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排序方式: 共有1530条查询结果,搜索用时 31 毫秒
1.
Karim Gharbi Louise Matthews James Bron Ron Roberts Alan Tinch Michael Stear 《Journal of the Royal Society Interface》2015,12(110)
Sea lice threaten the welfare of farmed Atlantic salmon and the sustainability of fish farming across the world. Chemical treatments are the major method of control but drug resistance means that alternatives are urgently needed. Selective breeding can be a cheap and effective alternative. Here, we combine experimental trials and diagnostics to provide a practical protocol for quantifying resistance to sea lice. We then combined quantitative genetics with epidemiological modelling to make the first prediction of the response to selection, quantified in terms of reduced need for chemical treatments. We infected over 1400 young fish with Lepeophtheirus salmonis, the most important species in the Northern Hemisphere. Mechanisms of resistance were expressed early in infection. Consequently, the number of lice per fish and the ranking of families were very similar at 7 and 17 days post infection, providing a stable window for assessing susceptibility to infection. The heritability of lice numbers within this time window was moderately high at 0.3, confirming that selective breeding is viable. We combined an epidemiological model of sea lice infection and control on a salmon farm with genetic variation in susceptibility among individuals. We simulated 10 generations of selective breeding and examined the frequency of treatments needed to control infection. Our model predicted that substantially fewer chemical treatments are needed to control lice outbreaks in selected populations and chemical treatment could be unnecessary after 10 generations of selection. Selective breeding for sea lice resistance should reduce the impact of sea lice on fish health and thus substantially improve the sustainability of Atlantic salmon production. 相似文献
2.
针对贺州地区基层水管单位存在的农业水价低、水费征收难和经济困难等现状,对基层水管单位的出路进行了一些探索,提出了一些解决对策。 相似文献
3.
This study deals with evaluating the energy and exergy utilization efficiencies in the Turkish agricultural sector over a 12‐year period from 1990 to 2001. In the energy and exergy analyses, two main energy sources, namely fuels and electricity, are taken into consideration, while the sectoral energy and exergy efficiencies are compared for this period. These main energy sources include diesel for tractors and other vehicles, and electricity for pumps. Overall energy utilization efficiencies are obtained to vary between 29.1 and 41.1%, while overall exergy utilization efficiencies are found to range from 27.9 to 37.4% in the analysed years, respectively. It may be concluded that the present technique proposed here may be used as a useful tool in analysing and evaluating the energy and exergy utilization efficiencies, identifying energy efficiency and/or energy conservation opportunities and dictating the energy strategies of countries. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
4.
孟之光 《浙江水利水电专科学校学报》2004,16(1):67-69
先对浙江农业总体优势状况进行了分析,再对浙江农业内部各大部门优劣势进行分析,得出林业、渔业具有相对比较优势的结论. 相似文献
5.
S. Multsch A. S. Alquwaizany O. A. Alharbi M. Pahlow H.-G. Frede L. Breuer 《国际水资源开发杂志》2017,33(2):292-309
Agriculture policy changes in Saudi Arabia are investigated by water footprint (WF) assessment. WF is calculated with the model SPARE:WATER for 3758 irrigated sites. The WF of agriculture areas (WFarea, km3 yr?1) has decreased (–17%) since the year 2000 to 13.84 km3 yr?1 (2011), which is mainly caused by the reduction of cropland by –33%. Nevertheless, water consumption per field has increased about 16%, which can be attributed to the cultivation of fodder crops (+12%). A scenario analysis revealed that a shifting cropping pattern towards less fodder crops reduces WFarea by –15%, and implementing improved irrigation technology leads to a combined reduction of up to 32% 相似文献
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高吸水性树脂在农业中的应用 总被引:10,自引:0,他引:10
介绍了高吸水性树脂的吸水机理及农用高吸水性树脂的性能、种类和使用方法,分析了高吸水性树脂抗旱节水、改良土壤和促进作物生长的作用机理和影响因素,指出了当前研究中所存在的问题及改进的方向. 相似文献
9.
江西省农业旱情预测模型的建立与应用 总被引:1,自引:0,他引:1
根据农业用地的不同性质分别建立旱地缺墒模型,灌溉水田、水浇地、菜地与望天田缺水度模型,并据此建立江西省农业旱情预测模型,对江西省农业旱情进行预测.为科学抗旱和减少旱灾损失提供依据和指导. 相似文献
10.
基于公众通信网络平台的精确农业网络构成 总被引:1,自引:1,他引:0
孙友伟 《西安邮电学院学报》2010,15(6):92-95
为提高信息化程度,构建精确农业网络,利用现代公众通信网络平台,结合无线传感器网络,配置网络拓扑,设计Sink节点802.15.4协议与GSM网络协议转换的适配器和协议集,可低成本便捷地实现多个农业生产场景综合监测和调控,使信息技术与农业生产有效融合。 相似文献