枣树原生质体培养及其植株再生

以无核小枣和鸡蛋枣两个枣树品种的胚性悬浮细胞经酶解获得的原生质体为材料,采用不同种类的培养基、不同含量的ＮＡＡ 和 ＺＴ 激素组合及不同原生质体培养密度对两个枣树品种的原生质体进行培养,以获得适宜的培养基种类、较佳ＮＡＡ 和ＺＴ 的激素组合及适宜的培养密度。结果表明：用ＫＭ ８ｐ 作培养基,附加 ０．３ ｍ ｇ／Ｌ ＮＡＡ＋ ０．２ ｍ ｇ／Ｌ ＺＴ 的激素组合,以５×１０５ 个原生质体／ｍ Ｌ 的培养密度, 对其原生质体经 １０ 周液体浅层培养,可获得直径约为 １ ｍ ｍ 的微愈伤组织。将这些微愈伤组织先后转入低渗ＫＭ ８ｐ ＋ ３．０ ｍ ｇ／Ｌ ＮＡＡ＋ ０． ２ ｍ ｇ／Ｌ ＺＴ 琼脂培养基和Ｍ Ｓ［（１／２）ＮＯ－３ ］＋ ３．０ｍ ｇ／Ｌ ＮＡＡ＋ ２．０ｍ ｇ／Ｌ ＺＴ 琼脂培养基上增殖, 再转入枣树分化培养基中,可获得完整的原生质体再生植株     

小叶杨原生质体培养中的激素和氨含量变化

以小叶杨（Ｐｏｐｕｌｕｓｓｉｍｏｎｉｉｃａｒｒ．）原生质体培养的愈伤组织为供试材料，用高压波相色谱法（ＨＰＬＣ），测定它们在四种不同分化培养基上四大类内源激素（ＩＡＡ，ＧＡ３，ＣＴＫ，ＡＢＡ）的含量变化，并检定有关Ｎ的生化反应。结果表明，不同分化培养基上的愈伤组织中内源激素含量和种类差异很大。导致细胞分裂素（ＣＴＫ）含量高，种类多以及细胞分裂素与生长素的比值（ＣＴＫ／ＩＡＡ）高的处理，有利于愈伤组织分化；但若愈伤组织中含有内源脱落酸（ＡＢＡ），则抑制分化。测定结果还表明，小叶杨原生质体培养的愈伤组织分化过程中，其硝酸还原酶活力与氨基态Ｎ含量互为消长。分化频率高的愈伤组织中，硝酸还原酶活力低，而氨基态Ｎ含量高．     

小叶杨原生质体培养中的激素和氮含量变化

以小叶杨原生质体培养的愈伤组织为供试材料，用高压液相色谱法（ＨＰＬＣ），测定它们在四种不同分化培养基上四大类内源激素（ＩＡＡ，ＧＡ３，ＣＴＫ，ＡＢＡ）的含量变化，并检定有关Ｎ的生化反应，结果表明，不同分化培养基上愈伤组织中内源激素含量和种类差异很大，导致细胞分裂素（ＣＴＫ）含量高，种类多以细胞分裂素与主长素的比值（ＣＴＫ／ＬＡＡ）高的处理，有利于愈伤组织分化；但若愈伤组织中含有内源脱落酸（ＡＢＡ）     

桉树原生质体分离体系建立研究初报

以雷林一号桉及尾叶桉为对象进行了原生质体分离体系建立研究,结果表明：雷林一号桉及尾叶桉胚性愈伤诱导的最适应培养基分别为：Ｂ５＋２,４－Ｄ２．０ｍｇ／Ｌ＋ＫＴ０．８ｍｇ／Ｌ及Ｂ５＋２,４－Ｄ２．０ｍｇ／Ｌ。胚性愈伤继代培养基为：Ｂ５＋２,４－Ｄ０．５～１．０ｍｇ／Ｌ＋ＫＴ０．５ｍｇ／Ｌ。黑暗下３～５天的预培养对愈伤组织上的褐化有明显的抑制作用。雷林一号桉及尾叶桉原生质体分离的最适酶液组合分别为：纤维素酶２％＋离析酶１％＋崩溃酶０．１％;纤维素酶２％＋离析酶１％＋崩溃酶０．０５％。愈伤组织在０．９ｍｏｌ／Ｌ蔗糖溶液中浸泡１ｈ,并于酶解后４ｈ更换一次酶液有利于原生质体产量与活力的提高。淡黄色松散愈伤组织原生质分离效果较其它质地的愈伤组织好。继代后８～１０天愈伤组织作原生质体的分离材料较其它年龄的愈伤组织合适。     

赤桉下胚轴不同再生途径建立研究

赤桉下胚轴不同再生途径建立研究表明，Ｂ５为基本培养基添加２，４－Ｄ１－２ｍｇ／Ｌ及２，４－Ｄ１－２ｍｇ／Ｌ附加ＫＴ０．５ｍｇ／Ｌ可以诱导出愈伤组织，诱导率达１００％；６ＢＡ０．５ｍｇ／ｌ与ＮＡＡ０．２ｍｇ／Ｌ配合使用，可使胚状体发生率达４２．８％。ＮＡＡ３ｍｇ／Ｌｇｎ ６ＢＡ０．２ｍｇ／Ｌ的结合愈伤诱导率也为１００％，例题胚状体发生率只有１７．５％，器官发生率７５．０％。ＡｇＮＯ３０．０５％可促进     

黄竹细胞悬浮培养和原生质体分离*

以牡竹属黄竹（ＤｅｎｄｒｏｃａｌａｍｕｓｍｅｍｂｒａｎｃｅｕｓＭｕｎｒｏ）的竹节及无菌苗根颈为外植体，培养于含有５ｍｇ／Ｌ２，４－Ｄ、０．２ｍｇ／ＬＫＴ和２００ｍｇ／ＬＬＨ的ＭＳ培养基上诱导愈伤组织，然后移至相同成份或不同浓度２，４－Ｄ的液体培养基中，进行悬浮培养，以建立分散性良好的悬浮细胞系。利用悬浮细胞和无菌苗叶片经酶解获大量原生质体，其产量分别约为每克鲜重２．５×１０５个和５×１０５个，活力均可达８０％。     

枣树愈伤组织培养时不定芽的分化

以枣树色白、结构紧密的愈伤组织为材料,对其不定芽的分化情况进行了研究．结果表明,用ＭＳ（ＮＯ－３／２）作基本培养基,并附加ＫＴ４．０００ｍｇ／Ｌ,ＺＴ１．７５０ｍｇ／Ｌ和ＮＡＡ０．０１５ｍｇ／Ｌ可以获得比较好的不定芽分化效果,鸡蛋枣和无核小枣不定芽再生频率分别达到３０％,２２％,其它品种再生频率低于１５％,不定芽在ＭＳ（ＮＯ－３／２）＋ＮＡＡ０．０１５ｍｇ／Ｌ＋ＺＴ１．７５０ｍｇ／Ｌ＋ＫＴ４．０００ｍｇ／Ｌ＋ＡｇＮＯ３２．０００ｍｇ／Ｌ的培养基上能获得最高的增殖系数．     

枣树原生质体分离条件的研究

枣树原生质体分离研究是其原生质体培养与融合、外源遗传物质转化等研究的基础工作．用胚性悬浮培养细胞、细粒状胚性愈伤组织、未细切愈伤组织和已细切愈伤组织等４种材料进行原生质体分离．结果表明,枣树胚性悬浮培养细胞是最佳起始材料,用浓度为１０ｇ／Ｌ纤维素酶＋１ｇ／Ｌ离析酶＋ＣＰＷ盐（１３２０ｍｇ／ＬＣａＣｌ２·２Ｈ２Ｏ和１００ｍｇ／ＬＫＨ２ＰＯ４·Ｈ２Ｏ组成的混合液）＋０．７ｍｏｌ／Ｌ甘露醇组成的混合酶液对起始材料进行１６ｈ的酶解,可获得较高的原生质体产量,且原生质体活力较高．     

EstablishmentofEmbryogenicCellSuspensionCulturesandDevelopmentofSomaticEmbryoonCameliasinensisvar．as

云南大叶茶成熟种子子叶诱导产生愈伤组织，在改良ＭＳ并附加０．０５ｍｇｌ－１２，４－Ｄ和０．５ｍｇｌ－１６－ＢＡ的琼脂培养基上经多次继代培养后，形成了五种类型的愈伤组织：黄色松散颗粒状（ＹＦ）、黄色半透明（ＹＳ）、绿色半透明（ＧＳ）、绿色坚硬（ＧＨ）、白色坚硬（ＷＨ）．愈伤组织的分散程度及液体培养基的组成成分影响细胞悬浮培养物的建立：①黄色松散颗粒状愈伤组织最适合建立细胞悬浮系统；②在改良的ＭＳ液体培养基中添加较高的维生素（１８．０３ｍｇｌ－１）和较高的生长素／细胞分裂素的比例（２，４－Ｄ／６－ＢＡ＝０．１／０．５）及２０ｍｌｌ－１的椰子乳，细胞生长和细胞分散程度良好．将ＹＦ接种到这种改良的ＭＳ的液体培养基中，在室温２５±２℃，每天１６小时散射光照射，１２０ｒｐｍ的旋转振荡器上悬浮培养，三周后建立了云南大叶茶的胚性悬浮系统：系统中单细胞占５．３６％，２～５个细胞的小细胞团占２３．８１％，６～２０个细胞的细胞团占７０．８３％；有丝分裂指数为３．２５％，活细胞率为７０％～８０％；悬浮培养物中细胞生长周期为１０天左右．     

蓝桉组织培养的研究

用蓝桉（Ｅｕｃａｌｙｐｔｕｓｇｌｏｂｕｌｕｓ）离体芽器官诱导培养，分化形成丛生芽，年繁殖系数３￣（１２）。０．１～０．５ｍｇ／Ｌ的６－ＢＡ或０．５～０．８ｍｇ／Ｌ的ＫＴ诱导外植体（带节茎段）腋芽萌动的效果最佳，诱导率分别达８０．３％和８１．５％。１．５～２０ｍｇ／Ｌ的６～ＢＡ或２０～２．５ｍｇ／Ｌ的ＫＴ分别与０．５～１．０ｍｇ／Ｌ的ＮＡＡ组合，对于促进腋芽分化形成丛生芽及继代培养中芽的增殖具有最佳效果。培养基中的无机盐浓度、蔗糖含量对蓝桉试管苗的生根具有显著影响；ＩＢＡ促进蓝桉试管苗的生根。至目前为止，在１／２ＭＳ无机盐培养基＋ＩＢＡ１．２～１．４ｍｇ／Ｌ＋Ｓ５ｇ／Ｌ中诱导生根，生根率最高可达２６．４％。     

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.