Impacts of population growth, economic development, and technical change on global food production and consumption

Over the next decades mankind will demand more food from fewer land and water resources. This study quantifies the food production impacts of four alternative development scenarios from the Millennium Ecosystem Assessment and the Special Report on Emission Scenarios. Partially and jointly considered are land and water supply impacts from population growth, and technical change, as well as forest and agricultural commodity demand shifts from population growth and economic development. The income impacts on food demand are computed with dynamic elasticities. Simulations with a global, partial equilibrium model of the agricultural and forest sectors show that per capita food levels increase in all examined development scenarios with minor impacts on food prices. Global agricultural land increases by up to 14% between 2010 and 2030. Deforestation restrictions strongly impact the price of land and water resources but have little consequences for the global level of food production and food prices. While projected income changes have the highest partial impact on per capita food consumption levels, population growth leads to the highest increase in total food production. The impact of technical change is amplified or mitigated by adaptations of land management intensities.     

Trophic interactions between rhizosphere bacteria and bacterial feeders influenced by phosphate and aphids in barley

The aim was to study the effects of P fertilization and leaf aphid attack on the trophic interactions of bacteria and bacterial feeders in the rhizospheres of barley plants. The density of protozoa peaked in the rhizospheres of plants fertilized with N and P, whereas nematodes peaked in the rhizospheres of plants to which only N had been added. Fingerprinting of bacterial communities by length heterogeneity polymerase chain reaction revealed differences in community structure between NP rhizospheres and N rhizospheres as well as aphid-related differences within N rhizospheres. Specifically, α-proteobacteria increased with P addition. To evaluate if differences in bacteria in terms of their quality as food could partly explain the observed differences in protozoan and nematode abundances, growth of the flagellate Cercomonas sp. was assessed with 935 bacteria isolated from the different treatments. This assay indicated that bacterial isolates were of higher food quality to Cercomonas sp. in NP than in N rhizospheres when plants were subjected to aphid attack. Bacteria of high and low food quality for Cercomonas sp., respectively, were fed to the nematode Caenorhabditis elegans and larval production examined. α-Proteobacteria supported the growth of Cercomonas sp. well, whereas Actinobacteria did not. In contrast, C. elegans reproduced poorly on most α-proteobacteria but were able to reproduce well on some Actinobacteria. These results suggest that the different response of protozoa and nematodes to P addition could be mediated through a food quality-related change in community composition of bacteria and that leaf aphid attack may interfere with nutrient effects on bacterial assemblages of rhizospheres.     

论诱导昆虫滞育的环境因素

昆虫滞育是在长期进化过程中昆虫对不利生活环境条件的不断适应以及环境对昆虫的选择造成的。文章论述了温度、光周期、湿度以及食料等主要环境因素对昆虫滞育诱导的影响,认为光周期和温度是诱导昆虫滞育最主要的因素;湿度主要通过改变昆虫对光周期和温度的刺激反应而影响滞育的诱导;食料作为昆虫的调节因子与光周期以及温度一起诱导昆虫的滞育,在温度和光周期都很少发生年变化的赤道地区,食料能够直接影响到昆虫的生长发育。     

农用化学品及废弃物对土壤环境与食物安全的影响

综述了农用化学品和废弃物(化肥、农药、酸沉降、污水污泥、畜禽粪便和“三废”等)利用现状及其对土壤环境污染与食物安全的影响。     

辽宁蔬菜水果硝酸盐含量及其安全性问题探讨

本文通过对辽宁省主要蔬菜和水果硝酸盐含量的测定,参比国内外硝酸盐含量分级评价标准,分析了目前全省蔬菜和水果食用的安全状况,提出了降低蔬菜水果产品中硝酸盐含量的有效途径。     

Accessing genetic resources: international law establishes multilateral system

The International Treaty on Plant Genetic Resources for Food and Agriculture is rapidly gathering sufficient ratifications to become international law. Once it enters into force, it will define the rules for access and benefit-sharing associated with most genetic resources of major food crops. This paper explains how the new Multilateral System established by the Treaty will work, and points out a number of ambiguities and problems in the text. Despite these shortcomings, the Treaty provides the international community of researchers, plant breeders, and farmers with an opportunity to foster cooperation and further the conservation and use of plant genetic resources.     

食品货架期预测研究进展与趋势

作为食品领域的重要研究方向,货架期预测已成为国内外研究的热点问题。在整理和总结现有相关研究文献的基础上,阐述了食品货架期预测的研究机理,梳理了相关研究思路与方法;对当前研究中采用的5种方法(基于化学动力学的方法、基于微生物生长动力学的方法、BP神经网络方法、威布尔危险值分析方法和Q10模型等基于温度的方法)进行了比较分析;对应用于肉类、水产品、果蔬等不同类别食品并取得良好预测效果的品质指标及所采用的模型方法进行了总结和分析。最后分析了食品货架期预测研究的现状,并展望了发展趋势。     

“稻鸭共生”生态系统重金属镉的转化、迁移及循环特征

重金属镉(Cd)通过污染的饲料和化肥而影响农产品进而危害人体健康已经成为食品安全和生态环境关注的焦点。为完善"稻鸭共生"系统的肥料和饲料管理,建立合理的物质产投结构及降低重金属Cd的生态毒理风险,在湖南省长沙市望城区桐林坳社区开展了2年田间试验,以常规稻作为对照,采用投入产出法,研究分析"稻鸭共生"生态系统重金属Cd的转化、迁移及循环特征。结果表明,"稻鸭共生"生态系统Cd输入量为:肥料饲料秧苗雏鸭,其中肥料Cd输入主要是磷肥输入。"稻鸭共生"生态系统Cd输出主要是水稻籽粒Cd和成鸭Cd。"稻鸭共生"生态系统内循环的Cd主要是鸭粪Cd、杂草Cd、害虫Cd及归还给系统的水稻秸秆Cd和根系Cd。鸭所摄食的Cd主要来自鸭饲料,大鸭饲料Cd输入大于小鸭饲料Cd输入。在"稻鸭共生"生态系统中重金属Cd沿食物链的转化、迁移过程以鸭粪Cd形式放大,且鸭粪Cd高于鸭饲料Cd输入。稻田土壤Cd输出来看,"稻鸭共生"和常规稻作相比无显著差异(P0.05)。无论是常规稻作还是"稻鸭共生",水稻植株Cd含量次序为根秸秆籽粒。与常规稻作相比,"稻鸭共生"没有增加水稻植株Cd含量和Cd积累。糙米和鸭肉镉含量分别为0.033 mg·kg-1和0.008 mg·kg-1,短期来看,"稻鸭共生"能够提供安全无Cd污染的农产品(鸭和稻米)。     

Carbon stable isotope fractionation and trophic transfer of fatty acids in fungal based soil food chains

Stable isotope analysis has been used as a powerful tool in food web studies in terrestrial ecosystems. In addition the occurrence and abundance of fatty acids may serve as indicator for feeding strategies of soil animals. Here we combine both approaches and investigate the fatty acid composition, δ¹³C values of bulk tissues and individual fatty acids in soil organisms. The fungi Chaetomium globosum and Cladosporium cladosporioides were isotopically labelled by fructose derived from either C₃ or C₄ plants, and the fungal-feeding nematode Aphelenchoides sp. was reared on C. globosum. Fungi and nematodes were used as diet for the Collembolan Protaphorura fimata. The sugar source was fractionated differently by fungal lipid metabolism in a species-specific manner that points to a sensitivity of physiological processing to the non-random distribution of ¹³C/¹²C isotopes in the molecule. As a general trend stearic acid (18:0) was depleted in ¹³C compared to the precursor palmitic acid (16:0), whereas its desaturation to oleic acid (18:1 ω9) favoured the ¹³C-rich substrate.Fatty acid profiles of P. fimata varied due to food source, indicating incorporation of dietary fatty acids into Collembolan tissue. Individuals feeding on fungi had lower amounts in C20 fatty acids, with monoenoic C20 forms not present. This pattern likely separates primary consumers (fungivores) from predators (nematode feeders). The isotopic discrimination in ¹³C for bulk Collembola ranged between −2.6 and 1.4‰ and was dependent on fungal species and C₃/C₄ system, suggesting differences at metabolic branch points and/or isotope discrimination of enzymes. Comparison of δ¹³C values in individual fatty acids between consumer and diet generally showed depletion (i.e. de novo synthesis) or no changes (i.e. dietary routing), but the fractionation was not uniform and affected by the type of ingested food. Fatty acid carbon isotopes were more variable than those of bulk tissues, likely due to both the distrimination by enzymes and the different lipid origin (i.e. neutral or polar fraction).     

Modeling trophic pathways, nutrient cycling, and dynamic stability in soils

Soil communities are compartmentalized into pathways of trophic interactions and nutrient flows that originate from plant roots, bacteria and fungi. The pathways differ in terms of the organisms that comprise them, the habitats that the organisms occupy and the rates by which the organisms process and transfer material and energy. The fungi, nematodes and arthropods within the fungal pathway live in air-filled pore spaces and water films, while the bacteria, protozoa, and nematodes within the bacterial pathway occupy water-filled pore spaces and water films. Organisms within the fungal pathway have longer generation times and process matter at slower rates than those within the bacterial pathway. Empirical studies have shown that under natural conditions the pathways co-exist in a stable manner. The relative sizes (indexed by the densities of organisms) and activities (indexed by nutrient-flow rates, excretion rates and respiration rates) of the pathways may change seasonally and in response to minor disturbances, but they persist. However, large anthropogenic and natural disturbances induce shifts in the relative sizes and activities of the pathways. Coincident with these shifts are reports of changes in the aboveground plant community and the availability and retention of plant limiting nutrients. We developed simple models of the bacterial and fungal pathways to explore the consequences of the observed shifts on the dynamic stability of the system. The more stable configurations occurred when there was a balance in the flow of nutrients between the two pathways. Large shifts in nutrient cycling and community structure towards either the fungal pathway or toward the bacterial pathway resulted in less stable or unstable configurations.