茄子黄萎病发病程度与根际土壤线虫种群数量的关系研究

研究结果表明茄子根围和根内线虫种群数量与茄子黄萎病发病程度有密切关系,重病株根围线虫密度明显高于轻病株和无病株;重病株根内线虫密度也明显高于轻病株和无病株;发病地块茄子根际与非根际线虫密度无明显差异;线虫与黄萎病菌混合接种茄子,黄萎病发病率显著高于仅接黄萎菌,且接线虫数越多其发病程度越重;混合接种较仅接线虫茄子根内线虫密度明显升高。经鉴定寄生茄子根的线虫主要为垫刃线虫属(Tylenchus)、短体线虫属(Prathylenchus)、矮化线虫属(Tylenchornychus)和滑刃线虫属(Aphelenchoidae)。     

棉花黄萎病生防菌脂肽类抑菌物质分离和鉴定

棉花黄萎病(Cotton Verticillium Wilt)是一种由大丽轮枝菌(Verticillium dahliae Kleb)引起的严重危害棉花生产的土传维管束病害[1]。因大丽轮枝菌菌丝体产生的大量微菌核在土壤中存活时间长以及病原菌变异快等特点,造成培育抗病品种、使用化学药剂和利用新的栽培技术等方法防病效果均不理想。近年来,以生物防治为主的综合防治措施日益受到人们重视,并取得了一定效果[2-4];该措施     

固体生物肥防治黄瓜枯萎病、青椒疫病的田间应用效果评价

利用田间小区试验进行固体生物肥料防治黄瓜枯萎病和青椒疫病的效果研究，对田间应用效果进行评价。结果表明，固体生物肥料对黄瓜枯萎病的防治效果为45．12％、对青椒疫病防治效果达51．79％，达到了差异显著的效果，而且分别增产11．06％和37．19％，其防病与增产效果显著。     

农产品/食品中农药残留快速检测方法研究进展

农药残留的识别和量化通常依赖于气相色谱法、高效液相色谱法、气/液相色谱-质谱联用法以及毛细管电泳法,这些方法需涉及大而贵重的仪器、费时的样品处理以及专门的技术培训。因此,建立在线、高灵敏度、高选择性、简单高效、低成本的农药残留快速检测方法和技术非常重要。该文综述了用于农产品/食品的农药残留分析快速检测方法,主要包括酶抑制法、免疫分析法、光谱法(包括可见/近红外、红外、拉曼和激光诱导击穿光谱等)以及各种生物传感器等,分别介绍了这些方法最新的研究进展,同时分析并总结了这些快速检测方法和技术的基本原理和特点。目前的研究在灵敏度、重复性、准确性方面存在着一些不足,商品化的农药残留检测仪器也比较单一。由于纳米生物技术、分子印迹技术和微流控技术等技术有着巨大的应用潜力,因此特别介绍了这些技术在农药残留分析中的应用。农药残留快速分析技术未来将会朝着检测仪器的小型化和集成化、多通道检测、无线通讯方向发展,提高快速检测方法和仪器的稳定性和可靠性是必然趋势。     

草莓原种苗工厂化育苗工艺设计与繁育量预测

为提高草莓原种苗繁育效率和种苗整齐度,设计了一种草莓原种苗高效扦插育苗工艺,通过构建原种苗繁育过程的数学模型,预测了可控环境下草莓原种苗的周年繁育量。通过预测母株和原种苗数量的动态变化,可以为草莓原种苗工厂化育苗的生产管理决策提供参考。模拟结果表明,在20 m2育苗面积内,由1株草莓原原种苗繁育一年可以累计收获12 697株茎粗10 mm且具有6片叶的优质原种苗,单位育苗面积原种苗繁育量达635株/m2,是露地育苗的10倍以上。在4～5层立体育苗方式下,单位占地面积原种苗繁育量是现有高架育苗方式的7～13倍。草莓原原种苗数量、母株的匍匐茎数量、匍匐茎萌发时间间隔、子苗扦插培养时间等因素对草莓原种苗繁育量均具有较大影响,建议在工厂化育苗生产时对其进行优化。     

Development of a sensitive high-performance liquid chromatography-diode array detection assay for the detection and quantification of the beauveria metabolite oosporein from submerged culture broth and bio-control formulations

A sensitive high-performance liquid chromatography-diode array detection (HPLC-DAD) assay is described for the detection and quantification of the Beauveria metabolite oosporein from fungal culture broth and two biocontrol agent formulations. In all cases, analyte recovery was achieved with a Britton-Robinson buffer system at pH 5.5 diluted with methanol 3:7 (v/v) (BR5.5-MeOH). The HPLC-DAD assay, using a binary solvent gradient with acidic modifiers and detecting the metabolite at 287 nm, showed linearity over 3 orders of magnitude and a limit of detection (LOD) of 6.0 +/- 2.3 microg of oosporein/L of BR5.5-MeOH. The oosporein content of the representative fungal culture broth samples and two Beauveria formulations (Melocont-Pilzgerste and Melocont-WP) was found to be 504.7 +/-13.6 mg of oosporein/L of culture filtrate, 7.4 +/- 0.6 mg of oosporein/kg of Melocont-Pilzgerste, and 38.2 +/- 1.3 mg of oosporein/kg of Melocont-WP with recovery rates of 93 +/- 2, 99 +/- 8, and 92 +/- 3%, respectively.     

Validation of a new LC-MS/MS method for the detection and quantification of phenolic metabolites from tomato sauce in biological samples

Tomato is a good source of bioactive molecules such as vitamin C, carotenoids, and phenolic compounds. Up to now, only a few studies have evaluated the bioavailability of phenolic compounds from tomato. This paper presents the optimization of a method for the determination of phenolics in tomato and their metabolites in human urine and plasma after ingestion of tomato sauce. The sample preparation includes a SPE step to obtain cleaner extracts for injection in the LC-MS/MS system. The mean recovery of analytes ranged from 73 to 104% in plasma and from 65 to 106% in urine, the accuracy was between 90.3 and 115.0% in urine and between 85.7 and 115.0% in plasma, and the precision coefficient of variation was <15%. The method allowed detection and quantification limits of 0.5-29 and 2.0-90 ng mL?1 in urine, respectively, and 0.5-30 and 2.0-105 ng mL?1 in plasma, respectively, for the same phenolic compounds.     

主要粮食品质快速光学检测技术与装备研究进展

玉米籽粒破损是制约中国玉米籽粒直收技术推广应用的瓶颈问题,如何快速准确地获取玉米收获过程中籽粒损伤情况是玉米智能化收获的关键。为了解决这一问题,该研究提出一种基于深度学习的玉米籽粒破损检测装置及方法,该方法采用籽粒单层化装置不断获取高质量玉米籽粒集图像数据,并通过深度学习分割、分类两阶段模型实现破损玉米籽粒检测。图像分割阶段通过深度学习经典实例分割模型（Mask R-CNN）完成区域内玉米籽粒单体分割;而图像分类则由该研究基于残差模块提出的新型网络模型（BCK-CNN）实现。为了评价BCK-CNN分类模型的有效性,将其和其他典型深度学习分类模型进行对比测试,并利用可视化的技术评估了不同模型对玉米籽粒的分类性能。结果表明：BCK-CNN模型对完整、破损玉米籽粒的分类准确性分别达到96.5%、94.2%。另外,选取平均相对误差为评价指标,通过模拟试验对比验证了该检测方法对破损玉米籽粒的检测性能。结果表明：相较于人工计算籽粒破损率,该研究提出的破损玉米籽粒检测方法计算得到的平均相对误差仅4.02%;且将其部署在移动工控机上对单周期玉米籽粒集图像检测时间可以控制在1.2 s内,研究结果为玉米收获过程中破损籽粒高效精准检测提供参考。

     

用于水肥系统的养分离子快检装置研制与试验

针对农业生产中难以现场、精准、快速获取水肥系统中养分离子含量的问题,该研究设计了一套针对水肥溶液与浇灌尾水中K+、NO3-、NH4+、PO43-4种养分离子的快检装置。该装置结合了毛细管电泳（Capillary Electrophoresis,CE）技术和电容耦合非接触电导检测（Capacitively Coupled Contactless Conductivity Detection,C4D）技术,首先使用CE的方式实现养分离子快速分离,再利用C4D原理进行精准测量,在10 min内即可完成单个指标检测。装置由高压系统、C4D检测器、毛细管通道、数据采集卡和上位机组成,采用触摸屏控制,操作简便。为了提升检测效果,在C4D检测器的电路设计上引入了锁相放大技术,测试了其在不同幅值Vp和工作频率f下的输出特性曲线,确定了最优参数为f =490 kHz,Vp=75 V（阳离子）,Vp=60 V（阴离子）。使用装置对K+、NO3-、NH4+、PO43-这4种离子的标准溶液进行检测分析,检测限均可达到1 μg/L。最后,为了验证装置的有效性和现场适应能力,在安装了水肥系统的草莓种植温室中对水肥溶液与浇灌尾水样品进行了现场测试,仅需少量样品和简单操作即可快速得出结果,4种养分离子的检测结果相对标准偏差均小于7%,表明该研究提出的装置可以有效地实现配比后的水肥溶液与浇灌尾水的现场快速检测。研究结果为水肥系统的养分离子检测提供了一种可靠的方法与装置,可为设施农业的高效肥料管理提供数据支持。     

A selective, sensitive, and rapid in-field assay for soil catechin, an allelochemical of Centaurea maculosa

Centaurea maculosa is a plant species native to Eurasia and invasive in many regions of North America that secretes a phytotoxin from its roots, (+/−)-catechin, which is thought to serve an allelopathic role by reducing fitness of neighboring species. However, catechin is a relatively unstable compound, is often found at relatively low concentrations, interacts with soil cations to form insoluble complexes and/or degradation products, and exhibits extremely variable accumulation patterns in the soil. These factors, coupled with a lack of knowledge of the regulation of catechin production by C. maculosa, confound our understanding of the importance of catechin as an allelochemical. The time and cost of current sampling procedures effectively limit the observations made on catechin accumulation patterns, without which it is extremely difficult to conclusively attribute allelopathic significance to this compound. Thus, a highly sensitive, fast, inexpensive and reliable method for soil catechin analysis is needed. We report a novel method that utilizes the colorimetric reagent dimethylaminocinnamaldehyde (DMACA) in an acidic ethanol solution for detection of soil catechin. This method is selective and extremely sensitive and can be used in the field for qualitative, but not quantitative, analysis. This assay will allow for a greater understanding of the role of catechin as an allelochemical.     

A system for the rapid analysis of organic phosphorus in water samples or fractions from chromotographic columns

Summary

An automatic method for the colorimetric determination of Al in soil extracts using catechol violet was developed. The method is very reproducible and precise. The manifold arrangement covers a range of 0–1 μg ml^?1. By using a dilution loop, solutions containing up to 10 μg ml^?1 can be analysed. The method compares favourable with a manual catechol violet method and the alumin on method.     

四端法土壤电导率原位快速检测传感器设计与试验

实现土壤电导率的快速获取可为农业生产精准管理提供有效的数据支撑。目前,田间电导率采集在农业生产前进行,需要专门的电导率检测设备对种植田块开展大范围数据采集并生成电导率空间分布图,该方式操作繁琐、费时费力,同时检测的电导率值由于时间滞后原因,难以准确反映农业生产各环节(如播种)实施过程中的真实电导率情况。针对上述问题,基于交流"电流-电压"四端法原理,该研究设计了一种土壤电导率原位快速检测传感器,用于搭载在不同的农业生产机具上,实现土壤电导率的实时检测与作业参数的在线调整。该传感器以STM32处理器为核心,配合电源电路、交流信号源电路、有效值检测电路及其他外围电路搭建了硬件及软件架构,同时集成了信息的实时检测与显示、定时存储与无线传输等功能,实现了土壤电导率的原位高精度获取。传感器标定试验及工作稳定性试验结果表明,传感器输出值与DDB-303A电导率仪测得的电导率值呈明显线性关系,线性拟合R2为0.995,且在不同电导率水平下,连续测量的标准偏差均小于0.76μS/cm,具有较高的准确性及工作稳定性。与JXBS-3001传感器在实验室条件下(温度25℃),对配置的不同电导率浓度土样(含水率15%)检测的对比试验结果表明,所设计的电导率传感器的测量误差及响应时间更低,绝对误差为-5.9～19.4μS/cm,相对误差为-1.05%～2.39%,响应时间小于2.01s。利用电导率传感器在现场(温度20.6℃)对地块不同位置测量的绝对误差为-11.36～25.30μS/cm,相对误差为-7.91%～7.88%。综合而言,该研究所设计的土壤电导率传感器能快速准确的检测土壤电导率信息,可为无人农场的土壤信息采集提供一种高精度的检测工具。     

Development of a rapid and inexpensive assay for the nonspecific detection of antimicrobial residues in chicken egg yolks and neonatal yolk sacs

Competitive exclusion of intestinal pathogens by administration of beneficial and defined cultures of normal intestinal microflora is a safe and effective means of reducing the incidence and severity of chick infections with Salmonella and other intestinal pathogens. It is important that competitive exclusion cultures not carry genetic material (e.g., plasmids), which could transfer antibiotic resistance to other microflora, including pathogens. As such, safe and effective competitive exclusion cultures must be sensitive to commonly used antimicrobial agents. By necessity, intentional or accidental exposure of these beneficial microflora to antibiotics will reduce or eliminate the protection provided by competitive exclusion culture establishment. As antibiotic residues can be present from embryonic, hatchling, or maternal administration, a rapid and sensitive assay for the nonspecific detection of residues, which could interfere with competitive exclusion culture establishment, is needed. This study was conducted to develop a rapid and inexpensive bioassay to detect multiple antimicrobial residues in egg yolk and neonatal yolk sacs. Aerobic bacterial strains with known sensitivity to several antibiotics used by the poultry industry were selected and individually compared for sensitivity to enrofloxacin, gentamicin, tetracycline, ceftiofur, and tylosin concentrations in egg yolks. This assay was found to be relatively sensitive for the detection of these antimicrobials, and detection of residues was associated with reduced competitive exclusion culture (PREEMPT) establishment in one experiment. Importantly, this assay can be implemented with minimal training or equipment under commercial hatchery practices and could be used to determine embryo groups, in advance of hatch, that are not suitable candidates for competitive exclusion treatment in the hatchery.     

Non-isotopic method for the quantification of biological nitrogen fixation and wheat production under field conditions

 A field experiment was conducted in the Inshas area (Sharkeia governorate) to study the potential of biofertilizers, when the quantities of commercial fertilizers were reduced, for optimal wheat production. The different treatments were arranged in a completely randomized block design with seven replicates. N fertilizer was applied in three treatments with one control, i.e. zero, full, half and one-fourth rates, in the presence or absence of inocula. Azospirillum brasilense strain Sp245 was used as a biofertilizer. Generally, inoculation increased the accumulation of shoot dry matter and grain yield by about 35%, relative to the control treatment. Similar trends were observed in the case of N and P uptake by shoots and grains, as well as the efficient use of both, where inoculation increased the acquisition of the two elements as compared with the uninoculated plants. The obtained data showed that N₂ fixed by shoots and grains ranged from 2 to 10 kg N ha^–1 and from 8 to 19 kg N ha^–1, respectively. With respect to fixed N₂, the best treatment was inoculation combined with the one-fourth dose of N, followed by inoculation combined with half of the recommended N dose. Most of the fixed N was utilized by grains and the results clearly reflected the negative effect of high N fertilizer rates on biological N fixation. It is obvious that inoculation, in general, enhanced the N fertilizer utilized by both shoots and grains of wheat plants. In conclusion, the application of biofertilization technology to a light-textured soil with low fertility had a positive effect on plant growth, N gained from the air and enhancement of fertilizer N uptake (apparent recovery fraction). Received: 22 April 1999     

Enzyme-linked immunosorbent assay based on a polyclonal antibody for the detection of the insecticide fenitrothion. Evaluation of antiserum and application to the analysis of water samples.

For development of an indirect competitive enzyme-linked immunosorbent assay (ELISA) for the organophosphorus insecticide fenitrothion, the specificity of the antiserum R-3 generated with the bifunctional hapten, LysMNPA (2-[[[(3-methyl-4-nitrophenyl)oxy]methylcarbonyl]amino]-6-(2,4-dinitrophenyl)aminohexanoic acid) and the application to the residual analysis of some water samples were evaluated. At optimized ELISA conditions, the quantitative working range was from 1 to 39 ng/mL with a limit of detection of 0.3 ng/mL and an IC(50) value of 6 ng/mL. Cross-reactivity to structurally similar organophosphorus compounds and related chemicals was determined. The antiserum R-3 showed significant cross-reactivity with fenitrooxon and 3-methyl-4-nitrophenol, which have a 3-methyl-4-nitrophenoxy group as common structures, but showed relatively low cross-reactivity with other compounds. Each water sample (river water, tap water, purified water, and bottled water) had a matrix effect and was investigated by adding Tween 20 in the assay buffer. These four kinds of water samples were fortified with fenitrothion at several concentration levels and were directly analyzed with only dilution with an equal volume of antiserum solution. The mean recovery was 105.9%, and the mean coefficient of variation was 10.9%. The results suggested that the developed ELISA would be very suitable for a preliminary screening for fenitrothion in water samples at such low levels.     

A new LC/MS/MS rapid and sensitive method for the determination of green tea catechins and their metabolites in biological samples

A new rapid and sensitive method has been developed, using liquid chromatography in tandem mass spectrometry (LC-ESI-MS/MS) to identify green tea catechin metabolites in plasma and urine after oral intake of a green tea extract. (-)-Epigallocatechin-3-gallate (EGCG), (-)-epicatechin-3-gallate (ECG), (-)-epigallocatechin (EGC)-glucuronide, (-)-epicatechin (EC)-glucuronide, and EC-sulfate were identified in plasma, whereas in urine only the conjugated catechins were detected (EGC-glucuronide, EGC-sulfate, EC-glucuronide, and EC-sulfate). Standard calibration curves prepared in plasma were found to be linear in the range of 10.9-1379.3 nmol/L for EGCG, EGC, ECG, and EC. The accuracy and precision of this assay showed a coefficient of variation of <15%. The method allowed the detection and quantification limits (for 20 microL injection) from 1.1 to 2.6 nmol/L and 3.8-8.7 nmol/L, respectively, in plasma and 0.8-1.8 nmol/L and 2.6-6.0 nmol/L, respectively, in urine. This method can be applied for future clinical and epidemiological studies, allowing the identification of the active metabolites that will reach the target tissues.     

A rapeseed-specific gene, acetyl-CoA carboxylase, can be used as a reference for qualitative and real-time quantitative PCR detection of transgenes from mixed food samples

Polymerase chain reaction (PCR) methods are very useful techniques for the detection and quantification of genetically modified organisms (GMOs) in food samples. These methods rely on the amplification of transgenic sequences and quantification of the transgenic DNA by comparison to an amplified reference gene. Reported here is the development of specific primers for the rapeseed (Brassica napus) BnACCg8 gene and PCR cycling conditions suitable for the use of this sequence as an endogenous reference gene in both qualitative and quantitative PCR assays. Both methods were assayed with 20 different rapeseed varieties, and identical amplification products were obtained with all of them. No amplification products were observed when DNA samples from other Brassica species, Arabidopsis thaliana, maize, and soybean were used as templates, which demonstrates that this system is specific for rapeseed. In real-time quantitative PCR analysis, the detection limit was as low as 1.25 pg of DNA, which indicates that this method is suitable for use in processed food samples which contain very low copies of target DNA.     

A miniaturized curcumin method for the determination of boron in solutions and biological samples

Methods for the determination of boron require either sophisticated and expensive equipment (e.g. ICP-OES or ICP-MS) or a relatively large sample volume (e.g. spectrophotometric methods). A modified and miniaturized spectrophotometric curcumin method is presented which allows the determination of boron in sample volumes of 50—150 μl with a detection limit of 0.010 mg B l¹. The calibration curve is linear up to a concentration of 3 mg B l¹. Interferences with other ions are eliminated by extraction of boron with 2-ethyl-1,3-hexanediol in chloroform. Simultaneously, enrichment of boron in the sample can be performed within the same extraction step. Results show good reproducibility with a relative standard deviation of 15% at B concentrations between 0.05 and 0.40 mg B l^—1. In different types of solutions, recovery of added boron was in the range of 98 to 99%. For several plant materials containing from 18 to 58 μg B (g dw)¹, an overall relative standard deviation of 4.5% was established. So far, the method has been successfully applied to determine boron in waters, nutrient solutions, different plant parts (roots, stems and leaves) as well as in phloem sap and apoplastic washing fluid of several plant species.     

A simple rapid method for the measurement of exchangeable cations and effective cation exchange capacity

Abstract

A simple single‐extraction procedure for measuring exchangeable cations and effective CEC (ECEC, the CEC at natural pH and ionic strength) has been developed for routine advisory soil analysis. The method is based on the use of Sr (1.26M SrCl₂) to displace exchangeable cations and effective CEC is taken as the sum of the exchangeable cations. A ten minute shaking time at 5 g:80 ml, soil solution ratio, was found to be optimum. Good agreement was found between the proposed method and the standard neutral IN ammonium acetate leaching procedure with correlation coefficients (r) for the individual cations Mg, Ca, Na and K of 0.99***, 0.99***, 0.83*** and 0.96*** respectively. Strontium chloride extracted more Al but less Mn (P<0.01) than IN KC1, but because of the low levels of these cations in relation to the total cations present, there was still a good relationship (r= 0.99) between ECEC determined by 1.26M SrCl₂ and that determined as the sum of ammonium acetate extractable Mg, Ca, Na and K plus IN KCl‐extracted Al and Mn.     

A field trial to evaluate the pollution potential to ground and surface waters from woodchip corrals for overwintering livestock outdoors

Outwintering beef cattle on woodchip corrals offers stock management, economic and welfare benefits when compared with overwintering in open fields or indoors. A trial was set up on a loamy sand over sand soil to evaluate the pollution risks from corrals and the effect of design features (size and depth of woodchips, stocking density, and feeding on or off the corral). Plastic‐lined drainage trenches at 9–10 m spacing under the woodchips allowed sampling of the leachate. Sampling of the soil to 3.6 m below the corral allowed evaluation of pollutant mitigation during vadose zone transport. Mean corral leachate pollutant concentrations were 443–1056 mg NH₄‐N L^?1, 372–1078 mg dissolved organic carbon (DOC) L^?1, 3–13 mg NO₃‐N L^?1, 8 × 10⁴–1.0 × 10⁶Escherichia coli 100 mL^?1 and 2.8 × 10²–1.4 × 10³ faecal enterococci 100 mL^?1. Little influence of design features could be observed. DOC, NH₄ and (in most cases) E. coli and faecal enterococci concentrations decreased 10²–10³ fold when compared with corral leachate during transport to 3.6 m but there were some cores where faecal enterococci concentrations remained high throughout the profile. Travel times of pollutants (39–113 days) were estimated assuming vertical percolation, piston displacement at field moisture content and no adsorption. This allowed decay/die‐off kinetics in the soil to be estimated (0.009–0.044 day^?1 for DOC, 0.014–0.045 day^?1 for E. coli and 0–0.022 day^?1 for faecal enterococci). The mean [NO₃‐N] in pore water from the soil cores (n = 3 per corral) ranged from 114 ± 52 to 404 ± 54 mg NO₃‐N L^?1, when compared with 59 ± 15 mg NO₃‐N L^?1 from a field overwintering area and 47 ± 40 mg NO₃‐N L^?1 under a permanent feeding area. However, modelling suggested that denitrification losses in the soil profile increased with stocking density so nitrate leaching losses per animal may be smaller under corrals than for other overwintering methods. Nitrous oxide, carbon dioxide and methane fluxes (measured on one occasion from one corral) were 5–110 g N ha^?1 day^?1, 3–23 kg C ha^?1 day^?1, and 5–340 g C ha^?1 day^?1 respectively. Ammonia content of air extracted from above the woodchips was 0.7–3.5 mg NH₄‐N m^?3.