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1.
The demand for rice in Eastern and Southern Africa is rapidly increasing because of changes in consumer preferences and urbanization. However, local rice production lags behind consumption, mainly due to low yield levels. In order to set priorities for research and development aimed at improving rice productivity, there is a need to characterize the rice production environments, to quantify rice yield gaps—that is, the difference between average on-farm yield and the best farmers’ yield—and to identify causes of yield gaps. Such information will help identifying and targeting technologies to alleviate the main constraints, and consequently to reduce existing yield gaps. Yield gap surveys were conducted on 357 rice farms at eight sites (19–50 farmers per site) across five rice-producing countries in Eastern and Southern Africa—that is Ethiopia, Madagascar, Rwanda, Tanzania and Uganda—for one or two years (2012–13) to collect both quantitative and qualitative data at field and farm level. Average farm yields measured at the eight sites ranged from 1.8 to 4.3 t/ha and the average yield gap ranged from 0.8 to 3.4 t/ha. Across rice-growing environments, major causes for yield variability were straw management, weeding frequency, growth duration of the variety, weed cover, fertilizer (mineral and organic) application frequency, levelling and iron toxicity. Land levelling increased the yield by 0.74 t/ha, bird control increased the yield by 1.44 t/ha, and sub-optimal management of weeds reduced the yield by 3.6 to 4.4 t/ha. There is great potential to reduce the current rice yield gap in ESA, by focusing on improvements of those crop management practices that address the main site-specific causes for sub-optimal yields.  相似文献   

2.
We provide a direct test of the extent to which the stringency of a Tax and Expenditure Limit (TEL) influences the creation of special district governments by examining one of the strictest TELs in U.S. history, the Colorado Taxpayer's Bill of Rights (TABOR). Through analysis of panel data from 1993 to 2004 of general purpose and special district governments, we test the relationship between TABOR and the creation of special districts. The novelty of our research involves the use of successful and failed attempts to override TABOR to measure variation in TEL restrictiveness at the county and municipal geography. Our results indicate that counties and municipalities unable to override TABOR's restrictions and therefore bound by the TEL have no greater use of special district governments than local jurisdictions experiencing similar demand for services but not bound by TABOR. These results are robust to failed override attempts specific to tax revenue as well as debt proceeds. Furthermore, results are unaffected by the use of multiyear lagged measures of override attempts and the inclusion of county debrucing initiatives that passed or failed by a small margin—i.e., less than 60 percent of votes. Contrary to anecdotal evidence, our results find no relationship between tax and expenditure limits and the formation of special districts.  相似文献   

3.
The virological situation of cassava in Africa is increasing in complexity due to the number and types of viruses isolated from different locations within the continent. Here, we report the complete nucleotide sequences of both A and B components of two geminivirus species infecting cassava in the Ivory Coast and review the current knowledge of the molecular and biological diversity of the African cassava geminiviruses. As a whole, newly obtained sequences are compared with those of the African cassava mosaic geminiviruses identified to date. Results indicate that all isolates of African cassava mosaic virus (ACMV), irrespective of their geographical origin are clustered together with little or no variation in their genomic sequence. On the contrary, the genomes of the East African cassava mosaic virus (EACMV) are more genetically diverse due to the frequent occurrence of recombinations within their two components. Indeed, the EACMV-like viruses vary so much that their classification is becoming problematic. In addition, there is also a large range of phenotypic symptom variation for each of these virus species, irrespective of the location of isolation. Furthermore, it has been shown that ACMV and EACMV can be synergistic in cassava, resulting in a greater DNA accumulation and consequently inducing severe symptoms. For all these reasons, this paper initiates a discussion concerning the species demarcation for cassava geminivirus. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

4.
5.
The aim of this paper is to discuss how community relational economic practices in virtual spaces are effective in building resilience because they are borne of and sustained by familiar traditional Fijian values of collective work and social interdependence. The researchers adopted a pandemic-induced methodology, conducting online-based talanoa (fluid conversations between two or more people) with a number of people leading, or involved in, these initiatives. We also engaged with online community groups behind a number of initiatives. Examples are provided of online crowdfunding, livestreaming of concerts to solicit donations, and bartering facilitated by social media sites. To conclude, we stress the enduring nature of communal bonds and traditional systems which Pacific people readily adapt and translate into different forums and forms in the face of challenges such as the restrictions and financial hardships caused by COVID-19. The findings highlight that solesolevaki – a tradition of working together for a common cause – can also occur in the digital era: this demonstrates the deep connection of Fijian peoples and their sense of obligation to one another and to their culture, regardless of where they are in the world.  相似文献   

6.
This paper asks whether the technological development of a nation reduces the inter‐regional hierarchy in knowledge flow. We examine two scenarios that are the alternative to each other. The first is what we call the globalization of regional innovation system/weakening of inter‐regional hierarchy scenario: As many regions develop their niches in the global economy, the national “anchor” region loses its relative importance as the importer and distributor of new knowledge, rendering the domestic inter‐regional hierarchy less significant as a result. The second scenario is the globalization of national innovation system/persistence of inter‐regional hierarchy. The nation’s traditional anchor region becomes even more active in importing technology and distributing it to other regions of the country. To test which scenario is closer to reality, we employ social network metrics to analyse inter‐regional technology diffusion networks using Chinese patent licensing data for the 1998–2013 period. Our findings support the second scenario, showing that the influence of the traditional anchor region persists in the hierarchical network structure as new cities enter the network. We found five anchor regions: the three usual suspects—Beijing, Shanghai and Shenzhen—plus two that were slightly less expected—Dongguan and Suzhou.  相似文献   

7.
In building Samoan academic researcher capacity in Samoa, we argue that there is a need to first establish the kind of researcher community advocated by Linda Tuhiwai Smith, and to do so through developing research tools, such as the talanoa and faafaletui, in partnership with researcher capacity‐building initiatives such as the applied postgraduate social and health research methods course (coded PUBX731‐HSA505) run by the Centre for International Health, University of Otago, in partnership with the National University of Samoa. This paper offers a commentary on the talanoa and faafaletui as Pacific research methodologies, and asks what its value might be for researchers in Samoa. It reflects on the learning experiences of staff and students of the applied social and health research methods course in relation to the talanoa and faafaletui as Pacific research methodologies or methods. It concludes that developing Pacific research and researcher capacity in Pacific Island countries, such as Samoa, must include opening up spaces within these communities to critically engage what is Pacific or Samoan or indigenous about these research tools, methods or methodologies, and how they might differ in form or substance from other methods or methodologies.  相似文献   

8.
ABSTRACT Producer services have been among the most rapidly growing industries, as measured by employment, in the United States and in Europe in recent decades. The production and delivery of these specialized forms of service industry work require the use of transportation and communications systems in a variety of ways, including the physical movement of people working in these industries, as well as the movement of the information related to the production and distribution of their work. Some of this work is performed in localized markets, requiring travel between clients and suppliers in local transportation modes, such as auto, bus, or other types of transportation. Other work is done by specialists who travel interregionally and globally to do their work, primarily traveling to their clients. There is little knowledge of how these production relationships have changed with the advent of the Internet and the widespread use of e‐mail in the business production process. Within the framework of this STELLA initiative, this paper outlines research needs in this area, and frames an approach that would produce badly needed knowledge about impacts on the producer services of the Internet and related e‐commerce initiatives on physical transportation systems at a local to interregional scale.  相似文献   

9.
Data gathered from 45 farms in the Kagera Region of Tanzania were used to estimate critical nutrient levels (CNL) of foliar tissue and norms of the Diagnosis and Recommendation Integrated System (DRIS) for bananas ( Musa spp.) grown in the highlands of East Africa.
CNL values are proposed as 3.1 % N, 1.13 % Ca, 0.48 % Mg, 18.4 ppm Zn and 10.0 ppm B. Optimum ranges for cation ratios were estimated as 0.54—0.67 for K/(K + Ca + Mg), 0.22—0.32 for Ca/(K + Ca + Mg) and 0.09—0.15 for Mg/(K + Ca + Mg). Productivity of bananas and foliar levels of P, K, S, Fe, Mn and Cu were too weakly related to estimate CNLs for these nutrients. A set of DRIS norms for East African Highland bananas is presented.  相似文献   

10.
Agro-biodiversity is currently experiencing severe genetic erosion due to mankind’s unsustainable activities. Because of initiatives following the goal of the conservation of biological diversity, so far seven million crop accessions are being conserved ex situ in gene banks worldwide. Many of these accessions are landraces being rich in gene diversity, silently awaiting their proper characterisation. This is a very critical part of any long-term strategy to enhance the productivity and resilience of crops and agricultural systems and—most importantly—to ensure the preservation of our cultural and biological heritage. In this study of an ex situ germplasm evaluation we analysed 27 flax (Linum usitatissimum L.) accessions originating in the Alpine region, provided by five local gene banks/providers. Based on genomic microsatellite markers (gSSRs), a varying extent of accession-specific gene diversity (expected heterozygosity, HE) was revealed ranging from 0.05 to 0.51. Admixture of individuals between accessions was uncovered, pointing towards past processes related to gene bank management activities (e.g. intentional selection, unintentional cross-pollination during regeneration) or towards the evolution of the landrace itself (e.g. same regional origin, traditional naming), highlighting the co-existence of cultural and biological diversity. Such an genetic analysis of accessions stored ex situ not only produces valuable agronomic and breeding data, but also is useful for the clarification of past processes leading to duplicates within and between collections or mislabelling, contributing to the potential for rationalisation of collections, which in turn can help ensure that the limited resources available for regeneration are used most efficiently and effectively.  相似文献   

11.
张静怡  马佳 《中国农学通报》2020,36(26):159-164
本文采用文献研究法,从评价指标选取原则、评价指标内涵、评价方法3个方面对国内都市现代农业发展水平评价体系文献进行梳理,发现国内都市现代农业发展水平评价体系渐趋完善,评价方法丰富。但还存在着一些问题如:指标内涵的确定主观性太强;文化指标、都市农业观光等功能性指标的研究较少;评价指标权重的确定太过主观能动性;研究对象较单一等。提出了未来应当继续从以下几个方面开展研究:(1)在确定指标时,应当选择典型性的指标,并且以因子分析法为主,使指标更加科学化、合理化;(2)重视文化、都市观光等新兴指标的研究,并与社会、经济、社会发展指标相融合、关联,展现都市农业的多功能特征;(3)在对指标权重进行赋值时,为了避免主观性,多采用数学建模的方式;(4)丰富研究对象,开展不同对象之间的比较研究(包括横向和纵向发展水平比较)。研究为科学评估现代都市农业发展水平、构建现代都市农业发展水平评价体系提供了借鉴。  相似文献   

12.
The recent change in the regional development strategy of the European Union (EU) results in an important need to study the terms of change and their respective implications. This study seeks, through a bibliometric analysis, to ascertain the developments taking place in studies on research and innovation strategies for smart specialisation (RIS3) to identify shortcomings and opportunities for future research. This bibliometric review drew upon the Scopus database with the sample selected containing all the articles containing the keywords “Research and Innovation Strategies for Smart Specialisation” or “RIS3.” This correspondingly reports how some authors maintain that the path the EU should take involves imitative innovation. Meanwhile, others propose that each region should specialise in those industries that are already established there and thus avoid targeting any areas they do not already know/specialise in. Our findings detail six clusters in RIS3 research, which help in contextualising the literature review: (a) business discovery; (b) smart specialisation; (c) innovation; (d) specialisation; (e) regional policies; and (f) regional development. This study furthermore sets out perspectives for future lines of research and correspondingly seeks to convey a vast theoretical basis that may serve as the point of departure for future studies.  相似文献   

13.
稻米品质改良越来越成为现代水稻育种工作的重要目标,探明新选育非洲栽培稻基因渗入系的稻米品质潜力将为其在水稻优质育种工作中的进一步应用奠定基础。对50份非洲栽培稻基因渗入系的12个稻米品质性状进行了考察鉴定,并结合相关性分析、聚类分析和判别分析方法对其综合品质表现进行了分类评价。供试材料均表现较高的糙米率(≥74.19%)、精米率(≥67.83%)、较大的长宽比(≥2.79)和低水分含量(≤13.03%),多数选系具有适宜的直链淀粉含量(17.00-22.00%)。聚类分析将供试材料分为5组,其中第I组的综合米质性状最优;典型判别分析获得2个典型判别函数,分别可解释89.5%和7.2%的方差变异,主要反映垩白粒率和长宽比等指标。新选育的非洲栽培稻基因渗入系在糙米率、精米率、长宽比和直链淀粉含量方面具有优势,垩白粒率和长宽比是非洲栽培稻基因渗入系品质改良的重要指标;本研究将为非洲栽培稻基因渗入系在高产优质水稻新品种选育中的研究应用提供依据。  相似文献   

14.
ABSTRACT The aim of this paper is to analyse the impact on firms' productivity of innovative activities and agglomeration effects among firms belonging to Marshallian industrial districts and the possible joint effect of these two forces. We study a sample of 2,821 firms active in the Italian manufacturing industry in the period 1992–1995. Our analysis uses an original data set based on three different Istituto Nazionale di Statistica statistical sources—Community Innovation Survey, Archivio Statistico delle Imprese Attive (Italian Business Register), and Sistema dei Conti delle Imprese (Italian Structural Business Statistics)—to estimate an “augmented” Cobb‐Douglas production function to account for the impact of technological innovations and district‐specific agglomeration effects on a firm's productivity growth. Our data set allows us to distinguish between product and process innovations, thus, through econometric analysis, we hope to achieve a better understanding of which of these two types of innovative activities benefits most from participation in an industrial district. Our empirical results show that belonging to an industrial district and making product innovations are key factors in the productivity growth of firms and that product innovations appear to have a greater effect on the economic performance of district rather than non‐district firms.  相似文献   

15.
Abstract: Changes in immigration and refugee policy since 1991 have led to an increasing number of minority ethnic groups settling in Aotearoa New Zealand. The number of Black African migrants and refugees granted permanent residence in New Zealand has increased substantially from about six in 1982 to over 770 in 1998 (New Zealand Immigration Services, 2001). The socio‐economic, professional and cultural characteristics of this emerging Black African minority ethnic community are complex but fascinating. In mid 2000 the majority of the Black African community in New Zealand were refugees ( Chile 1999A ). This paper is part of a broader study to analyse the nature and structure of Black African migration and settlement in New Zealand. It is an attempt to undertake applied migration research from a participatory methodology framework that addresses the expressed needs of the grass‐roots level client community. The paper examines the socio‐economic status of Black African refugees in New Zealand and analyses the factors and processes that create an impoverished community that is increasingly excluded from mainstream society. Strategies to reverse the process of marginalisation and create a healthy, vibrant community with the capacity to participate effectively in New Zealand society are examined.  相似文献   

16.
W. Schuch 《Euphytica》1994,79(3):287-291
Tomato fruit quality is determined by a complex set of characters. Fruit used by the fresh market industry must have different attributes than those used by the processing industries. We have determined the major targets of the tomato industry and have isolated from the tomato itself genes which based upon their biochemical function are expected to improve texture and rheology, colour, soluble solids and flavour. Our research is aimed at proving this concept. So far we have demonstrated that polygalacturonase (PG) is a major fruit quality gene providing the processing tomato industry with improved viscosity. Commercial tomato hybrids have been developed in collaboration with Petoseeds (USA) which carry this effect gene. The regulatory system in Europe will be reviewed. Field trials are covered by the EC directive 90/220, which has now been implemented by all countries belonging to the European Union. On the contrary there are no European-wide regulations in place to cover the production of genetically modified plants as food sources. The evolving food regulations will be reviewed and evaluated in the context of competitiveness of the European plant biotechnology industry.  相似文献   

17.
This study examines how institutional varieties at the subnational (state) level influence firm-level innovation in an emerging economy—India. Knowledge of how institutional varieties influence firm-level innovation is derived principally from country-level studies involving multiple developed countries. Research on emerging economies is sparse and tends to follow country-level approaches involving multiple countries. Research involving a single emerging economy where there are substantial institutional varieties between regions is thin. The institutional varieties of some emerging countries are so striking that they can be viewed as several countries within a country, for example, India, China. This study contributes to the innovation literature on the role of institutional varieties on firm-level innovation by focusing on a different level of analysis—a single, emerging economy with substantial institutional varieties across the different states of India. Innovation in emerging economies is a topic of increasing academic interest. A multilevel study involving regional- and firm-level factors is employed. Firm-level data are from the World Bank Enterprise Survey and regional-level data are from statistical agencies in India. The results confirm that institutional varieties have major impacts on firm-level innovation. The research, policy, and managerial implications are discussed.  相似文献   

18.
Indigenous crops also known as orphan crops are key contributors to food security, which is becoming increasingly vulnerable with the current trend of population growth and climate change. They have the major advantage that they fit well into the general socio-economic and ecological context of developing world agriculture. However, most indigenous crops did not benefit from the Green Revolution, which dramatically increased the yield of major crops such as wheat and rice. Here, we describe the Tef Improvement Project, which employs both conventional- and molecular-breeding techniques to improve tef—an orphan crop important to the food security in the Horn of Africa, a region of the world with recurring devastating famines. We have established an efficient pipeline to bring improved tef lines from the laboratory to the farmers of Ethiopia. Of critical importance to the long-term success of this project is the cooperation among participants in Ethiopia and Switzerland, including donors, policy makers, research institutions, and farmers. Together, European and African scientists have developed a pipeline using breeding and genomic tools to improve the orphan crop tef and bring new cultivars to the farmers in Ethiopia. We highlight a new variety, Tesfa, developed in this pipeline and possessing a novel and desirable combination of traits. Tesfa’s recent approval for release illustrates the success of the project and marks a milestone as it is the first variety (of many in the pipeline) to be released.  相似文献   

19.
Legumes are important components of sustainable agricultural production, food, nutrition and income systems of developing countries. In spite of their importance, legume crop production is challenged by a number of biotic (diseases and pests) and abiotic stresses (heat, frost, drought and salinity), edaphic factors (associated with soil nutrient deficits) and policy issues (where less emphasis is put on legumes compared to priority starchy staples). Significant research and development work have been done in the past decade on important grain legumes through collaborative bilateral and multilateral projects as well as the CGIAR Research Program on Grain Legumes (CRP‐GL). Through these initiatives, genomic resources and genomic tools such as draft genome sequence, resequencing data, large‐scale genomewide markers, dense genetic maps, quantitative trait loci (QTLs) and diagnostic markers have been developed for further use in multiple genetic and breeding applications. Also, these mega‐initiatives facilitated release of a number of new varieties and also dissemination of on‐the‐shelf varieties to the farmers. More efforts are needed to enhance genetic gains by reducing the time required in cultivar development through integration of genomics‐assisted breeding approaches and rapid generation advancement.  相似文献   

20.
Fuzzy c-means (FCM) algorithm is dynamic cluster algorithm whose result often is local optimal decision. There often exists insignificant clustering in the result of Fuzzy c-means algorithm when traditional union, Intersection and inclusion work in fuzzy set. Our research indicates there are no insignificant clustering in the result of Fuzzy c-means algorithm over genetic algorithm and partial optimal solution can be avoided with this algorithm to a certain extent. The coding, select, corresponding crossover and mutation operators are designed. Finally we compared the performance of GFCM and FCM with testing data. Results show that the performance of GFCM is far better than FCM.  相似文献   

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