用层次分析法多指标评价优选金花茶超声提取工艺

为了探寻以超声波法提取金花茶多种生物活性成分的最佳工艺条件,以金花茶花为研究对象,采用均匀试验设计,就不同乙醇浓度、提取时间、料液比、提取温度对金花茶花中各种活性成分提取效率的影响情况进行了试验,并以总黄酮、多酚、总皂苷提取率为评价指标,采用层次分析法和综合评分法对其提取工艺条件进行了分析与评价。试验结果表明,不同提取工艺条件下金花茶花活性成分的提取率存在明显差异,试验确定的最佳提取工艺条件为:超声提取温度为50℃,乙醇浓度为50%,料液比为1︰40,提取时间为50min。按此工艺条件超声提取,总黄酮的平均得率为15.88%,多酚得率为4.83%,总皂苷得率为12.28%。对金花茶提取工艺条件的综合评价平均分值为13.69,说明所选提取工艺稳定可行。     

金银花中总黄酮的超声波提取工艺优化

采用超声波法提取了金银花中的总黄酮,通过单因素试验研究了乙醇体积分数、超声温度、超声时间、料液比和超声频率等因素对提取效率的影响。在此基础上,选择乙醇体积分数、超声温度、料液比和超声时间进行L9（34）正交试验,得出了总黄酮的最佳提取工艺参数：乙醇体积分数为70％,超声温度为50℃,料液比为1∶25（g · mL1）,超声时间为2．0h ,超声功率为900W ,最大提取率达到9．37％。     

皱皮柑果皮中总黄酮的回流提取工艺研究

采用回流提取法,通过单因素试验和正交试验,研究了皱皮柑果皮中总黄酮的提取工艺。结果表明：皱皮柑果皮中总黄酮的最佳提取工艺条件为乙醇浓度70%、水浴温度90℃、料液比1∶30、回流时间60 min、粒径为20目（0.90 mm）。在此条件下,总黄酮提取率可达1.56%。各因素对总黄酮提取率影响的主次顺序为回流时间〉粒径〉水浴温度〉乙醇浓度〉料液比。     

响应面法优化乌饭树叶总黄酮超声提取工艺的研究

为确定乌饭树叶总黄酮超声辅助提取最佳工艺条件,以总黄酮提取量为指标,在单因素试验基础上,利用响应面法建立数学模型考察乙醇体积分数、液料比、超声时间及超声温度对乌饭树叶总黄酮提取量的影响,优化乌饭树叶总黄酮提取工艺。结果表明,最佳提取工艺条件为:以体积分数75%乙醇为提取溶剂,液料比65∶1 mL/g,超声时间80 min,超声温度65℃,在此工艺条件下的总黄酮提取量为23.41 mg/g。该结果与模型预测值相近,表明利用响应面法优化乌饭树叶总黄酮提取工艺合理可行。     

沉香叶中芒果苷的提取工艺

以沉香叶为原料,采用单因素试验和正交试验,探讨乙醇浓度、液固比、提取时间和提取温度对芒果苷提取率的影响,并以提取率为评价指标,优化提取工艺。试验结果表明,沉香叶中芒果苷的最佳提取工艺为:采用体积分数70%的乙醇,液固比20,提取温度90℃,回流提取2次,每次1h。在此优化工艺条件下,芒果苷得率达3.31%。     

超声波辅助萃取法提取乌药叶黄酮类化合物的工艺研究

以乌药叶为原料,用均匀设计试验法优化了乌药叶总黄酮(FL)的超声波提取工艺,考察了乙醇体积分数、液固比、超声波功率和超声波作用时间4个因素对乌药叶总黄酮提取率的影响,确立了乌药叶总黄酮的优化超声波提取工艺条件为:5 g乌药叶粉,超声波作用时间18 min,超声波功率250 W,乙醇体积分数40%,液固比10∶1(mL∶g),测得乌药叶总黄酮得率为2.13%。对超声波提取进行了数学模拟,模拟值与试验结果吻合良好。     

四季菊中总黄酮超声提取工艺研究

为研究超声法提取四季菊中总黄酮的工艺,通过正交实验确定了四季菊中黄酮超声提取的最佳工艺条件。结果表明:料液比为1∶12,乙醇浓度为70%,超声提取10min,所得黄酮含量最高为3.06%。通过放大试验证实,此最佳条件下放大实验结果高于正交实验,说明此工艺条件可行。     

超声波提取黄花菜中总黄酮的工艺研究

对黄花菜花中的总黄酮的含量和提取工艺进行了研究。通过单因素实验和正交试验,确定超声提取最佳工艺是:以70%乙醇作为溶剂,料液比为1∶20进行超声提取30min。其黄酮含量为0.527%。     

响应面法优化辣木叶总黄酮超声波辅助提取工艺

采用超声波辅助提取辣木叶总黄酮,并利用响应面法对提取工艺参数进行优化。首先通过单因素试验分别考察超声波提取的料液比、提取时间、提取温度和提取功率对辣木叶总黄酮提取率的影响,确定各因素的适宜水平;在此基础上进行四因素三水平的Box-Behnken中心组合设计法设计响应面试验,分析不同因素、不同水平对辣木叶总黄酮得率的影响。超声辅助提取辣木叶总黄酮的最佳提取工艺条件为:料液比1∶35(g/m L)、提取时间40 min、提取温度52℃、功率210 W,在此条件下辣木叶总黄酮提取率的预测值为5.082%,验证试验所得总黄酮含量为5.17%,所得回归模型拟合情况良好。     

长沙青皮竹叶中黄酮类化合物的提取工艺条件

为给长沙青皮竹叶中黄酮类成分的深入研究提供参考依据,采用四因素三水平正交试验法,对长沙青皮竹竹叶中黄酮的提取工艺条件进行了优化试验。结果表明了提取竹叶黄酮的最优条件为:乙醇浓度70%,固液比为1∶25(g∶mL),提取3次,每次提取时间为1.5 h。在此工艺条件下,长沙青皮竹叶中黄酮的提取率可达1.85%。     

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.     

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.