Soil fumigation and compost amendment alter soil microbial community composition but do not improve tree growth or yield in an apple replant site

Apple replant disease (ARD) is a disease complex that reduces survival, growth and yield of replanted trees, and is often encountered in establishing new orchards on old sites. Methyl bromide (MB) has been the fumigant used most widely to control ARD, but alternatives to MB and cultural methods of control are needed. In this experiment, we evaluated the response of soil microbial communities and tree growth and yield to three pre-plant soil treatments (compost amendment, soil treatment with a broad-spectrum fumigant, and untreated controls), and use of five clonal rootstock genotypes (M.7, M.26, CG.6210, G.30 and G.16), in an apple replant site in Ithaca, New York. Polymerase chain reaction (PCR)—denaturing gradient gel electrophoresis (DGGE) analysis was used to assess changes in the community composition of bacteria and fungi in the bulk soil 8, 10, 18 and 22 months after trees were replanted. PCR-DGGE was also used to compare the community composition of bacteria, fungi and pseudomonads in untreated rhizosphere soil of the five rootstock genotypes 31 months after planting. Tree caliper and extension growth were measured annually in November from 2002 to 2004. Apple yield data were recorded in 2004, the first fruiting year after planting. Trees on CG.6210 rootstocks had the most growth and highest yield, while trees on M.26 rootstocks had the least growth and lowest yield. Tree growth and yield were not affected by pre-plant soil treatment except for lateral extension growth, which was longer in trees growing in compost-treated soil in 2003 as compared to those in the fumigation treatment. Bulk soil bacterial PCR-DGGE fingerprints differed strongly among the different soil treatments 1 year after their application, with the fingerprints derived from each pre-plant soil treatment clustering separately in a hierarchical cluster analysis. However, the differences in bacterial communities between the soil treatments diminished during the second year after planting. Soil fungal communities converged more rapidly than bacterial communities, with no discernable pattern related to pre-plant soil treatments 10 months after replanting. Changes in bulk soil bacterial and fungal communities in response to soil treatments had no obvious correlation with tree performance. On the other hand, rootstock genotypes modified their rhizosphere environments which differed significantly in their bacterial, pseudomonad, fungal and oomycete communities. Cluster analysis of PCR-DGGE fingerprints of fungal and pseudomonad rhizosphere community DNA revealed two distinct clusters. For both analyses, soil sampled from the rhizosphere of the two higher yielding rootstock genotypes clustered together, while the lower yielding rootstock genotypes also clustered together. These results suggest that the fungal and pseudomonad communities that have developed in the rhizosphere of the different rootstock genotypes may be one factor influencing tree growth and yield at this apple replant site.     

Residues of spiroxamine in grapes following field application and their fate from vine to wine

Dissipation of the fungicide spiroxamine in grapes of two vine varieties, Roditis and Cabernet Sauvignon, exposed to field treatments was evaluated. Vines of a grape vineyard located in central Greece were sprayed once or twice with a commercial formulation of the fungicide at 30 g a.i./hL. Residues in grapes, must, and wine were determined by gas chromatography/IT-MS after extraction with cyclohexane-dichloromethane (9:1), with a limit of quantitation 0.02 mg/kg in grapes and 0.012 mg/kg in wine. Under field conditions, spiroxamine dissipation on grapes was faster during the first 2 weeks and then slower to the sixth week. About 7 days after application, half of the initial spiroxamine concentration remained on the grapes; the respective proportion at 42 days was about 10%. At 14 and 35 days, residues were lower than 0.44 and 0.22 mg/kg, respectively, values below the maximum residue levels set by the European Union (1 mg/kg). Spiroxamine residues transferred from grapes into the must and through the vinification process into the wine were also studied. Mean transfer factors of 0.26 and 0.55 were found from grapes into wine for the wines obtained without maceration and with maceration, respectively. Residues in wine, prepared from grapes with a spiroxamine content of 0.11-0.20 mg/kg, varied from <0.026 to 0.09 mg/kg. Spiroxamine diastereomer B was found to dissipate slower than diastereomer A in the field as well as during the vinification process.     

芦荟对肉仔鸡生长性能和免疫功能的影响

将360只1日龄雄性AA肉仔鸡随机分成6个组,每组设6个重复,每个重复10只.Ⅰ组为空白对照组,饲喂基础日粮,Ⅱ-Ⅵ组分别在基础日粮中添加600 mg.kg-1芦荟粉、600 mg.kg-1芦荟水提取物、600 mg.kg-1芦荟醇提取物、600mg.kg-1芦荟水提取物+600 mg.kg-1芦荟醇提取物和150 mg.kg-1金霉素.结果表明:Ⅲ组3、6周鸡的体增重均显著高于Ⅰ组(P<0.05);Ⅲ-Ⅳ组的料肉比与Ⅰ组比较均极显著降低(P<0.01),Ⅲ组与Ⅵ组比较显著降低(P<0.05);Ⅱ-Ⅴ组3周鸡的脾脏指数与Ⅰ组相比,差异均显著提高(P<0.05);Ⅲ组3周鸡的胸腺指数显著高于Ⅰ组(P<0.05);Ⅱ-Ⅴ组3周鸡的自然杀伤细胞的杀伤活性均极显著高于Ⅰ组(P<0.01),Ⅱ-Ⅴ组6周鸡均极显著高于Ⅰ、Ⅵ组(P<0.01).可见芦荟粉、水提取物、醇提取物和提取物混合组均能提高肉仔鸡的生产性能和免疫功能,其中水提取物组的效果最佳.     

动态调节人工乳粘稠度和营养成分饲喂无菌大鼠效果研究

根据无菌大鼠乳鼠吮吸乳汁的规律,建立一套新的人工哺乳(AR)无菌乳鼠的方法.设计并配制6种适合不同日龄乳鼠的人工乳(LWF),并测定人工乳主要的营养成分含量和粘稠度等.无菌剖腹产术得到30只无菌乳鼠,采用吮吸法饲喂乳鼠至21日龄断乳,以30只代乳母鼠哺乳(MR)的乳鼠为对照,每日称量乳鼠体重,观察生长发育情况,计算离乳时乳鼠的生存率,检查8对100日龄以上AR无菌大鼠的生育能力.6种人工乳除LWF-6外,其余人工乳的蛋白质、脂肪、糖类、灰分、钙、钾、钠、氯、磷的含量、总能量和pH与大鼠乳相似,但这些人工乳的粘稠度不同.从LWF-1至LWF-5,蛋白质、脂肪、糖类的含量、能量和粘稠度不断增加.虽然AR乳鼠的体重增长不如MR乳鼠(2日龄时,P＜0.05;3日龄时,P＜0.01),但其生长发育正常.AR乳鼠的离乳率为73.3%,MR鼠为100%.8对AR无菌大鼠都有生育力.说明采用动态调节人工乳粘稠度和营养成分含量的方法可以用于饲喂无菌乳鼠,并且存活率较高.     

城市微型公共空间景观设计

随着城市的发展,城市公共空间对城市生活的重要性不断凸显,城市微型公共空间作为其层次结构中不可或缺的一环,在世界范围内也得到了长足发展。但对于我国城市微型公共空间景观设计领域而言,却一直未能得到足够的重视。以深圳市罗湖区嘉宾公园为研究对象,阐述城市微型公共景观设计对于城市公共空间层次结构的重要意义,并展现其为城市所带来的独特魅力。深圳市罗胡区嘉实公园的建成为我国城市微型公共空间提供了一个极佳的参考样本。     

“珍珠”的工艺配方研究

通过正交试验,对"珍珠"的工艺配方进行了研究,结果表明,胶液最佳配方为海藻酸钠∶明胶∶琼脂为3∶1∶2,奶油含量5%,蔗糖含量10%。氯化钙浓度3.0%,固化时间10min。得到的"珍珠"颗粒形状圆润,口感滑嫩,3个月内不发生溶解。     

Climate variability and marine survival of coho salmon (Oncorhynchus kisutch) in the Oregon production area

Time series of adult recruitment for natural runs of coho salmon from the Oregon coastal region (1970–94) and marine survival of hatchery-reared coho salmon from California to Washington (1960–94) are significantly correlated with a suite of meteorological and oceanographic variables related to the biological productivity of the local coastal region. These variables include strong upwelling, cool sea surface temperature (SST), strong wind mixing, a deep and weakly stratified mixed layer, and low coastal sea level, indicating strong transport of the California Current. Principal component analysis indicates that these variables work in concert to define the dominant modes of physical variability, which appear to regulate nutrient availability and biological productivity. Multiple regression analysis suggests that coho marine survival is significantly and independently related to the dominant modes acting over this region in the periods when the coho first enter the ocean and during the overwintering/spring period prior to their spawning migration. Linear relationships provided good fits to the data and were robust, capable of predicting randomly removed portions of the data set.     

Model uncertainty in the ecosystem approach to fisheries

Fisheries scientists habitually consider uncertainty in parameter values, but often neglect uncertainty about model structure, an issue of increasing importance as ecosystem models are devised to support the move to an ecosystem approach to fisheries (EAF). This paper sets out pragmatic approaches with which to account for uncertainties in model structure and we review current ways of dealing with this issue in fisheries and other disciplines. All involve considering a set of alternative models representing different structural assumptions, but differ in how those models are used. The models can be asked to identify bounds on possible outcomes, find management actions that will perform adequately irrespective of the true model, find management actions that best achieve one or more objectives given weights assigned to each model, or formalize hypotheses for evaluation through experimentation. Data availability is likely to limit the use of approaches that involve weighting alternative models in an ecosystem setting, and the cost of experimentation is likely to limit its use. Practical implementation of an EAF should therefore be based on management approaches that acknowledge the uncertainty inherent in model predictions and are robust to it. Model results must be presented in ways that represent the risks and trade‐offs associated with alternative actions and the degree of uncertainty in predictions. This presentation should not disguise the fact that, in many cases, estimates of model uncertainty may be based on subjective criteria. The problem of model uncertainty is far from unique to fisheries, and a dialogue among fisheries modellers and modellers from other scientific communities will therefore be helpful.