无土栽培非洲菊的矿物成分

对珍珠岩基质和泥炭与珍珠岩3∶1混合基质的盆栽非洲菊ＢｏｒａＢｏｒａ进行调查,发现混合基质栽培的非洲菊叶片中的矿物质含量比单一基质的高20%,切花产量高80%。无土栽培非洲菊的矿物成分     

非洲菊无土栽培:循环式水培与开放式水培比较

将非洲菊Ｒｏｓｕｌａ、ＱｕｅｅｎＲｏｂｅｃｃａ、ＳｕｎＳｐｏｔ、ＰａｓｃａｌＨｏｒｚｏｎ和Ｆｌｅｕｒ品种用珍珠岩或岩棉栽培 (水培 ) ,与传统的泥炭或膨胀泥土混合物栽培作比较。其中 ,无土栽培分循环式水培与定期更换营养液的开放式水培两种方式。试验于 4月 5日起至 11月 30日最后一次采收时止。结果 ,整个作物生长周期的商品切花总产量以开放式水培方式最高 ,达 178 4枝 / ,而循环式水培最低 ,仅 10 3 2枝 / 。冬季切花产量以开放式水培最高。泥炭栽培的非洲菊产量比岩棉栽培的高 ,但从整个作物生长周期来看 ,两者产量无明显差…     

补充光照对非洲菊并非总是有效的

调查补充光照对温室非洲菊Ｔｉｆｆａｎｙ(小花)和Ｏｐｔｉｍａ(大花)的影响。非洲菊栽培于岩棉基质,Ｔｉｆｆａｎｙ6株/ｍ2,Ｏｐｔｉｍａ4株/ｍ2。当自然光照为150Ｗ/ｍ2时进行补充光照(3000ｌｘ),每星期定期观测株花量、花柄长度、花重和花径。与对照相比,补充光照使Ｏｐｔｉｍａ品种单位面积花量显著增加,达33.5%,12月至翌年5月尤其如此。补充光照还使花柄更长(12～5月)和切花更重(10～3月)。补充光照后,Ｔｉｆｆａｎｙ品种的切花产量略微提高了6%,但是花径(10～12月)、花柄长度(11～4月)和花柄重量(10～5月)显著增加补充光照对非洲菊并…     

营养液浓度和施用频率对栽培在稻壳基质中非洲菊的影响

试验调查了营养液浓度 ( 0 5～ 2倍 )和施用频率 ( 6、12、18次 /ｄ)对稻壳基质栽培非洲菊的影响。处理浓度为1 5倍时 ,花柄长度和直径 ,切花宽、重和产量都高 ;而浓度为 0 5倍时 ,生长减缓。高浓度 ( 2倍 )处理时 ,花柄长度短。与 2倍浓度的处理相比 ,浓度为 0 5～ 1倍时 ,每天施用 6次或 12次可采到更多的切花。大多数的花是在5月而不是 3～ 4月采收。叶片中叶绿素含量在浓度为 1倍时最高营养液浓度和施用频率对栽培在稻壳基质中非洲菊的影响     

灌水重复使用对非洲菊的影响

1994年 7月～ 1996年 3月 ,对比利时温室岩棉基质和椰壳基质栽培的非洲菊Ａｕｒｅｌｉａ采用自由灌水与灌水重复使用等两种方法灌溉。结果表明 ,各种处理的花枝数量和花径均无明显差异。相对而言 ,在岩棉基质中栽培的非洲菊花枝长度较长 ,而在椰壳基质中栽培的非洲菊花枝重量更重。经过 312ｄ的试验测定 ,观察到不同处理的Ｎ、Ｐ、Ｋ、Ｃａ、Ｍｇ总含量变化。结果 ,灌水重复使用可使这些元素用量减少 35%。灌水重复使用对非洲菊的影响     

非洲菊在攀枝花的栽培实验

非洲菊切花品种在攀枝花市有过少量栽培历史,但没有形成本地供给市场。一直以来,攀枝花的非洲菊切花主要来自昆明。为了实现非洲菊切花本地供给,经过在攀枝花市2 a来,8个品种的试验性栽培,表现良好,值得推广应用。本文将非洲菊在攀枝花市区的试验性生产过程进行了总结。     

低热量对非洲菊产量和品质的影响

调查热量对温室非洲菊Ｔｉｆｆａｎｙ(小花)和Ｏｐｔｉｍａ(大花)的影响。非洲菊栽培于岩棉基质,Ｔｉｆｆａｎｙ6株/ｍ2,Ｏｐｔｉｍａ4株/ｍ2。采用两种不同供热方式:地上和地下供热,昼夜温度分别为20℃和18℃。处理包括:同时使用两种供热方式(对照)以及如果单独使用地下供热(50℃)不能达到最低热量要求时使用地上供热方式。每星期定期观测株花量、花柄长度、花重和花径。地上供热使Ｏｐｔｉｍａ品种单位面积花量显著增加,达145.8枝(对照为117.6株),花柄显著变短(9～4月)。Ｔｉｆｆａｎｙ花的产量无显著变化(分别为286.8和240朵/ｍ2),然而花…     

彩色马蹄莲引种栽培技术初探

对14个从荷兰引进的彩色马蹄莲品种，从种植时间、栽培基质、栽培密度和株型调控等研究其栽培技术，结果表明，春季的种植时间越晚，生育期越短，但对生长有一定不良影响，如使切花花枝变短等。用泥炭＋河沙＋园土（3：1：1）基质栽培可以生产出品质优良的切花和观赏价值高的盆花；合理密植可提高单位面积的切花产量而不影响质量，对于盆花则应根据株型来选择适宜的密度；用多效唑处理可使植株矮化，但各品种对多效唑的敏感度不同，多数品种的适宜质量浓度为1000mg/L。     

鲁南地区非洲菊日光温室切花栽培技术研究

对鲁南地区引进的非洲菊品种的主要性状及品质表现进行了对比研究,筛选出了适宜我区栽培的10个非洲菊优良品种;优化栽培设施,创新大棚建筑模式;对非洲菊的切花栽培措施进行研究,包括配套温湿度调控技术、配套肥水管理措施、植物保护措施优化等技术,形成科学合理的操作模式,为提高非洲菊产业的栽培效益及产业的可持续发展提供了有力的技术支撑。     

5种保鲜剂对非洲菊保鲜效果研究

以非洲菊红色系“大臣”品种为试验材料,用由蔗糖8、-HQ(8-羟基喹啉)、柠檬酸等配制的不同保鲜剂对非洲菊切花进行处理,观察对其外观品质的影响。结果表明:在5种保鲜剂处理中,以3%蔗糖 250 mg/L8-HQ 200 mg/L硫酸铝的保鲜效果最佳,能增大切花开放度,增加鲜重,花色鲜亮,花梗坚韧,可显著延长非洲菊切花瓶插寿命,提高其观赏价值。     

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.     

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.     

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。     

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.