木麻黄水培生根能力及遗传变异研究

通过木麻黄不同树种、激素类型、浓度、浸泡时间对木麻黄水培生根影响的试验,认为树种是影响木麻黄水培生根最主要的因素,在参试的因素水平中,以山神木麻黄小枝在60×10-6的奈乙酸溶液中浸泡18h后水培为最佳水平组合。从种源、无性系方面探讨短枝木麻黄水培生根能力的遗传变异规律。结果表明:生根率在种源、无性系水平上均存在极显著差异,而且受强度遗传控制,具有选择改良的潜力。粤1、东山2号、东山1号和东山3号是生根能力较强的无性系。     

木麻黄优良无性系选育及在二代更新造林中的应用

通过采用木麻黄优树选择与子代测定的方法,从63个木麻黄家系中筛选出10个优良家系,再经苗期测定选出4个无性系在木麻黄更新造林中应用表明,其造林成活率、保存率和生长量以及抗病性均明显优于对照的木麻黄实生苗;综合抗风力、水培生根率和干形等评价指标表明,选育的粤501、平18、惠1和莆20等4个木麻黄无性系较为优良,可以在全省沿海防护林建设中推广应用。     

木麻黄无性系选择及其在滨海沙地更新造林中的应用

为解决木麻黄更新难的问题,在福建省平潭县开展了木麻黄无性系选择研究,结果表明,木麻黄2号无性系具有水培易生根、抗木毒蛾虫害强、营建农田林网和防护片林生长快、早成林和短时间内能发挥防护作用的特点。木麻黄2号是平潭县木麻黄更新中理想的无性系。     

耐盐杨树新无性系选育续报

通过４种浓度盐溶液水培、砂培试验，探讨了盐处理条件下鲁杨６、鲁杨３１、鲁杨６９、鲁杨７０四个杨析无性系和八里庄杨插穗生根、幼苗生长和生理指标的变化。结果表明，在高浓度盐胁迫下，４个新无性系的生根能力，生长和形态表现的均优于八里庄杨；其生理指标，Ｃｌ积累量、叶片质膜透性、膜脂过氧化程度则显著小于八里庄杨。说明４个杨树新无性系比八里庄杨有较经的耐盐性。     

短枝木麻黄不同种源及家系的水培生根能力差异分析

为了研究沿海防护林碳汇优势树种短枝木麻黄Casuarina equisetifolia水培生根能力的遗传变异,以短枝木麻黄4个天然分布或引种区(澳洲天然分布区、亚洲天然分布区、亚洲引种区和非洲引种区)内10个国家的21个种源共70个家系的种子苗嫩枝为材料,开展生根能力差异的比较研究.结果 表明,短枝木麻黄嫩枝水培生根能力在区域间、国家间差异显著,在种源间、家系间差异极显著,其中生根能力最强的种源为肯尼亚次生种源18142,生根率高达95.2％,最弱的种源为中国次生种源18269,生根率仅为46.7％.生根率、生根数和根长之间无线性相关性,短枝木麻黄生根能力评价应以生根率为主要指标.     

几个木麻黄优良无性系在平潭县育苗造林中的评价

通过对几个木麻黄优良无性系在平潭县沿海防护林建设中的应用进行评价，结果认为，P10—33、501、701、A13这4个无性系的水培生根率、移植成活率、造林保存率较高，生长量较大，适合于平潭县营建沿海防护林的推广虚髓。     

盐胁迫对灌木柳无性系生长及蛋白表达的影响

通过盐胁迫下两个灌木柳无性系水培试验发现,盐胁迫对水培苗生长有显著影响.JW22-2和JW2345无性系地上部分(茎叶)生长受到盐胁迫的显著抑制,地下部分(根)生长在高盐胁迫(3 g/L)下也受到明显抑制,JW2345的耐盐能力强于JW22-2.通过SDS-PAGE电泳对盐胁迫下两无性系特异蛋白表达分析表明,JW22-2和JW2345无性系在盐胁迫下分子量为38.6kD和40.6kD的蛋白含量减少,92.5kD蛋白表达增加.JW22-2无性系在2 g/L和3g/L盐处理下合成了分子量为60.5kD的新蛋白.分子量为92.5kD蛋白可能与两个灌木柳无性系耐盐性有关.     

干旱胁迫下木麻黄15个无性系幼苗生理指标的变化

以木麻黄15个无性系幼苗为试材,用聚乙二醇-6000(PEG-6000)在室内模拟干旱条件,研究了上述15个无性系在干旱胁迫下生理指标的变化.结果表明:除了南山8,其余参试无性系在重度(15%)胁迫下叶绿素含量均高于对照;在重度胁迫下(15%),细胞膜透性增加最多的是莆6和龙4,分别比对照增加了2.55和2.27倍,增...     

福建柏抗盐无性系初步选择研究

对福建柏1年生无性苗木用100 mmol.L-1NaCl进行胁迫处理,在处理60 d后对苗木的叶绿素、脯氨酸、可溶性糖、丙二醛等指标进行测定,结果表明:参试的福建柏无性材料间叶绿素含量、可溶性糖含量、丙二醛含量、脯氨酸含量等指标存在明显差异,且受遗传力制约,这些指标可作为抗盐无性系选育的依据;盐胁迫下309、327、328、381-2无性系的叶绿素、脯氨酸、可溶性糖含量分别比总体平均值增加了6.8%～57.1%、11.7%～17.3%、0.7%～14.5%,丙二醛含量减少了17.8%～56.8%。说明这4个无性系有相对较高的抗盐性,初步筛选出309、327、328、381-2抗盐无性系。     

木麻黄嫩枝水培育苗试验

以木麻黄无性系501和惠-1嫩枝为材料,研究了不同浓度NAA处理及处理时间、水培方法对其成活率的影响,结果表明,40 mg·L-1 NAA处理24 h、流动水培育为最优条件,在此条件下,水培20 d时501和惠-1无性系插穗生根率分别为88%和87%,相应的不定根长度在0.5~0.7 cm;501和惠-1无性系水培小苗经移植后其容器育苗成活率分别为78%和80%。     

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.     

qPCR quantification of Ophiognomonia clavigignenti‐juglandacearum from infected butternut trees under different release treatments

The use of a molecular assay for quantifying conidia of Ophiognomonia clavigignenti‐juglandacearum, the fungal pathogen responsible of butternut canker, was investigated. Purified DNA from conidia collected on glass fibre filters of a passive rain collectors was quantified using a TaqMan real‐time quantitative polymerase chain reaction (qPCR) assay. The qPCR assay could specifically discriminate the target species from all other North American known species of Ophiognomonia, and it was sensitive enough to repeatedly detect one conidium. A linear relationship between numbers of conidia and qPCR C_t values was determined, and used to assess the sporulation of the pathogen under trees that were released to promote their vigour. In total, 977 samples of field‐captured conidia from 49 trees, at two locations, and from two successive growing seasons were analysed. No significant difference of sporulation was observed under control and release treatments. However, our results demonstrated that qPCR assay was reliable for detecting and quantifying O. clavigignenti‐juglandacearum from environmental samples, which will be useful to assess further control methods for this disease.     

The potential of alley cropping in improvement of cultivation systems in the high rainfall areas of Zambia I. Chitemene and Fundikila

Three trials investigating the potential of alley cropping to improve the traditional systems of cultivation, chitemene and fundikila, in the Northern Province of Zambia are described. Flemingia congesta, Tephrosia vogelii, and Sesbania sesban, were grown in association with finger millet, groundnut, cowpea, and maize in various traditional cropping sequences. The indigenous species Tephrosia vogelii and Sesbania sesban were not able to withstand repeated pruning and the long following dry season, and were replaced with Calliandra calothyrsus, and Cassia spectabilis.Over a four year period, there was no benefit by alley cropping with any of the tree species on crop yields, and yields in alley crop treatments even dropped significantly below the control treatments in the fourth year, casting doubt on the potential of alley cropping for sustainable production. There was also no consistent effect on soil chemical characteristics in any of the trials. It was suggested that this lack of beneficial response to alley cropping was due to low tree biomass production low quality of prunings, and an inappropriate cropping sequence. There was no evidence that alley cropping contributed to enhanced nutrient recycling, despite substantial localised pools of soil nutrients, particularly in the chitemene, with which recycling could potentially occur.     

Toxicity of biocide GCSC-BtA on arthropod pests under different temperature conditions

The present research dealt with the toxicity of GCSC-BtA (Germany–China Scientific Cooperation-Bacillus thuringiensis-Abamectin), a new type biocide developed by conjugating a toxin from Bacillus thuringiensis (B.t.) with Abamectin from Streptomyces avermitilis, on arthropod pests under different temperature conditions. The results showed that GCSC-BtA possessed higher toxicity than B.t. crystal, Abamectin or Cypermethrin, with pest mortalities of 97.9, 93.7, 96.4, 82.3 and 96.7% for Tetranychus cinnabarinus (Boisd.) (Acari, Tetranychidae), Frankliniella occidentalis Pergande (Thys., Thripidae), Aphis fabae Scopoli (Hom., Aphididae), Plutella xylostella (L.) (Lep., Plutellidae) and Cameraria ohridella Deschka et Dimić (Lep., Gracillariidae), respectively. Toxicities of GCSC-BtA to T. cinnabarinus and P. xylostella decreased significantly at the older developmental stage with an exception that egg stage had the highest tolerance, in which LC₅₀s of GCSC-BtA were 0.0001, 0.0019 and 0.0708 mg/ml for nymph, adult and egg of T. cinnabarinus, and that 0.0399, 0.2035 and 0.9033 mg/ml for the 2nd instar larvae, 4th instar larvae and egg of P. xylostella, respectively. Also, the biocide was more effective to the lower stage of A. fabae than the higher one with LC₅₀s of 0.0023, 0.0086 and 0.0171 mg/ml against 1st instar nymph, 3rd instar nymph and adult, respectively. In general, toxicity of the new type of biocide was positively related to temperature against all the tested pests, except against T. cinnabarinus, where it was almost similar at the three temperature conditions. GCSC-BtA displayed significantly lower toxicities at 15/20°C than 20/25°C or 25/30°C against F. occidentalis, A. fabae, P. xylostella and C. ohridella. However, no significant difference was found in the toxicities against F. occidentalis, A. fabae and C. ohridella above 20°C, whereas toxicity against P. xylostella increased as temperature raised. Therefore, to achieve higher efficacy in the field, application rate and time should be devised according to these factors.