Evaluating the accuracy of VEMAP daily weather data for application in crop simulations on a regional scale     

Wei Wu  Hong-Bin Liu  Gerrit Hoogenboom  Jeffrey W. White 《European Journal of Agronomy》2010,32(3):187-194

Weather plays a critical role in eco-environmental and agricultural systems. Limited availability of meteorological records often constrains the applications of simulation models and related decision support tools. The Vegetation/Ecosystem Modeling and Analysis Project (VEMAP) provides daily weather variables on a 0.5 latitude–longitude grid across the conterminous USA. Daily weather data from the VEMAP (1961–1990) for the state of Georgia were compared with data from 52 individual ground stations of the National Weather Service Cooperative Observer Program (COOP). Additionally, simulated crop grain yields of soybean (Glycine max) were compared using the two data sources. Averaged daily maximum and minimum temperatures (Tmax and Tmin, respectively), solar radiation (SRAD), and precipitation (PPT) differed by 0.2 °C, ?0.2 °C, 1.7 MJ m^?2 d^?1, and 0 mm, respectively. Mean absolute errors (MAEs) for Tmax, Tmin, SRAD, and PPT were 4.2 °C, 4.4 °C, 4.4 MJ m^?2 d^?1, and 6.1 mm, respectively, and root mean squared errors (RMSEs) for Tmax, Tmin, SRAD, and PPT were 5.5 °C, 5.9 °C, 5.8 MJ m^?2 d^?1, and 13.6 mm, respectively. Temperature differences were lowest during summer months. Simulations of grain yield using the two data sources were strongly correlated (r = 0.68, p < 0.01). The MAE of grain yield was 552 kg ha^?1. The RMSE of grain yield was 714 kg ha^?1. Hybrid analyses indicated that the variation of simulated yield was mainly associated with the differences in rainfall. The results showed that the VEMAP daily weather data were able to be adequately applied to crop growth simulation at spatial and temporal scales, especially for long-term climate change research. Overall, the VEMAP weather data appears to be a promising source for crop growth modeling concerned with scale to 0.5° coordinate grid.  相似文献   

Regional simulation of maize production in tropical savanna fallow systems as affected by fallow availability   总被引：1，自引：0，他引：1  

Thomas Gaiser  Michael Judex  Arnim Kuhn 《Agricultural Systems》2010,103(9):656-665

Upscaling of crop models from the field scale to the national or global scale is being used as a widespread method to make large-scale assessments of global change impacts on crop yields and agricultural production. In spite of the fact that soil fertility restoration and crop performance in many developing countries with low-input agriculture rely strongly on fallow duration and management, there are only few approaches which take into account the effect of fallowing on crop yields at the regional scale. The objectives of this study were to evaluate the sensitivity of maize yield simulations with the Environmental Policy Integrated Climate (EPIC) model to fallow availability at the field and regional scale and (2) to present a novel approach to derive a model-based estimate of the average fallow availability within a typical catchment of the sub-humid savanna zone of West Africa. Therefore, the EPIC model has been validated at the field scale and then incorporated into a spatial database covering a typical catchment within the sub-humid savanna zone of West Africa with 121 sub-basins. Maize-fallow rotations have been simulated within 2556 quasi-homogenous spatial units and then aggregated to the 10 districts within the catchment assuming three different scenarios of fallow availability: 100% of the bush-grass savanna area is available and used in fallow-crop rotations (FU100), 50% of the bush-grass savanna area is available and used in fallow-crop rotations (FU50) and 25% of the bush-grass savanna area is available and used in fallow-crop rotations (FU25). A new aggregation procedure has been developed which is based on changes in the frequency of fallow-cropland classes within the sub-basins to render the simulation results in the spatial database sensitive to changes in fallow availability. Comparison of the average simulated grain yield with the mean yield over the catchment shows that the simulations overestimate maize yields by 62%, 44% and 15% for scenario FU100, FU50 and FU25, respectively. The best agreement between simulated and observed crop yields at the district scale was found when using the assumption that 25% of the savanna is available as fallow land under the present cropping patterns, which corresponds to a fallow-cropland ratio of 0.9. Comparison with farm surveys shows that the combination of remote sensing and dynamic crop modelling with yield observations provides realistic estimates of effective fallow use at the regional scale.  相似文献   

Influence of temperature on embryo developmental cycles and mortality of female Chionoecetes opilio (snow crab) on the Scotian Shelf,Canada     

Penny S. Kuhn  Jae S. Choi 《Fisheries Research》2011,107(1-3):245-252

Chionoecetes opilio (snow crab) in Atlantic Canada is a valuable fishery. A key factor in the conservation and sustainability of C. opilio is the length of its reproductive cycle, which in different regions has been observed to be ca. 1 or 2 years and temperature dependent. Ten years of embryo colour (a proxy for embryo development) data from the Scotia Shelf (SS) is analyzed using a binomial Generalized Linear Model. The influences of temperature and time variations upon the transition of early developmental stages are described. Over 80% of the females were estimated to follow a ～1 year reproductive cycle, corresponding to the relative proportion of springtime SS bottom temperatures greater than 1 °C. As an upper bound, total annual larval production is expected to have ranged from 280 billion and 32 trillion since 1997 with an associated female mortality from larval stage to maturity of 63–81% per annum (Z = 1–1.65). Climate variability can therefore have a large influence upon the total potential reproductive output. Global Circulation Models predict that there will be more positive North Atlantic Oscillation years for the North Atlantic, assuming this to be the case we speculate that the associated warmer bottom temperatures along the central and west SS would lead to even greater percentages of the C. opilio females entering a 1 year reproductive cycle, whereas cooling along the eastern shelf (where the majority of the population resides) would shrink the warm water habitat available and potentially force more females into a two year cycle. If the magnitude of warming extends beyond C. opilio's preferred range, the entire population may shift north-east.  相似文献   

Stizzen über forstliche Zustände in Bayern am Cnde des 18. Jahrhunderts     

Jorftamtsassessor Dr. W. Kuhn 《European Journal of Forest Research》1919,41(8-9):347-354

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The influence of methimazole on the thyrotrophic and peripheral activity of thyrotrophin and thyrotrophin-releasing hormone in the chick embryo and growing chicken     

Iqbal A.  Decuypere E.  Kuhn E. R.  Schneider R.  Verheyen G.  Huybrechts L. M. 《Domestic animal endocrinology》1987,4(4):291-298

Plasma concentrations of thyroxine (T₄) and triiodothyronine (T₃) were profoundly depressed both in chick embryos and growing chickens after methimazole (MMI) treatment. There was no response of T₄ and T₃ levels to TRH or TSH injections in the MMI group, either in embryos or growing chickens.

Peroxidase activity measured in the thyroid gland was significantly higher in embryos and growing chickens treated with MMI. However, neither TRH nor TSH affected this activity 2 hr after injection in either control or the MMI-treated group.

Hepatic 5′-monodeiodinase activity was significantly stimulated in the MMI-treated groups of embryos and growing chickens but only when additional sulphydryl groups (DTT) were provided. In embryos, monodeiodination activity 2 hr after TSH injection was not significantly different from control values for either DTT-stimulated or unstimulated conditions within the control and MMI-infused groups. However, in both control and MMI-treated embryos monodeiodination activity significantly increased 2 hr after TRH injection. In the growing chickens, monodeiodination activity 2 hr after TRH or TSH injection was not significantly different from control values in either stimulated or unstimulated conditions of each group.  相似文献   

Impact of Climate Change on the Phenological Development of Winter Wheat,Sugar Beet and Winter Oilseed Rape in Lower Saxony,Germany     

Racca  Paolo  Kakau  Joachim  Kleinhenz  Benno  Kuhn  Christian 《植物病害和植物保护杂志》2015,122(1):16-27

Journal of Plant Diseases and Protection - There is a general agreement that climate change, in the medium and long term perspective, may affect agricultural crops. As part of the KLIFF project...  相似文献   

Biochemical analysis and in vivo hypoglycemic activity of a grape polyphenol-soybean flour complex     

Roopchand DE  Kuhn P  Poulev A  Oren A  Lila MA  Fridlender B  Raskin I 《Journal of agricultural and food chemistry》2012,60(36):8860-8865

Defatted soybean flour (DSF) can efficiently sorb, concentrate, and stabilize polyphenols, but not sugars, from Concord grape juice, to yield grape polyphenol-enriched DSF. Sorption of grape polyphenols to DSF particles was dependent on the ratio of DSF and grape juice concentrate used, but not time of mixing or pH. Depending on ratios of starting materials, 1 g of grape polyphenol-enriched DSF contained 1.6-10.4 mg of anthocyanins, 7.5-93.1 mg of proanthocyanidins, and 20.5-144.5 mg of total polyphenols. LC-MS analysis of grape juice samples before and after addition and removal of DSF and eluate from grape polyphenol-enriched DSF confirmed that a broad range of grape compounds were sorbed to the DSF matrix. Finally, grape polyphenol-enriched DSF was able to significantly lower blood glucose levels in hyperglycemic C57BL/6J mice. The data indicate that grape polyphenol-enriched DSF can provide a high-protein, low-sugar ingredient for delivery of concentrated grape polyphenolics.  相似文献   

Growing food,growing a movement: climate adaptation and civic agriculture in the southeastern United States     

Carrie Furman  Carla Roncoli  Donald R. Nelson  Gerrit Hoogenboom 《Agriculture and Human Values》2014,31(1):69-82

This article examines the role that civic agriculture in Georgia (US) plays in shaping attitudes, strategies, and relationships that foster both sustainability and adaptation to a changing climate. Civic agriculture is a social movement that attracts a specific type of “activist” farmer, who is linked to a strong social network that includes other farmers and consumers. Positioning farmers’ practices within a social movement broadens the understanding of adaptive capacity beyond how farmers adapt to understand why they do so. By drawing upon qualitative and quantitative data and by focusing on the cosmological, organizational, and technical dimensions of the social movement, the study illuminates how social values and networks shape production and marketing strategies that enable farmers to share resources and risks. We propose a conceptual framework for understanding how technical and social strategies aimed to address the sustainability goals of the movement also increase adaptive capacity at multiple timescales. In conclusion, we outline directions for future research, including the need for longitudinal studies that focus on consumer motivation and willingness to pay, the effects of scale on consumer loyalty and producer cooperation, and the role of a social movement in climate change adaptation. Finally, we stress that farmers’ ability to thrive in uncertain climate futures calls for transformative approaches to sustainable agriculture that support the development of strong social networks.  相似文献   

Establishment of an early warning system against bluetongue virus in Switzerland     

Racloz V  Straver R  Kuhn M  Thur B  Vanzetti T  Stärk KD  Griot C  Cagienard A 《Schweizer Archiv für Tierheilkunde》2006,148(11):593-598

Bluetongue (BT) is a vector-borne animal disease of economical importance due to the international trade restrictions likely to be put into place in a country once the infection is discovered. The presence of BT and its vectors in countries adjacent to Switzerland stresses the need of implementing a surveillance system and to raise disease awareness among potential stakeholders. A national survey in Switzerland 2003 indicated freedom of Bluetongue virus (BTV), although a single individual of the main BT vector Culicoides imicola was caught in the canton of Ticino. The survey also demonstrated that potential BT vectors, C. obsoletus and C. pulicaris are locally abundant in Switzerland. Therefore, a new surveillance method based on sentinel herds in high risk areas was implemented in 2004 for the early detection of both an incursion of BT vectors into Switzerland, and potential virus circulation among cattle.  相似文献   

Review and simulation of homoplasy and collision in AFLP     

Gerrit Gort  Fred A. van Eeuwijk 《Euphytica》2012,183(3):389-400

In this paper we give a short review of the problems of homoplasy and collision in AFLP, and describe a software tool that we developed to illustrate these problems. AFLP is a DNA fingerprinting technique, producing profiles of bands, the result of the separation of DNA fragments by length on a gel or microcapillary system. The profiles are usually interpreted as binary band absence/presence patterns. We focus on two major problems: (1) Within a profile two or more fragments of the same length but of different genomic origin may have been selected, colliding into a single band. This collision problem, akin to the birthday problem, may be surprisingly large. (2) In a pair of profiles two equally long fragments of different genomic origin may have been selected, appearing as identical bands in the two profiles. This is called homoplasy. Both problems are quantified by modeling AFLP as a random sampling technique of fragment lengths. AFLP may be used in phylogenetic studies to estimate the pairwise genetic similarity of individuals. Similarity coefficients like Dice and Jaccard coefficients overestimate the true genetic similarity because of homoplasy, with increasing bias for higher numbers of bands per profile. Corrected estimators are described, which do not suffer from bias. The ideas are illustrated using a new software tool. Data from studies on Arabidopsis and tomato serve as examples. Finally, we make some recommendations with respect to the use of AFLP.  相似文献