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Incidence, Severity and Gravity of Cassava Mosaic Disease in Savannah agro-Ecological Region of DR-Congo: Analysis of agro-environmental Factors

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American Journal of Plant Sciences 2012年第4期3卷 512-519页

作者： Marcel Muengula-Manyi Kabwe K. Nkongolo Claude Bragard Patrick Tshilenge-Djim Stephan Winter Adrien Kalonji-Mbuyi Department of Biology Laurentian University Sudbury Ontario Canada Earth and Life Institute Applied Microbiology-Phytopathology Univer-sité Catholique de Louvain Louvain-la-Neuve Belgium Plant Virus Collection DSMZ Deutsche Sammlung von Mikroorganismen und Zellkuturen GmbH Braunschweig Germany Unit of Phytopathology Faculty of Agronomy University of Kinshasa Kinshasa Democratic Republic of Congo

African Cassava mosaic disease (ACMD) is the most severe and widespread disease caused by viruses limiting production of the crop in sub-Saharan Africa. The objective of the present study was to evaluate CMD incidence, severity, and gravity under different agro-environmental conditions. A total of 222 fields were surveyed in 23 different locations. All the farmers grow only local cassava varieties without applications of fertilizers. Overall, mean CMD incidences for all sites surveyed were 58.2% and 51.7%, in 2009 and 2010, respectively. Disease severity ranged from 2.4 to 3.1 on a scale of 1 to 5. Mean disease gravity varied from 29.7% to 62%, in 2010, and 2009, respectively. Detailed analysis of agronomic and environmental revealed no significant association between cassava stand locations, age, land topography and the development of CMD. Likewise intercropping practices and field topping did not affect the development of CMD in all the fields surveyed. There were significant differences in the number of white flies (Bemisia tabaci) per plant in 2009 and 2010, but no significant correlations between the number of B. tabaci per plant and CMD incidence, severity, and gravity was found. In most fields, CMD appears to originate mostly from unhealthy cassava cuttings used for planting.

关键词： Cassava Mosaic Disease Farmers’ Fields agro-environmental Factors Gandajika DR-Congo

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Economic Growth and agro-environmental Fragility——Based on the Provincial Panel Data Analysis

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Asian Agricultural Research 2010年第10期2卷 46-49页

作者： XIONG Wen Key laboratory of Education Ministry of Geography Information Science,East China Normal University,Shanghai 200062,China

The agro-environmental fragility of 31 provinces and regions (except Hong Kong,Macao and Taiwan) of our country during the years 1978-2004 is measured by adopting the method of principal component *** the support of analytical model of panel data,regressive analysis is achieved from the aspects of introducing regional differences,not introducing regional differences,existing industrial differences and not existing industrial differences *** conclusion points out that there are both industrial and regional differences in the economic growth effect on the environmental fragility;these differences are reflected on the industrial or regional development *** higher the development level it is,the less the effect it is when the economic growth effect on the environmental fragility is negative,the more when the effect is positive,and it will change from being negative to positive when on the critical point;and vice versa.

关键词： Economic growth agro-environmental fragility Princ

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Development of Perverse environmental Subsides for Sheep Production in Iceland

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Agricultural Sciences 2019年第9期10卷 1135-1151页

作者： Olafur Arnalds Faculty of Agricultural and environmental Sciences Agricultural University of Iceland Borgarnes Iceland

Sheep production in Iceland is heavily subsidized with a part of the payments tied to land condition and compliance with sustainable land use according to a Quality Management System (QMS). A large proportion of the rangelands used for sheep grazing are public lands. The paper is based on Land Improvement Plans (LIP’s) and Soil Conservation of Iceland (SCSI) correspondence obtained by appeal under the Information Act. The results show that “green payments” are made for use of land that fails to meet the criteria given for such payments, based on the extent of barren areas, active soil erosion, and vegetation condition. Strong formal objections by the SCSI about the content and implementation of QMS have been ignored. It is further shown that the land use section of the QMS (L-QMS) is non-transparent and not well scientifically grounded. The use of the term “sustainable land use” is confounded when used to justify the use of collapsed ecosystems. The LIP’s show high to extreme grazing intensities on land in poor condition, thus further defying ideas for green subsidy schemes. The investigation reveals serious conflicts between environmental and agricultural sectors, at agency and ministerial levels, which is enhanced by incoherent legislation structures. It is vital to reconstruct the green subsidies for sheep farming in Iceland, based on science and best available information with a much broader stakeholder participation than at present, involving multi-sectoral agencies and scientists, NGO’s, communities, the general public, and land users.

关键词： Agricultural Subsidies agro-environmental SLM Land Condition Sheep Grazing

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Global sensitivity analysis for choosing the main soil parameters of a crop model to be determined

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Agricultural Sciences 2012年第7期3卷 949-961页

作者： Hubert Varella Samuel Buis Marie Launay Martine Guérif INRA UMR 1114 INRA-UAPV EMMAH Avignon France INRA Unite Agroclim Avignon France Syngenta Crop Protection Münchwilen AG Stein/AG Switzerland

The use of a crop model like STICS for appropriate management decision support requires a good knowledge of all the parameters of the model. Among them, the soil parameters are difficult to know at each point of interest and costly techniques may be used to measure them. It is therefore important to know which soil parameters need to be determined. It can be stated that those which affect significantly the output variable deserve an accurate determination while those which slightly affect the model output variable do not. This paper demonstrates how a global sensitivity analysis method based on variance decomposition can be applied on soil parameters in order to divide them in the two categories. The Extended FAST method applied to the crop model STICS and a set of 13 soil parameters first allows to calculate the part of variance explained by each soil parameter (giving global sensitivity indices of the soil parameters) and the coefficient of variation of the output variables (measuring the effect of the parameter uncertainty on each variable). These metrics are therefore used for deciding on the importance of the parameter value measurement. Different output variables (Leaf Area Index and chlorophyll content) are evaluated at different stages of interest while others (crop yield, grain protein content, soil mineral nitrogen) are evaluated at harvest. The analysis is applied on two different annual crops (wheat and sugar beet), two contrasted weather and two types of soil depth. When the uncertainty of the output generated by the soil parameters is large (coefficient of variation > 1/3), only the parameters having a significant global sensitivity indices (higher than 10%) are retained. The results show that the number of soil parameters which deserve an accurate determination can be significantly reduced by the use of this relevant method for appropriate management decision support.

关键词： Global Sensitivity Analysis Uncertainty Analysis Soil Parameters Crop Model STICS Management Decision Support agro-environmental Variables

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