美国环境素养测评发展及对我国的启示

环境素养测评研究起源于美国,并且历经30年的发展得以完善,而我国环境素养测评研究尚处于起步阶段。该研究对比分析了中美学者在环境素养测评方面的差距,以提高国内研究水平,培育公众环境素养,促进生态文明、环境友好型社会建设。     

美国和加拿大有机农业及国际等效互认的意义

有机农业于近30年在全球兴起并快速发展,美国和加拿大都是有机农业发展较早的国家之一。主要介绍了美国和加拿大两国的有机农业在产业发展、政策法规、监管体系、研究服务等方面的概况,介绍并分析了美国-加拿大有机等效协议对国际多边互认的借鉴意义,指出有机农业标准法规的国际多边互认有利于减少贸易技术壁垒,对全球有机产业的健康有序发展具有重要意义。     

美国林木种苗培育技术现状及启示

美国林木苗圃在种苗培育上有着较好的技术和经验, 作者以1992年掌握的美国种苗信息为基础, 对20年后美国林木苗圃主要育苗技术情况进行分析和综述。其中主要介绍美国东南部和西北部地区近15个林木种苗生产相关企业及研究所的实用技术和技术推广情况, 讨论美国林木种苗行业协会和技术推广专家在育苗技术推广中的作用和形式, 提出了技术创新、苗圃分类经营、政府引导和产学研紧密结合等建议, 以期为我国的林木种苗产业发展提供借鉴。     

Pre-maturity α-amylase in wheat: The role of abscisic acid and gibberellins

The occurrence of pre-maturity α-amylase (PMA) is a major cause of poor bread-making quality (low Hagberg Falling Number) in wheat grain. In susceptible genotypes, it involves the excessive accumulation of high isoelectric point (pI) α-amylase in mature grain prior to germination and in the absence of pre-harvest sprouting. Several factors regulate PMA formation in developing grain, including genotype, agronomy, and environmental conditions. In particular, a cold period during mid-grain development has been found to be a major stimulus for PMA induction. Although the factors affecting the PMA occurrence are well known, little is known about the molecular mechanism governing its induction. The plant hormones abscisic acid (ABA) and gibberellins (GAs) influence various aspects of grain development, and it has been suggested that PMA involves changes in the amount of these hormones or the sensitivity of the grain to these hormones. This review summarizes recent studies investigating the role of ABA and GAs in PMA induction and PMA occurrence.     

2013年美国玉米高产竞赛简报

美国农民大卫·胡拉在2013年创造了28 560 kg/hm2的世界玉米高产纪录。在分析大卫·胡拉高产竞赛史的基础上,从土壤培育、选择品种、耕作栽培、运筹水肥、防治病害等方面研究了他的创纪录历程,总结他的成功经验及其对玉米生产的启示,为中国玉米高产创建提供借鉴。     

美国世纪大旱引发的思考

2012年入夏以来,持续发展的旱情致使美国农作物大幅减产、农产品价格持续飙升,美国的经济和社会受到了极大的影响。与此同时,美国大旱对我国这样一个自然灾害频发的农业大国也敲响了警钟。通过分析美国世纪大旱的特点、成因、影响以及气候变化背景下我国农业生产面临的自然灾害频发多发、农业投入品增加等问题,提出应从建立和完善气象监测预警系统,加强以水利为主的农业基础设施建设,加大农业减灾技术研究与推广的投入等角度提升我国农业生产应对气候变化的能力。     

美国农产品地标保护的做法及对中国的启示

美国农产品的地理标志保护历史源远流长,形成了鲜明、成熟的体系,对于中国完善地理标志保护体系有着重大的借鉴作用。中国具有极其丰富的农产品资源,然而在法律层面上的保护却有所欠缺,因此导致了许多直接或间接的经济损失。分析中美间农产品贸易现状数据,探讨美国对于农产品地理标志保护的法律体系,从美国和其他国对于地理标志谈判的案例吸取经验,为中国建立完善农产品地标保护的做法提供一些启示。     

Establishing native plants on newly‐constructed and older‐reclaimed sites along West Virginia highways

Many state highway departments in the USA must use native plants for revegetating roadsides. We conducted two field studies in West Virginia to assess native plant establishment under two different conditions. On newly‐constructed sites, native species were seeded alone or combined with non‐native species. On older roadsides, native species were seeded in disturbed existing vegetation. In the first study, we used four seed mixtures comprised of seeds of native and non‐native species, and two N‐P‐K fertilizer treatments at three newly‐constructed sites. Native, warm‐season grasses were slow to establish and only contributed 25 per cent cover in some plots after three years. Indiangrass (Sorghastrum nutans [L.] Nash), big bluestem (Andropogon gerardii Vitman), Brown‐Eyed Susan (Rudbeckia triloba L.), and wild senna (Cassia hebecarpa Fernald) were the only seeded native species found. Fertilizer at 150 kg ha⁻¹ of 10‐20‐10 showed little influence on increasing plant cover. In the second study, we disturbed three different‐aged established stands of vegetation composed of tall fescue (Festuca arundinacea Screb.) and crownvetch (Coronilla varia L.) by mowing, herbicide, or tillage, and native plants were seeded with and without fertilizer. Native cover was <10 per cent in all plots during the first year, but greatly increased by the second year to as much as 45 per cent in tilled plots, indicating that disturbance was necessary for natives to become important contributors within 2 years. Only switchgrass (Panicum virgatum L.), little bluestem (Andropogon scoparius Vitman), partridge pea (Chamaecrista fasciculate Michx.), and Brown‐Eyed Susan were observed in plots. Fertilizer at 300 kg ha⁻¹ of 10‐20‐10 did not increase native plant cover on these sites. Based on our results, introducing or increasing the cover of native species along roadsides requires (1) reducing competition from non‐native species, and (2) longer time periods for these slower‐establishing species to be observed. Copyright © 2008 John Wiley & Sons, Ltd.     

Multi-scale effects of habitat loss and fragmentation on lesser prairie-chicken populations of the US Southern Great Plains

Large-scale patterns of land use and fragmentation have been associatedwith the decline of many imperiled wildlife populations. Lesserprairie-chickens(Tympanuchus pallidicinctus) are restricted to thesouthernGreat Plains of North America, and their population and range have declined by> 90% over the past 100 years. Our objective was to examine scale-dependentrelationships between landscape structure and change and long-term populationtrends for lesser prairie-chicken populations in the southern Great Plains. Weused a geographic information system (GIS) to quantify landscape composition,pattern and change at multiple scales (extents) for fragmented agriculturallandscapes surrounding 10 lesser prairie-chicken leks. Trend analysis oflong-term population data was used to classify each population and landscape(declined, sustained). We analyzed metrics of landscape structure and changeusing a repeated measures analysis of variance to determine significant effects( = 0.10) between declining and sustained landscapes across multiplescales. Four metrics of landscape structure and change (landscape change index,percent cropland, increases in tree-dominated cover types, and changes in edgedensity) contained significant interactions between population status andscale,indicating different scaling effects on landscapes with declining and stablepopulations. Any single spatial scale that was evaluated would not have givencomplete results of the influences of landscape structure and change on lesserprairie-chicken populations. The smallest spatial scales (452, 905, and 1,810ha) predicted that changes in edge density and largest patch sizewere the only important variables, while large-scale analysis (7,238ha) suggested that the amount of cropland, increase in trees(mostly Juniperus virginiana), and general landscapechanges were most important. Changes in landscape structure over the pastseveral decades had stronger relationships with dynamics of lesserprairie-chicken populations than current landscape structure. Observed changessuggest that these local populations may be appropriately viewed from ametapopulation perspective and future conservation efforts should evaluateeffects of fragmentation on dispersal, colonization, and extinction patterns.This revised version was published online in May 2005 with corrections to the Cover Date.     

美国西瓜育种历程及育成品种的种质基础

 在对美国1870～2001年育成的235个西瓜品种选育方法及系谱分析的基础上，概括了美国一百多年间的西瓜育种发展历程，计算了91个通过杂交选育的品种直接亲本和祖先亲本的核遗传贡献值，评定出核心直接亲本和核心祖先亲本及核心中间亲本，并对如何重点引进和有效利用这些核心种质进行了讨论。