合东方百合种球的冷藏,在此温度下东方百合种球冷藏210d依然保有80％的萌发率,是切实可行的。     

椰心叶甲成虫对7个椰子品种的选择性

研究椰心叶甲成虫对7个椰子品种的寄主选择性,椰子品种分别为:‘本地高种'、‘马哇'、‘香水椰'、‘文椰78F1'、‘黄矮'、‘绿矮'、‘红矮'.从椰心叶甲成虫对7个椰子品种心叶的取食选择和产卵选择来进行探讨,结果表明:当7个品种心叶同时存在时,椰心叶甲成虫喜欢取食的顺序为:‘黄矮种'、‘文椰78F1'＞‘绿矮'、‘红矮'、‘香水椰'＞‘马哇'＞‘本地高种';其‘黄矮'、‘78F1'与其他5个品种之间有明显差异,‘绿矮'、‘红矮'、‘香水椰'与其他4个品种差异明显,‘马哇'与其他6个品种差异明显,‘本地高种'与其他6个品种差异显著.成虫产卵选择性顺序则表现为:‘本地高种'、‘红矮'＞‘香水椰'＞‘马哇'＞‘文椰78F1'、‘黄矮'＞‘绿矮';除了对‘本地高种'、‘红矮'的产卵选择没有明显差异及对‘文椰78F1'、‘黄矮'的产卵选择性没有差异之外,其他各品种之间的差异均十分显著.表明椰心叶甲成虫对这7种寄主的取食选择性与产卵选择性的喜好顺序不一致.     

4个杨树品种的扦插育苗试验

采用正交试验设计,分析了品种、扦插密度、采条部位及施肥4因素对4个杨树品种扦插育苗效果的影响.结果表明:在试验条件下,获得最佳扦插效果的组合为'中菏1号',扦插密度为40 cm×80 cm,采条部位选择60～120 cm处插条,施肥状况选择氮肥量40 g/株;苗高受品种的影响最大,4个因素对苗高的影响大小顺序为品种＞施肥＞采条部位＞扦插密度;扦插密度对地径的影响最大,4个因素对地径的影响大小顺序为扦插密度＞品种＞采条部位＞施肥.     

百合的叶烧生理现象研究

在工厂化栽培条件下，通过对４个种系１５个百合品种不同种球规格和种植季节叶烧指数的测定，分析了种系间、品种间的生长差异，初步揭示了百合种系、各个品种、以及不同种球规格和种植季节与发生百合叶烧生理现象的关系及控制叶烧现象的基本要素，为百合花的良种选育和栽培管理提供了依据。     

日本百合引种及其栽培试验初报

对引进的41个日本百合品种进行了组培保种,获得了3010瓶试管苗。从部分百合品种种球的大棚种植表现出的生长开花结果看,所引品种均可在本地发展。其中S1、S2、S3、S5、S17是很好的切花品种;S13、S23可作百合品种育种的适宜材料;S39、S40更适合作盆栽观赏。     

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.     

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.     

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。     

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.