推进山区县绿色农业产业链发展策略研究——以垣曲县为例

构建与推进山区县绿色农业产业链发展,是推动绿色农业产业化经营可持续发展的重要路径。根据绿色农业产业链发展的内涵和特征,以山西省垣曲县为例,具体构建其核桃、果酱、蜂、辣椒、红薯系列产品绿色农业产业链的发展框架,有针对性地提出合理布局产业结构、提升生产技能专业水平、规范企业运营管理机制、加大科技创新投入力度、扩大经营组织规模、创新经营模式的发展策略,对推进山区县绿色农业产业化经营发展有一定的借鉴作用。     

鲆鲽类养殖不同产业链模式的经济效益比较研究

产业结构直接影响产业经济效益,而产业结构是产业链长期发展和优化的产物。产业链越长,分工经济越明显,但随之而来的交易环节增多会导致费用增加,分工带来的经济效益的提升有可能被交易费用的增加所抵消。同一产业内不同养殖户对产业链各环节的不同组合会形成不同的产业链模式。对不同产业链模式经济效益的比较研究,不仅有利于养殖户效益最大化,且有利于产业结构的优化,进而促进整个产业的发展。以我国鲆鲽类养殖为例,基于2013年不同鲆鲽类养殖模式经济效益的跟踪调查,用秩和检验的方法对"育苗+成鱼养殖"模式、"仅育苗"模式及"仅成鱼养殖"模式的成本、收益和资本回报率进行了对比分析。结果显示:(1)专业化分工程度越低的产业链模式,其可变成本越低,固定成本中的要素成本越高;(2)专业化分工程度越高的产业链模式,单位净收益越高,资本回报率越高。基于此,建议管理部门通过合理整顿市场来提高专业化分工程度,为养殖生产者经济效益提供更好的市场环境,建议养殖生产者加强技术创新和科学管理能力从而提高经济效益。     

VALUE CHAIN OF SNAKEHEAD FISH IN THE LOWER MEKONG BASIN OF CAMBODIA AND VIETNAM

Snakehead fish are the most preferred fish species for food in Cambodia and Vietnam, and are consumed in both fresh and processed forms. The purpose of this paper is to describe the value chains of captured and cultured snakeheads in the Lower Mekong Basin (LMB). The important actors involved in the value chain of snakeheads in the LMB of Cambodia and Vietnam were fishers, fish farmers, wholesalers, retailers, and processors. The value chain of wild captured snakeheads in Cambodia was focused on 11 marketing channels, and for cultured snakeheads in Vietnam, 10 market channels. The distribution of benefits among the chain actors was unequal, with the highest proportion of profit going to wholesalers in Cambodia and collectors in Vietnam. In order to develop the value chain of snakehead for the long-term in the LMB, appropriate plans must be prepared for each country in association with better management and protection of natural aquatic resources.     

采用双峰驼重链抗体特异的抗血清检测不同抗原免疫骆驼过程中血清重链抗体的水平

为了探究重链抗体在骆驼免疫保护中的生物学作用,本研究利用Protein G和Protein A亲和层析纯化新疆双峰驼血清中总IgG和重链抗体IgG2,并免疫昆明小白鼠制备抗双峰驼总IgG和抗双峰驼重链抗体IgG2的多抗血清;通过ELISA检测双峰驼在体液免疫应答过程中针对spaA-N、溶菌酶和蒜氨酸酶3种抗原的重链抗体的滴度变化。结果从新疆双峰驼血清中亲和层析纯化出天然重链抗体IgG2,蛋白质分子质量约为46 ku;免疫昆明小白鼠后获得抗双峰驼总IgG多抗血清的效价为1∶204800,抗双峰驼重链抗体IgG2多抗血清的效价为1∶6400。在spaA-N免疫骆驼诱导的体液免疫应答过程中,重链抗体IgG2出现延迟反应。3种蛋白均能诱导抗原特异的IgG2亚类重链抗体的产生。     

关键成员发展循环经济的模糊综合评价研究——基于集成农产品供应链

通过对关键成员发展循环经济评价因素的综合分析,建立了包括农产品质量、附加品增值效益、成本、客户反映、绿色绩效和创新能力等6个一级指标、17个二级指标的评价指标体系。以模糊理论为基础,采用层次分析法确定各指标权重,建立了双层模糊综合评价模型,并利用该方法对某集成农产品供应链关键成员发展循环经济能力进行了综合评价,得到的评价结果可以为政府找到合适的投资主体,并为政府投资或推进循环经济项目提供依据和指导。     

基于权马尔可夫链的宝鸡市年降水量状态预测

为了全面分析宝鸡市自然降水的时间分布规律和变化趋势,为该区域水资源预测、旱涝灾害防治、水量调度和水资源管理提供依据,对宝鸡市年降水量状态进行了权马尔可夫链分析。针对降水过程中的不确定和不精确性,采用均值-标准差分级法,将宝鸡市1956-2009年降水量分为干旱、偏旱、正常、偏涝、雨涝5个状态。以规范化的各阶自相关系数为权重,采用权马尔可夫链模型对宝鸡市未来年份的降水量状态进行预测。平稳分析结果表明,宝鸡市多年降水过程中干旱、偏旱、正常、偏涝、雨涝等5种状态出现的概率分别为0.1305、0.2767、0.2751、0.2075、0.1101。宝鸡市未来多年降水过程中偏旱和正常状态占优势,而雨涝出现概率较低,反映了该区域气候暖干化的长期变化。     

转基因植物重组DNA和表达蛋白的环境分子行为

转基因植物的安全性已经在全球范围内引起了普遍关注。本文从分子水平上就转基因植物的重组DNA在环境中的降解动态、转基因植物重组DNA在生物体内的传递、转基因植物杀虫蛋白在环境中的降解及在食物链间的传递等有关研究进展作一简要介绍。     

Differentiation of two powdery mildews of sunflower (<Emphasis Type="Italic">Helianthus annuus</Emphasis>) by a PCR-mediated method based on ITS sequences

Powdery mildew can be found in most sunflower fields during the winter season in Taiwan and causes severe yellowing on the blade, petiole, stem, and calyx, as well as serious defoliation. Two types of powdery mildew fungi isolated from sunflower leaves showed variable status for fibrosin bodies. But only the cleistothecium of Podosphaera xanthii, one of the pathogens causing this disease, was observed on samples from Chungpu County at the beginning of 2005. With a species-specific primer pair, PN23/PN34, no specific PCR product was amplified from the pathogen’s genomic DNA. Based upon the ITS sequence of rDNA, three PCR primer sets (S1/S2, G1/G2, and L1/L2) specific to P. xanthii, Golovinomyces cichoracearum and Leveillula taurica, respectively, were designed to detect and differentiate pathogens causing powdery mildews on sunflower. Only the primer pairs S1/S2 and G1/G2 could amplify PCR products, with product sizes of 454 and 391 bp, respectively. Four samples of fungal DNA were subjected to a multiplex PCR amplification with primer pairs S1/S2 and G1/G2; P. xanthii and G. cichoracearum were successfully detected. These results suggest that the multiplex PCR method is a rapid, simple, and effective technique to detect and differentiate powdery mildews, for example P. xanthii and G. cichoracearum, found on sunflower. With morphologic characteristics, ITS sequence analysis and pathogenicity testing, P. xanthii and G. cichoracearum, the first case, are two powdery mildews on sunflower in Taiwan.     

Internal fruit rot of netted melon caused by <Emphasis Type="Italic">Pantoea ananatis</Emphasis> (=<Emphasis Type="Italic">Erwinia ananas</Emphasis>) in Japan

An internal fruit rot with a malodor was found in netted melons (Cucumis melo L.) in commercial greenhouses in Kochi Prefecture, Japan, in 1998, despite their healthy appearance and lack of water-soaking or brown spots on the surface. A yellow bacterium was consistently isolated from the affected fruits. To confirm the pathogenicity of eight representative isolates of the yellow bacterium, we stub-inoculated ovaries (immature-fruits) 5–7 days after artificial pollination, with a pin smeared with bacteria. After the melon fruits had grown for 60 more days, an internal fruit rot resembling the natural infection appeared, and the inoculated bacterium was reisolated. The melon isolates had properties identical with Pantoea ananatis, such as gram-negative staining, facultative anaerobic growth, indole production, phenylalanine deaminase absence, and acid production from melibiose, sorbitol, glycerol, and inositol. Phylogenetic analysis based on 16S rDNA sequences showed that the melon bacterium positioned closely with known P. ananatis strains. The melon bacterium had indole acetic acid (IAA) biosynthesis genes (iaaM and iaaH) and a cytokinin biosynthesis gene (etz). The bacterium could be distinguished from the other ‘Pantoea’ group strains by rep-PCR genomic fingerprinting. From these results, the causal agent of internal fruit rot was identified as a strain of P.ananatis [Serrano in (Philipp J Sci 36:271–305, 1928); Mergaert et al. in (Int J Syst Bacteriol 43:162–173, 1993)]. The nucleotide sequence data reported are available in the DDBJ database under accessions AB297969, AB373739, AB373740, AB373741, AB373742, AB373743 and AB373744.     

Detection of Koi herpesvirus: impact of extraction method,primer set and DNA polymerase on the sensitivity of polymerase chain reaction examinations

Since virus isolation is seldom successful, KHV infection is commonly detected by PCR examination. A number of different PCR assays have been described in recent years. However, at present no commonly accepted PCR method is used amongst different laboratories. The aim of this study was to check if the examination of infected fish by different PCR methods yielded comparable results. We used tissue samples of three KHV‐infected koi, one KHV‐infected common carp, one KHV‐infected goldfish and one non‐infected common carp. DNA was extracted with DNAzol Reagent, High Pure PCR Template DNA Preparation Kit and QIAamp DNA Mini Kit. The DNA was tested by PCR with different combinations of published primer sets –KHV‐F and ‐R, KHV‐Gray‐2F and ‐2R and KHV‐TKf and ‐TKr – plus different DNA polymerases – a standard Taq DNA polymerase, a Platinum (hotstart) Taq DNA polymerase and a Platinum (hotstart) Pfx DNA polymerase with proofreading activity. The different extraction methods produced DNA solutions with different yields of DNA and different degrees of homogeneity. Also, the sensitivity of the PCR depended on the choice of the primer set and polymerase. Not all infected fish could be identified with all methods; there were large differences in the sensitivity between methods.