甜樱桃的组织培养

用甜樱桃早红宝石的茎段为外植体,以MS为基本培养基,研究6-BA对外植体芽诱导的影响、2种激素6-BA和IBA不同浓度组合的芽增殖效应及IBA的生根效果。试验结果表明:甜樱桃的最佳增殖培养基为MS+6-BA1.0mg/L+IBA0.1mg/L+蔗糖30g/L+Agar7g/L,最有效的生根培养基为1/2MS+IBA0.5mg/L+Sug-ar30g/L+Agar7g/L。     

甜樱桃的组织培养技术研究

用甜樱桃早红宝石的茎段为外植体,以MS为基本培养基,研究6-BA对外植体芽诱导的影响,研究2种激素6-BA和IBA不同浓度组合的芽增殖效应及IBA的生根效果。试验结果表明:甜樱桃的最佳增殖培养基为MS+6-BA1.0mg/L+IBA0.1mg/L+Sugar30g/L+Agar7g/L,最有效的生根培养基为1/2MS+IBA0.5mg/L+Sugar30g/L+Agar7g/L。     

木鳖子茎蔓无菌培养及植株再生研究

以木鳖子幼嫩茎蔓为外植体进行组织培养研究,结果表明,最适宜的诱导培养基为MS+6-BA 0.8 mg/L+NAA0.1 mg/L+蔗糖30 g/L,诱导率为66.7%;继代增殖培养基为MS+6-BA 0.6 mg/L+NAA 0.2 mg/L+马铃薯泥2%+活性炭1 g/L+蔗糖30 g/L,增殖倍数为5.6倍;生根培养基为MS+NAA 0.4 mg/L+香蕉泥5%+活性炭2 g/L+蔗糖20 g/L,生根率100%,平均生根数4.8条,平均根长3.9 cm。炼苗10 d后移栽腐殖土∶火烧土∶腐熟艾蒿(体积比5∶3∶2)混合基质的成活率最高达93.3%。     

南京椴茎段植株再生繁育技术

通过对南京椴无菌实生苗茎段的组织培养,探索南京椴带芽茎段分化、增殖及生根的最佳培养条件.结果表明,最适宜诱导南京椴不定芽分化的培养基为MS+BA 1.0 mg/L+NAA 0.1 mg/L+蔗糖30.0g/L+琼脂5.2 g/L,诱导分化率为100%;最佳芽增殖及继代培养基为MS+BA 0.5～1.0 mg/L+NAA 0.05 mg/L+蔗糖30.0 g/L+琼脂5.2 g/L,繁殖系数达4.0～5.0;在生根培养基(1/2MS+BA 0.1 mg/L+IBA 0.5 mg/L+蔗糖20.0 g/L+琼脂5.2 g/L)中添加5.0 g/L AC能明显促进不定根形成,40 d后生根率达56.6%;生根苗移栽至泥炭土中,成活率达80.0%.     

大叶杨组培快繁体系的建立

以大叶杨幼嫩的带腋芽茎段为试材,建立以腋芽诱导途径为基础的植株组培快繁体系。结果表明:大叶杨腋芽诱导的最适宜培养基为MS+NAA0.1 mg/L+6-BA0.1 mg/L,接种30 d,腋芽萌发率可达100%;最适宜增殖培养基为MS+NAA0.1 mg/L+6-BA2.0 mg/L,培养30 d,增殖系数可达4.0,幼苗生长健壮;最佳生根培养基为1/2MS+NAA0.1mg/L+IBA0.2 mg/L,培养30 d,平均生根达4条,平均根长为4.7 cm。     

蓝花楹组织培养研究

文章以蓝花楹(Jacaranda mimosifolia)种子无菌育苗获得的外植体为材料,进行增殖和生根培养条件优化筛选研究,以建立其高效稳定的离体再生技术。结果表明,泥炭土中蓝花楹种子萌发最快,芽最健壮;最适宜的增殖培养基为MS+6-BA1.0 mg/L+IBA0.1mg/L+蔗糖30g/L+琼脂6 g/L,继代周期20d,增殖系数达4.77;最佳生根培养基为1/2MS+IBA0.5mg/L,20d生根率达100%;移栽到泥炭土:珍珠岩=2:1混合基质上,30d移栽成活率达92%以上。     

铺茎栒子组织培养快速繁殖技术研究

通过对铺茎栒子组织培养快速繁殖技术进行研究,结果表明,采用带腋芽的茎段和茎尖作外植体,用0.1%氯化汞消毒2min可获得79.4%的存活率;外植体接入1/2MS+6-BA1.0mg/L+IBA0.1mg/L培养基中,30d时叶腋芽伸长4cm;在培养基MS+6-BA1.0mg/L+IBA0.3mg/L中培养40d,增殖系数达9.12;用培养基1/2MS+IAA0.3mg/L诱导生根,35d时生根率达80.89%;用200mg/LNAA进行瓶外生根试验获得50%的生根率。     

台湾桤木组培再生体系的建立

以台湾桤木(Alnus formosana)优良单株半木质化茎段诱导的初代芽为材料,研究培养基对继代增殖、生根的影响,建立组培再生体系。结果显示:初代芽在MS+6-BA 3.0 mg/L+KT 0.3 mg/L+NAA 0.06 mg/L+琼脂4 g/L+蔗糖30 g/L的培养基上进行继代增殖培养,增殖系数可达2.17以上;在1/2 MS+6-BA 0.3 mg/L+NAA 0.4 mg/L+IBA 0.8 mg/L+琼脂4g/L+蔗糖30 g/L的培养基上生根培养,株平均根条数3.12以上,平均生根率67%以上。     

“小仙女”观音莲工厂化组织培养技术研究

为提高"小仙女"观音莲的组培工厂化水平,以其顶芽为试材,对丛生芽诱导、丛生芽增殖及状态调整、生根等因素进行了研究。结果表明:最适宜单芽诱导丛生芽培养基为MS+6-BA2.5mg/L+NAA0.1mg/L,最适丛生芽增殖培养基为MS+6-BA1.5mg/L+NAA0.1mg/L,最适丛生芽增殖培养基为改良MS+6-BA1.5mg/L+NAA 0.1mg/L,最适生根培养基为MS+NAA0.4mg/L+IBA0.2 mg/L+活性炭0.5g/L+糖30g/L。     

尾叶桉优良无性系组培快繁研究

文章以尾叶桉(Eucalypt urophylla)优良新无性系的无菌组培苗为材料,MS培养基为基本培养基,研究6-BA、NAA不同质量浓度配比对尾叶桉无菌幼苗丛芽增殖率,以及生根粉种类、质量浓度、不同IBA和NAA配比对不同尾叶桉无性系生根率的影响.试验结果表明,当6-BA质量浓度为0.01 mg/L,丛芽增殖率在NAA质量浓度为0.01、0.1 mg/L时递增;而NAA质量浓度为1、5 mg/L时,则有利于生根;筛选出适宜尾叶桉优良无性系ZQUA10的增殖培养基为MS+0.01 mg/L 6-BA+0.01 mg/L NAA+30 g/L蔗糖+6 g/L卡拉胶,增殖系数达到4.7;筛选出适宜尾叶桉优良无性系ZQUA13的生根培养基为1/2MS+0.5 mg/L ABT1+30 g/L蔗糖+6 g/L卡拉胶,生根率达到57.5%;筛选出适宜尾叶桉优良无性系ZQUB58的生根培养基为1/2MS+1 mg/L IBA+0.5 mg/L NAA+30 g/L蔗糖+6 g/L卡拉胶,生根率达到100%.     

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.     

Biogeochemical impacts of clearfelling and reforestation on blanket-peatland streams: II. major ions and dissolved organic carbon

Streams and drains in blanket-peatland forest in western Ireland were sampled weekly over 5 years, 1996–2000, using continuous, depth-proportional passive sampling. Analysis was for pH, alkalinity by Gran titration, anions by IC, metals by ICP, aluminium speciation by loaded-resin exchange, and dissolved organic carbon (DOC) by absorbance at 320 nm.

Effects of felling are identified graphically from two forest drains whose catchments (both about 1 ha) were clearfelled, and partial clearfelling of one larger catchment (somewhat over 1 km²), in summer 1999. Calcium concentrations and alkalinity were increased in the drain- and streamwater from the felled areas. The pH was increased in drains, while in the larger stream, pH range decreased while the mean increased. Phosphorus increased markedly with clearfell, in the absence of recent fertilising, and also increased with fertilising; these results are reported in an accompanying paper. Ammonium-nitrogen concentrations were increased in the two drains with felling, and temporarily decreased in the larger stream. Nitrate increased in some cases. Potassium and manganese concentrations also increased. Concentrations of DOC and organic monomeric aluminium increased gradually, subject to a continuing strong annual cycle. There were no clearfelling effects on concentrations of solphate, suspended solids or inorganic monomeric aluminium. In the two drains (fully clearfelled), concentrations of sodium, chloride and magnesium, and conductivity, were all reduced after felling. Fertilising effects other than for phosphorus were indistinct.

Effects of the combined clearfell–reforestation treatment were testable statistically, using randomised intervention analysis, between two larger streams (1 km²) as a treatment–control comparison. There were statistically significant positive responses in streamwater concentrations of nitrate, potassium, calcium, DOC and aluminium fractions. The implications for management practice depend on whether the loss of nutrients is sustainable for future crop productivity, and whether critical limits and loads of receiving ecosystems are exceeded.     

Effect of Drought on Growth and Mortality of Actively Growing Norway Spruce Container Seedlings Planted in Summer

Survival, root egress and height growth of 13-month-old actively growing Norway spruce ( Picea abies (L.) Karst.) container seedlings exposed to preplanting drying treatments (0, 4, and 8 days) and postplanting drought periods (1, 2, 3, and 4 weeks) were studied in the field between 5 July and 18 August 1999. The mortality of seedlings increased and the height growth and root egress decreased throughout the postplanting drought period. Postplanting performance was also affected by preplanting drying treatments. The results indicate that no risk of excessive mortality and growth restrictions occurs when actively growing seedlings are planted in summer, provided that seedlings are well watered before planting and the drought period does not exceed 3 weeks.     

Rehabilitation of diseased cacao fields in Peru through shade regulation and timing of biocontrol measures

The objective of this case study was to test the effectiveness of biocontrol for the rehabilitation of abandoned, diseased (moniliasis, witches' broom and black pod) cocoa and to develop testable hypotheses regarding the effect of shade and biocontrol timing. Three trial fields differed in their shade regimes. Biocontrol was administered starting either at flowering or pod filling. Disease incidence and yield were compared with cultural control alone. Biocontrol reduced moniliasis from 49% to 25%, independent of the shading regime and application time. Witches' broom was most severe without shade and unaffected by biocontrol. No significant effects on black pod were observed. Although biocontrol increased percentage healthy fruit independent of shading and timing, only the shaded plot with biocontrol from flowering onwards responded with increased yield. Our hypothesis is: 'In the rehabilitation of abandoned cacao, only fields under sustainable shade management and early onset of biocontrol can realise their production potential.' This revised version was published online in June 2006 with corrections to the Cover Date.