Consensus maps of cloned plant cuticle genes

Plant cuticle,which covers the plant surface,consists of waxes and cutins,and is associated with plant drought,cold,and salt resistance.Hitherto,at least 47 genes participating in the formation of plant cuticle have been cloned from Arabidopsis thaliana,Oryza sativa,Zea mays,Ricinus communis,Brassica napus,and Medicago truncatula;and about 85% of them encode proteins sharing above 50% identities with their rice homologous sequences.These cloned cuticle genes were mapped in silico on different chromosomes of rice and Arabidopsis,respectively.The mapping results revealed that plant cuticle genes were not evenly distributed in both genomes.About 40% of the mapped cuticle genes were located on chromosome 1 in Arabidopsis,while 20% of the mapped cuticle genes were located on chromosome 2 but none on chromosome 12 in rice.Some cloned plant cuticle genes have several rice homologous sequences,which might be produced by chromosomal segment duplication.The consensus map of cloned plant cuticle genes will provide important clues for the selection of candidate genes in a positional cloning of an unknown cuticle gene in plants.     

AIDS mitigation through agriculture‐based interventions in rural contexts: Junior farmer field and life schools and future livelihoods in central Mozambique

This article summarizes findings from a research project on junior farmer field and life schools (JFFLS) as an agriculture‐based intervention to improve the livelihood prospects of children and orphans made vulnerable by HIV/AIDS in central Mozambique. In the sites investigated JFFLS have opened up concrete present and potential livelihood options in agriculture and beyond. More generally, the resource profile dynamics of participants are altered in ways that provide strong grounds to believe that the skills and knowledge they have gained will positively impact the trajectories of their future lives. In terms of HIV/AIDS mitigation, the findings recommend livelihood‐based interventions aimed at altering the vulnerability context of specific population groups.     

遥感和GIS支持下的湘西北喀斯特山区县域农业生态环境脆弱度评价

将GIS和遥感技术引入传统的脆弱度定量评价方法,采用专家咨询法和层次分析法建立指标体系,应用GIS建立评价模型,对典型的湘西北喀斯特山区农业生态环境脆弱度进行了评价。结果显示,研究区存在澧水河谷和以罗水乡为中心西北部两个农业生态环境脆弱度高值区,农业生态环境脆弱度分布与由人类活动所致的胁迫脆弱度分布匹配。根据评价结果,为了避免农业生态环境退化,应采取加强东南和西北山区坡耕地退耕还林、增加水田比重和减少西北农业区农药、化肥和地膜的使用量等措施。     

Percolation losses in paddy fields with a dynamic soil structure: model development and applications

The hydraulic characteristics of the plough pan of paddy fields provide continuous ponding conditions during the growing season and control the water use efficiency in wet rice production. Its saturated hydraulic conductivity K_s, however, exhibits a large spatiotemporal variability as a consequence of a highly dynamic soil structure involving temporary shrinkage cracks. Water flow through the earthen bunds surrounding the fields further contributes to the uncertainty in water flux calculations. The objective of this study was to develop a simple deterministic model with stochastic elements (‘PADDY‐FLUX’) for depiction of deep percolation, and to assess the effect of different water management scenarios on percolation in two channel command areas. Darcy's law is used as the fundamental equation for water flow calculations with the ponding water depth h as a time‐dependent variable. Flux uncertainty is estimated by a Monte‐Carlo‐type implementation. K_s is treated as a random variable of a bimodal probability density function (PDF), which is the weighted sum of two Gaussian PDFs (accounting for a matrix and a preferential flow domain). The weighing factor α is a function of h, reflecting an increasing risk for preferential flow situations after desiccation and the development of shrinkage cracks. Under‐bund percolation is calculated using transfer functions. The results demonstrate that percolation losses increase in the following order: continuous soil saturation < continuous flooding (CF) < mid‐season drainage and intermittent irrigation (MD + II) < mid‐season drainage and continuous flooding. The bunds contribute up to 54 and 17% to total fluxes under CF and MD + II, respectively. Preferential water fluxes are responsible for the major part of water losses as soon as desiccation causes the formation of shrinkage cracks. As a conclusion, continuous soil saturation should be promoted as the least water‐intensive irrigation regime, while intermittent irrigation is recommended only in case that irreversible shrinkage cracks have already developed. Copyright © 2010 John Wiley & Sons, Ltd.     

地理信息系统在资源环境评价与管理中的应用

介绍了地理信息系统在资源环境评价与管理中的具体功能,讨论了GIS,RS,GPS在资源环境特别是水资源和精准农业管理上的应用,并指出地理信息系统作为一种信息处理工具能满足数字信息获取的三个阶段:数据的收集、数据的分析、数据的转换和信息处理。     

The Major Soils of a Village in Northern Burkina Faso

Krogh, Lars: The Major Soils of a Village in Northern Burkina Faso. Geografisk Tidsskrift 93:90–100. Copenhagen 1993.

In the Oudalan Province of Sahelian Northern Burkina Faso soil investigations have been carried out in order to evaluate the sustainability of millet production with emphasis on the dynamics of soil fertility. Some results of pedological investigations carried out in 1990 are included. Three commonly occurring soil types in a village territory are examined and their genesis and fertility discussed. Analyses show that the soils are inherently low in organic matter. The level of macro-nutrients is low, soil structure is weak or unfavourable: all probably due to a combination of natural and human factors. Crop yields are generally low and cannot be raised without more intensive cultivation.     

Function of Soils for Human Societies and Environment

This study assessed the spatial distribution of vulnerability to extreme heat in 1990 and 2000 within metropolitan Phoenix based on an index of seven equally weighted measures of physical exposure and adaptive capacity. These measures were derived from spatially interpolated climate, normalized differential vegetation index, and U.S. Census data. From resulting vulnerability maps, we also analyzed population groups living in areas of high heat vulnerability. Results revealed that landscapes of heat vulnerability changed substantially in response to variations in physical and socioeconomic factors, with significant alterations to spatial distribution of vulnerability especially between eastern and western sectors of Phoenix. These changes worked to the detriment of Phoenix's Hispanic population and the elderly concentrated in urban-fringe retirement communities.     

Trading in the dark – The medicinal plants production network in Uttarakhand

Medicinal plant cultivation and gathering can play a vital role in the course of livelihood diversification for the marginalized population living in remote areas. However, this requires an integration of the respective production networks that allows the producers a fair and reliable income and does not endanger rare plant species. This paper analyses the situation within the Indian state of Uttarakhand, and identifies structures and entities hindering medical plant cultivation and its potentials. Based on the broad network understanding of the Global Production Network approach, the case study focuses on the middlemen and their hidden embeddedness. It shows how governmental organizations and in particular non‐governmental organizations and farmers' institutions can help to overcome clandestine structures of illegal trade and contribute towards a redesign of the medicinal plant network in a more equitable and transparent way.     

Gendered Spaces of Informal Entrepreneurship in Soweto,South Africa

Abstract

The full diversity of economic activities in the informal economy is not well understood. The apartheid legacy of limiting informal entrepreneurship explains the most obvious geographical patterns in South Africa. After a decade and a half since the end of apartheid, however, knowledge about the places from which informal entrepreneurs operate is incomplete. Retailing is overemphasized and production firm entrepreneurs, both male and female, remain a neglected spatiality. This study reports on a survey of 100 firms in Soweto and in-depth interviews with 30 firm owners. The findings challenge the representations of isolated urban entrepreneurs dependent on inherited social capital and of women's exclusive engagement in retail. Entrepreneurs create their own social capital in work-related realms, but there are important gender differences. More finely tuned conceptualizations of entrepreneurs and of gendered working spaces need to be developed so that policy does not perpetuate unitary myths and incomplete spatial representations. [Key words: entrepreneurship, Soweto, informal economy, gender.]