美国SL-9甘薯茎尖脱毒组织培养的最适激素浓度配比初探

为探索高淀粉甘薯品种美国SL-9茎尖脱毒组织培养的最适激素浓度配比,选择6-BA和α-NAA两种激素,通过不同浓度的配比,利用线性综合评价模型对愈伤组织诱导率L、出芽（成苗）率M和芽长（苗高）N三个培养效果指标进行综合评价。结果表明,最适于该品种茎尖脱毒组织培养的培养基配方为MS＋1.00 mg/L6-BA＋0.50 mg/Lα-NAA;在此培养基上,美国SL-9愈伤组织诱导率L为83.3%,出芽（成苗）率M为100%,且成苗速度快,培养时间短,接种培养40d苗高达11.4mm,优于其它激素浓度配比。     

美日石油安全储备对我国建立战略石油储备的启示

对战略石油储备和经济安全问题进行了理论研究,分析了我国石油产业安全的基本内涵以及建立战略石油储备的必要性等问题。结合我国石油行业的实际情况,借鉴国际战略石油储备的经验,探讨了提高我国石油产业安全性的战略途径。     

北美白云杉、黑云杉在中国的引种研究

云杉属 (Picea)树种是高大乔木 ,生态适应性强 ,利用价值高 ,近 2 0 0年来欧、亚、美作了大量的引种栽培工作。很多国家已将它们作为主要的造林树种和珍贵的绿化观赏树种 ,因此研究云杉属的引种 ,对促进林业生产和国民经济发展 ,具有重要意义。主要探讨了北美最重要的用材树种白云杉、黑云杉在国外的研究现状及发展趋势以及在我国的引种可能性、引种历史、现状、存在的问题及展望 ,以期对今后的引种、驯化和遗传改良工作提供科学的依据和参考     

晚近北美森林土壤研究动态

本文综合介绍了北美森林土壤晚近的主要研究方向、苗头、新趋势以及研究方法技术的发展等情况,并与中国森林土壤学研究作了相互比较。     

美国新农场安全网的主要内容和影响分析

美国联邦政府将管理农场生产经营风险的一系列支持计划统称为农场安全网,具体包括主要针对农业生产经营中市场风险的农产品计划、主要针对农业生产经营中自然风险的农作物保险计划以及对上述两个计划未覆盖风险进行补充的农业灾害援助计划。2014年美国农业法案对其农场安全网的内容和结构进行调整,试图构建一个各支持计划间有机组合、注重补贴效率和强化风险管理的新农场安全网。新农场安全网下的综合支持量虽然不会超过美国在WTO的减让承诺,但增加美国农产品贸易争端的潜在范围,降低美国在WTO新协议中削减"黄箱政策"补贴的意愿,对世界农产品贸易产生重要影响。新农场安全网一方面将加剧我国农产品进口压力,另一方面对我国农业补贴政策改革有如下启示:继续加大支持保护力度;坚持市场化改革方向;健全农业保险制度。     

Evidence of hybridization between Yaqui catfish Ictalurus pricei (Rutter, 1896) and channel catfish Ictalurus punctatus (Rafinesque, 1818) in north-west México revealed by analysis of mitochondrial and nuclear genes

1. The Yaqui catfish, Ictalurus pricei, is the only native ictalurid species described from north-west México and south-west USA. It is an endangered species owing to the decline and loss of most of its historical populations, mainly because of competition and hybridization with the non-native channel catfish, Ictalurus punctatus. The Arroyo Cajón Bonito is one of the few remnant populations of Yaqui catfish in the Yaqui River basin, and it is threatened by the presence of channel catfish that escaped from private culture facilities.
2. Phylogenetic analysis of two mitochondrial and two nuclear genes was used to detect evidence of hybridization with channel catfish in a collection of 20 catfish from Arroyo Cajón Bonito. Fourteen putatively pure Yaqui catfishes, five hybrids and one channel catfish were detected.
3. This study further highlights hybridization between channel and Yaqui catfish as the main threat to the remaining Yaqui catfish populations. We recommend urgent evaluation of the remnant populations of native catfish elsewhere and their current conservation status.

     

In Focus: Spotted wing drosophila, Drosophila suzukii, across perspectives

In August 2008, the first detection of the spotted wing drosophila, Drosophila suzukii, to the North America mainland in California caused great concern, as the fly was found infesting a variety of commercial fruits. Subsequent detections followed in Oregon, Washington, Florida and British Columbia in 2009; in Utah, North Carolina, South Carolina, Michigan, and Louisiana in 2010; and in Virginia, Montana, Wisconsin, Pennsylvania, New Jersey, Maryland and Mexico in 2011. In Europe, it has been detected in Italy and Spain in 2009 and in France in 2010. Economic costs to the grower from D. suzukii include the increased cost of production (increased labor and materials for chemical inputs, monitoring and other management tools) and crop loss. An effective response to the invasion of D. suzukii requires proper taxonomic identification at the initial phase, understanding basic biology and phenology, developing management tools, transferring information and technology quickly to user groups, and evaluating the impact of the research and extension program on an economic, social, and environmental level. As D. suzukii continues to expand its range, steps must be initiated in each new region to educate and inform the public as well as formulate management tactics suitable for the crops and growing conditions in each.     

美国土壤侵蚀过程及其预报模型研究进展

土壤侵蚀过程的研究将为基于物理过程的侵蚀预报模型研发提供重要的理论基础。介绍了美国土壤侵蚀过程研究进展 ,叙述了土壤侵蚀过程研究对研发水蚀预报模型 (WEPP)的重要贡献 ,阐述了近期侵蚀过程研究对WEPP模型中侵蚀过程概念模型的挑战 ,希望对中国侵蚀过程及其预报模型的研究有借鉴作用。     

美国农产品的供求信息服务

主要介绍了美国农产品市场供求信息收集体系及其应用状况。