Differences between wheat genotypes in damage from freezing temperatures during reproductive growth

Cereal crops in the reproductive stage of growth are considerably more susceptible to injury from freezing temperatures than during their vegetative growth stage in the fall. While damage resulting from spring-freeze events has been documented, information on genotypic differences in tolerance to spring-freezes is scarce. Ninety wheat genotypes were subjected to a simulated spring-freeze at the mid-boot growth stage under controlled conditions. Spring-freeze tolerance was evaluated as the number of seeds per head at maturity after plants were frozen at −6 °C. Plants that froze, as confirmed by infrared (IR) thermography, died shortly after thawing and consequently the heads did not mature. Only in plants that had no visible freezing (super-cooled) were heads able to reach maturity and produce seeds. In plants that super-cooled four genotypes had significantly higher seed counts after being exposed to freezing than three with the lowest. In addition, significant differences between genotypes were found in whole plant survival among those that had frozen. Genotypes with high whole-plant freezing survival were not necessarily the same as the super-cooled plants with the highest seed counts. Spring-freeze tolerance was not correlated with maturity suggesting that improvement in freezing tolerance could be selected for without affecting heading date. Spring-freeze tolerance was not correlated with freezing tolerance of genotypes of plants in a vegetative state, either under non-acclimated or cold-acclimated conditions indicating that vegetative freezing tolerance is not a good predictor of spring-freeze tolerance.     

Escherichia coli challenge and one type of smectite alter intestinal barrier of pigs

An experiment was conducted to determine how an E. coil challenge and dietary clays affect the intestinal barrier of pigs. Two groups of 32 pigs （initial BW： 6.9 ± 1.0 kg） were distributed in a 2 x 4 factorial arrangement of a randomized complete block design （2 challenge treatments： sham or E. coil, and 4 dietary treatments： control, 0.3% smectite A, 0.3% smectite B and 0.3% zeolite）, with 8 replicates total. Diarrhea score, growth performance, goblet cell size and number, bacterial translocation from intestinal lumen to lymph nodes, intestinal morphology, and relative amounts of sulfo and sialo mucins were measured. The E. coli challenge reduced performance, increased goblet cell size and number in the ileum, increased bacterial translocation from the intestinal lumen to the lymph nodes, and increased ileal crypt depth. One of the clays （smectite A） tended to increase goblet cell size in ileum, which may indicate enhanced protection. In conclusion, E. coli infection degrades intestinal barrier integrity but smectite A may enhance it.     

参与式植物育种与可持续利用生物多样性--以广西玉米为例

遗传多样性是植物育种的基础,但“遗传侵蚀”现象十分严重。以长期技术供给为主要任务而形成的自上而下的农业研究和推广与需求相脱节,它在新的农村经济社会条件下已不适应。通过对广西玉米育种机构研究人员、科研管理人员及县、乡(镇)、村有关指导农业生产的管理干部和技术员进行访谈,对玉米种植的社区农户进行了深入的调查。运用系统科学的方法对广西玉米遗传多样性降低的影响因素进行分析得出结论和对策,同时通过《玉米种质遗传多样性与农民参与式育种研究》项目在广西实施为案例,进行调查和分析,以促进新的研究理念的形成。     

我国农产品贸易面临的技术性贸易壁垒及对策

技术性贸易壁垒是非关税壁垒中最隐蔽的一种。在WTO框架下,各国纷纷采取技术性贸易壁垒对本国农产品实施保护。分析我国在目前状况下所面临的壁垒,提出突破壁垒的几点建议。     

我国绿色食品出口现状和问题分析

经过十多年的发展,我国绿色食品事业取得了可喜的成绩.在总量规模不断扩大的同时,绿色食品出口也保持了快速增长,开始成为我国农产品出口贸易中的一大亮点和热点 .但是,随着我国加入WTO,绿色食品的出口也面临着一些问题,这就要求我们要积极采取一些有效措施来应对WTO的挑战,进一步加快绿色食品的出口创汇.     

High survivorship of an annually decreasing aggregation of hawksbill turtles,Eretmochelys imbricata,found foraging in the northern Great Barrier Reef

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Engaging Great Barrier Reef Stakeholders: Mediation Analyses of Barriers Among the Antecedents of Pro-Environmental Behavior

Resource managers continually attempt to influence stakeholder behavior to protect ecosystems. To aid managers and further our understanding of the human dimensions of natural resource management researchers have developed theories of pro-environmental behavior and to identify barriers to such behavior. However, there is a paucity of research integrating the two. There is a need to understand how perceived barriers influence the adoption of pro-environmental behaviors directly and how these barriers interact with the antecedents to pro-environmental behavior. Using the value-belief-norm theory as a guiding framework, we sought to fill this gap by investigating the effect of two barriers (lack of knowledge and low self-efficacy) among the antecedents to climate change–related behavior of anglers and other stakeholders (n = 324) living adjacent to Australia’s Great Barrier Reef. Results suggested that modeling/theorizing about how barriers fit into this process is complex because of differing contexts and levels of inclusion of barriers in existing theories.     

集成联合用药、隔离早期断奶（SEW）和“三点式”生产体系培育猪气喘病阴性群

为探索猪肺炎支原体阴性群的培育方法,本试验研究了集成联合用药、SEW和“三点式”饲养管理体系等技术对猪肺炎支原体的净化效果。先通过妊娠母猪的筛选,母猪程序性用药,SEW技术,屏障隔离系统,“三点式”生产饲养管理体系及仔猪程序性用药的培育方法,再通过猪肺炎支原体血清抗体检测和荧光定量 PCR检测鼻拭子的方法对所培育的仔猪进行长达4个月的监测,结果发现新培育的5批猪在35日龄后血清抗体均为阴性,鼻拭子抗原检测全为阴性。结果表明集成联合用药、SEW和"三点式"生产管理体系技术可以有效净化猪肺炎支原体,为国内猪气喘病的控制和净化提供理论基础及临床实践经验。     

大豆连作障碍机制研究初报

大豆连作减产早已为生产实践所证实。本文在对连作大豆减产规律调查研究的基础上,从大豆—土壤两个生态系统出发,对减产原因进行了分析,提出导致大豆连作障碍产生的原因是由土壤营养元素亏缺,物理、化学及生物活性改变,病虫害加剧等原因综合作用于大豆,使大豆生育受阻,产量下降。     

An ecosystem‐scale predictive model of coastal seagrass distribution

• 1. Maintaining ecological processes that underpin the functioning of marine ecosystems requires planning and management of marine resources at an appropriate spatial scale.
• 2. The Great Barrier Reef World Heritage Area (GBR) is the world's largest World Heritage Area (approximately 348 000 km²) and second largest marine protected area. It is difficult to inform the planning and management of marine ecosystems at that scale because of the high cost associated with collecting data. To address this and to inform the management of coastal (approximately 15 m below mean sea level) habitats at the scale of the GBR, this study determined the presence and distribution of seagrass by generating a Geographic Information System (GIS)‐based habitat suitability model.
• 3. A Bayesian belief network was used to quantify the relationship (dependencies) between seagrass and eight environmental drivers: relative wave exposure, bathymetry, spatial extent of flood plumes, season, substrate, region, tidal range and sea surface temperature. The analysis showed at the scale of the entire coastal GBR that the main drivers of seagrass presence were tidal range and relative wave exposure. Outputs of the model include probabilistic GIS‐surfaces of seagrass habitat suitability in two seasons and at a planning unit of cell size 2 km×2 km.
• 4. The habitat suitability maps developed in this study extend along the entire GBR coast, and can inform the management of coastal seagrasses at an ecosystem scale. The predictive modelling approach addresses the problems associated with delineating habitats at the scale appropriate for the management of ecosystems and the cost of collecting field data. Copyright © 2010 John Wiley & Sons, Ltd.