绿色杷夫藻用于罗氏沼虾人工生态系育苗

本文通过培养试验探讨了绿色杷夫藻（Pavlovaviridis）的生长特性，认为该藻具有指数生长期较长、藻群绝对密度较高且维持高峰时间较长等优良特性。该藻具有较广泛的生态适应性，能适应光强500～10000lx、温度6～30℃、海水比重1．002～1．016，特别能在低盐度（比重为1．002）、低光照（400～500lx）条件下良好生长，生态上符合罗氏沼虾人工育苗的客观要求。在育苗水体中保持一定数量饵料性微藻并投饲其他生物饵料构成人工生态育苗体系进行工厂化育苗，以角毛藻（Chaetocerossp．）、小球藻（Chlorellasp．）为对照，比较3种微藻培育罗氏沼虾状幼体的效果，发现绿色杷夫藻与角毛藻效果相当而明显好于小球藻。本文作者认为绿色杷夫藻是罗氏沼虾人工生态系育苗的理想用藻。     

Evaluation of techniques for detection of small trematode eggs in faeces of domestic animals

This study was conducted to evaluate techniques for detection of small trematode eggs in faeces of dogs, cats and pigs. Faecal samples from dogs (n=80), cats (n=35) and pigs (n=114) were examined by Kato-Katz technique (KK), formalin-ether sedimentation technique (FE) and a method of combining: filtration, sedimentation and centrifugation, developed at DBL - Centre for Health Research and Development (former Danish Bilharziasis Laboratory) (DBL). Necropsy was performed on 38 dogs, 25 cats and 16 pigs and was considered as a gold standard method for evaluation of the techniques. The results showed 100% specificity for the three techniques. Lower sensitivity was seen for the KK-technique in dog samples in comparison to that for DBL- and FE-technique. The sensitivity of the three techniques was similar in cats and pigs. Based on these findings and practical issues, DBL-technique was chosen as most suitable because the eggs were easily detected and quantified. No toxic chemicals or special equipment were required in comparison with FE-technique that needs ether solution and thus fume cupboards which are often unavailable in local veterinary centres in Vietnam and other developing countries.     

两种不同穗型小麦品种光合生理特性研究

比较了大穗型和多穗型小麦品种的光合生理特性。结果表明 ,与多穗型品种豫麦 4 9相比 ,大穗型品种鲁麦 91 - 3具有较好的光合源和光合能力 ,在整个灌浆期旗叶具有较高的净光合速率和蒸腾速率 ,灌浆中后期旗叶叶绿素含量较高 ,叶面积系数 (L AI)衰减迟缓 ,叶片功能期较长。进一步提高大穗品种产量潜力的途径是 ,在保持或适当提高生物学产量的同时 ,较大幅度提高收获指数     

果园土壤铜污染状况及其对作物生长的影响

调查了由于长期使用铜制剂农药波尔多液,铜在果园土壤中的残留积累状况;并用采自果园的铜污染土壤进行盆栽试验,研究了铜对作物的危害影响。结果表明,一些果园地区由于长期使用波尔多液,土壤铜含量严重超标。果园土壤一旦遭受铜污染,将造成持久性影响,因此建议要逐步限制或禁止使用波尔多液,用新型农药代替波尔多液。     

元江干热河谷低海拔地带退化生态系统植物多样性及物种分布模式

元江干热河谷是一个低海拔的脆弱生态系统,以环境干旱、植被贫乏为主要特征。17世纪中期以前它曾经植被茂盛,但是17世纪末以后,它逐渐演变退化为一个典型的热带山地萨王纳类型。本研究旨在阐明元江干热河谷低海拔地带典型干热区植物的多样性及其分布状况,从而深入了解气温、降水、地下水等主要的环境因子对植物种类及种群的影响以及植物对干热环境的适应,以及植物种类及其组成对元江干热河谷环境的指示作用。考察的主要指标包括物种多样性α,生境多样性β,物种期望值Species_estimated,稀有指数Singletons和Uniques,以及物种丰富度指数ACE、ICE和Chao2等。结果显示：（1）在不同的样带设计中,以紧靠河流的样带和样方(< 25 m) α多样性高,远离河道则逐渐变小。（2）在平行于河道的L样带,随着沿河流从上游向下游延伸,β多样性变化趋势明显,Bray-Curtis < 0.500;而在垂直于河道的P样带,随着环境干热化加剧及河道渗水的急剧减少,生境趋同性明显,Bray-Curtis > 0.500。（3）总体趋势上,干热河谷低海拔地带的植物对水分的依赖性表现得相当明显,在紧靠河道的样带,以及河流下游河漫滩发育地区,物种期望值Species_estimated、稀有种指数Singletons和Uniques以及物种丰富度指数ACE,ICE和Chao2都明显偏高。本研究研究证明干热河谷低海拔地区存在特殊水热条件,影响植物的种类和分布,同时阐明了干热河谷低海拔地区植物多样性及种类分布与河道周边的小生境密切相关,为脆弱生态环境环境变化监测提供建议。     

Agrotourism and fast urbanisation: The double pressure of development on peri-urban agriculture in Hôi An,a small city of central Vietnam

Agrotourism in Vietnam has been identified as one of the strategies used to achieve green growth and countryside modernisation, and it is often included as part of the national and local agenda. In this paper, we examine agrotourism in a village in the periphery of Hội An city (an international tourism hub in central Vietnam) to question tourism's interaction with ongoing development processes. More specifically, we aim to understand the impact of fast peri-urbanisation on agrotourism and the impacts of agrotourism on people's daily lives, specifically when it comes to physical changes in their living environment, tensions in their social life and their concerns about the future. Our analysis is supported with data generated from interviews with farmers, local officials, tourism workers and tourists. We find that agrotourism products lacked authenticity and farming was not of great interest for tourists, yet the state's investment in the village tended to favour spaces and infrastructure that could attract more tourists and generate profit, to the detriment of cultural infrastructure. Land speculation and an unequal distribution of income were the main tensions in the village along with farmers' concerns about their rural heritage, income diversification and environmental quality. As such, agrotourism in the village has been driven by rapid urbanisation and mass tourism, creating a competition between a consumption activity and a productive activity. Those are important parameters that future policymakers need to take into consideration in order to sustain the city's food production and tourism.     

Social differentiation revisited: A study of rural changes and peasant strategies in Vietnam

This article analyses the processes of transformation and differentiation since the 1950s in a Vietnamese rural village, hereafter called Chieng Hoa. ¹ It examines how radical changes in political discourse and economic policies at the national level have affected the welfare and social relations of villagers and how the latter have in turn coped, resisted, as well as shaped such structural changes. Using concrete life stories of local people, the article identifies the winners and losers in this transformation process, the trajectories households or individuals have taken to arrive at their current positions, and the strategies that they are adopting for the future. It demonstrates that differentiation in Chieng Hoa implies changes in social relations, including but not limited to relations of production, and that even within this single locality, differentiation can take various forms and processes over time, whether specific to or cutting across changes in macro‐policies. The article also reveals that in the often perceived equal collectivisation, inequalities still existed and became causes of differentiation in the subsequent decollectivisation period. However, while conditions for a permanent differentiation were present, such process has failed to materialise in the current integration period. Differentiation has become more unpredictable as past winners can lose out due to unstable market conditions.     

Pathogenicity of H5N1 influenza A viruses isolated in Vietnam between late 2003 and 2005

Since late 2003, highly pathogenic H5N1 influenza A viruses have spread among poultry and wild aquatic birds in Asian countries. Transmission of these viruses to humans can be lethal. Most human cases of infection with H5N1 viruses have occurred in Vietnam. Therefore, to understand the pathogenicity in mammals of these H5N1 viruses, we took viruses isolated from poultry (5 strains) and humans (2 strains) in Vietnam and tested their virulence in mice. The results showed that the H5N1 viruses from humans were pathogenic in mice and that one avian isolate was also pathogenic. These findings suggested that the H5N1 viruses circulating in poultry adapted during replication in humans or that strains pathogenic in mice were transmitted directly to humans.