特殊医学用途婴儿配方食品中氯的国标检测方法适用性

依据GB 5009.44—2016《食品安全国家标准 食品中氯化物的测定》，对特殊医学用途婴儿配方食品中氯的检测方法适用性展开研究。结果表明：采用GB 5009.44—2016第三法（银量法）检测特殊医学用途婴儿配方食品中乳蛋白部分水解配方、乳蛋白深度水解配方、氨基酸配方得到的样品加标回收率分别为95%～108%、98%～125%、100%～106%，相对标准偏差为12.7%～32.9%；采用GB 5009.44—2016第一法（电位滴定法）得到的检测结果低于第三法检测结果。     

4种氯制剂对养殖废水中高硝酸盐和亚硝酸盐的影响

在高硝酸盐和亚硝酸盐养殖水体中添加一定浓度氯制剂,研究了漂白粉、漂粉精、强氯精和二氧化氯对养殖水体高亚硝酸盐和高硝酸盐消除能力的影响。结果发现：4种氯制剂对硝酸盐和亚硝酸盐消除都有显著性效果(P<0.05),水体中氨氮在试验过程中无显著变化,浓度为0.00 mg/L;二氧化氯组消除效果最明显,30 min时硝酸盐和亚硝酸盐的消除率高达99%、100%,处理组和空白组的硝酸盐浓度为(0.15±0.72)、(16.82±0.97) mg/L,亚硝酸盐浓度为(0.07±0.01)、(19.95±0.61) mg/L,强氯精次之,漂白粉效果最差,30 min时消除率分别为50%、38%,漂白粉和空白组硝酸盐的浓度为(8.49±0.66)、(16.82±0.97) mg/L,亚硝酸盐浓度为(12.33±0.48)、(19.95±0.6) mg/L;水体的pH值在试验后,各处理组都发生了显著的变化(P<0.05),空白组pH 7.63±0.10,强氯精和二氧化氯添加组,pH值都为降低趋势,二氧化氯组pH值降幅最大(pH 2.68±0.06),漂白粉和漂粉精添加组,pH值呈升高趋势,漂白粉组pH值升幅最大(pH 9.6)。通过本试验的研究,4种氯制剂在消除养殖废水中高亚硝酸盐效果显著,并且无氨氮累积,不产生二次污染物,对于养殖废水的处理排放及循环使用有重要意义。     

The efficiency of nitrogen in cattle manures when applied to a double‐annual forage cropping system

The use of cattle manure (CM) for fertilization presents challenges for optimizing nitrogen (N) use. Our work aimed to assess N efficiencies, in a 6‐year experiment with three biennial rotations of four crops: oat–sorghum (first year) and ryegrass–maize (second year) in a rainfed humid Mediterranean area of Spain. Fertilization treatments included the following: control (no N), 250 kg mineral N ha^?1 year^?1 (250MN), three CM rates (supplying 170, 250 and 500 kg N ha^?1 year^?1) and four treatments where the two lowest CM rates were complemented with either 80 or 160 kg mineral N ha^?1 year^?1. Treatments were distributed randomly in each of three blocks. Maximum dry‐matter yield (~44–49 t ha^?1 rotation^?1) was achieved in the third rotation, and only the control and the 170CM yielded significantly less. Within the limitations of the EU Nitrate Directive, the N steady state supply of 170CM always requires a complement of mineral N (80 kg N ha^?1) to maximize N agronomic efficiency. The maximum N‐fertilizer replacement value (250CM vs. 250MN) was 0·67, without significant differences between the two treatments in other N‐related efficiency indexes, which indicates that plants took advantage of residual‐N effects. Nitrogen losses by leaching in the 250CM treatment were around 5–7% of the N applied. This reinforces the sustainability of manure recycling in long cropping seasons.     

Considering the preferences for nitrogen forms by invasive plants: a case study from a hydroponic culture experiment

Although preference for NH₄⁺, NO₃^? or a combination of the two often differs among species, we know little about the responses of invasive plants to different inorganic N forms. Furthermore, many studies have suggested that an increase in N availability may facilitate further invasions. However, most of these studies predicted the positive feedback without considering the preference for N forms of invasive plants. Therefore, we cultivated four common invasive species (Mikania micrantha, Ipomoea cairica, Wedelia trilobata and Bidens pilosa) in South China with hydroponic media containing different forms of N (i.e. NO₃^?, NH₄NO₃ and NH₄⁺) at equimolar concentrations. Our results showed that the N forms significantly affected the growth, biomass allocation and physiological traits of the plants. All four invasive plants supplied with NO₃^? alone had better performance and greater allocation to root biomass than did plants that were supplied with NH₄⁺ alone. Moreover, the photosynthetic rate, pigment content and photosystem II activity of plants supplied with NO₃^? or NH₄NO₃ were significantly higher than those of plants supplied with NH₄⁺alone. The results suggested that all four invasive plants preferred NO₃^? rather than NH₄⁺, and changes in NO₃^? played an important role in furthering the invasions of these plants than did changes in NH₄⁺. Our results implied that decreasing NO₃^? may be a useful tool for controlling and managing invasive plants preferring NO₃^?. In addition, this study highlighted the importance of considering plant N form preference to better understand plant invasions.     

东北棕壤长期不同施肥处理轮作大豆氮素吸收和土壤硝态氮特征

【目的】在玉米–玉米–大豆轮作体系下,基于棕壤肥料长期定位试验,研究不同施肥处理对东北地区大豆生物量、产量、各部位吸氮量及收获期土壤0―100 cm硝态氮累积的影响,为该地区合理施肥提供理论依据和科学指导。【方法】棕壤肥料长期定位田间试验始于1979年,包括不施肥(CK)、单施氮肥(N)、氮磷钾肥配施(NPK)、低量厩肥(M1)及其与化肥配施(M1N和M1NPK)、高量厩肥(M2)及其与化肥配施(M2N和M2NPK)9个处理。厩肥为猪厩肥,1992年后大豆季不施猪厩肥,仅在玉米季相关处理中施用。39年后,调查分析了大豆生物量、产量、氮素吸收利用及大豆收获期0―100 cm土壤硝态氮累积特征。【结果】高量、低量厩肥配施化肥处理大豆生物量、产量、总吸氮量及各部位吸氮量均显著高于单施氮肥和不施肥处理,其中,M1NPK处理大豆生物量、产量和总吸氮量最高,分别为9107、2979和314.2 k g/h m^2,较其他处理分别提高了6.1%~133.6%、23.9%~232.5%和11.7%~359.4%。施肥提高了大豆氮收获指数,但氮素生理效率降低。NPK和M1NPK处理的氮素收获指数最高,均为63.5%,而氮素生理效率较CK分别降低了30.6%和28.1%。大豆收获期各处理土壤硝态氮累积量随土层深度的增加而降低。与播前相比,大豆收获期单施氮肥处理的0―100 cm土层硝态氮积累量显著增加,NPK处理变化不显著,M1、M1N和M1NPK处理显著降低。低量厩肥配施化肥处理收获期0―100 cm土壤硝态氮积累量远低于高量厩肥配施化肥处理,较播前平均降低了79.2%。所有处理中,土壤硝态氮积累量以M1NPK处理最低,比其他处理平均降低了58.2%。【结论】在东北棕壤地区玉米–玉米–大豆轮作体系下,玉米季低量厩肥(13.5 t/hm^2)与氮磷钾化肥配合施用时,大豆季仅施氮磷钾化肥既可提高大豆生物量、产量,促进氮素吸收,同时还可降低大豆收获期土壤硝态氮累积量,降低环境风险,是该轮作体系较为合理的施肥方式。     

盐碱地玉米产量及土壤硝态氮对深松耕作和秸秆还田的响应

【目的】盐碱地是我国重要的土地资源,研究合理可行的耕作技术和培肥措施,为提高产量和实现盐碱地农业可持续发展提供理论依据。【方法】2014-2017年,在山东省滨州市无棣县的盐碱土上,以玉米为供试作物,连续进行了4年田间试验。试验采用裂区设计,以耕作方式为主区,分别设夏季旋耕15 cm (R)和旋耕后再深松35 cm处理(S);副区为冬季秸秆还田量,设秸秆半量还田(3350 kg/hm^2,B)和秸秆全量还田(6700kg/hm^2,Q)两个用量,以无秸秆还田为对照。所有处理的养分总量保持一致。开花后每隔10天取样1次,直到收获期,测定植株干物质和穗位叶硝酸还原酶活性。在玉米小口期、开花期及收获期,取0-100 cm土层样品,每10 cm为一层,测定了土壤硝态氮含量及累积量。【结果】各生育期玉米干物质积累量和产量在两个耕作方式间的差异不显著,与秸秆半量还田相比,秸秆全量还田处理开花期前干物质量较少,但在开花期时,已经开始赶超秸秆半量还田的处理。在收获期,秸秆全量还田处理的干物质量显著高于秸秆半量还田处理的干物质量,4年中的提高幅度为8.6%~9.7%,秸秆全量还田处理的籽粒产量显著优于秸秆半量还田处理(P <0.05)。4年干物质积累量,SQ处理平均比SB、RQ和RB分别提高2.5%~7.3%、1.6%~4.2%和7.6%~20.3%。深松与秸秆全量还田有明显的正耦合作用,秸秆全量还田与深松耕作相结合有利于籽粒产量的提高,与其他处理差异显著(P <0.05)。相同耕作方式下,4年中秸秆全量还田处理的平均硝态氮含量在小口期低于秸秆半量还田,在开花期显著高于秸秆半量还田,但在收获期又显著低于秸秆半量还田的处理,硝态氮累积量平均降低17.9%(P <0.05)。在4年中深松耕作处理的0-100 cm平均硝态氮累积量比旋耕处理的显著降低8.9%。【结论】在供试盐碱地土壤条件下,秸秆全量还田结合浅旋耕后再深松的效果最好,可提高玉米产量,减少土壤中硝态氮的累积。     

有机肥施用对红地球葡萄产量、品质及土壤环境的影响

【目的】明确有机肥施用对河北葡萄主产区高产优质红地球葡萄产量、品质及土壤环境的影响,为葡萄种植合理施用有机肥提供理论依据。【方法】以河北张家口市怀来县葡萄试验示范基地13年生红地球葡萄为试验材料,进行为期4年的田间试验。设置6个处理,分别为农民传统施肥(CK)、单施化肥(NPK)、单施有机肥9 t/hm^2 (M)、有机肥7.5 t/hm^2+化肥(M1NPK)、有机肥15 t/hm^2+化肥(M2NPK)、有机肥45 t/hm^2+化肥(M3NPK),采用常规方法测定葡萄产量、品质、重金属含量及果园土壤中硝态氮、微生物量碳和氮、重金属含量,并对葡萄园土壤重金属累积达到限量所需年限进行推算。【结果】施用有机肥处理葡萄产量均显著高于单施化肥(NPK),其中以中量有机肥+化肥处理(M2NPK)的产量最高,4年(2010-2013)平均产量为21503kg/hm^2,较农民传统施肥(CK)提高了14%;施用有机肥处理葡萄Vc含量比对照显著增加。各处理间葡萄百粒重、pH、可溶性固形物、可滴定酸和固酸比差异不显著。收获后M2NPK处理0-20 cm和20-40 cm土壤硝态氮累积量下降,土壤微生物生物量碳、氮含量显著高于CK。连续4年施用有机肥后,葡萄果实及果园土壤的重金属含量(Cr、Cd、As、Pb、Hg、Cu、Zn)均未超标,但随着有机肥施用量的增加,葡萄及土壤中的重金属分别呈现线性和二次函数累积趋势。M3NPK处理土壤重金属含量较其他施用有机肥处理提前累积到限量水平。【结论】中量有机肥+化肥(M2NPK)处理葡萄的产量最高,品质最佳,而且降低了土壤硝态氮在各土层的累积,增加了土壤微生物生物量碳、氮含量,且葡萄果实和果园土壤重金属含量未超标。高量有机肥处理不会进一步提高红地球葡萄的产量和品质,但快速增加果园土壤重金属累积。     

Application of urease inhibitor improves protein composition and bread‐baking quality of urea fertilized winter wheat

Background: Nitrogen losses is an economic problem for wheat production and a high risk to the environment. Therefore, improved N fertilizer management is a key to increasing the N efficiency and minimizing N losses. To increase N efficiency, enhanced fertilizers such as urea combined with urease inhibitor can be used. Aims: The aim of present study was to evaluate the effects of different N forms on grain storage protein subunits in winter wheat and to examine whether the observed changes correlate with parameters of baking quality. Methods: The investigation was performed over two consecutive years at two locations in Germany. Protein subunits were analyzed by SDS‐PAGE. Results: Protein concentrations were similarly increased after fertilization with ammonium nitrate and urea + urease inhibitor. Analysis of the individual storage protein fractions indicated that both fertilizers specifically enhanced ω‐gliadins and HMW glutenins, but the effect was more pronounced in the ammonium nitrate treatment. Application of urea + urease inhibitor had greater influence on the protein composition and resulted in higher specific baking volume as well as the best fresh keeping ability, in comparison with urea treatment. Conclusion: Considering that the urea + urease inhibitor treatment resulted in almost comparable improvements of NUE and baking quality, with the additional benefit of reduced N losses in combination with easy handling, urea + urease inhibitor can be recommended as a viable alternative to both urea alone and ammonium nitrate treatments. This opens up an opportunity for the reduction of N loss in wheat production when use of urea is preferred.     

体外法研究硝酸钠调控水牛瘤胃甲烷生成对脂肪酸生物氢化途径的影响

本试验旨在研究硝酸钠调控水牛瘤胃甲烷生成对脂肪酸生物氢化途径的影响。选取3头体重约为（650±50）kg、安装永久性瘤胃瘘管的水牛作为瘤胃液供体动物，通过体外批次培养，设计发酵底物的精粗比为40：60，试验设4个组，每组5个重复，每组各添加0.25 mg/mL的α-亚麻酸，硝酸钠添加水平分别为0（对照）、1、2、3 mg/mL。分别培养3、6、9、12、24 h时测定产气量和甲烷产量，在培养24 h结束后测定体外发酵参数和脂肪酸含量。结果表明：①添加硝酸钠显著降低了瘤胃培养液24 h的总产气量、甲烷（CH₄）含量和甲烷/总产气量的比例（P<0.05），添加1、2和3 mg/mL硝酸钠后瘤胃液甲烷含量分别降低了89.62%、91.20%、91.75%。②添加硝酸钠组瘤胃培养液的pH和氨态氮（NH₃-N）含量显著高于对照组（P<0.05），添加1 mg/mL硝酸钠组微生物蛋白（MCP）含量也显著高于对照组（P<0.05），其他组别差异不显著（P>0.05）；添加硝酸钠组瘤胃液乙酸浓度差异不显著（P>0.05），但丙酸、丁酸、异丁酸、戊酸和异戊酸浓度显著低于对照组（P<0.05），乙酸/丙酸显著高于对照组（P<0.05），添加3 mg/mL硝酸钠组瘤胃液总挥发性脂肪酸（TVFA）含量显著低于对照组（P<0.05）。③添加1 mg/mL硝酸钠组瘤胃液C18：2 cis-9，trans-11、C18：2 trans-10，cis-12、C20：1、不饱和脂肪酸（UFA）含量及UFA/SFA显著高于其他组（P<0.05）；添加硝酸钠组瘤胃液C18：2n6c、C18：1n9t、C20：5n3（EPA）和C22：6n3（DHA）的含量均高于对照组，且1 mg/mL硝酸钠组含量最高，但差异不显著（P>0.05）；添加1 mg/mL硝酸钠组瘤胃液C18：3n3、C18：2n6c和C18：1n9c含量均高于对照组，差异不显著（P>0.05）。由此可见，体外添加硝酸钠显著降低了瘤胃液总产气量和甲烷含量，pH和NH₃-N含量显著升高，TVFA含量降低，通过显著减少丙酸含量而升高乙酸/丙酸；添加1 mg/mL硝酸钠可显著提高瘤胃液共轭亚油酸（CLA）和UFA含量，且在抑制甲烷产生的同时能够降低不饱和脂肪酸的生物氢化程度。     

硝酸钠和乙酸铵配施对黄果柑幼苗光合特性的影响

利用Li–6400便携式光合测定系统，测定了硝酸钠与乙酸铵11个不同配比处理的黄果柑幼苗在不同季节的光合能力。结果表明：1) 硝酸钠与乙酸铵配比处理黄果柑幼苗的光合能力均表现为夏季最强，冬季最弱，秋季强于春季；叶绿素a、叶绿素b和总叶绿素含量均表现为夏季最高，冬季最低，秋季高于春季。2) 硝酸钠和乙酸铵配比(质量比)为8∶2时，黄果柑幼苗叶片的净光合速率、蒸腾速率、水分利用率和气孔导度以及叶绿素a、叶绿素b和总叶绿素含量均高于其他处理，单施硝酸钠或乙酸铵处理都低。综合比较分析，硝酸钠和乙酸铵配比为8∶2时，黄果柑幼苗的光合能力最强。