带箨冬笋的化学贮藏（2）

利用液体保鲜剂进行了常温下带箨冬笋的保鲜贮藏试验。根据贮藏期间笋体外观及其营养成分含量的变化，以正交试验方法选择出了该保鲜剂主要成分的最佳组合为２，４－Ｄ（５００×１０－６）、ＢＨＴ（７００×１０－６）、ＮａＨＣＯ３（１０％）及Ｃ６Ｈ５ＣＯＯＮａ（７００×１０－６）。利用筛选出的本配方可保鲜冬笋７周左右，成本约为６０元／ｔ。     

不同保鲜剂对切花康乃馨脂质过氧化的影响

选用３种不同类型保鲜剂（Ⅰ,Ⅱ,Ⅲ）作为处理,以蒸馏水作对照,对康乃馨保鲜过程中脂质过氧化作用进行研究。结果表明：在对照下,康乃馨花瓣中可溶性蛋白质含量、ＳＯＤ和ＣＡＴ活性都明显下降,ＰＯＸ酶活性迅速增加。而在３种保鲜剂处理下,康乃馨花瓣中可溶性蛋白质、ＳＯＤ、ＣＡＴ活性在保鲜的前几天都会增加;ＰＯＸ活性是前期下降,后期上升。保鲜剂影响花瓣脂质过氧化作用,其效果Ⅲ＞Ⅱ＞Ⅰ。     

高得率浆废水生物净化处理系统研究（Ⅱ）：山杨CTMP,APMP废水活 …

研究山杨高得率乐废水在实验室用活性污泥法连续处理的净化效果。结果表明：１．两种废水用活性污泥法处理可得到良好的净化效率。ＣＴＭＰ废水在全部水力仪时间内，ＣＯＤ负荷量在２．１８－１２．９ｋｇ／ｍ＾３．ｄ时，ＣＯＤｃｒ，ＢＯＤ５去除率分别为６５．９％－８１．０％和９５．５％－９８．１％；ＡＰＭＰ废水在ＨＲＴ为１０－４６ｈ，ＣＯＤ负荷量为３．４７－１６．１２ｋｇ／ｍ＾３．ｄ时，ＣＯＤｃｒ，ＢＯＤ５去除率     

桃综合贮藏保鲜技术研究 Ⅱ.适宜的贮藏条件

研究了大久保、京玉和燕红桃在不同贮藏温度（自然温度、３～４℃、０～２℃）和不同贮藏方式（冷藏、塑料袋小包装贮藏和人工气调贮藏）下的贮藏效果。结果表明,在０～２℃下,将桃果实装入０．０３ｍｍ厚的聚乙烯塑料薄膜保鲜袋中,并加入乙烯吸收剂进行塑料袋小包装贮藏,其效果最好。在这一贮藏条件下,保鲜袋中的Ｏ２为１４．５％～１５．９％,ＣＯ２为３．７％～４．１％。这一条件可明显延长贮藏期并能保持桃的品质,减少腐烂和褐变程度,增加商品果率。同时果实的硬度、淀粉、糖、有机酸和Ｖｃ的保存率也比冷藏对照高。     

现代木工刀具材料与展望(续)

２．５陶瓷 陶瓷刀具材料分为三大类： （１）氧化铝基陶瓷：一般在Ａｌ２Ｏ３基中加入ＴｉＣ、ＷＣ、ＳｉＣ、ＴａＣ、ＺｒＣ等成分，经热压制成复合陶瓷，硬度达ＨＲＣ９３～９５，抗弯强度０．７～０．９ＧＰａ。为提高韧性，常加少量Ｃｏ、Ｎｉ等。 （２）氮化硅基陶瓷：常用的是 Ｓｉ３Ｎ４＋ ＴｉＣ＋Ｃｏ复合陶瓷，其韧性高于氧化铝基陶瓷，硬度相当。 （３）复合氮化硅—氧化铝陶瓷：其组成为Ｓｉ３Ｎ４占 ７７％，Ａｌ２Ｏ３占 １３％，Ｙ２Ｏ３占 １０％。硬度可达 ＨＶ１８００，抗弯强度１．２ＧＰａ。该陶瓷又称赛阿隆（ Ｓｉ…     

高得率浆废水生物净化处理系统研究(Ⅱ)——山杨CTMP、APMP废水活性污泥法处理

研究山杨高得率浆（ＣＴＭＰ、ＡＰＭＰ）废水在实验室用活性污泥法连续处理的净化效果。结果表明：（１）两种废水用活性污泥法处理可得到良好的净化效果。ＣＴＭＰ废水在全部水力停留时间（ＨＲＴ＝１０～５６ｈ）内,ＣＯＤ负荷量在２１８～１２９ｋｇ／ｍ３·ｄ时,ＣＯＤｃｒ、ＢＯＤ５去除率分别为６５９％～８１０％（平均７４６％）和９５５％～９８１％（平均９６８％）;ＡＰＭＰ废水在ＨＲＴ为１０～４６ｈ,ＣＯＤ负荷量为３４７～１６１２ｋｇ／ｍ３·ｄ时,ＣＯＤｃｒ、ＢＯＤ５去除率分别为８４０％～８５６％（平均８４９％）和９８０％～９８９０％（平均９８６％）;（２）在试验采用的全部水力停留时间内,通过处理产生的污泥的ＳＶＩ（污泥指数）均低于１５０ｍＬ／ｇ,污泥的沉降性能良好,在整个试验中,未发现污泥膨胀现象;（３）活性污泥法操作管理简单、方便,对废水的适应性强     

柳毒蛾核型多角体病毒毒力衰减测定

以天然饲料室内饲养的３龄柳毒蛾幼虫为供试虫，测定用同一标准方法生产的柳毒蛾核型多角体病毒杀虫剂的毒力，以当年生产的病毒杀虫剂为标准试剂，感染幼虫死亡率为９４％，ＬＣ５０为３．１５×１０＾３ＰＩＢ／ｍｌ，４℃条件下贮藏１年，２年、３年的病毒杀虫剂，其活性分别丧失１．９％，３．３％，７．９％。     

桃综合贮藏保鲜技术研究

研究了大久保、京玉和燕红桃在不同贮藏温度和不同贮藏方式下的贮藏效果。结果表明,在０－２℃下,将桃果实装入０．０３ｍｍ厚的聚乙烯塑料薄膜保鲜袋中,并加入乙烯吸收剂进行塑料袋小包装贮藏,其效果最好。在这一贮藏条件,保鲜袋中的Ｏ２为１４．５－１５．９％,Ｃ炎３．７－４．１％。这一条件可明显延长贮藏期并保持桃的品质,减少腐烂和褐变程度,增加商品果率,同时果实的硬度、淀粉、糖、有机酸和ＶＣ的保存率也比冷藏对     

桧柏幼苗生长对高浓度CO2的反应

本研究利用ＢＥＭ－Ｉ自动测控系统，对塑料大棚内的桧柏实生幼苗连续３个月施用６００ｐｐｍ、８００ｐｐｍ、１０００ｐｐｍ、１５００ｐｐｍ和２０００ｐｐｍ等５种浓度ＣＯ２气肥。试验结果表明，５种浓度ＣＯ２气肥均能显著促进桧柏苗生长，其中１０００ｍｍｐＣＯ２气肥促生效果最佳，与对照相比较，提高桧柏苗高生长量４９．８％，地径生长量３６．１％；基次为８００ｐｐｍ与１５００ｐｐｍＣＯ２气肥；停止施用ＣＯ２气肥后     

板栗丰产栽培的生理生态机理研究进展

１　板栗丰产的生理生态机理研究进展１．１　板栗光合生理研究１．１．１　板栗光合生理特性研究板栗属光合能力较低的Ｃ３植物，即使在适宜的条件下，叶片净光合速率（Ｐｎ）仍小于Ｃ４植物和草本的Ｃ３植物。由于受试验材料、所处生境、测定方法的影响，目前报道板栗净光合速率（Ｐｎ）的结果存在较大的差别。彭方仁（１９９７）用ＧＨ—Ⅲ型光合仪对８年生的“九家种”品种密植园测定的Ｐｎ为４～１０ｍｇＣＯ２·ｄｍ－２·ｈ－１。据牟云官等（１９８８）利用ｐＨ比色法和红外线ＣＯ２分析仪对实生板栗树测定的Ｐｎ为４～１１ｍｇＣＯ…     

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.     

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。     

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.