The environmental fate of diuron under a conventional production regime in a sugarcane farm during the plant cane phase     

Stork PR  Bennett FR  Bell MJ 《Pest management science》2008,64(9):954-963

BACKGROUND: Field studies of diuron and its metabolites 3-(3,4-dichlorophenyl)-1-methylurea (DCPMU), 3,4-dichlorophenylurea (DCPU) and 3,4-dichloroaniline (DCA) were conducted in a farm soil and in stream sediments in coastal Queensland, Australia. RESULTS: During a 38 week period after a 1.6 kg ha(-1) diuron application, 70-100% of detected compounds were within 0-15 cm of the farm soil, and 3-10% reached the 30-45 cm depth. First-order t(1/2) degradation averaged 49+/-0.9 days for the 0-15, 0-30 and 0-45 cm soil depths. Farm runoff was collected in the first 13-50 min of episodes lasting 55-90 min. Average concentrations of diuron, DCPU and DCPMU in runoff were 93, 30 and 83-825 microg L(-1) respectively. Their total loading in all runoff was >0.6% of applied diuron. Diuron and DCPMU concentrations in stream sediments were between 3-22 and 4-31 microg kg(-1) soil respectively. The DCPMU/diuron sediment ratio was >1. CONCLUSION: Retention of diuron and its metabolites in farm topsoil indicated their negligible potential for groundwater contamination. Minimal amounts of diuron and DCMPU escaped in farm runoff. This may entail a significant loading into the wider environment at annual amounts of application. The concentrations and ratio of diuron and DCPMU in stream sediments indicated that they had prolonged residence times and potential for accumulation in sediments. The higher ecotoxicity of DCPMU compared with diuron and the combined presence of both compounds in stream sediments suggest that together they would have a greater impact on sensitive aquatic species than as currently apportioned by assessments that are based upon diuron alone.  相似文献   

Glycemic Response to Oat Bran Muffins Treated to Vary Molecular Weight of β‐Glucan     

Susan M. Tosh  Yolanda Brummer  Thomas M. S. Wolever  Peter J. Wood 《Cereal Chemistry》2008,85(2):211-217

Oat bran muffins, containing 4 or 8 g of β‐glucan per two‐muffin serving, were prepared with or without β‐glucanase treatment to produce a range of β‐glucan molecular weights from 130,000 to just over 2 million. Following an overnight fast, the glycemic responses elicited by the untreated and treated muffins was measured in 10 healthy subjects and compared with a control whole wheat muffin. Taken all together, the 4‐g β‐glucan/serving muffins reduced blood glucose peak rise (PBGR) by 15 ± 6% compared with the control. The 8‐g β‐glucan/serving muffins had a significantly greater effect (44 ± 5% reduction compared with the control, P < 0.05). The efficacy of the muffins decreased as the molecular weight was reduced from a 45 ± 6% reduction in PBGR (P < 0.05) for the untreated muffins (averaged of both serving sizes) to 15 ± 6% (P < 0.05) for muffins with the lowest molecular weight. As the molecular weight was reduced from 2,200,000 to 400,000, the solubility of the β‐glucan increased from a mean of 44 to 57%, but as the molecular weight was further decreased to 120,000, solubility fell to 26%. There was a significant correlation (r² = 0.729, P < 0.001) between the peak blood glucose and the product of the extractable β‐glucan content and the molecular weight of the β‐glucan extracted.  相似文献   

Seed Potato Quality Improvement through Positive Selection by Smallholder Farmers in Kenya     

Peter R. Gildemacher  Elmar Schulte-Geldermann  Dinah Borus  Paul Demo  Peter Kinyae  Pauline Mundia  Paul C. Struik 《Potato Research》2011,54(3):253-266

In Kenya, seed potato quality is often a major yield constraint in potato production as smallholder farmers use farm-saved seed without proper management of seed-borne pests and diseases. Farm-saved seed is therefore often highly degenerated. We carried out on-farm research to assess whether farmer-managed positive seed selection could improve yield. Positive selection gave an average yield increase in farmer-managed trials of 34%, corresponding to a 284-€ increase in profit per hectare at an additional production cost of only 6 €/ha. Positive selection can be an important alternative and complementary technology to regular seed replacement, especially in the context of imperfect rural economies characterized by high risks of production and insecure markets. It does not require cash investments and is thus accessible for all potato producers. It can also be applied where access to high-quality seed is not guaranteed. The technology is also suitable for landraces and not recognized cultivars that cannot be multiplied formally. Finally, the technology fits seamlessly within the seed systems of Sub-Saharan Africa, which are dominated by self-supply and neighbour supply of seed potatoes.  相似文献   

Systematic agronomic farm management for improved coffee quality     

Peter Lderach  Thomas Oberthür  Simon Cook  Marcela Estrada Iza  Jürgen A. Pohlan  Myles Fisher  Raul Rosales Lechuga 《Field Crops Research》2011,120(3):253

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Quantifying the yield gap in wheat-maize cropping systems of the Hebei Plain, China   总被引：1，自引：0，他引：1  

Wei-li Liang  Peter CarberryGui-yan Wang  Run-hai LüHong-zhan Lü  Ai-ping Xia 《Field Crops Research》2011,124(2):180-185

Wheat-maize double cropping is the most important cropping system on the Hebei Plain and is one of the most important cropping systems in China. In a scenario of greater food demand, and increasing water and rural labour scarcity, it is critical that the annual productivity of the system is improved in water-energy-cost efficient and low carbon ways. Based on farm surveys, this paper benchmarked the performance of wheat-maize double crops on the Hebei Plain during the 2004-2005 season. These farm yields were assessed both against experimental yields collected from on-farm maximum yield trials conducted during the same 2004-2005 season and relative to simulated estimates of the climate-driven potential productivity of the region.The survey of 362 farms in six counties of the Hebei Plain during the 2004-2005 season found wheat yields ranging from 3375 kg ha⁻¹ to 9000 kg ha⁻¹ with an overall average yield of 6556 kg ha⁻¹. Maize yields averaged 7549 kg ha⁻¹ and ranged from 3375 kg ha⁻¹ to 11,250 kg ha⁻¹. The aggregate production for the wheat-maize double crops grown in the 2004-2005 season averaged 14,105 kg ha⁻¹ across the six counties. This was 72% of the average production (19,586 kg ha⁻¹) recorded from on-farm trials conducted in each of the six counties and 60% of the simulated average production potential (24,147 kg ha⁻¹) for the Hebei Plain in the 2004-2005 season. Thus, the annual productivity of the current cropping system could be increased with currently available technologies by 28%, while a yield increase of 42% is possible if farm yields approach the simulated yield potential.Based on farmer interviews and field observations, a number of real and perceived reasons for the current yield gaps in farmers’ fields were recognised. For instance, irrigation at stem-elongation of wheat is a current recommendation, yet only a proportion of the surveyed farmers were able to follow this strategy due to lack of access to shared irrigation facilities. Improving the region's infrastructure to enable more timely irrigation of crops will be a necessary prerequisite to improved productivity.The results from the farm surveys and on-farm trials indicate that, with current recommended practices, farmers can improve their annual farm productivity and close the current yield gaps. However, the survey identified that increasing system performance and efficiency will require a focus on both agronomic and socio-economic issues.  相似文献   

Site fidelity,survival and conservation options for the threatened flapper skate (Dipturus cf. intermedia)          下载免费PDF全文

Francis Neat  Cecilia Pinto  Ian Burrett  Lewis Cowie  Justin Travis  James Thorburn  Fiona Gibb  Peter J. Wright 《水产资源保护:海洋与淡水生态系统》2015,25(1):6-20

Habitat suitability,coverage by protected areas and population connectivity for the Siamese crocodile Crocodylus siamensis Schneider, 1801          下载免费PDF全文

Flora Ihlow  René Bonke  Timo Hartmann  Peter Geissler  Natascha Behler  Dennis Rödder 《水产资源保护:海洋与淡水生态系统》2015,25(4):544-554

Environmental associations with broad‐scale Japanese and Taiwanese pelagic longline effort in the southern Indian and Atlantic Oceans          下载免费PDF全文

Pamela E. Michael  Geoffrey N. Tuck  Peter Strutton  Alistair Hobday 《Fisheries Oceanography》2015,24(5):478-493

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Understanding the impact of growing conditions on oysters: a study of their sensory and biochemical characteristics          下载免费PDF全文

Maëva Cochet  Malcolm Brown  Peter Kube  Nick Elliott  Conor Delahunty 《Aquaculture Research》2015,46(3):637-646

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How Could Agricultural Land Systems Contribute to Raise Food Production Under Global Change?          下载免费PDF全文

WU Wen-bin  YU Qiang-yi  Verburg H Peter  YOU Liang-zhi  YANG Peng  TANG Hua-jun 《农业科学学报》2014,13(7):1432-1442

To feed the increasing world population, more food needs to be produced from agricultural land systems. Solutions to produce more food with fewer resources while minimizing adverse environmental and ecological consequences require sustainable agricultural land use practices as supplementary to advanced biotechnology and agronomy. This review paper, from a land system perspective, systematically proposed and analyzed three interactive strategies that could possibly raise future food production under global change. By reviewing the current literatures, we suggest that cropland expansion is less possible amid fierce land competition, and it is likely to do less in increasing food production. Moreover, properly allocating crops in space and time is a practical way to ensure food production. Climate change, dietary shifts, and other socio-economic drivers, which would shape the demand and supply side of food systems, should be taken into consideration during the decision-making on rational land management in respect of sustainable crop choice and allocation. And finally, crop-specific agricultural intensification would play a bigger role in raising future food production either by increasing the yield per unit area of individual crops or by increasing the number of crops sown on a particular area of land. Yet, only when it is done sustainably is this a much more effective strategy to maximize food production by closing yield and harvest gaps.  相似文献