大豆生长后期田间管理

调控干湿度。大豆鼓粒期对水分反应敏感,当土壤水分低于田间最大持水量的70%时,应及时灌溉;成熟时水分不宜过大,保持田间最大持水量的60%～65%即可。拔除大草。到了大豆生长中后期,以前锄草遗漏的杂草长成大草,与大豆争水争肥,影响光合作用,必须在草籽形成前拔除。     

大豆生长后期田间管理

调控干湿度。大豆鼓粒期对水分反应敏感,当土壤水分低于田间最大持水量的70%时,应及时灌溉;成熟时水分不宜过大,保持田间最大持水量的60%～65%即可。拔除大草。到了大豆生长中后期,以前锄草遗漏的杂草长成大草,与大豆争水争肥,影响光合作用,必须在草籽形成前拔除。     

不同单株负载量与调亏灌溉对赤霞珠葡萄酒品质及颜色的影响

为了探究不同单株负载量与调亏灌溉对葡萄酒品质及色泽的影响,以新疆和硕产区酿酒葡萄赤霞珠（Cabernet Sauvignon）为原料,分别设置不同负载量处理（20穗/株、25穗/株、30穗/株）、不同调亏灌溉时长处理（4.2 h、4.8 h、5.4 h）及对照（CK）组：不疏穗（＞30穗/株）,正常灌溉时间6.0 h。结果表明,与CK组相比,疏穗后处理组葡萄酒的总酸、挥发酸含量降低;调亏灌溉处理组葡萄酒的残糖含量降低。不同负载量处理组葡萄酒总酚、花色苷含量显著高于对照（P＜0.05）;调亏灌溉4.2 h处理葡萄酒总酚、花色苷、类黄酮含量显著高于其他处理（P＜0.05）,不同负载量处理与调亏灌溉处理均能增加葡萄酒的红色色调。主成分分析（PCA）结果能够较好区分不同处理的酒样。综上,单株负载量为25穗/株,灌溉时长为4.2 h处理能够提高葡萄酒品质。     

水分胁迫下肥料配比对葡萄光合速率与氮代谢的影响--测试文章

以无核白鸡心葡萄为试材，设置3个水平的水分处理和3个肥料配比，研究水分胁迫下肥料配比对无核白鸡心葡萄叶片叶面积、叶绿素含量、光合速率及氮代谢相关酶活性的影响。结果表明：萌芽期和坐果期土壤水分含量为田间持水量的55%～60%、施肥配比为N∶P∶K=2∶5∶3的水肥处理能有效促进叶面积增加，提高光合速率，是较好的水肥处理组合；转色期和采收后需维持正常含水量和适当增施钾肥可提高光合速率；土壤水分含量为田间持水量的55%～60%、施肥配比为N∶P∶K=2∶5∶3的水肥处理无核白鸡心葡萄硝酸还原酶活性较高，能有效促进氮肥的吸收利用；水分胁迫处理使谷氨酰胺合成酶活性先升高后降低，且使谷丙转氨酶活性升高。在生长期中轻度水分胁迫、适当增施钾肥能明显提高硝酸还原酶、谷氨酰胺合成酶与谷丙转氨酶活性，提高氮肥的转化利用。     

水钾耦合对大豆光合特性及其产物积累运转的影响

盆栽条件下,研究了不同生育时期水钾耦合对大豆光合特性及水分利用效率的影响,并对光合速率与各器官干物重进行相关分析。结果表明：苗期与花期控水时,土壤水分及水钾互作极显著影响净光合速率（Pn）;结荚期控水时,水分极显著影响Pn。花期与荚期控水后测定的Pn要高于苗期的Pn。水钾耦合对光合速率（Pn）、蒸腾速率（Tr）和气孔导度（Gs）的影响趋势相似,即水分效应要优于钾肥,且一般而言同一钾肥水平下,土壤水分的影响表现为：充足W4〉适宜W3、特涝W5〉略旱W2〉特旱W1。只有当土壤水分供应适宜（W3）时,钾肥的施用提高了植株的Pn、Tr和Gs。水分对植株水分利用效率（WUE）的影响要优于钾肥,且水分为正效应。苗期及开花期控水条件下,植株的Pn与根、茎、叶干物重呈极显著正相关（p〈0.01）,且Pn与各器官的相关程度表现为茎〉叶〉根;结荚期植株Pn与根、茎、叶干物重仍呈极显著正相关（p〈0.01）,与荚粒干物重呈显著正相关（p〈0.05）。     

张力仪和低张力灌溉方案(Ⅰ)

作物对低张力灌溉方案的反应低张力灌溉方案的目的是在整个季节使土壤水分保持在正常的田间持水量 ,以免发生植物水分胁迫。当根区土壤维持高土壤水分含量和低的土壤水分吸着力时 ,很多作物在产量上表现出可观的增加。正确的土壤水分管理应保证通气不被阻止和植物养分不被淋溶。这些理想的条件可以通过新的滴灌系统或中心枢纽灌溉系统获得。这些系统能够根据需要不时地向土壤输送少量水分 ,并且不明显增加成本。过去 ,利用手工移动的喷灌系统的灌溉方案是根据耗掉 50 %的植物有效水进行灌溉。这个数字是以在许多作物上进行的喷灌研究为依…     

接触脱水膜干燥对南美白对虾干复水特性的影响

接触脱水膜（contact dehydrating sheet,CDS）是一种适用于鱼肉等富含蛋白质食品干燥的新型冷脱水技术。为研究低温脱水对南美白对虾干复水特性的改善作用及其内在原因,本实验研究了CDS脱水至不同水分质量分数虾干的蛋白质结构变化及复水过程中复原率、持水力和水分状态的分布情况,并和热风干燥（hot air drying,HAD）的虾干进行比较。结果表明：采用CDS脱水法制备的不同水分质量分数（60%、45%、30%,以湿基计）虾干复原率、持水力均高于相对应的HAD脱水虾干组,其中水分质量分数为30%时,CDS脱水虾干的复原率、持水力分别为85.22%、69.17%,明显高于HAD脱水虾干（62.55%、65.73%）。低场核磁共振分析表明CDS脱水处理的水分质量分数为30%的虾干复水后虾仁的结合水、不易流动水、自由水比例均比HAD处理组更接近鲜虾。表面疏水性和蛋白质结构分析表明CDS脱水虾干蛋白的表面疏水性变化程度比HAD脱水低,蛋白质二级结构变化比HAD脱水虾干小。因此,CDS脱水法能维持蛋白质结构的完整性,复水后的虾干有更好的复原率、持水力,使产品品质更接近鲜虾,可以作为对虾及其他高值水产品的脱水干燥新途径。     

海藻酸钠分子质量对低脂乳化肠凝胶特性的影响

以低脂（10%）乳化肠为研究对象,在0%～0.75%添加水平下,研究3 种分子质量（2660、3890、4640 kDa）海藻酸钠（sodium alginate,SA）对其凝胶特性（持水与质构）的影响及机理。结果表明：3 种分子质量的SA均显著改善了低脂乳化肠的持水性（P＜0.05）,且SA分子质量越大,凝胶持水性越强;但对低脂乳化肠质构的改善作用不显著（P＞0.05）;随着SA分子质量的增大,静电排斥和空间位阻作用增强,降低了肉蛋白的表面疏水性,形成了具有更大孔隙的微结构,可截留更多的水分,进而显著改善了凝胶的持水性。     

大豆品种抗旱性早期鉴定方法

为探讨鉴定大豆品种抗旱性的简易方法,依据吸水后48h的发芽率对109个大豆种质材料进行抗旱性分级。继而在萌发期、营养生长期（V3）和生殖生长期（R4）进行盆栽控水试验,根据抗旱等级验证大豆植株的抗旱性。结果发现,大豆品种间抗旱性存在显著差异。种子吸水量与抗旱性无关,吸水后48h发芽率与抗旱性密切相关。幼苗侧根数量、主根长度和根系干重与抗旱性呈显著（P〈0.05）相关。对萌发后幼苗供水24h后,随即停水24h,反复干旱处理,抗旱品种存活率显著高于普通品种。在V3期对盆栽植株进行暂时萎蔫（土壤含水量为9%～11%）的水分胁迫处理,发现停水后普通品种叶片首先发生萎蔫,且株高、茎直径及叶面积下降的程度均高于抗旱品种。水分胁迫下,抗旱品种株高、茎直径和叶片面积均显著（P〈0.05）高于普通品种,其中茎直径和叶片面积达到极显著水平（P〈0.01）。在R4期暂时萎蔫的水分胁迫下,抗旱品种根的生物量和分枝的生物量显著（P〈0.05）高于普通品种。鼓粒期（R6）普通品种发生永久萎蔫、植株死亡,而抗旱品种仍能保持生长能力。研究结果表明,大豆种子48h发芽率可作为大豆品种抗旱性的鉴定和筛选方法,鼓粒期大豆对水分胁迫最敏感。     

部分根域干燥栽培条件下藤稔葡萄灌水下限的研究

以3年生藤稔葡萄为材料,探讨了灌水下限对部分根域干燥栽培葡萄生长发育的影响.结果表明,部分根域干燥条件下,转色期之后设施葡萄灌水下限应该控制在-30kPa左右,即土壤饱和持水量的70%左右,此时叶面积生长量没有显著减少,果实产量、品质与双侧灌溉处理没有显著差异,但灌溉水利用效率显著提高.     

Arsenic content of some edible mushroom species

The arsenic contents of 162 fruit body samples of 37 common edible mushroom taxa were analyzed. The samples were gathered from different habitats of Hungary (mainly from mountains) between 1984 and 1999. The arsenic content of the samples was measured by the inductively coupled plasma spectrometry method. Very low [lower than 0.05 mg/kg dry matter (DM)] concentrations were found in the samples of 13 taxa, while higher (or very high) contents were quantified in other common taxa (the highest arsenic content was recorded in the fruit body of Laccaria amethysthea at 146.9 mg/kg DM). The species of eight genera (Agaricus, Calvatia, Collybia, Laccaria, Langermannia, Lepista, Lycoperdon, Macrolepiota) belong to the so-called accumulating taxa, and this tendency is evident on all habitats. This arsenic accumulation capability is found in two orders of Basidiomycetes (Agaricales and Gasteromycetales), which is to say this phenomenon occurs in the families Agaricaceae, Tricholomataceae and Gasteromycetaceae. The accumulating taxa found all have a saprotrophic type of nutrition; arsenic accumulation is not detectable in xilophagous or in mycorrhizal species. The consumption of the accumulating species found has only a low toxicological risk for three reasons: the consumed fresh fruit bodies contain about a tenfold lower arsenic level than the dried ones, the majority of arsenic occurs not in poisonous inorganic, but in less dangerous (or not poisonous) organic forms, and the frequency of consumption is low.     

Susceptibility of stored product insects to high concentrations of ozone at different exposure intervals

Ozone is a highly reactive gas with insecticidal activity. Past studies have indicated that ozone technology has potential as a management tool to control insect pests in bulk grain storage facilities. The objective of this study was to determine the efficacy of short periods of exposure to high ozone concentrations to kill all life stages of red flour beetle (Tribolium castaneum (Herbst)) (Coleoptera: Tenebrionidae), and Indianmeal moth (Plodia interpunctella (Hübner)) (Lepidoptera: Pyralidae), adult maize weevil (Sitophilus zeamais (Motsch.)) (Coleoptera: Curculionidae) and adult rice weevil (S. oryzae (L)) (Coleoptera: Curculionidae). Insects were treated with six ozone concentrations between 50 and 1800 ppm. The specific objective was to determine minimal time needed to attain 100% mortality. The most ozone-tolerant stages of T. castaneum were pupae and eggs, which required a treatment of 180 min at 1800 ppm ozone to reach 100% mortality. Eggs of P. interpunctella also required 180 min at 1800 ppm ozone to reach 100% mortality. Ozone treatments of 1800 ppm for 120 min and 1800 ppm for 60 min were required to kill all adult S. zeamais and adult S. oryzae, respectively. The results indicate that high ozone concentrations reduce the treatment times significantly over previously described results. Our results also provide new baseline information about insect tolerance to ozone treatment.     

Organization and localization of the dnaA and dnaK gene regions on the multichromosomal genome of Burkholderia multivorans ATCC 17616

The Burkholderia multivorans strain ATCC 17616 carries three circular chromosomes with sizes of 3.4, 2.5, and 0.9 Mb. To reveal the distribution and organization of the genes for fundamental cell functions on the genome of this bacterium, the dnaA and dnaK gene regions of ATCC 17616 were cloned and characterized. The gene organization of the dnaA region was rnpA-rmpH-dnaA-dnaN-gyrB with a single consensus DnaA-binding box (TTATCCACA) between the rmpH and dnaA genes. This intergenic region, however, did not work as an autonomously replicating sequence in ATCC 17616. On the other hand, the gene organization of the dnaK region was grpE-orf1 (gene for thioredoxin homologue)-dnaK-dnaJ-pabB (gene for p-aminobenzoate synthetase component homologue). A putative heat-shock promoter that showed good homology to the sigma32-dependent promoter consensus sequence in Escherichia coli was found upstream of the grpE gene, suggesting that these five genes constitute an operon. In M9 succinate minimal medium the dnaJ mutant grew more slowly than the wild-type strain, indicating that this operon is functional. Pulsed-field gel electrophoresis and Southern blot analyses indicated that both the dnaA and dnaK gene regions exist as single copies on the 3.4 Mb chromosome.     

Contamination with storage fungi of human food from Cameroon

In a mycological study, a total of 95 human food samples were investigated to evaluate the incidence of fungal contamination in Cameroon by conventional identification method and partly confirmed by DNA sequencing. The isolated fungal spp. were further studied to determine their toxigenic potentials. The investigation revealed the predominance of Aspergillus and Penicillium with 96% of samples contaminated with at least one species of these fungi, whereas the incidence of co-contamination of samples was 85%. Aspergillus flavus and Aspergillus parasiticus (Flavi section) were the most predominant species contaminating mainly maize and peanuts. In addition, P. crustosum and P. polonicum were the most common contaminants belonging to the genus Penicillium. On the other hand, A. ochraceus (Circumdati section) registered a low incidence rate of 5%, including other members of the Aspergillus group. Other members of the genera Rhizopus and Alternaria spp. were also registered in the study. A majority of fungal strains of A. ochraceus, A. parasiticus, P. crustosum and P. polonicum isolated were toxigenic, producing the mycotoxins tested for, while none was detected in cultures of A. fumigatus. The high incidence rate of fungi contamination coupled with their potentials in producing mycotoxins gives a strong indication that the samples tested may likely be contaminated with various mycotoxins. There is need for further study to assess the incidence of mycotoxins contamination in similar food samples.     

Assessment of the microbiological safety of salad vegetables and sauces from kebab take-away restaurants in the United Kingdom

The purpose of this study was to establish the microbiological safety of salad vegetables and sauces served in kebab take-away restaurants. Comparison with published microbiological guidelines revealed that 4.7% of 1213 salad vegetable samples were of unsatisfactory microbiological quality due to Escherichia coli and/or Staphylococcus aureus levels at ≥10² cfu g⁻¹. Another 0.3% of salad samples were of unacceptable quality due to S. aureus at ≥10⁴ cfu g⁻¹ (2 samples) or the presence of Salmonella Kentucky (1 sample). Cucumber was the most contaminated salad vegetable with regards to unsatisfactory levels of E. coli (6.0%) or S. aureus (4.5%). Five percent of 1208 sauce samples were of unsatisfactory microbiological quality due to E. coli, S. aureus at ≥10² cfu g⁻¹ and/or Bacillus cereus and other Bacillus spp. at ≥10⁴ cfu g⁻¹. A further 0.6% of sauce samples were of unacceptable quality due to Bacillus spp. (Bacillus subtilis, Bacillus pumilus, Bacillus licheniformis) at ≥10⁵ cfu g⁻¹ or the presence of Salmonella Agbeni (1 sample). More samples of chilli sauce (8.7%) were of unsatisfactory or unacceptable microbiological quality than any other sauce types. The results emphasize the need for good hygiene practices in kebab take-away restaurants handling these types of ready-to-eat products.     

鸡源大肠埃希氏菌mcr-1基因携带及分析

目的 了解在农业农村部禁止使用多黏菌素作为动物促生长使用后四川部分地区鸡源大肠埃希氏菌（E.coli）mcr-1基因的携带情况,为制定进一步防控措施提供依据。方法 采集四川部分地区市场售卖点肉鸡直肠拭子,用含有多黏菌素（终浓度4 μg/mL）的EC肉汤增菌接种含多黏菌素（终浓度4 μg/mL）的麦康凯平板,挑取可疑菌落,采用PCR方法鉴定菌株并检测mcr-1基因;微量肉汤稀释法测定mcr-1基因阳性菌株对临床常见抗菌药物耐药情况。脉冲场凝胶电泳（PFGE）对mcr-1基因阳性菌株进行同源分析。耐药基因质粒结合实验验证mcr-1基因传播途径。结果 从70份肉鸡样本中的13份检出mcr-1基因阳性大肠埃希氏菌,检出率18.57%（13/70）,对实验的13种抗生素,除13株mcr-1阳性菌株对头孢西丁有12株敏感以外,对其他抗生素都表现出不同程度的耐药,其中四环素和甲氧苄啶/磺胺甲恶唑耐药率最高,达到了100%（13/13）;其次是氨苄西林和氯霉素,耐药率为84.62%（11/13）。PFGE显示13株mcr-1阳性大肠埃希氏菌分属13个不同的型别;质粒结合实验显示mcr-1基因能够通过质粒传播。结论 mcr-1基因在鸡大肠内大肠杆菌中检测率比较高,且鸡大肠中mcr-1阳性大肠埃希氏菌的耐药情况比较严重。     

Formation of cereulide and enterotoxins by Bacillus cereus in fermented African locust beans

Afitin, iru and sonru are three spontaneously fermented African locust bean Benin condiments. The fermentation processes are exothermic, with temperatures mostly being above 40 °C. A total of 19 predominant Bacillus cereus isolates from afitin, iru and sonru, were investigated. The enterotoxin genes nhe (A, B, C) were present in all 19 isolates, the hbl (A, C, D) in one (afitin), and the cytK gene in three isolates (afitin). Levels of cytotoxicity to Vero cells and NheA production in BHI-broth was within the range of known diarrheal outbreak strains. Autoclaved cooked African locust beans inoculated with emetic (cereulide producing) B. cereus Ba18H2/RIF supported growth at 25, 30 and 40 °C with highly different maximum cereulide productions of 6 ± 5, 97 ± 3 and 0.04 ± 0.02 μg/g beans, respectively (48 h). For non-autoclaved cooked beans inoculated with 2, 4 and 6 log₁₀B. cereus Ba18H2/RIF spores/g beans, cereulide production was 5 ± 4, 64 ± 8 and 69 ± 34 μg/g beans, respectively at 24 h, while it was 70 ± 43, 92 ± 53 and 99 ± 31 μg/g at 48 h of fermentation at 30 °C. Even though high toxin levels were observed, to date there are no known reports on diarrhea or vomiting due to the consumption or afitin, iru and sonru in Benin, which also according to the present study is likely to be expected from the low levels of cereulide produced at 40 °C.     

Comparison of the most odour-active volatiles in different hop varieties by application of a comparative aroma extract dilution analysis

Application of a comparative aroma extract dilution analysis on the volatiles isolated from five different hops (Hallertau Perle, Hallertau Hersbrucker Spät, Slowenian Golding, Hallertau Smaragd, US Cascade) revealed linalool and myrcene with the highest Flavour Dilution (FD)-factors in all varieties, followed by 2-isopropyl-3-methoxypyrazine, 3-methylbutanoic acid and geraniol. Some odourants, however, showed high FD-factors only in certain varieties, for example, (5Z)-octa-1,5-dien-3-one and germacrene B in Hersbrucker Spät, (3E,5Z)-undeca-1,3,5-triene in Hersbrucker Spät and Cascade and nonanal in Cascade. The overall odour profile of the Cascade sample clearly differed from the other varietes, and was dominated by a black currant like odour note. The identification experiments revealed 4-methyl-4-sulfanylpentan-2-one, so far unknown as hop constituent, as key contributor to this odour. In addition, an odour-active undecatetraene was present, in particular, in Perle and Cascade. Synthesis and structural assignment of the four stereoisomers of (3E)-undeca-1,3,5,9-tetraene allowed the identification of the fresh, pineapple-like smelling compound as (3E,5Z,9E)-undeca-1,3,5,9-tetraene. Among the four isomers synthesised, this compound showed by far the lowest odour threshold of 0.01 ng/L in air.     

Diversity of lactic acid bacteria in suan-tsai and fu-tsai, traditional fermented mustard products of Taiwan

Fu-tsai and suan-tsai are spontaneously fermented mustard products traditionally prepared by the Hakka tribe of Taiwan. We chose 5 different processing stages of these products for analysis of the microbial community of lactic acid bacteria (LAB) by 16S rRNA gene sequencing. From 500 LAB isolates we identified 119 representative strains belonging to 5 genera and 18 species, including Enterococcus (1 species), Lactobacillus (11 species), Leuconostoc (3 species), Pediococcus (1 species), and Weissella (2 species). The LAB composition of mustard fermented for 3 days, known as the Mu sample, was the most diverse, with 11 different LAB species being isolated. We used sequence analysis of the 16S rRNA gene to identify the LAB strains and analysis of the dnaA, pheS, and rpoA genes to identify 13 LAB strains for which identification by 16S rRNA gene sequences was not possible. These 13 strains were found to belong to 5 validated known species: Lactobacillus farciminis, Leuconostoc mesenteroides, Leuconostoc pseudomesenteroides, Weissella cibaria, and Weissella paramesenteroides, and 5 possibly novel Lactobacillus species. These results revealed that there is a high level of diversity in LAB at the different stages of fermentation in the production of suan-tsai and fu-tsai.