板栗结果母枝中氮磷钾含量与产量之间关系的研究

对板栗结果母枝中 N、P、K三种主要营养元素动态变化规律及与产量间的关系进行了研究。结果表明 :N、P、K三种主要元素在板栗结果母枝中的动态变化与其自身的生长规律相吻合 ,在生长和开花高峰期 ,母枝中 N、P、K的含量最低。 N、P、K三种主要元素含量变化之间存在一定的相关性 ,N和 P含量之间的相关性达到了极显著水平。 P在板栗雌花分化过程中发挥较大的作用且对产量形成有较大影响。生产中对氮、磷、钾的补充应在生长消耗高峰出现之前进行。     

板栗的光合性状

为了了解光合性状对板栗产量的影响,对板栗的光合特性进行研究.通过对不同板栗品种的光合性状测定,探究了板栗光合性状的日变化和光合性状之间的相互关系.结果表明:不同板栗品种光合性状的日变化有一定的差异,并具有相似的变化规律;同时,气孔导度和蒸腾速率因子与光合速率具有显著相关性;光合性状影响光合作用,影响质量.     

板栗叶绿素含量与光合速率研究

通过对不同板栗品种的光合速率、叶绿素含量的测定,研究了光合速率的日变化和叶绿素含量的季节性变化。结果表明,不同板栗品种光合速率的日变化有一定的差异,并具有相似的变化规律性。光合速率与叶绿素含量具有显著相关性。     

南岭山区杉木大径材林针叶矿质营养诊断

以广东省韶关林场和天井山林场的杉木大径材林针叶为试验材料,对N、P、K、Ca、Mg 矿质营养元素含量进行测定分析,以期为杉木大径材培育平衡施肥提供理论依据。结果表明：杉木中龄林矿质营养元素含量高低顺序为K>N>Ca>P>Mg,近熟林的为N>K>Ca>P>Mg;杉木中龄林、近熟林针叶矿质营养元素含量在不同坡位间存在一定程度的差异的排序;杉木中龄林针叶矿质营养元素含量变异系数范围为8.64%~44.76%,而近熟林针叶矿质营养元素含量变异系数变化范围为8.44%~26.36%。相关分析结果表明,杉木中龄林生长性状与各矿质营养元素含量分别有不同程度正相关,其中胸径、树高、材积与N 含量均呈显著或极显著正相关,而近熟林与矿质营养元素含量的相关性有所不同,其中胸径与P、Ca 含量间为显著正相关,但高生长与N、K 含量极显著负相关。运用主成分分析法对不同龄林、不同坡位的杉木针叶矿质营养元素进行综合评价,结果表明N、K 含量对杉木生长起关键作用。     

引进葡萄柚营养状况与果实品质的相关性

为给果园进行科学、合理培肥提供参考依据,以葡萄柚的9个品种为试材,主要对葡萄柚试验园土壤矿质元素有效性、果实内矿质元素含量、果实内矿质元素间相关关系及果实内矿质元素含量对果实糖、酸、维生素C、可溶性固形物含量的影响等方面进行了研究。结果表明,本试验园葡萄柚各品种种植区的土壤养分含量较均匀,无明显差异;葡萄柚果实N、K、Ca、Mg、Mn元素的含量较低,均有不同程度的缺乏状态;Fe元素的含量适宜;P元素的含量偏高;对葡萄柚9个品种的果实品质进行了综合评价,结果表明,火焰、亨路比和哈路比品种品质表现较好,而帕利斯品种品质表现较差;葡萄柚果实中矿质元素含量与果实内含物的相关性表现在:总糖与N、P、K、Ca、Zn含量呈极显著正相关,酸含量与N含量呈极显著负相关,Vc含量与P、K、Ca、Zn含量呈极显著正相关,可溶性固形物含量与果实内Ca、Zn含量呈显著正相关。     

不同灌水量对生菜品质和矿质元素含量的影响

以两个生菜品种(弘农和绿领)为材料,研究了4种单株灌水定额处理(100mL,75mL,50mL和25mL)对生菜品质和矿质元素含量的影响。结果表明:随着灌水量的减少,生菜可溶性糖、可溶性蛋白、维生素C含量呈增加趋势。地上、地下部矿质元素含量呈降低趋势,其中N、K、Mg三种元素降低趋势明显,各处理之间差异显著。品种绿领地上部Ca元素含量在75mL灌水处理条件下显著降低,在50、25mL处理条件下又缓慢升高;品种弘农地下部Ca元素含量呈先增高后降低趋势。综合考虑,单株灌水量75mL可以保证生菜N、K、Ca、Mg元素的代谢受到较轻的影响而又能兼顾保证较高的品质的最适灌水量。     

红锥不同种源叶片养分含量分析

对红锥3个不同种源2 a生苗的叶片进行营养元素含量测定分析,结果表明:与大多数植物体内营养元素含量适宜范围相比,红锥叶片营养元素N、Ca、Mg、Zn、Fe、B含量在适宜范围之内;Cu的含量只有浦北种源在正常范围之内,博白和东兰种源处于缺乏状态;Mn含量处于安全水平之下;P和K的含量严重缺乏。常量元素中含量最高的是N,其次是Ca,最低的是Mg和P;微量元素中含量最高的是Fe,其次是Mn,最低的是Cu;叶片中N、P、Ca、Mg、Cu、Fe、Mn和B营养元素含量在不同种源间的差异均达到显著或极显著的水平。不同种源叶片内矿质元素含量变幅不同,变幅最大的是B,其次为P,再次为Cu,最小的是N、Zn和K;大部份元素之间有显著或极显著的正相关,表明元素间存在着相互的协同作用。     

新疆沙壤土枸杞园不同土层营养元素的相关性

为给新疆枸杞主产区制定合理的配肥方案以及实现高产优质提供理论参考,以新疆精河县沙壤土初果期枸杞园年不同生长时期0~20 cm、20~60 cm深度土壤为研究对象,通过采集园内年不同生长时期不同深度土样并测定其相关土壤营养元素含量,分析各营养元素年际动态分布规律并对不同深度土壤营养元素含量的相关性进行研究。结果显示:各土层土壤大量营养元素N、K含量大于P含量,且此3种元素多以夏果膨大期和夏果采后花芽分化期含量相对较高;不同深度土壤有机质及矿质元素含量多存在显著差异,有机质、N、K总体表现为表层(0~20 cm)含量大于底层(20~60 cm),P、Zn、Fe、Mn则表现为表层含量小于底层;年不同生长时期、不同深度土层相同常规营养元素N、K和微量元素Fe、B含量间存在显著的正相关性,不同元素N、P与K,N、P、K与Zn、Fe、B和有机质含量之间也存在显著的正相关性,而其他相同或不同元素含量间无显著相关性。     

湖南省马尾松飞播林的养分循环研究

对湖南省3种不同密度类型的马尾松飞播林分的养分循环进行了研究.结果表明:各组分营养元素的含量均以树叶最高,树干最低,在各组分中大量元素以N、K、Ca的含量较高,而P和Mg的含量较低;微量元素以Mn的含量为最高,Cu的含量为最低.单株林木营养元素的积累量随着林分密度的增大而减小,低密度林分营养元素积累量分别是中密度、高密度林分的2.75倍和4.04倍.不同密度单株林木各营养元素积累量依次为N>K、Ca>Mg>P>Mn>Fe>Zn>Cu.随着林分密度的增加,乔木层营养元素的积累量逐渐增大,地被层所积累的营养元素量有减少的趋势.林分年净积累量随着林分密度的增加而增加,各元素的净积累量以N最大,Cu最小.各种元素的吸收量、存留量都随着林分密度的增大而增大.营养元素的循环速率也因林分密度的增大而逐渐变小,并且大量元素的循环速率要高于微量元素.     

核桃叶片生理性焦枯与矿质元素关系研究

[目的 ]以叶片营养诊断为主的方法对核桃叶片的矿质元素等指标进行测定和分析,找出核桃叶片焦枯发生的原因,为核桃生产栽培管理提供理论依据。[方法 ]按叶片焦枯程度对核桃树进行分级,测定不同焦枯程度、不同时期核桃叶片中N、P、K、Na、Ca、Mg、Fe、Mn、Cu、Zn、B元素含量、叶绿素含量,并进行叶片矿质元素间、矿质元素与焦枯程度之间的相关性分析和多元Logistic回归分析。[结果 ]不同焦枯程度的叶片光合色素的含量随着焦枯程度及时间的推移大体呈下降的趋势,焦枯现象会从叶缘向叶片中部发展。病情程度与N含量呈显著正相关,相关系数为0.63,与P含量呈极显著正相关,相关系数为0.76,与Mn、B含量呈极显著负相关,相关系数分别为-0.73、-0.91。B含量与病情程度的Logistic回归系数值为-0.872,且呈现出0.05水平的显著性（p<0.05）,对焦枯程度有显著的负向影响关系。且喷施不同浓度的B肥后焦枯症状得到了有效缓解。[结论 ]测定分析了‘绿岭’核桃焦枯叶片11种矿质元素含量的关系,发现缺B是引起‘绿岭’核桃叶片焦枯的最主要原因。     

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.