木荷和杉木人工林天然降水、穿透雨和树干茎流DOC和DON 浓度及动态(英文)

尽管溶解有机碳(DOC)和溶解有机氮(DON)在森林养分循环中的作用日渐为人们所关注,但对它们的浓度及动态,特别是对亚热带森林DOC 和DON 的研究甚少。本文于2002 年通过野外天然降水及亚热带木荷和杉木人工林(monoculture plantations of Schima superba and Cunninghamia lanceolata,15 年生)穿透雨和树干茎流各水样的收集及室内各水样中DOC、NO3 -N、NH4 -N 和总溶解有机氮(TDN)浓度的测- +定,其中DON 浓度通过TDN 与NO3 -N、NH4 -N 的浓度差值来计算,- +结果表明,天然降水DOC 和DON 浓度分别为1.7 和0.13 mg·L-1。木荷人工林穿透雨DOC 和DON 浓度分别为11.2 和0.24 mg·L-1,高于杉木人工林的DOC 和DON 浓度(10.3 和0.19 mg·L-1)。杉木人工林树干茎流DOC 和DON 浓度(分别为19.1 和0.66 mg·L-1)明显高于木荷人工林(分别为17.6 和0.48 mg·L-1)。天然降水DOC 浓度的月变化不明显,而DON 浓度在夏季和秋季较高。两林分穿透雨DON 浓度的月动态与树干茎流的十分相似,均在雨季开始时(3 月)浓度增大。两林分穿透雨DOC 浓度在2-4 月间较高,而树干茎流DOC 浓度在9-11 月间较高。图4表2 参24。     

猪肉和鸡肉中脱氧雪腐镰刀菌烯醇和T-2毒素酶联免疫吸附检测方法的建立

为保障动物源性食品安全,本研究建立了分别检测猪肉和鸡肉中脱氧雪腐镰刀菌烯醇(deoxynivalenol,DON)和T-2毒素残留的间接竞争酶联免疫吸附法.结果显示,该方法在猪肉和鸡肉样本中DON的检测限分别为34.9和43.5 μg/kg,添加回收率为72.7%~97.1%,变异系数小于8.7%;T-2毒素的检测限分别为33.7和28.7 μg/kg,添加回收率为72.1%~95.0%,变异系数小于11.3%.该方法灵敏度高、准确、简便,适用于猪肉和鸡肉中DON和T-2毒素残留的快速检测.     

Within-field variability of Fusarium head blight pathogens and their associated mycotoxins

Within-field variability in the Fusarium head blight (FHB) and its associated mycotoxins was studied in four European countries. At each of 14 sites, each FHB pathogen and associated mycotoxins were quantified in 16 quadrat samples at harvest. Overall, the incidence of quadrat samples with detectable and quantifiable pathogen DNA was significantly lower in the grain than in the corresponding chaff. Deoxynivalenol (DON) was the most frequently detected toxin in the samples and its accumulation was most strongly associated with the presence of Fusarium graminearum. Nivalenol (NIV) accumulation was significantly associated only with the presence of F. culmorum. Zearalenone (ZON) accumulation was strongly associated with the presence of all three pathogens (F. graminearum, F. culmorum and F. poae). The levels of both DON and ZON concentrations were positively related to the amount of F. graminearum DNA in the grain or in the chaff. The presence/absence of FHB pathogens within a single quadrat appeared to be independent of each other. The presence of a particular FHB pathogen and the amount of its DNA, as well as the associated mycotoxin(s), varied greatly among samples at each site. This study demonstrated the large extent of within-field variability of FHB and its associated mycotoxins, and the importance of representative sampling in FHB studies.     

有机物料输入对干润砂质新成土可溶性有机碳、氮的影响

对采集于干润砂质新成土不同土层土壤分别添加高C/N(黑麦草)和低C/N(苜蓿)有机物料后进行了室内培养试验。结果表明,各土层土壤添加有机物料后,均存在不同程度的矿质氮微生物净固定现象,且氮固定时间及程度与有机物料的C/N和土壤层次密切相关,添加高C/N黑麦草的深层低肥力土壤氮固定现象最明显。添加有机物料后,培养期间可溶性有机碳(DOC)累积量前期较高,中期先减后增,后期趋于稳定,不同土层土壤DOC的变化有所不同。0～20、20～40cm可溶性有机氮(DON)累积同时受矿质氮固定影响,低C/N苜蓿残体加入土壤后,在短暂氮素固定后,后期DON累积量明显提高;而加入高C/N黑麦草残体后,在较长时间内DON累积量无明显增加。添加有机物料导致培养前期土壤DOC/DON上升,随后降低。以上研究结果表明,如果从增加干润砂质新成土土壤有机质角度考虑,应该种植高C/N比的植物。因此,研究有利于进一步深入理解土壤溶液速效C、N养分的来源及其转化,对该地区土壤质量的调控具有一定参考价值。     

镰刀菌毒素DON和NIV研究进展

对脱氧雪腐镰刀菌烯醇（DON）和雪腐镰刀菌烯醇（NIV）的理化性质、污染状况、毒性作用和检测方法进行了综述,以期为同类研究提供参考。     

Evaluation of type I fusarium head blight resistance of wheat using non-deoxynivalenol-producing fungi

A series of experiments was conducted to determine whether type I resistance (resistance to initial infection) to fusarium head blight (FHB) in wheat could be assessed using fungal species/isolates that do not produce deoxynivalenol (DON), a mycotoxin critical to the spread of Fusarium graminearum in the wheat spike. It was shown that, while the non-toxin-producing species Microdochium nivale and M. majus could infect following spray inoculation of wheat spikes, they were unable to spread within the spike following point inoculation. However, although these species might reveal type I resistance, they are not highly pathogenic towards wheat. A nivalenol (NIV)-producing isolate of F. graminearum caused high levels of disease following spray inoculation, but spread only very slowly within the spike and rarely induced bleaching above the point of inoculation. It is proposed that spray inoculation with an appropriate, aggressive, non-DON-producing FHB pathogen may be used to characterize type I resistance to complement point inoculation with a DON-producing isolate to assess type II resistance (resistance to spread within the spike).     

免疫组织化学法定位猪脾脏中脱氧雪腐镰刀菌烯醇的研究

利用免疫组织化学法研究了脱氧雪腐镰刀菌烯醇(deoxynivalenol,DON)在猪脾脏分布定位,为DON体内残留及DON对免疫系统影响进一步研究提供依据。选用10头健康阉公猪,随机分为二组,一组经乳静脉注射DON标准品,注射剂量为75μg/kg体重,另一组经乳静脉注射相当体积生理盐水。注射完成后开始计时,并观察记录猪的反应情况,待30min后放血宰杀,并迅速取脾脏,4%多聚甲醛固定,经脱水、包埋及切片后,采用免疫组化法定位脾脏中DON的分布情况。免疫组化法定位结果显示,在75μg/kg体重给药组中,脾组织中的血管壁周围见有DON阳性反应颗粒,而对照组未见阳性反应颗粒。     

Jasmonic acid and abscisic acid play important roles in host–pathogen interaction between Fusarium graminearum and wheat during the early stages of fusarium head blight

The effect of phytohormones on the defense response of wheat against Fusarium graminearum infection was investigated. Infection of heads with F. graminearum induced accumulation of salicylic acid (SA), jasmonic acid (JA), abscisic acid (ABA), and indole acetic acid (IAA). Exogenous phytohormone treatments showed crosstalk between them and a complex effect on expression of the genes ATB2, ExpB6, LEA Td16, PR1, Pdf1.2, PR4. JA treatment reduced F. graminearum growth and fusarium head blight (FHB) symptoms while an increase in FHB was observed with ABA. Transient down-regulation of allene oxide synthase (AOS) supports a complex role for JA in wheat head.     

新型复合吸附剂HG对黄曲霉毒素B1和呕吐毒素的吸附脱毒研究

[目的]评价一种新型吸附剂HG对黄曲霉毒素B1(aflatoxin B1,AFB1)和呕吐毒素(deoxynivalenol,DON)的吸附效果.[方法]以水合硅酸铝钠钙(HSCAS)为基础,配合葡甘露聚糖(GM),以合理配比制备成一种新型复合吸附剂HG,通过体外等温吸附试验、不同pH值下的吸附试验以及蛋雏鸡体内试验等,综合评价其吸附效果.[结果]HG对AFB1的吸附符合Langmuir方程,平均吸附率为90.24％;HG对DON的等温吸附则无规律,平均吸附率为28.08％.HG能够改善由霉变饲料引起的肝脏、肾脏、脾脏的肿胀,以及胸腺和法氏囊的萎缩,可将总蛋白、白蛋白含量和血清酶活性恢复至正常水平,而且可改善霉变饲料引起的氧化应激作用.同时,单纯添加HG对蛋鸡的各项指标并无显著影响.[结论]体外试验中HG对两种毒素的吸附表现良好;体内试验结果同样证明了HG对动物机体几乎无损害,各检测指标充分表明HG具备与体外试验同样效果的吸附性,这对实现畜产品的绿色生产具有重要的实际价值.     

秸秆还田配施氮肥对稻田土壤活性碳氮动态变化的影响

【目的】土壤微生物量碳氮和水溶性有机碳氮是土壤中最活跃的碳氮组分,是衡量土壤碳氮周转与养分有效性的重要指标。探讨秸秆配施氮肥、氮肥用量及基追比例对稻田土壤微生物量碳氮、水溶性有机碳氮、易氧化有机碳和速效氮的影响,明确秸秆还田条件下水稻生长季不同氮肥用量与基追比的土壤活性碳氮变化特征,为稻麦轮作区秸秆还田的氮肥管理提供理论依据。【方法】2012—2015年在湖北省荆门市田间试验中设置施氮量、秸秆配施氮肥和施氮时期3个大田试验。施氮量：不施氮（N0）,推荐施氮（165 kg·hm ^-2,N165）,习惯施氮（195 kg·hm ^-2,N195）;秸秆配施氮肥：秸秆移除（CK）,秸秆还田（移栽前将上季小麦秸秆全部还田,S）,秸秆还田+习惯施氮量（SN）,秸秆还田+推荐施氮量（SF）,秸秆还田+推荐施氮量+腐解菌剂（SM）;施氮时期：基施﹕拔节期﹕抽穗期氮肥施用比例为7﹕3﹕0（R1）,5﹕3﹕2（R2）,10﹕0﹕0（R3）。【结果】秸秆还田+习惯施氮量（SN）显著提高了水稻拔节期土壤微生物量碳（SMBC）含量,但是其成熟期水溶性有机碳含量（DOC）显著降低。秸秆还田+推荐施氮量（SF）显著提高了水稻拔节期土壤水溶性有机氮含量（DON）。腐解菌剂的施用显著降低了水稻成熟期DON含量,拔节期易氧化有机碳含量（ROC）也显著降低。秸秆还田下增加氮肥用量显著提高了水稻抽穗期和灌浆期土壤速效氮含量（AN）;推荐施氮处理（165 kg N·hm ^-2）的DON和AN含量显著升高;农民习惯施氮处理（195 kg N·hm ^-2）降低了DON和AN含量;增加追施氮肥比例对土壤SMBC和DOC含量无明显影响,但提高了水稻拔节期SMBN和ROC含量。【结论】施氮量及其基追比是影响秸秆还田下稻田土壤活性碳氮含量的主要因素,合理配施氮肥能提高土壤微生物量碳、速效氮及水溶性有机氮等活性碳氮组分含量,增加追肥比例也能提高水稻生育期内土壤活性碳氮含量。