壳寡糖对花椒干腐病菌的抑菌活性研究

干腐病是花椒Zanthoxylum bungeanum种植中的重大病害,为了开发防治花椒干腐病的绿色生物农药,采用菌落生长速率法和显微观察法检测壳寡糖对花椒干腐病菌Fusarium zanthoxyli的菌落生长、孢子活力和孢子萌发的影响,并检测壳寡糖对花椒盆栽苗干腐病的防治效果。结果表明:壳寡糖对干腐病菌菌落生长的抑制率随质量浓度增加而增加,最适施用质量浓度为0.4～0.6 mg/mL,菌落生长抑制率可达65%以上;0.7 mg/mL的壳寡糖溶液与孢子共培养24 h时,孢子死亡率可达100%;孢子萌发率随壳寡糖质量浓度的升高而降低,芽管生长长度显著缩短,当使用0.5 mg/mL壳寡糖溶液处理孢子12 h时,对孢子萌发的抑制率可达100%;当壳寡糖的施用质量浓度为0.5 mg/mL,对花椒盆栽苗干腐病防治效果可达65.02%。壳寡糖能显著地抑制花椒干腐病菌的菌落生长,降低病菌孢子活力和萌发能力,并能减轻花椒盆栽苗干腐病的发生,可为壳寡糖在花椒干腐病的田间防治应用中提供依据。     

花椒锈病流行规律及药剂防治研究

1983—1989年在陕西花椒产区进行此项研究。研究结果表明,此病年流行规律与气象条件有关,发病温度13—25℃;每年6—8月连续有两个月降雨量大于57毫米,必发生病害;病害的流行程度与7—8月份的降雨量成正比,病害的季节动态符合罗辑斯蒂方程。不同花椒品种之间存在抗病性差异,以苟椒抗病性较强。位于山脊上的椒园较山谷椒园发病重。采用粉锈宁防治有一定的防治效果。     

五针松疱锈病在我国适生性分析

五针松疱锈病发生及流行,除了需要足够数量的病原菌和大量的感病寄主外,关键在于气候条件是否适合病害的发生,即锈孢子和冬孢子萌发均需要20℃以下的温度是限制病害发生、流行及分布的关键因子,本文结合全国的气象资料,初步拟定出五针松疱锈病在我国的适生区。     

山椒芽营养成分及其评价

为了开发与利用山椒芽菜,测定了朝仓山椒和花山椒的主要营养成分,并以大红袍花椒和香椿为参照系,采用氨基酸比值法评价了椒芽中氨基酸的营养价值。结果表明:山椒芽是一种优良的木本蔬菜,其粗蛋白、粗脂肪含量分别为27.6%～35.3%、1.29%～1.96%,均显著高于香椿芽,其Ca、Fe和P的含量分别为香椿的6.25～8.54、1.89～2.79与4.15～5.31倍;山椒芽的粗蛋白、粗脂肪和总糖含量略高于大红袍花椒;山椒芽的氨基酸含量在25%～27%之间,与大红袍花椒的基本一致,却显著高于香椿芽;山椒芽蛋白质的氨基酸比值系数分为74.20～74.60,这表明其蛋白质中各种氨基酸的比例合理,质量优良。     

呼和浩特地区银新杨叶锈病的发生规律研究

对呼和浩特地区银新杨叶锈病的发生状况、发生规律、病原菌孢子及侵染能力进行了系统研究。研究过程中未发现转主寄主,冬孢子能萌发但作用不明显。病原菌菌丝在冬芽中越冬,形成夏孢子堆。越冬后的夏孢子能萌发有侵染能力。性孢子器着生在银新杨韧皮部。     

毛白杨锈病发生发展规律及其病原菌形态的观察

毛白杨锈病对于毛白杨苗木和幼树生长是极不利的。这种病害在我国尚系初次发现。病原菌以菌丝状态在寄主冬芽或嫩梢中越冬,春季3、4月间冬芽开展时即在嫩叶上出现夏孢子堆,成为初灰侵染的主要来源。4月下旬—5月上旬是病害的大暴发期,6月底—7月初达到高峰,并持续到9月底。接种在叶背面绒毛上者,予以大气饱和湿度,在19.8—23.6℃中,1—2天即萌发;但接种在叶面者极少萌发。潜育期在日平均温度14.2—19℃中(变温范围15.6—23℃)为时4—4.5天。病害流行期中,月平均温度为18.2—26.8℃,相对湿度低达48.1%时仍不受影响。冬孢子堆多生于叶背面原来生夏孢子堆处的外围或附近处,隆起作馒头状,其上复有寄主的表皮组织。各孢子为棱柱状,顶端略平而圆,无棱角,上宽下窄,淡褐色,37.5—50×7.5—10微米大小,壁厚2微米,表面平滑。根据冬孢子形态,病原菌暂定名为 Melampsora rostrupii Wagner。     

花椒雹后恢复性生长规律及其栽培技术

对韩城市桑树坪镇花椒遭遇40多年危害最严重雹灾后的发芽、抽枝、生长、越冬、结果等情况进行了调查,以期了解雹灾对花椒生长的影响程度,为灾后树体存活、树势恢复、产量稳定等技术提供理论依据,结果为,受灾当年椒树仍可恢复性生长,有一定产量,76.5%椒园正常越冬无冻害:灾后第2年椒树生长普遍偏弱,病害较多,减产20%～30%。应采取化学防病、增施肥料、疏松土壤等措施,促使恢复树势。     

山丁子圆柏锈病的研究

兴安圆柏球胶锈病病原菌——山田胶锈菌的春孢子寄主为山丁子等苹果属树木。该菌从产生担孢子到性孢子约12—18天,到春孢子约2个月左右,到冬孢子近2年。冬、春孢子萌发最适温度均为17—20℃,担孢子最适为17—22℃。各种孢子均在相对湿度50%以上和蔽阴或黑暗条件下萌发。担孢子传播活力随时间、距离增加而递减。百菌清等8种药剂毒杀春孢子效果达99%,松焦油柴油混合液、75%百菌清乳油、柴油原液涂菌瘤效果均达100%。     

山楂圆柏锈病的研究

山楂圆柏锈病病原为亚洲胶锈菌，冬孢子在圆柏属，锈孢子和性孢子在山楂属和梨属树木上。从担孢子产生到性孢子12-20d，到锈饱子35-40d，到冬孢子近2a。孢子萌发最适温度为：冬孢子17-20℃，担孢子15-23℃，锈孢子10-25℃，各种孢子均在相对温度50%以上和蔽荫或黑暗条件下萌发，直射光，全光抑制萌发，冬孢子胶化充分，6h即可出现担孢子，担孢子在适温适湿时，1h即可萌发，担孢子寿命暂短，活孢子传播距离近，百菌清等药剂喷杀锈孢子和松焦油柴油混液涂圆柏病部效果最好。     

冬枣树皮疱斑病病原菌生物学特性的研究

桃尖炫菌(桃茎点霉菌)Phoma persicae Sacc.单独侵染引起的冬枣树皮疱斑病是冬枣树皮上的一种重要病害。该菌在PDA,OUA,CMA培养基上均生长良好;菌丝生长与孢子萌发的最适温度均为25℃;在pH6时菌落生长最好,孢子萌发最适pH6～7;在光照与黑暗交替(12L∶12D)和24 h黑暗条件下菌丝生长较快,光照对产孢、孢子萌发无影响;不同营养液中,树皮煮汁液中孢子萌发率最高。     

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.     

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.     

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。