10种杀菌剂对橡胶树嘴突凸脐蠕孢菌的室内毒力测定

采用菌丝生长速率法测定10种杀菌剂对橡胶树嘴突凸脐蠕孢叶斑病菌的抑菌能力,结果表明各杀菌剂对嘴突凸脐蠕孢菌的毒力差异显著,苯醚甲环唑、丙环唑、咪鲜胺、异菌脲对橡胶树叶斑病菌的毒力较强,EC50范围在0.0133～0.5572μg/mL,其中苯醚甲环唑、丙环唑对橡胶树叶斑病菌的抑制效果最佳,EC50均小于0.1μg/mL;代森锰锌、百菌清、三唑酮的抑制效果较差,EC50为1～100μg/mL;而多菌灵、甲基硫菌灵、嘧菌酯对嘴突凸脐蠕孢叶斑病菌基本无效。     

8种杀菌剂对桉树枝枯病病原菌室内毒力测定

选择8种不同的杀菌剂,用菌落生长速度法对桉树枝枯病主要病原菌可可毛色二孢、拟隐孢壳菌进行了室内毒力测定。结果表明:对可可毛色二孢抑菌效果最好的是25%咪鲜胺,EC50值为0.03 mg/L,效果最差的是50%异菌脲,EC50值为11.49 mg/L;对拟隐孢壳菌抑菌效果最好的是25%咪鲜胺,EC50值0.23 mg/L,效果最差的是25%苯醚甲环唑,EC50值为6.65 mg/L。     

9种杀菌剂对桉树轮斑病原菌室内毒力测定

采用菌丝生长速率法测定9种杀菌剂对桉树轮斑病原菌(Pilidiella eucalyptorum、P. diplodiella)的室内毒力。结果表明,供试的杀菌剂对病原菌具有不同程度的抑制作用。对P. eucalyptorum毒力最强的杀菌剂是10%苯醚甲环唑ME,EC50值为0.011 6 mg/L;其次是25%吡唑醚菌酯SC,EC50值为0.045 3 mg/L;毒力最弱的是80%乙蒜素EC,EC50值为6.839 3 mg/L。对P. diplodiella毒力最强的杀菌剂是43%戊唑醇SC,EC50值为0.047 3 mg/L;其次是20%丙环唑ME,EC50值为0.085 7 mg/L;毒力最弱的是80%乙蒜素EC,EC50值为2.809 9 mg/L。     

7种杀菌剂对杨树烂皮病、溃疡病病菌的室内毒力测定

室内测定了7种杀菌剂对杨树烂皮病病原菌金黄壳囊孢菌Cytospora chrysosperma (Pers.)Fr.、溃疡病病原菌Dothiorella gregaria Sacc.的毒力.72 h含药平板对抑制金黄壳囊孢菌的菌丝生长毒力最强的有10％苯醚甲环唑水分散剂、250 g/L嘧菌酯悬浮剂,EC50值依次为0.0006,0.020 2μg/mL;其次为70％甲基托布津可湿性粉剂,EC50为0.195 8μg/mL;最弱的是树乐粉剂,EC50为319.658 0μg/mL.48 h对杨树溃疡病病原菌的毒力最强的有250 g/L嘧菌酯悬浮剂、10％苯醚甲环唑水分散剂,EC50依次为0.072 2,0.090 4μg/mL;其次为70％甲基托布津和50％多菌灵可湿性粉剂,EC50依次为2.5603,19.0454 μg/mL;树乐最弱,EC50为366.415 7μg/mL.同一药剂对杨树烂皮病菌的毒力强于溃疡病菌.     

八种杀菌剂对八角炭疽病菌的室内毒力

采用菌丝生长速率法测定了25%丙环唑EC等8种杀菌剂对八角炭疽病菌胶孢炭疽菌Colletotrichum gloeosporioides Penz.的室内毒力,结果表明:8种杀菌剂对八角炭疽病菌均有抑制作用,其中毒力最强的是25%丙环唑,EC_(50)值为0.022 3 mg/L,其次是25%咪鲜胺EC,EC_(50)值为0.034 2mg/L;效果最差的是43%戊唑醇SC,EC_(50)值为2.047 mg/L。     

杨树壳梭孢溃疡病菌的室内毒力测定

在室内培养条件下,采用生长速率法测定了6种常用杀菌剂对杨树壳梭孢溃疡病菌Fusicco-cum fesculi的抑制效果,结果表明:80%代森锰锌WP和50%异菌脲WP对F.fesculi抑制效果最好,EC50值分别是38.175,41.947 mg/L;70%甲基硫菌灵WP2,5%三唑酮WP和75%百菌清WP抑菌效果次之,EC50值分别是137.43,149.90,205.98 mg/L;60%多菌灵WP抑菌效果最差,EC50值是419.91 mg/L。     

几种杀菌剂对花椒炭疽病的抑菌活性研究

本研究采用菌丝生长速率法测定了4种高效低毒杀菌剂对花椒炭疽病的抑菌活性,旨在为花椒炭疽病的有效防治提供理论依据。结果表明:4种供试杀菌剂对花椒炭疽病菌的菌丝生长均有一定抑制作用,但具明显差异。其中,苯醚甲环唑和百菌清的抑菌效果较强,其EC50值分别为2.18mg/L和2.20mg/L,其次为多菌灵,克菌丹对花椒炭疽病菌的抑制效果较差,其EC50值为851.14mg/L。因此,苯醚甲环唑和百菌清对花椒炭疽病菌具有较好的抑菌作用,可作为花椒炭疽病的有效防治药剂。     

三唑类杀菌剂对苹果褐斑病菌生长发育的毒力及其防病作用

戊唑醇和苯醚甲环唑对苹果褐斑病菌生长发育的毒力测定结果表明:对菌丝生长和繁殖体产生具有明显的抑制作用,戊唑醇的EC50分别为0.06和0.055 μg·mL-1,苯醚甲环唑的EC50分别为0.009和0.024μg·mL-1;但2种药剂对分生孢子萌发的抑制效果较差,其EC50值较菌丝生长和繁殖体产生高104～105倍,分别为128.825和331.131μg·mL-1.苯醚甲环唑对菌丝生长和繁殖体产生的毒力较强,EC50值明显低于戊唑醇,说明其抑制效果较好;而戊唑醇在抑制分生孢子萌发时效果略优于苯醚甲环唑,表现为EC50值相对较小.2年独立的田间试验结果表明:2种药剂在推荐使用浓度对苹果褐斑病均有较好的防治效果,戊唑醇比苯醚甲环唑的防病效果好,在2005,2006年分别达到82.10%和81.83%,而苯醚甲环唑分别为42.37%和62.38%.新杀菌剂嘧菌酯防病效果达到88.74%与戊唑醇相当,明显优于十二烷基苄基二甲基氯化铵.病害发生初期(陕西关中6月中旬前后)喷施1-2次内吸性杀菌剂即可基本控制当年的病害.建议交替使用这2种药剂及嘧菌酯来控制病害,可以避免病菌产生抗药性.     

苹果丝核菌室内药效对比试验

选用PDA培养基25℃条件下用抑菌圈法进行防治苹果丝核叶枯病病原菌Rhizoctonia sp.室内药效对比试验,结果表明:25%戊唑醇EW和25%丙环唑EC抑菌效果较好。25%戊唑醇EW1 000,2 000,3 000,4 000,5 000倍的抑制率分别为97.16%,85.08%,70.04%,52.28%,42.29%;25%丙环唑EC 1 000,2 000,3 000,4 000,5 000倍的抑制率分别为100%,93.96%,80.39%,61.41%,47.35%。25%丙环唑EC的EC50值仅为0.86 mg/mL,毒力最强。在生产上防治苹果丝核叶枯病建议使用25%丙环唑EC和25%戊唑醇EW。     

不同杀菌剂对杏果实黑斑病病原菌毒力作用测定

采用生长速率法和孢子萌发法分别测定了不同杀菌剂对杏果实黑斑病病原菌的毒力。生长速率法测定结果表明:氟环唑、多氧霉素、异菌脲、苯醚甲环唑、甲基硫菌灵、代森锰锌和阿米西达的EC50值分别为7.063 1mg/L、5.339 5 mg/L、21.252 mg/L、12.184 3 mg/L、380.978 1 mg/L、28.933 4 mg/L和12.448 mg/L,以多氧霉素的毒力最高。孢子萌发法测定结果表明:氟环唑、多氧霉素、异菌脲、苯醚甲环唑、甲基硫菌灵、代森锰锌和阿米西达的EC50值分别为0.660 8 mg/L、0.114 3 mg/L、5.594 9 mg/L、3.209 2 mg/L、70.892 4 mg/L、6.591 7 mg/L和0.477 7 mg/L,以多氧霉素的抑菌效果最好。     

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.