翅荚木扦插育苗技术研究

采用2次重复的L_9(3~4)正交试验设计试验方法,分析不同浓度的混合灭菌剂与诱导激素种类对翅荚木扦插成活率、生根数量及主根长的影响。结果显示:不同浓度的混合灭菌剂与诱导激素种类对翅荚木扦插成活率、生根数量及主根长有显著影响,以300 mg·L~(-1)的多菌灵+恶霉灵+农用链霉素或500~800 mg·L~(-1)的百菌清+多福混合灭菌剂进行灭菌、800~1000 mg·L~(-1)的萘乙酸溶液诱导的翅荚木扦插效果为最好,其扦插成活率与生根数量相对较高,主根长相对较长。     

红翅槭扦插育苗技术研究

红翅槭是一种优良的园林观赏树种,随着园林城市和美丽乡村建设的推进,市场需求一度呈激增态势。本研究采用L9(34)正交试验设计,研究了不同生根激素种类、浓度及处理时间组合对红翅槭嫩枝扦插成活率的影响。结果表明:激素种类对扦插的成活率影响最大,以ABT6的效果最好;其次依次为处理浓度和处理时间。最优方案为采用浓度1000(mg·L-1)的ABT6生根激素处理插穗15min后进行扦插。此法可以获得89.33%的扦插成活率。     

翅荚木扦插繁殖技术研究

为了探索福建地区翅荚木栽培和管理方法,通过研究不同激素种类、激素浓度和处理时间对翅荚木的扦插育苗的影响,结果表明:3种因子对翅荚木扦插生根率、苗高和地径的影响均表现为浸泡时间>激素浓度>激素种类,激素种类对于翅荚木扦插影响不大,有利于提高翅荚木扦插幼苗苗高生长的最优组合为:100mg/L的ABT1#(IBA或者IAA)浸泡处理1 h,而有利于提高翅荚木扦插幼苗地径生长的最优组合则为:100mg/L的ABT1#(或IAA)浸泡处理1 h。     

格药柃扦插繁殖试验

报道了山茶科植物格药柃(Eurya muricata Dunn)的扦插繁殖试验情况。结果表明，格药柃扦插繁殖适宜在春季进行，用50mg／L质量浓度的吲哚丁酸处理，其生根率达到59．5％。     

南方红豆杉扦插试验研究初报

南方红豆杉是国家一级保护树种，具有观赏，用材，药用等多种用途，由于种源少，种子繁殖困难，我们进行了不同时间，不同基质，不同激素及不同激素浓度处理的扦插试验。试验结果表明，南方红豆杉扦插繁殖应选择在秋季进行，其扦插其质，激素及浓度的最佳组合为珍珠岩，采用５００ｐｐｍ浓度的吲哚丁酸通过１２小时的浸泡，其成活率可达到９５％。     

外源激素对杜梨扦插繁殖效果的影响

采用正交试验设计,对外源激素种类和浓度2个因素分别设置4个水平。最终4种不同外源激素种类及激素浓度对杜梨硬枝扦插繁殖的研究表明:嫩枝扦插选用浓度为600mg/L的外源激素CTK处理,硬枝扦插选用800mg/L的外源激素CTK处理,其扦插效果最好。     

小花忍冬硬枝扦插影响因素分析

小花忍冬是观赏性和抗逆性兼具的优良树种之一。为了解决其种子繁殖子代分化变异大的问题,结合小花忍冬特性,通过不同基质、激素及不同浓度的处理,对其进行了硬枝扦插试验。结果表明：基质种类、激素种类、激素浓度都直接影响其扦插成活率,激素种类直接影响地下根系的生长量。其中,使用珍珠岩︰沙子=1︰2、NAA、100 mg/L组合,...     

野生软枣猕猴桃扦插繁殖研究

通过NAA、IBA不同激素浓度对硬枝扦插的影响试验和不同基质处理对嫩枝扦插的影响试验,结果表明:硬枝扦插时NAA∶IBA(1∶1)2000倍激素浓度成活情况良好,成活率达78%,适合硬枝扦插的激素浓度为NAA∶IBA(1∶1)2000倍;嫩枝在基质沙子中成活率最高,达到83%,适合嫩枝扦插的基质是沙子。     

楸树嫩枝扦插试验初报

通过品种、激素种类、激素浓度、插穗类型等4因素3水平正交试验,进行楸树嫩枝扦插育苗试验,考察影响楸树生根的主要因子,结果表明不同楸树品种间扦插生根率差异较大。激素浓度为插穗生根的主要影响因素,其次是品种和激素种类,插穗部位影响较小。单因子试验分析表明1 000 mg/kg浓度处理比500 mg/kg浓度处理生根效果更好。     

不同激素及基质对大马士革玫瑰扦插生根的影响

为研究不同激素种类及浓度、不同基质、枝条的不同部位等对大马士革玫瑰扦插生根的影响,以大马士革玫瑰为试验材料,采用不同激素种类(IBA、ABT、NAA)、不同激素浓度水平(50、100、200 mg/kg)、不同基质(河沙、蛭石、河沙+珍珠岩)、枝条的不同部位(上部、中部和下部)等处理对大马士革玫瑰嫩枝进行扦插试验。结果表明:以100 mg/kg的IBA处理的生根率最高,为78.3%;3种激素处理的生根率最高为100 mg/kg,但激素浓度上升到200 mg/kg时,生根率反而下降;以基部嫩枝扦插的生根率最高,为74.6%;河沙与珍珠岩混合的基质最适用于大马士革玫瑰嫩枝扦插,其生根率达75.3%。     

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.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.     

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.     

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.     

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.     

Boron in forest trees and forest ecosystems

This review critically examines the role of boron (B) in forests in view of recent findings on B nutrition and the continuing occurrence of B deficiency. Many perceptions about the role of B in plants and its uptake and mobility have been altered since the last review on B in forest trees in 1990. Now there is evidence for a fundamental role of B in the formation of the pectic structure in primary cell walls in plants, and further roles in membrane function are being explored. In plants, channel-mediated B uptake, active B uptake and B uptake by mycorrhizas have been shown, B transporters have been identified, and B retranslocation has been shown. We explore these findings and their consequences on forest trees and on ecosystems that they dominate. Particular emphasis is placed on B retranslocation and B in mycorrhizal symbiosis, given their importance in trees.     

Survival and Growth of Picea abies Regeneration after Shelterwood Removal with Single- and Double-grip Harvester Systems

Three stands in Sweden were followed for 7 yrs to study the survival and growth of Norway spruce [Picea abies (L.) Karst.] regeneration after shelterwood removal with single- and double-grip harvester systems. The height of all seedlings within circular plots was recorded before and after final cutting. The tallest seedling and one randomly selected seedling on each circular plot were permanently marked and their annual height growth was measured each year during the period 1993-1999. No significant differences between single- and double-grip harvester systems were found with respect to their effects on regeneration density, survival or annual height growth. The annual height growth of the individual seedlings after shelterwood removal was significantly correlated with seedling height before shelterwood removal. Significant differences were found in annual height growth between seedlings with high and low vitality. Logging damage did not affect the annual height growth. Several practical conclusions were drawn. First, the choice of harvester system does not affect seedling height growth or survival after shelterwood removal. Secondly, the removal of a 200 m³ shelterwood with 200 stems ha^-1 does not seem to constitute a serious problem for seedling survival and growth. Finally, estimated vitality and seedling height both seem to be fairly good predictors of postrelease survival and growth.     

Development of Pinus sylvestris Main Stems Following Three Different Precommercial Thinning Methods in a Mixed Stand

Reducing competition by point cleaning may be an attractive alternative to conventional precommercial thinning in forestry. In this study, survival and development of main stems of Scots pine (Pinus sylvestris L.) following point cleaning were examined in a mixed stand of mainly Scots pine and birch (Betula pendula Roth and Betula pubescens Ehrh.) in northern Sweden. Treatments studied were: no precommercial thinning, conventional precommercial thinning, point cleaning of all secondary stems, and point cleaning of only the secondary stems that were higher than the main stem, within a radius of 0.8 m from the main stem, respectively. A randomised complete block design with three replicates was used. Measurements taken 13 growing seasons after these treatments showed that conventional precommercial thinning was the best treatment for retaining Scots pines as main stems. However, conventional precommercial thinning resulted in the poorest timber quality of the remaining Scots pines in terms of stem taper, thickest branch diameter and relative live crown height. In conclusion, point cleaning has to be followed by a complementary cleaning operation if the objective is to retain Scots pines as main stems in such mixed stands.