自交新高梨叶片的培养繁殖技术

以新高梨人工自交授粉所获种子经胚培养产生的试管苗为试材,采用正交试验设计,研究了基本培养基、TDZ、IAA和6-BA四因素及其组合对该自交种叶片不定芽再生的影响.结果表明,基本培养基的种类在愈伤组织分化出芽的过程中起着主导作用,而6-BA和IAA分别在诱导愈伤组织和诱导丛生芽阶段起主要作用.通过综合平衡法得出最佳培养基配方为NN69 0.5 mg*L-1 TDZ 0.3 mg*L-1 IAA;最佳接种试材为出芽后无菌培养15～30 d的叶片;最佳接种方式为叶基部向上插入接种.     

樟树胚萌发早期影响因素及植株再生

【目的】植物体细胞胚胎发生和植株再生受多重因素影响。为了完善樟树体细胞胚胎发生培养技术,提高其遗传转化效率,满足樟树用材的需要。【方法】本研究以樟树未成熟种子为试材,探讨了预处理、不同采种时间、活性炭、肌醇及激素浓度对樟树胚萌发早期的影响,并对不同种源樟树胚性愈伤组织诱导体细胞胚胎发生、分化、生根等进行研究。【结果】预处理对樟树幼胚萌发无显著性影响;不同的采种时间对胚萌发率和平均出芽数影响很大;随着活性炭浓度的升高,胚萌发率呈现先升高后下降的趋势;肌醇浓度对樟树幼胚萌发率和平均出芽数均无显著性影响;对6-BA、NAA、IBA和链霉素进行正交设计试验,其影响的主次顺序为:6-BA> NAA>链霉素> IBA;长沙和郴州种源樟树胚性愈伤组织诱导率最高,达66.67%,但生长情况最好的是长沙和岳阳种源胚性愈伤组织;岳阳、郴州、醴陵、长沙、怀化、娄底愈伤组织诱导体胚发生最大诱导率分别为56.41%、42.31%、48.96%、64.71%、63.25%、56.31%;各种源樟树生根率良好,长沙种源有最高生根率89.25%,郴州和醴陵种源樟树最佳生根激素配比为1 mg/L IBA+0.1 mg/L IAA,其余种源生根最适激素均为1 mg/L IBA+0.1 mg/LNAA。【结论】浸泡处理不利于幼胚后期生长发育;附加150 mg/L的活性炭,培养基褐化率较低;6-BA对幼胚早期萌发占主导作用;实验时选择7月未成熟合子胚的长沙种源樟树最佳。     

蔷薇属植物远缘杂交组合的幼胚拯救

蔷薇属植物的远缘杂交是月季品种改良的主要途径,为获得蔷薇属植物远缘杂交植株,以‘白雪山’（Rosa hybrida‘white mountain’）为母本,粉红香水月季（R.odoratavar.erubescens）、‘湖中月’（R.hybrida‘huzhongyue’）、‘紫红香’（R.hybrida‘zihongxiang’）、‘香粉蝶’（R.hybrida‘xiangfendie’）为父本杂交。于杂交后15～40天每5天取幼胚离体培养,并借助石蜡切片技术观察各时段幼胚发育情况。结果表明,正常培养条件下,在MS＋6-BA1.0 mg/L＋NAA0.05 mg/L培养基上,‘白雪山’、‘湖中月’、‘白雪山’ב香粉蝶’、‘白雪山’ב紫红香’可直接萌发并成苗,但成苗率较低,‘白雪山’×粉红香水月季在该培养基上无法萌发。对35天‘白雪山’×粉红香水月季杂交幼胚进行（10±2）℃、光强1 600～2 000 lx预处理后,在相同培养基上可获得杂交幼胚。加入GA3后可提高各幼胚萌发率,各类型幼胚萌发的最适浓度不同。     

葡萄二倍体与四倍体杂交胚挽救技术中珠被处理方式的研究

以玫瑰香×户太8号、玫瑰香×巨峰杂交胚珠为试材,研究取样时期对经剥胚处理后胚珠内胚发育,以及剥胚和剪喙两种处理方式对杂交胚珠胚萌发和胚成苗的影响。结果表明:两组杂交组合在授粉后55d取样,胚发育率最高;经剪喙处理过的杂交胚珠成苗率高且畸形苗率低,在授粉后45d经剪喙处理更容易获得正常苗。     

地锦体细胞胚胎发生研究

以地锦幼胚为外植体,接种在附加6 BA2mg·L-1及2,4 D0～4mg·L-1的改良B5培养基中诱导愈伤组织,愈伤诱发率0～100% 对诱导出的愈伤组织采用6 BA和2,4 D不同浓度组合的培养基进行继代,对能稳定继代的愈伤组织,以改良B5为基本培养基进行分化培养,采用L16(44)正交设计,研究6 BA、NAA、AC及LH四因素不同浓度组合对体细胞胚胎发生的影响。结果表明:适宜地锦幼胚体细胞胚胎发生的培养基为:愈伤组织诱导:改良B5 6 BA2 0mg·L-1 2,4 D2 0mg·L-1;愈伤组织继代:改良B5 6 BA2 0mg·L-1 2,4 D1 0mg·L-1;胚状体分化及萌发:改良B5基本培养基。胚状体诱发率33%,成苗率53%,移栽成活率85%。胚状体为外起源发生方式,经球形胚、心形胚、鱼雷形胚、子叶形胚等阶段发育成熟。     

绒毛白蜡成熟胚和茎段培养繁殖体系的建立

以绒毛白蜡成熟胚和茎段为外植体，研究了培养基、激素组合对繁殖系数和生长的影响，适合绒毛白蜡离体繁殖的培养基为WPM培养基，胚萌发率为100％，4—5天萌发成幼苗；最适分化培养基为MS＋BA4．0．6．0mg／L＋NAA2．0mg／L，分化率为39．29％，平均增殖系数为3．59；生根培养基为1／2MS＋IBA1．5mg／L，生根率达65．0％。     

北美鹅掌楸组培快繁技术体系的建立

通过北美鹅掌楸(Liriodendron tulipifera)种子诱导的无菌苗茎段,建立北美鹅掌楸的组培快繁体系,种子接种10d后开始萌动,实验的4种培养其中,最好的培养基是MS+3%蔗糖,种子萌发率达38.4%;MS+6-BA1.0mg/L+NAA0.1 mg/L是最好的外植体分化培养基,其增值率达2.04倍;小芽丛在MS+6-BA0.5 mg/L+NAA0.05mg/L上外植体分化数最高,达2.45倍,芽茁生长较好;芽苗在1/2MS+IBA0.5 mg/L+NAA0.1 mg/L生根培养基上,13 d后开始生根,生根率最高达66.7%,炼苗移栽20 d后苗木成活率达80%以上.     

水杉茎段的离体培养

取水杉(Metasequoia glyptostroboides Hu et cheng)嫩茎茎段,经无菌操作接种于事先准备好了的无菌培养基上.接种的外植体,在无激素的MS培养基上表现良好.接种一星期后侧芽开始萌动、抽生.除污染外萌发率可达100%.三星期后绿苗高可达2厘米左右,最高达5厘米以上.当无根绿苗转入到1/2MS付加萘乙酸(NAA)O～1毫克/升的生根培养基上,半个月后根系陆续开始分化.根的分化随试验组合的不同,差异甚大,有的可达100%.     

I-69杨与小叶杨杂交种胚培养研究

本研究利用组织培养技术对进行培养挽救,以为了提高育种成功率.试验结果表明:外植体的最佳消毒方法为75％酒精消毒30 s后在0.1％升汞处理8min,幼胚的成活率为90％.随着外植体消毒时间增加,幼胚成活率先上升后下降.幼胚最佳萌发培养基为1/2MS+ BA0.1 mg·L-1+ NAA0.01 mg·L-1.最佳继代增殖培养基为MS+ BA0.1 mg· L-1+ NAA0.01 mg·L-1,增殖系数达到6.33.对不定芽增殖最有利条件为:pH值6.0、琼脂浓度6g·L-1和蔗糖浓度30 g·L-1.最佳生根培养基为1/2MS+ IBA0.2 mg·L-1,生根率为93.2％.     

桂花幼胚培养及愈伤组织增殖诱导

采用不同培养基对桂花胚的培养进行了试验研究,结果表明:MS 1-1.5 mg.L-16-BA有利于桂花幼胚的萌发;MS 2 mg.L-16-BA 0.3 mg.L-12,4-D有利于幼胚苗的幼叶愈伤组织的诱导,诱导率高,且质地致密;B5 1.5 mg.L-16-BA 0.05 mg.L-1NAA有利于幼胚苗基部产生的愈伤组织的增值诱导,所形成的新愈伤组织呈淡绿色,且质地致密,生长很好,并能分化出根。     

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.