NaCl处理对胡杨生长及生理生态特征的影响

以胡杨(Populus euphratica)幼株为材料,采用盆栽试验研究不同NaCl浓度(0、50、100、200 mmol·L-1和400 mmol·L-1)处理对胡杨生长及叶片过氧化氢(H2O2)和丙二醛(MDA)含量,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)活性、水势、可溶性糖和脯氨酸含量的影响。结果表明:在≥200 mmol·L-1NaCl处理下,胡杨株高较对照显著减少,在400 mmol·L-1NaCl处理下,基茎粗较对照显著减少,在NaCl浓度≥100 mmol·L-1时,冠幅面积和叶、枝干重较对照显著减少,根干重随NaCl浓度的增加呈显著线性减少趋势。在NaCl浓度≥200 mmol·L-1时,根冠比较对照显著减少。H2O2和MDA含量随NaCl处理浓度升高呈增加趋势。低浓度NaCl处理下(50 mmol·L-1),胡杨叶片SOD、POD、CAT和APX活性较对照均有所提高,在NaCl浓度≥100 mmol·L-1时,SOD、POD和APX活性较对照降低。胡杨叶片水势随NaCl处理浓度升高而降低。在NaCl处理90 d后,胡杨叶片可溶性糖含量随NaCl浓度升高呈逐渐降低趋势。胡杨叶片脯氨酸含量随NaCl处理浓度增加呈先增加后减少的趋势。     

蜜蜂肠道菌群的调节作用及影响因素

近年来, 蜜蜂数量的大量减少导致全球养蜂业面临重要的经济损失,并对农业各个方面造成了严重后果。最新的研究表明肠道菌群与宿主的健康息息相关。综述了肠道菌群的种类和特性,阐述了肠道菌群在蜜蜂等昆虫健康中的调节作用及影响肠道菌群的因素,并对今后的研究方向进行了展望。     

以鹿茸为模型探索软骨组织发生

软骨组织的研究一直依赖于哺乳动物胚胎模型,这种方法存在取材困难、难以明确界定分层边界等弊端。而鹿茸非常独特,可以作为一种新的生物医学模型对软骨发育进行研究。通过比较传统的软骨研究模型和鹿茸这种新型模型,分析了鹿茸作为软骨研究模型的优势,同时对鹿茸软骨组织发生与生长的组织基础,以及分子调控机制的研究进展进行了综述,并对鹿茸软骨组织中血管生成的调控因子进行了探讨,以期为寻找更有效的软骨发育研究模型提供理论参考。     

Food safety management and regulation:International experiences and lessons for China

China is experiencing rapid urbanization,changes in diets,and modernization of food retailing and production. In this context,food safety can become a greater concern for a variety of reasons. The purpose of this article is to review the international experiences and lessons regarding food safety management,regulation,and consumer behavior,with the goal of identifying how to improve food safety in middle income countries such as China. International experience in addressing food safety provides two general kinds of lessons. First,a middle-income country such as China needs to develop the capacity to carry out risk analysis in order to better focus public resources on the most important risks. Second,it will be important to leverage market incentives so as to make the best use of limited public capacity to enforce standards. International experiences show that food safety management is feasible where market incentives exist,and that public-private partnerships can support the process of improving food safety management. Market incentives require effective consumer or buyer demand,mechanisms to identify and reward quality,and supply chain coordination. Public efforts can be targeted to supporting these market developments for the risks that are the greatest burden to public health.     

网式散叶密集烘烤下部烟叶失水规律与烘烤效应关系研究

为明确网式散叶密集烘烤过程中不同装烟层烟叶的失水规律及其与烟叶烘烤效应的关系,采用称重器对气流上升式密集烤房网式烟框装烟下部叶烘烤过程中失水量进行了实时测定,并考查烘烤过程中烟叶外观性状变化及烤后烟叶质量性状。结果表明:(1)烘烤过程中上、中、下三层烟叶失水率均呈Logistic曲线变化规律,在干筋期以前烟叶失水率下层明显大于中层,中层明显大于上层;(2)不同层次烟叶失水速率均呈"先上升后下降"的"∧"型变化趋势,全炕烟叶的平均失水率与中层烟叶接近;(3)各层烟叶失水变化规律及烟叶外观性状变化与烘烤过程中温湿度变化、烘烤时间的关系密切,对烟叶外观质量和内在质量都有影响。     

根层调控措施对甜玉米-黄瓜设施蔬菜轮作体系土壤硝态氮的影响

【目的】以甜玉米作为填闲作物,探讨不同的根层调控措施对消减土壤剖面累积硝态氮及下茬黄瓜生长的影响。【方法】在华北平原传统棚室蔬菜的休闲季种植甜玉米,针对甜玉米设置添加土壤调理剂和秸秆还田2种根层调控措施,以甜玉米传统种植作为对照,进行田间小区试验。试验于2008年5月至2011年5月进行,共3次甜玉米-黄瓜轮作,6季作物。每年6月初至9月底种植甜玉米,10月初至次年1月底扣棚育黄瓜苗,当年2月初种植黄瓜。在甜玉米季,共3个处理,随机排列,重复3次。小区面积为4 m×2 m,小区间隔0.3 m,区组之间布设1 m的保护行。【结果】甜玉米种植季,调理剂处理的玉米籽粒产量最高,2008、2009和2010年的产量分别为6.2、7.4和7.9 t·hm^-2;土壤调理剂和秸秆还田2种根层调控处理的甜玉米总吸氮量高于传统种植。秸秆还田和调理剂处理能够促进20-60 cm土层根系的生长发育,促使根系吸收更深层的土壤养分。2种根层调控措施均能降低土壤剖面NO₃^--N的累积,尤其对100-200 cm的作物根区NO₃^--N的消减能力更强,NO₃^--N消减趋势大致为：调理剂>秸秆还田>传统种植。3季黄瓜种植季,不同前茬处理的黄瓜产量、生物量和吸氮量差异均不显著;3季平均土壤NO₃^--N在0-200 cm土层的残留量为秸秆还田<调理剂<传统种植。3个轮作季后,传统种植、调理剂和秸秆还田处理在0-200 cm土层的氮素盈余量分别为1 911.6、1 966.3和1 930.2 kg·hm^-2,调理剂处理显著高于传统种植。【结论】在硝态氮高累积的设施土壤上,随着种植年限的增加,加入土壤调理剂和适当的秸秆还田对100-200 cm的作物根区土壤剖面NO₃^--N的消减能力更强。填闲作物种植第二年对下茬黄瓜土壤NO₃^--N的消减作用最为明显。土壤调理剂和秸秆还田措施能够显著提高甜玉米对土壤剖面NO₃^--N的消减能力,减缓土壤NO₃^--N 的淋失,提高经济效益。     

转录因子调控果实成熟和衰老机制研究进展

重点综述近年来关于果实成熟和衰老相关转录因子及其调控机制的研究进展,为进一步阐明果实成熟和衰老的转录调控网络提供参考。     

基于乙烯受体下游转录因子的果实品质调控机制研究进展

近年来乙烯作用机制的研究已陆续从乙烯受体等上游级别延伸至下游转录因子（EIN3/EIL和AP2/ERF）,其中转录调控机制是研究热点之一。本文综述了基于乙烯受体下游转录因子的果实品质调控研究进展,讨论了果实品质转录调控存在的问题和研究趋势。     

西南干热河谷休闲农田温度与蒸发量日变化规律及协同关系

针对西南干热河谷旱季休闲农田面积扩大的实际,选择旱季初和旱季末2个时段,研究24 h休闲农田温度与农田蒸发量的变化规律及协同关系。结果表明：休闲农田温度曲线和蒸发量累计曲线大致呈现波形函数曲线变化,随着土壤深度和农田覆盖物的增加,曲线依次向后推移,波幅也逐渐变小,表明农田覆盖物对土壤起到一定的稳温和保水作用,可明显降低农田土壤水分散失;休闲农田温度与农田蒸发量的协同函数均呈现正向协同关系,且协同系数普遍较大,随着土壤深度和地表覆盖物逐渐增加,协同关系逐渐减弱,而干旱却有利于协同关系加强,说明在气候干燥区,农田温度升高,农田蒸发量增大,温度与蒸发量的协同关系增强,农田温度仍然是农田蒸发的主要推动因素。故西南干热河谷地区要开发利用季节性休闲农田,就必须做好旱季农田土壤水分的保蓄,增加地表覆盖物,减少农田水分的无效蒸发,为休闲农田的开发利用奠定良好的水分基础。     

Common vole (Microtus arvalis) ecology and management: implications for risk assessment of plant protection products

Common voles (Microtus arvalis) are common small mammals in some European landscapes. They can be a major rodent pest in European agriculture and they are also a representative generic focal small herbivorous mammal species used in risk assessment for plant protection products. In this paper, common vole population dynamics, habitat and food preferences, pest potential and use of the common vole as a model small wild mammal species in the risk assessment process are reviewed. Common voles are a component of agroecosystems in many parts of Europe, inhabiting agricultural areas (secondary habitats) when the carrying capacity of primary grassland habitats is exceeded. Colonisation of secondary habitats occurs during multiannual outbreaks, when population sizes can exceed 1000 individuals ha^?1. In such cases, in‐crop common vole population control management has been practised to avoid significant crop damage. The species' status as a crop pest, high fecundity, resilience to disturbance and intermittent colonisation of crop habitats are important characteristics that should be reflected in risk assessment. Based on the information provided in the scientific literature, it seems justified to modify elements of the current risk assessment scheme for plant protection products, including the use of realistic food intake rates, reduced assessment factors or the use of alternativee focal rodent species in particular European regions. Some of these adjustments are already being applied in some EU member states. Therefore, it seems reasonable consistently to apply such pragmatic and realistic approaches in risk assessments for plant protection products across the EU. © 2013 Society of Chemical Industry