电子鼻和电子舌单独与联合检测掺大豆蛋白或淀粉的鸡肉糜

为实现掺杂掺假鸡肉的快速、客观评价,该研究利用电子鼻和电子舌联合检测技术对掺杂鸡肉糜进行快速检测,通过对采集的数据进行主成分分析和偏最小二乘法分析,所得结果表明,采用主成分分析,电子鼻和电子舌联合检测掺大豆蛋白鸡肉糜和掺淀粉鸡肉糜的主成分总贡献率分别为99.8%和99.1%;采用偏最小二乘法分析,电子鼻和电子舌联合检测鸡肉糜中掺杂大豆蛋白含量的预测值与真实值之间的决定系数为0.992,均方根误差为2.8%;联合检测鸡肉糜中掺杂淀粉含量的预测值与真实值之间的决定系数为0.996,均方根误差为2.4%。表明电子鼻和电子舌联合检测对鸡肉糜的掺杂情况具有良好的区分和预测能力,并且是一种有效、高精度的肉类掺假检测方法。     

发酵床垫料翻耙结合网床养殖改善鸭舍空气质量与鸭生产性能

为解决规模化肉鸭生产中粪污影响鸭健康和污染环境的问题,研发了一种发酵床结合网床架养新技术及其配套的可移动式网床下发酵床垫料翻耙系统,并研究了该模式在控制舍内气载微生物数量和提高鸭生产性能中的优势。结果显示:1)可移动式发酵床垫料翻耙系统实现不同发酵床体共用一台翻耙机。2)与发酵床平养相比,鸭26日龄之前未翻耙垫料时,发酵床网养舍内需氧菌总数(1.531×105 CFU/m3)和大肠杆菌数量(1.298×104 CFU/m3)显著升高(P0.05);鸭27~34日龄时每4 d翻耙垫料,发酵床网养舍内需氧菌总数(2.304×105 CFU/m3)和金黄色葡萄球菌数量(1.353×105 CFU/m3)显著降低(P0.05);鸭35~39日龄时每天翻耙垫料,发酵床网养舍内需氧菌总数(1.255×105 CFU/m3)和"沙门+志贺"氏菌数量(14.13 CFU/m3)显著降低(P0.05)。3)在发酵床平养舍内,与每4 d翻耙1次垫料相比,每天翻耙1次垫料舍内需氧菌总数(2.688×105 CFU/m3)、大肠杆菌(2.038×104 CFU/m3)、金黄色葡萄球菌(8.90×104 CFU/m3)和"沙门+志贺"氏菌(47.11 CFU/m3)数量显著(P0.05)降低,而在发酵床网养舍内,每天翻耙1次垫料舍内需氧菌总数(1.255×105 CFU/m3)和"沙门+志贺"氏菌(14.13 CFU/m3)数量显著降低(P0.05)。4)与发酵床平养相比,发酵床网养增加鸭体质量(P0.05),降低死亡率和上市淘汰率(P0.05)。结果表明研发的肉鸭养殖新模式能更好地减少舍内空气中病原菌浓度,改善鸭舍内空气环境,提高鸭生产性能。该研究为发酵床结合网床架养新模式在规模企业中推广应用提供技术支持。     

pH-dependent distribution of soil ammonia oxidizers across a large geographical scale as revealed by high-throughput pyrosequencing

Purpose

Ammonia-oxidizing archaea (AOA) and bacteria (AOB) are ubiquitous and important for nitrogen transformations in terrestrial ecosystems. However, the distribution patterns of these microorganisms as affected by the terrestrial environments across a large geographical scale are not well understood. This study was designed to gain insights into the ecological characteristics of AOA and AOB in 65 soils, collected from a wide range of soil and ecosystem types.

Materials and methods

Barcoded pyrosequencing in combination with quantitative PCR was employed to characterize the relative abundance, diversity, and community composition of archaeal 16S rRNA gene, and AOA and AOB amoA genes in 65 soil samples.

Results and discussion

The operational taxonomic unit richness and Shannon diversity of Thaumarchaeota, AOA, and AOB were highly variable among different soils, but their variations were best explained by soil pH. Soil pH was strongly correlated with the overall community composition of ammonia oxidizers, as measured by the pairwise Bray–Curtis dissimilarity across all sites. These findings were further corroborated by the evident pH-dependent distribution patterns of four thaumarchaeal groups (I.1a-associated, I.1b, I.1c, and I.1c-associated) and four AOB clusters (2, 3a.1, 10, and 12). The ratios of AOA to AOB amoA gene copy numbers significantly decreased with increasing pH, suggesting a competitive advantage of AOA over AOB in acidic soils.

Conclusions

These results suggest that the distribution of ammonia oxidizers across large-scale biogeographical settings can be largely predicted along the soil pH gradient, thus providing important indications for the ecological characteristics of AOA and AOB in different soils.     

鱼稻共生条件下陶粒载体水稻浮床提高细菌活性及多样性

以轻质陶粒为主要原料开发出一种新型生物浮床载体,并通过种植水稻构建了陶粒载体水稻浮床对池塘水环境进行修复。研究了陶粒载体水稻浮床对精养池塘的水质净化作用,并采用Biolog-ECO技术分析了陶粒载体水稻浮床对池塘浮游细菌碳源代谢模式和多样性的影响。结果显示,试验组池塘水中总氮(TN)、总磷(TP)和亚硝态氮(NO2–-N)等水质指标在8月份显著低于对照组,高锰酸盐指数(IMn)在8月份和10月份显著低于对照组。试验组池塘浮游细菌群落代谢活性(AWCD)、Shannon指数和丰富度指数在8月份显著高于对照塘,Shannon均匀度指数在10月份显著高于对照塘。浮床种植水稻产量达到5 900 kg/hm~2。结果表明陶粒载体水稻浮床在具备一定生产性能基础上,降低了精养池塘水中氮磷营养水平,改变了精养池塘浮游细菌群落碳源利用模式,并提高了池塘浮游细菌群落代谢活性和功能多样性。结果可为应用陶粒载体水稻浮床调控池塘水环境提供理论指导。     

Effect of Assessment Scale on Spatial and Temporal Variations in CH4, CO2, and N2O Fluxes in a Forested Wetland

Emissions of methane (CH₄), carbon dioxide (CO₂), and nitrous oxide (N₂O) from a forested watershed (160 ha) in South Carolina, USA, were estimated with a spatially explicit watershed-scale modeling framework that utilizes the spatial variations in physical and biogeochemical characteristics across watersheds. The target watershed (WS80) consisting of wetland (23%) and upland (77%) was divided into 675 grid cells, and each of the cells had unique combination of vegetation, hydrology, soil properties, and topography. Driven by local climate, topography, soil, and vegetation conditions, MIKE SHE was used to generate daily flows as well as water table depth for each grid cell across the watershed. Forest-DNDC was then run for each cell to calculate its biogeochemistry including daily fluxes of the three greenhouse gases (GHGs). The simulated daily average CH₄, CO₂ and N₂O flux from the watershed were 17.9 mg C, 1.3 g C and 0.7 mg N m⁻², respectively, during the period from 2003–2007. The average contributions of the wetlands to the CH₄, CO₂ and N₂O emissions were about 95%, 20% and 18%, respectively. The spatial and temporal variation in the modeled CH₄, CO₂ and N₂O fluxes were large, and closely related to hydrological conditions. To understand the impact of spatial heterogeneity in physical and biogeochemical characteristics of the target watershed on GHG emissions, we used Forest-DNDC in a coarse mode (field scale), in which the entire watershed was set as a single simulated unit, where all hydrological, biogeochemical, and biophysical conditions were considered uniform. The results from the field-scale model differed from those modeled with the watershed-scale model which considered the spatial differences in physical and biogeochemical characteristics of the catchment. This contrast demonstrates that the spatially averaged topographic or biophysical conditions which are inherent with field-scale simulations could mask “hot spots” or small source areas with inherently high GHGs flux rates. The spatial resolution in conjunction with coupled hydrological and biogeochemical models could play a crucial role in reducing uncertainty of modeled GHG emissions from wetland-involved watersheds.     

循环式海绵基质培设施结构和性能的研究与应用

循环式海绵基质培是根据世界无土栽培技术发展趋势和中国具体国情进行试验设计、研制而成的新型无土栽培设备.其主要特点是1)基质用量少,成本低;2)供排液分开,避免根际病害传播;3)配套营养液生物过滤装置,提高系统安全稳定性;4)营养液供给自动控制.循环式海绵基质培由贮液池、农用海绵基质(黑白双色膜包被)、双层槽式集液系统、营养液滴灌系统及自控设备、营养液生物过滤系统等组成.循环式海绵基质培在中国东南沿海地区一年量达10000 kg以上,亩产值1.5万元以上,适合农业示范园区内的大型温室应用.     

WRKY转录因子及其在植物防御反应中的作用

WRKY蛋白是只存在于植物中较为复杂的转录因子家族。由WRKY蛋白N端高度保守的WRKYGQK氨基酸序列及其特殊的锌指结构而命名的WRKY结构域能专性与其顺式作用元件W-盒[(T)(T)TGAC(C／T)]结合。根据WRKY结构域的数量及锌指结构的特征将WRKY蛋白家族分为3类,其中拟南芥中第三类家族中几乎所有的WRKY成员都与应答生物胁迫有关。WRKY蛋白的表达特性为快速、瞬时、具组织特异性诱导表达。目前,WRKY蛋白被广泛认为参与植物生物与非生物胁迫应答反应、植物衰亡、种皮及毛状体发育及果实发育等一系列的生理活动,本文综述了WRKY转录因子的结构特征及其功能特性,重点讨论了它们在植物防卫反应中的调控作用。     

稻田套播和氮素对中筋小麦产量和品质的调节效应

采用稻田套播与传统条播两种栽培方式系统比较的方法,研究不同氮肥运筹下稻田套播方式对中筋小麦扬麦10号籽粒产量和品质的调节效应。结果表明：稻田套播方式对中筋小麦籽粒产量和品质影响显著。与传统条播方式相比,在同一氮肥运筹下套播方式中筋小麦除籽粒总淀粉及其组分含量显著高于条播方式外,籽粒产量、蛋白质含量、蛋白质产量、磨粉品质和面粉品质以及淀粉糊化特性的主要指标低于传统条播,且差异显著。稻田套播方式不利于中筋小麦扬麦10号优质的形成,在江苏淮南地区中筋专用小麦采用稻田套播方式宜适当增加施氮量且追氮适度后移。     

杂交粳稻几个数量性状的配合力分析

利用6个粳型不育系和6个恢复系，采用不完全双列杂交法配制了36个杂交组合，对其8个数量性状的一般配合力及亲本间组合的特殊配合力效应进行了分析。结果表明，株高、穗长、穗总粒数、穗实粒数、稳秕粒数、千粒重这几个性状受亲本一般配合力的影响，单株粒重受特殊配合力的影响，单株稳数的一般配合力和特殊配合力作用相近。其中不育系552A的穗总粒数、稳实粒数、单株粒重等一般配合力的相对效应值较大，恢复系FR796、2002FR24的穗总粒数、穗实粒数、单株粒重的一般配合力的相对效应值较大。     

利用SSR标记进行玉米品种一致性检测研究

为了评估SSR标记在玉米品种一致性鉴定中的应用价值及确定基于SSR标记的玉米一致性鉴定标准,利用13个SSR标记对213份来自2004年国家区域试验的玉米单交种(包括16份重复材料)进行了一致性分析,每个品种取20个个体,除在染色体6和8上各选取了2个和3个标记外,其他染色体上均各选取1个SSR标记.结果显示:一致性检测中异型带的类型有7种,每种出现的概率不同;不同品种在不同引物位点的一致性分布情况差别较大.比较位于同一染色体的引物一致性检测结果,发现在相同染色体上位置较近的不同引物一致性检测结果具有较高的相关性,因此提出在选用一致性检测的引物时应遵循均匀分布的原则,减少引物间的相关性.通过剔除自交个体对品种一致性比率进行校正(仅有7个品种),校正值可反映品种真实的遗传一致性和稳定性.综合考虑品种在单个引物位点的一致性和在所有位点的平均一致性,提出了划分玉米品种一致性级别的标准.