几种禾草内生固氮菌的分离及固氮活性测定

从13种禾草组织中分离内生细菌,研究比较不同禾草品种,不同组织中内生细菌的菌群密度和分布特点;筛选内生固氮菌菌株,经乙炔还原法测定其固氮酶活性.结果表明,不同禾草品种的内生细菌菌群密度有较大差异,菌群密度为8.70×104～8.06×106CFU/g鲜重.根组织中菌群密度高于叶.采用CCM培养基结合无氮选择性培养基筛选获得21株内生固氮菌菌株,其固氮酶活性在8～2865 nmol/h·mL.研究结果证明从禾草中可分离到具有高固氮酶活性的菌株,具有开发应用的潜力.     

狗牙根内生固氮菌生长条件

从已分离的多个狗牙根(Cynodon dactylon)内生固氮菌株中筛选到两株固氮酶活性较高的菌株7D和BM13,为明确固氮菌株对环境因子的适应性,研究了在不同的生长环境条件下菌株的生长量。采用Ashby无氮培养基,测定了温度、pH、渗透压以及不同氮源和碳源等环境条件对固氮菌生长的影响。结果表明,在10~40℃的温度范围内、pH值3.92~9.64的酸碱环境和30g·L~(-1) NaCl的高渗透压下,固氮菌7D和BM13均能正常生长;菌株能耐受0~10mmol·L~(-1)的NH_4~+和NO_3~-,而且能利用蔗糖、甘油、麦芽糖、甘露醇和葡萄糖等多种碳源生长。说明狗牙根内生固氮菌株7D和BM13对环境因子有很强的抗逆性和适应性,但两菌株之间存在一定差异,可望进一步研发成为优良的固氮微生物肥料生产菌种。     

化肥减量配施菌草固氮菌肥对巨菌草生长、营养品质及土壤养分的影响

生物肥料替代部分化肥在植物种植中发挥了重要作用。利用从巨菌草根部筛选的优良内生固氮菌株制作菌草固氮菌肥,并进行田间随机完全区组试验,设不施肥（空白对照,CK₀）,灭菌的菌草固氮菌肥（基质对照,CK₁）,全量化肥（FHF）,菌草固氮菌肥（T₁）,菌草固氮菌肥+75%化肥（T₂）共5个处理,研究其对巨菌草生长、产量、营养品质及土壤理化性质的影响。结果表明：与不施肥相比,只施菌草固氮菌肥和菌草固氮菌肥+75%化肥处理均能显著促进巨菌草生长,提高其产量,改善巨菌草品质和土壤理化性质;与只施化肥相比,只施菌草固氮菌肥处理在不同程度上降低了巨菌草产量、粗纤维、木质素、粗灰分含量和土壤碱解氮、速效磷、速效钾、有机质含量;而菌草固氮菌肥+75%化肥处理下,巨菌草叶片数、分蘖数、粗蛋白、粗纤维、酸性洗涤纤维、木质素、粗灰分含量均显著高于只施化肥处理,巨菌草产量、株高、粗脂肪含量和土壤碱解氮、速效磷、速效钾、有机质含量比只施化肥高但差异不显著,中性洗涤纤维含量则低于只施化肥处理。因此,适当减施化肥配施菌草固氮菌肥（化肥菌草固氮菌肥+75%化肥）在稳定巨菌草产量的同时,也能够在一定程度上促进其生长,改善其营养品质和土壤理化性质。     

阔叶树内生真菌的研究进展

我国阔叶树资源丰富,种类多,研究阔叶树内生真菌及其次生代谢产物具有重要意义。介绍了近年来有关阔叶树内生真菌的种类、分布及次生代谢物质应用的最新研究进展,以期更好地利用阔叶树内生真菌资源。     

棕色固氮菌对一年生黑麦草生产的影响

通过对一年生黑麦草分别施以棕色固氮菌、农家肥和未施肥的对比试验,得出棕色固氮菌在增加草产量方面显著优于其他两个处理(P0.01),说明棕色固氮菌对提高一年生黑麦草产量有明显效果。     

茶树根际固氮菌研究进展

随着绿色生态农业兴起和发展,茶产业进入绿色、生态、环保的产业升级和转换期。生物固氮是指固氮菌将大气中的氮气还原成氨的过程,在绿色生态农业可持续发展、化肥减量减施、环境生态保护等方面具有重要的意义。茶树根际固氮菌是指分布于茶树根际表面土壤环境中的一类具有固氮能力的微生物,有利于茶树的生长发育、品质提升以及茶树抗逆性增强等作用。从茶树根际固氮菌的多样性、影响因素以及对茶树的作用、研究技术等方面综述茶树根际固氮菌的研究进展,同时探讨了固氮菌在农业可持续发展中的应用前景。     

禾草Epichloё属内生真菌分类学研究进展

禾草内生真菌(Epichloё属)是指在宿主禾草的组织间隙内完成其全部或大部分生命周期，但不引起宿主禾草产生外部明显症状的一类真菌。其作为重要的农业微生物资源，一方面能促进宿主植物的生长、提高宿主对不良环境的抵抗能力；另一方面，部分内生真菌与宿主形成的共生体所产生的部分生物碱可引致草食家畜中毒，影响草地畜牧业的健康发展。禾草内生真菌的这一双重特性已经成为国际草业领域近30年来的研究热点。本文首先综述了有性型和无性型Epichloё属禾草内生真菌的命名历史和分类现状，其次对我国目前已发现的禾草内生真菌资源及其分布以及禾草内生真菌在抗逆育种方面的研究进展进行归纳总结，最后针对禾草Epichloё属内生真菌的分类和应用进行了展望，以期为挖掘和利用有益禾草内生真菌资源、培育优良植物新品种、发展现代草地畜牧业和生态环境建设提供科学依据。     

联合固氮菌对植物促生作用的研究进展

综述了联合固氮菌的种类、生物学特性、对植物的促生作用、影响因素以及联合固氮菌在禾本科植物上取得的研究进展。     

2株青贮玉米根际固氮菌的筛选鉴定及促生作用研究

为了获得优良的固氮菌,并评价其对青贮玉米的促生效果,本研究采用稀释涂布平板法,利用阿须贝氏固体培养基从青贮玉米根际土壤中分离筛选到10株固氮菌,对其固氮能力进行分析,结果表明,菌株ZL-2和ZL-13的固氮能力较强,菌株ZL-2的固氮量为1.07μg·mL^-1,ZL-13的固氮量为0.95μg·mL^-1。通过细菌形态学、16S rDNA序列分析和生理生化特征,确定菌株ZL-2为生癌肠杆菌和ZL-13为成团泛菌。对2株固氮菌的促生特性进行分析,结果表明,2个菌株具有泌铵能力、溶磷能力、产嗜铁素能力和合成吲哚-3-乙酸(IAA)的能力。盆栽试验结果表明,接种固氮菌ZL-2和ZL-13能够显著提高青贮玉米的株高、根长、地上和地下干、鲜重(P<0.05)。田间试验结果表明,2株固氮菌单接种和双接种均能提高青贮玉米的株高、茎粗、产量、粗蛋白含量和全磷含量(P<0.05)。接种2株固氮菌的青贮玉米,其氮代谢和氨同化相关基因(ZmAMT-4、ZmAMTB、ZmGOGAT2和ZmGS1-3)的表达量显著提高(P<0.05)。因此,2株固氮菌...     

固氮菌喂猪試驗总結

細菌肥料之一——固氮菌培养液是含中丰富养分的,特別是培养液中含有大量B类維生素及某些微量元素,可以促进猪只生长。1958年5月18日,南方日报就曾介紹南海县試用效果良好的消息。我們也曾用本县菌肥厂制造的固氮菌培养物来作过两次饲猪試驗,其结果証实:固氮菌培养物喂猪促进猪只生长。现将試驗經过及結果介紹于后。一、試驗培养物所用固氮菌培养物为本县細菌肥料厂培养,测定每毫升含菌体2亿以上。其培养液配方如下:     

母猪流产病因和综合防控措施

在现代畜牧业不断发展,猪价再创历史新高的大环境下,生猪养殖占比越来越大,能繁母猪饲养管理越显重要,母猪流产防控越来越受到从业者重视。该文主要针对引发母猪流产的病因及相关的防控措施进行分析和研究。     

复合有益微生物在水貂生产中的应用试验

随着生物技术的发展,人们对有益微生物的应用越来越重视,应用范围也越来越广泛。为了减少肠道疾病的发生,提高水貂抗病能力、生产性能和综合效益,我们试验应用复合有益微生物茵饲喂水貂,获得了良好的技术成效和经济效益。     

土壤Cu^2＋污染对植物生长影响的研究进展

工农业生产的飞速发展,导致土壤中的重金属越来越多。Cu^2＋是植物必需的金属营养元素之一,但过量会对植物产生一系列的毒害作用。因此,有关Cu^2＋胁迫对植物的毒害方面的研究成为人们关注的焦点之一。综述了土壤Cu^2＋污染对植物种子萌发、植株生长和生理效应3个方面的毒害作用。     

Impacting policy through science and education

Scientists, researchers, and their findings are critical factors in helping to resolve contemporary societal problems. Because of the tremendous interconnectivity of our lives and the expanded scope and scale of the medical and health problems we face, the research community needs to be both more involved and more competent in the development of public policy and to become more effective participants in the political and media activities in which their work is firmly embedded. This article suggests that researchers and scientists will be more relevant, have more impact, and be more productive if they can blend outstanding science with new non-cognitive skills that can reinforce the important social context of their work.     

赤羽病病毒检测方法研究进展

赤羽病是目前对养牛业和养羊业危害较为严重的疫病,在我国已广泛存在,一旦暴发将会给我国畜牧业造成严重的经济损失。迅速、准确的诊断是防制和消灭该病的重要前提。几十年来,赤羽病诊断技术经历了早期的病毒分离鉴定到血清学试验,再到分子生物学检测这一发展过程,正逐渐向着更敏感、更特异、更方便、更经济的方向发展。本文就赤羽病病毒的实验室检测技术研究进展作一综述。     

水资源紧缺条件下永昌县农户苜蓿灌溉及种植效益调查

永昌县属水资源紧缺地区,以随机走访的方式,调查了当地井灌区、河灌区55户农户的灌溉和种植效益情况,发现对苜蓿、小麦、大麦在河灌区与井灌区采取不同的灌溉方式:河灌区为多量少次,井灌区为少量多次;河灌区作物灌溉总量显著高于井灌区(P<0.05),井灌区种植作物更加节水;苜蓿的净收益在河灌区较小麦好,而在井灌区却低于小麦,河灌区是苜蓿种植的理想地方,虽然苜蓿在井灌区的灌溉水效益高于河灌区,从节水角度,在井灌区种植苜蓿比较适宜,而农户考虑的主要是经济效益,所以河灌区固然浪费水,但仍有相当大面积的苜蓿种植。应通过政策引导,使节水的同时经济效益也较好,这将有利于苜蓿经济效益与节水效益共同提高。     

论生态环境与畜禽健康——环境污染对畜禽健康的影响

由于工业生产排放的废水、废气和废渣数量日益增多以及农牧业生产大量使用农药、化肥、兽药和饲料添加剂，环境污染物和有毒有害物质对畜禽生产性能和畜产品品质的影响日益严重，本文论述了环境污染物对畜禽毒害的形式和环境污染物的剂量效应与毒性测定方法，对于消除环境中有害物质，生产绿色食品具有重要的意义。     

Canine atopic dermatitis: a retrospective study of 266 cases examined at the University of California, Davis, 1992-1998. Part I. Clinical features and allergy testing results

The medical records of 266 dogs diagnosed as having atopic dermatitis were reviewed. Statistical data were evaluated referable to breed predilections, clinical signs and positive reactions to allergens. Positive reactions were most common to house dust mites (more common with clinical signs in the fall) followed by moulds (more common with clinical signs in the fall and spring). Dogs with positive reactions to moulds, trees or cultivated plants were more likely to have skin and ear yeast infections. Dogs with positive reactions to cultivated plants were more likely to have otitis externa and pedal lesions. Positive reactions to house dust were more common in dogs with early onset of signs and in those tested early in the disease. Dogs had more positive reactions to weeds when allergy tests were performed in the summer and fall. Positive reactions to flea antigen were highly correlated with the clinical diagnosis of flea allergy dermatitis.     

土壤Cu~(2+)污染对植物生长影响的研究进展

工农业生产的飞速发展.导致土壤中的重金属越来越多.Cu2+是植物必需的金属营养元素之一,但过量会对植物产生一系列的毒害作用.因此,有关Cu2+胁迫对植物的毒害方面的研究成为人们关注的焦点之一.综述了土壤Cu2+污染对植物种子萌发、植株生长和生理效应3个方面的毒害作用.     

Risk factors associated with the incidence of veterinary-treated clinical mastitis in Swedish dairy herds with a high milk yield and a low prevalence of subclinical mastitis

We conducted a case-control study to investigate factors associated with the incidence rate of veterinary-treated clinical cases of mastitis (IRVTCM) in Swedish dairy herds with the overall objective to reduce the incidence of clinical mastitis (CM) and excessive use of antibiotics. Herds with documented high milk yield, low prevalence of subclinical mastitis and high (27.3-67.5 cases/100-cow years=case) or low (0.0-10.8 cases/100-cow years=control) IRVTCM were selected for this study. One hundred and fifty-eight herds participated. Logistic-regression models were used to assess statistically significant risk factors associated with a high or low IRVTCM. HI-herd farmers more often contacted a veterinarian for treatment of a cow with CM as soon as the milk appearance was altered, compared to LO-herd farmers that more often waited until the general condition of a cow was altered. HI-herd farmers also treated more cows due to high somatic-cell counts during lactation and/or at drying off. There were more high-yielding cows with dirty lower hind-legs, a higher percentage of first-parity cows and a higher incidence of veterinary-treated teat injuries in HI-herds. HI-herd farmers had their cows claw-trimmed more than once per year, compared to LO-herd farmers that had their cows claw-trimmed only once per year, and the condition of silage storage at HI-farms more often had one or more remarks. LO-herds consisted more often of cows of the Swedish Red and White breed, and their roughage diet was more often complemented with only commercial concentrates compared to HI-herds that more often fed grain in combination with commercial concentrates. The herds participating in this study were all well managed herds, and the attitude towards treatment and production seemed to influence the IRVTCM more than environmental factors.