间作方式与林地类型对魔芋病害及产量的影响

在岚皋县对与作物间作和5种林下套种方式下的魔芋产量及病害发生情况进行了试验研究,结果表明,5种林下套种魔芋方式魔芋产量为14 025～18 619.5kg.hm-2,显著高于大田(玉米—魔芋)间作方式的产量10 830kg.hm-2(p<0.05),其中刺槐—魔芋、漆树—魔芋套种方式产量显著高于杜仲—魔芋、杉树—魔芋、板栗—魔芋等3种林下套种方式;5种林下套种方式魔芋发病率为1.63%～2.2%,分别极显著低于大田(玉米—魔芋)间作方式的10.4%(p<0.01),其中刺槐—魔芋套种方式魔芋发病最轻,极显著低于其他4种套种方式(p<0.01);刺槐林下种植魔芋具有发病轻、产量高、效益好等显著特点,值得推广。     

不同间作方式对魔芋病害及产量的影响

随着国内外市场对魔芋及其产品需求量的增大,因连作引起的魔芋软腐病、白绢病已成为制约该产业发展的瓶颈。为了有效遏制病害,增加山区群众收入,笔者通过在全国魔芋种植重点县岚皋进行间作方式对魔芋病害及产量的影响试验,提出了抗病、丰产的刺槐-魔芋立体种植技术。     

魔芋的保健功能及发展前景

魔芋是天南星科魔芋属一种多年生草本植物,在我国有2000多年栽培历史。随着人们生活水平的不断提高,魔芋的医疗保健作用和潜在价值也愈来愈受到众多消费者的重视和青睐。通过魔芋保健功能及社会生态价值的阐述,以增进、鼓舞从业者对魔芋事业的认知和信心。     

滇西南热区珠芽魔芋仿生环境利用模式研究——以耿马县勐撒镇撒马坝珠芽魔芋种植基地为例

以云南省耿马县勐撒镇撒马坝珠芽魔芋种植基地为例,对珠芽魔芋特性和种植基地的发展现状进行了研究,结果表明:滇西南热区海拔800~2500m区域为珠芽魔芋的适生区,在适生区内应以混交和套种为主营造适度遮荫的珠芽魔芋生长环境,并尽快通过品种选育推出适宜不同热区珠芽魔芋仿生环境利用模式的优良品种,以此构建滇西南热区珠芽魔芋仿生环境利用模式。     

陕西榆林毛乌素沙地魔芋引种试验

在榆林的毛乌素沙地引种魔芋,经过3年的引种试验,魔芋在该地生长良好、产量稳定,与原产地基本接近,单株平均年增重3倍左右。魔芋在该地能够完成生长发育周期,引种试验初步获得成功。     

魔芋系列产品开发研究

从云南引进白魔芋栽培成功，经研制提出由鲜芋制成精粉生产工艺，已与各厂家协作研制出魔芋系列产品，包括魔芋软糖、魔芋罐头，魔芋饼干、魔芋精面、魔芋糕等。本文还对市场前景作了粗略分析。     

魔芋干及魔芋精粉加工技术

魔芋的加工利用是变资源优势为商品优势 ,促进魔芋产业健康发展的重要途径。高质量的魔芋产品来自于优质的魔芋精粉 ,优质的魔芋精粉需要高质量的魔芋干原料。本文从提高魔芋产品质量的根本出发 ,对魔芋的最初级制品——芋干及精粉的加工技术进行了较详细的论述 ,以供生产中参考。1　魔芋干的加工1.1　工艺流程魔芋块茎→去芽根→水洗→晾干→去皮→切片→烘烤 (同时漂白 )→检验→包装→成品。1.2　操作步骤1.2 .1　清洗、去皮、切片 :一般重 0 .3kg以上的鲜芋即可用于加工 ,加工前先除去芽根 ,将魔芋表面用清水洗净、凉干 ,然后用不锈钢刀…     

魔芋中总生物碱提取试验初报

提取了陕西花魔芋不同部位及其加工副产物飞粉中的总生物碱,并用重量法测定了总生物碱含量。结果为魔芋皮中总生物碱为0.280%;魔芋块茎中总生物碱为0.134%;魔芋叶中总生物碱为0.232%;魔芋飞粉中总生物碱为0.501%。     

森林资源富集区魔芋产业与林下经济协同发展机制研究

安康市地处秦巴山区森林资源富集区,依托优势资源发展林下魔芋产业是提升林下经济和保护生态环境的新出路。以安康市为例,选取2010—2021年全市林业经济增加值及魔芋产业产值等数据,采用实地调研法和数据分析法,分别从魔芋产值产量、种植面积、产业优势等方面对魔芋产业和林下经济发展现状进行分析,并构建魔芋产业与林下经济协同互动发展机理及路径,依据资源禀赋理论,提出充分利用当地森林资源优势和富硒特色产业政策扶持,创造魔芋产业原生态种植条件和环境,扩大林下魔芋种植基地,引进专业技术人才,提高林下种植人员专业素养,科学开展林下魔芋种植技术等对策,共同促进魔芋产业与林下经济协同互赢高质量发展。     

魔芋干及魔芋精粉加工技术

魔芋的加工利用是变资源优势为商品优势，促进魔芋产业健康发展的重要途径，高质量的魔芋产品来自于优质的魔芋精粉，优质的魔芋精粉需要高质量的魔芋干原料。本文从提高魔芋产品质量的根本出发，对魔芋的最初级制品——芋干及精粉的加工技术进行了较详细的论述，以供生产中参考。     

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.     

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.     

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。