大叶榉不同无性系嫁接效果比较

以大叶榉2年生容器苗为砧木,采用芽接法嫁接,研究大叶榉不同无性系嫁接苗的嫁接成活率及其生长情况。结果表明:大叶榉嫁接成活率平均达64.90%,且不同无性系间嫁接成活率差异明显;嫁接苗的苗高生长量在不同无性系间差异显著,地径生长量在不同无性系间差异不显著;除母树枝下高与嫁接成活率呈极显著负相关外,母树其他生长性状对其嫁接成活率均无显著影响;嫁接成活率与嫁接苗的生长呈正相关,且嫁接苗的苗高与地径生长呈极显著正相关。     

珍稀植物广东含笑嫁接繁殖技术

为提高珍稀植物广东含笑(Michelia guangdongensis)的嫁接成活率,于2015—2017年春、冬季,以1～3年生的黄兰为砧木,分别对采集于广东省石门台自然保护区内的前进、上天堂、金子山、木笼顶、船底顶5个分布点的广东含笑进行嫁接试验,比较不同的嫁接方法、接穗来源、接穗个数、嫁接时间及砧木年龄、砧木地径等因素对嫁接成活率的影响。结果表明:嫁接方法采用髓心形成层对接法最好;来源于上天堂(SG_4)的接穗嫁接成活率最高,其株数成活率可达92.11%,接穗成活率达81.97%;每株3～5个接穗的株数成活率显著高于1个接穗的株数成活率;利用3年生的砧木嫁接成活率及接穗成活率最高;嫁接最佳时间为冬季(12月底—翌年1月),株数成活率和接穗成活率分别为79.14%和68.84%;嫁接后对苗木进行侧芽摘除处理能明显提高成活率。研究结果可为提高珍稀植物广东含笑嫁接成活率和扩大其生产以及迁地保护提供参考。     

日本落叶松二代优树嫁接苗成活率和生长情况分析

笔者以日本落叶松二代优树嫁接苗为对象,对嫁接成活率和嫁接苗生长情况进行调查分析,结果表明:二代优树嫁接成活率平均值为36.40%;无性系间嫁接成活率和生长量差异较大,无性系内各单株生长差异大,变异系数最大达到72.49%;家系间嫁接成活率存在极显著差异,生长量差异不显著;第3 a生主梢长度与2 a苗高存在极显著正相关,用2 a苗高对第3 a苗高生长进行校正后发现家系间第3 a苗高生长存在显著差异;不同树龄母树穗条的嫁接成活率及嫁接后苗木生长情况均存在极显著差异,采穗母树年龄为10～12 a的嫁接苗嫁接成活率、苗高和地径生长量均大于采穗母树年龄为14～17,18～20 a的嫁接苗。     

母树种源与砧木地径对青钱柳嫁接成活率及嫁接苗生长的影响

以湖南省石门县、江华县、双牌县以及江西省修水县、庐山等5地的青钱柳大树或古树为嫁接穗条采集母树，以2年生青钱柳实生苗为砧木，研究母树种源、砧木地径对青钱柳嫁接成活率及嫁接苗生长的影响。结果表明：不同种源青钱柳嫁接成活率大小排序为双牌的﹥修水的﹥江华的﹥庐山的﹥石门的，其中石门种源的最小，为48.69%;双牌种源的最大，达65.23%。嫁接苗的新梢基径、新梢长、新梢节数与砧木地径有一定的相关性，其相关系数分别为0.772、0.457、0.422,其大小排序为新梢基径的﹥新梢长的﹥新梢节数的；嫁接苗的新梢基径、新梢长、新梢节数与母树的年龄、胸径、树高及枝下高均不存在明显的相关性。说明青钱柳嫁接对砧木地径有一定的要求，实际生产中应选择适宜粗度的砧木进行嫁接；母树的年龄对嫁接苗的生长没有显著影响。     

日本落叶松二代优树嫁接苗成活率和生长情况分析

摘要：笔者以日本落叶松二代优树嫁接苗为对象,对嫁接成活率和嫁接苗生长情况进行调查分析,结果表明：二代优树嫁接成活率平均值为36.40%;无性系间嫁接成活率和生长量差异较大,无性系内各单株生长差异大,变异系数最大达到72.49%;家系间嫁接成活率存在极显著差异,生长量差异不显著;第3 a生主梢长度与2 a苗高存在极显著正相关,用2 a苗高对第3 a苗高生长进行校正后发现家系间第3 a苗高生长存在显著差异;不同树龄母树穗条的嫁接成活率及嫁接后苗木生长情况均存在极显著差异,采穗母树年龄为10～12 a的嫁接苗嫁接成活率、苗高和地径生长量均大于采穗母树年龄为14～17,18～20 a的嫁接苗。     

紫花含笑嫁接繁殖技术研究

选择深山含笑、野含笑的1年生苗为紫花含笑嫁接砧木,以多年生乐昌含笑为大树换冠砧木,进行紫花含笑不同砧木嫁接试验,并探索总结紫花含笑嫁接繁殖技术.结果表明:深山含笑、野含笑两种砧木在嫁接成苗率、1年生嫁接苗高度及径高比值均无明显差异;乐昌含笑大树换冠,单株成活率达94％,表明以上3个树种均是嫁接紫花含笑较好的砧木树种.2月下旬至3月中旬是嫁接紫花含笑的适宜时期,采用单芽枝切接方法,简单易行,效果较好.     

不同类型穗条嫁接对油茶芽苗砧嫁接苗生长发育的影响研究

对油茶接穗木质化程度和砧木与嫁接苗成活率及其生长的相关性进行了研究,结果表明：①刚木质化、半木质化、全木质化3个试验处理对嫁接苗成活率、抽梢率、高生长、地径差异极显著,接穗刚木质化处理成活率94.67%、抽梢率92.00%、高生长6.19cm效果较好;②砧木采用胚芽和胚根嫁接对嫁接苗成活率、抽梢率、生长势差异显著,胚芽...     

不同地径砧木对山桐子嫁接苗成活及生长特性的影响

为给山桐子丰产栽培技术提供参考依据,就不同地径砧木对山桐子嫁接苗生长特性的影响情况进行了试验研究。结果表明:(1)山桐子苗嫁接成活率为86.00%~93.20%,保存率为82.63%~90.43%;地径为7~9 cm的大规格砧木组嫁接苗的成活率和保存率均显著高于3~5 cm砧木组的。(2)地径为7~9 cm的大规格砧木组嫁接苗的接穗粗度、树高、冠幅、枝条数量、最长枝长度、最长枝粗度、叶长、叶宽、单叶面积、单株叶片数量和叶面积指数均显著大于地径为5~7 cm的中规格和3~5 cm的小规格砧木组的,而不同地径砧木对最短枝长度、最短枝粗度和叶柄长度的影响均不显著。(3)接穗粗度、树高、冠幅、枝条数量、最长枝长度、最长枝粗度、叶长、叶宽、单叶面积、单株叶片数量、叶面积指数与砧木地径间均存在显著正相关关系。文中因此认为,山桐子砧木的粗度对嫁接苗木的生长具有重要的影响。     

香梓楠嫁接繁殖试验

采用香梓楠、黄玉兰、火力楠、山白兰、观光木5种砧木和枝型皮下腹接、穗型皮下腹接、芽接3种嫁接方法对香梓楠进行了3次嫁接繁殖试验。结果表明，嫁接时期、嫁接方法对嫁接成活率有显著影响。最好嫁接成活率达93.8%，生长最好的1年生嫁接苗，平均苗高100.9cm，地径1.18cm。     

砧木类型及菌根化对板栗嫁接苗生长及光合特性的影响

以河北省迁西县板栗品种‘燕山早丰’为试验材料,芽苗和1 a苗为砧木,进行单砧和双砧嫁接试验,研究了不同砧木类型对嫁接成活的影响、菌根化处理对不同砧木类型嫁接苗新梢生长、生物量、SPAD值及光合特性的影响。结果表明:(1)1 a幼砧嫁接成活率高达91.1%,愈合快,显著优于芽砧嫁接,但双芽砧显著优于单芽砧嫁接。(2)双芽砧嫁接苗新梢生长量与SPAD值最大,生物量亦与1 a砧嫁接苗相当。(3)菌根化处理后三种砧木类型嫁接苗的形态指标均有提高。(4)不同处理净光合速率差异显著,以菌根化双芽砧嫁接苗(24.86μmol·m-2s-1)最大。(5)芽砧嫁接苗水分利用效率RWUE显著高于1 a砧嫁接苗,菌根化嫁接苗水分利用效率显著高于无菌根嫁接苗。     

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。