湖南一季超级稻种植气候区划

根据湖南省各站1961-2003年共43a历史气象资料和2002-2003年田间试验结果,针对一季超级稻播种育秧期的连阴雨及抽穗扬花期的高温热害两种主要气象灾害指标,从气象条件出发,利用GIS手段,研究了湖南省一季超级稻适宜种植区域。     

Copper in the terrestrial environment: Verification of a laboratory-derived terrestrial biotic ligand model to predict earthworm mortality with toxicity observed in field soils

This study was set up for validation of a regression model to predict mortality in the terrestrial earthworm Aporrectodea caliginosa following exposure to copper. This model was derived from a terrestrial biotic ligand model and incorporates the protective effects of H⁺ and Na⁺ on copper toxicity.Three soil sets were used for the experiments, all of which had a different copper contamination history over more than 20 years and were considered to be aged field soils. The soils were characterized by analysis of various copper pools in the solid phase and in the pore water, analysis of physical and chemical soil properties and by regression analysis. Measured and calculated copper activities (expressed as pCu) correlated reasonably well. Measured copper activities correlated with the total copper concentration in the pore water and the pH. The organic matter in the solid phase had no influence on the pCu in these soil sets.Earthworms were exposed to the soils for 28 days, after which survival was scored. Observed earthworm mortality after 28-days exposure was plotted as a function of the log-transformed difference between predicted (log₁₀ transformed) LC50-values and measured values of pCu for validation of the regression model. The results obtained were in agreement with the assumption that mortality is to be observed in those soils where the predicted LC50 exceeds the measured pCu. However, a structural underestimation of toxicity was apparent, which is most likely due to mixture effects related to the presence of additional substances in field soils. Nevertheless, the trend of the results in the validation tests demonstrates that the newly developed toxicity model is a useful tool in predicting lethality of copper contamination to earthworms in field soils.     

Quantification of the biocontrol agent Pseudomonas fluorescens Pf153 in soil using a quantitative competitive PCR assay unaffected by variability in cell lysis- and DNA-extraction efficiency

Although often neglected, variability in cell lysis efficiency and DNA extraction yield represents the major hurdles of any polymerase chain reaction (PCR)-based quantification protocol in soil and other natural environments. In this study we developed a technique that minimizes the effects of these constraints, providing at the same time a reliable internal control to distinguish between PCR-inhibition and negative results. We used Pseudomonas fluorescens Pf153, a root-colonizing bacterium that shows biocontrol activity against tobacco and cucumber black root rot, as the target organism for PCR quantification. Prior to DNA extraction, the genetically engineered, cognate reference strain P. fluorescens CHA0/c2 was inoculated in a reference soil. CHA0/c2 in the reference soil and Pf153 in the soil sample were lysed in parallel and afterward the lysates were mixed in known proportions. CHA0/c2 carries the plasmid pME6031-cmp2 that contains an allelic variant (competitor) of the Pf153 specific sequence Pf153_2. In a quantitative competitive PCR (QC-PCR) assay the competitor allows the quantification of the target strain down to 0.66 Pf153 CFU/mg soil. Processing the reference strain in the same way as Pf153 enables the exact quantification of the target strain in biocontrol assays performed in natural soil, overcoming differences in DNA extraction efficiency and PCR amplification from different soil environments. This technique is easily adaptable to other Pseudomonas strains simply by replacing the competitor used here with one derived from a SCAR-marker which is specific for the strain of choice.     

北京市水土流失重点防治区划分及防治对策

 北京山区水土流失严重,山洪、泥石流灾害时有发生。根据防护目的、土壤侵蚀强度和土壤侵蚀潜在危险度等,应用地理信息系统技术,采用人机交互判读分析方法,将水土流失防治区划分为重点预防保护区、重点监督区和重点治理区,并提出北京地区水土流失防治对策。     

食品包装学采用地域化教学模式的实例

为了更好地适应地区经济发展特色和社会需求,在食品包装学的教学模式中注重地域化的案例展示、实验编排、调研认识和知识结构贯通,形成开放性教学资源和地域性教学模式并肩发展的良性循环,不仅可以提高课程整体的教学质量,使学生乐学好学,更能培养出符合国家对新疆建设需求的本土科技人才,促进区域经济的发展。     

Revenue risk management, risk aversion and the use of Livestock Gross Margin for Dairy Cattle insurance

The Livestock Gross Margin Insurance for Dairy Cattle is a federally reinsured insurance program that enables US dairy producers to establish minimum levels of milk income net of feed cost. Given the structure of this program there are an infinite number of possible contract designs based on the choice of deductible level and proportion of production insured. Adding to this complexity, producers vary in their risk preferences, which affect the incentive to insure their margin. It is unclear as to how producers may adopt this program for revenue risk management. This paper investigates the interplay between producer risk preferences, contract design and the subsidization of premium in determining program coverage. We undertook this analysis within an expected utility framework. Optimal contracts under different rates of constant relative rate of risk aversion and subsidies were analyzed using a nonlinear optimization model. We found that total optimal coverage increased significantly with the level of risk of aversion at lower deductibles but as deductible level increased, the level of risk aversion had a lesser impact on total optimal coverages. As expected, at the same deductible and risk aversion levels, inclusion of a premium subsidy increased the total optimal coverage.     

广西贺州市脐橙种植气候区划

与国内外脐橙优产区相比,贺州市热量条件对脐橙生产更具优势。但复杂的地形地貌使市内各地在湿度、最高气温等气候要素差异较大,影响当地脐橙产量及品质。通过分析贺州市气候特点,结合脐橙生长发育对气候条件要求,确定了贺州市脐橙适宜种植气候指标,在GIS技术下绘制出贺州市脐橙适宜种植气候区划专题图。通过对专题图中的最适宜、适宜、次适宜、不适宜区气候区域气候论述,为贺州市脐橙生产的优化布局提供气候依据。     

我国农业保险经营模式分析

通过对我国农业保险经营模式进行归纳和评述,建议各地应因地制宜,建立多层次体系,多渠道支持,多主体经营的现代农业保险制度。     

主成分聚类分析在县域生态经济分区中的应用——以东营市河口区为例

生态经济分区是宏观管理区域社会经济发展的一种新的模式.在介绍县域生态经济分区原则与方法的基础上,以东营市河口区为例,首先从资源环境、社会、经济3方面共选取27个指标构建了分区指标体系,然后以乡镇为样本进行主成分分析,再利用提取的主因子作为新的综合变量,并以各主因子得分矩阵为新的综合变量数据进行聚类分析,在考虑地形地貌和区域特征的基础上将该县域划分为4个生态经济区.在分析各生态经济区基本情况的基础上为各区经济发展方向提出了建议.     

河北省土壤水资源划区探讨

综述了土壤水和土壤水资源的概念以及土壤水资源划区的意义,以土壤的地带性规律为基础,与农业综合区划相协调并保持乡级行政区界的完整性为划区原则,提出了河北省土壤水资源的划区方案.即河北省土壤水资源分为区、亚区和片3级,共划分为7个土壤水资源区、14个土壤水资源亚区和28个土壤水资源片.