Microbial community composition and enzyme activities in a sandy loam soil after fumigation with methyl bromide or alternative biocides     

Susanne Klose  Veronica Acosta-Martínez 《Soil biology & biochemistry》2006,38(6):1243-1254

A sandy loam soil was fumigated in microcosms for 24 h with methyl bromide and chloropicrin (MeBr+CP), propargyl bromide (PrBr), combinations of 1,3-dichloropropene and CP (InLine), iodomethane and CP (Midas), an emulsifiable concentrate of CP (CP-EC), or methyl isothiocyanate (MITC). The effects of these pesticides on fatty acid methyl ester (FAME) profiles and selected enzymatic activities were evaluated in fumigated soils and a nonfumigated control at 1, 3, 7, 14, 21, 28, and 90 days post-fumigation. Bacterial (a15:0, i15:0, i16:0, cy17:0, a17:0 and i17:0) and fungal (18:2ω6, 18:3ω6, 18:1ω9) FAMEs were initially (1 day post-fumigation) reduced by fumigation with CP-EC, InLine, and Midas. Microbial communities of soils fumigated with MeBr+CP, MITC, and PrBr resembled those of the control soil. At 14-28 days post-fumigation, FAME profiles were changed in all fumigated soils relative to the control, with the exception of soils treated with MITC. At 90 days post-fumigation, FAME profiles suggested that actinomycetes (10 Me 16:0, 10 Me 17:0, 10 Me 18:0) and Gram-positive bacteria may recover preferentially after fumigation with most of the pesticides studied. Among the fumigants tested, InLine, Midas, and CP-EC had a higher potential to alter the microbial community structure in the longer term than MeBr+CP, PrBr and MITC, with MITC having the least effect. Soil enzyme activities in fumigated microcosms were significantly (P≤0.037) different from the nonfumigated soil, with the exception of β-glucosidase in soils treated with PrBr and MITC, and dehydrogenase in MeBr+CP-fumigated soils. Over the 90-day study, soil fumigation (average of all fumigants and sampling dates) reduced the activities of arylsulfatase (62%), dehydrogenase (35%), acid phosphatase (22%), and β-glucosidase (6%), suggesting that S mineralization in soils and the total oxidative potential of microorganisms were more affected by fumigation than P and C mineralization. This study also indicates that soil fumigation with MeBr+CP alternative biocides has the potential to alter microbial communities and important key reactions involved in nutrient transformation.  相似文献   

山枇杷基因组DNA的提取及自然群体内ISSR遗传多样性分析     

赖瑞联  徐洋  赖恭梯  钟春水  林玉玲  赖钟雄 《福建林学院学报》2015,(1):53-59

为探究山枇杷基因组DNA提取方法及群体内个体之间的遗传多样性,以采自福建省戴云山脉九仙山山枇杷(Garcinia multiflora)自然群体的41份叶片样品为材料,比较2种改良十六烷基三甲基溴化铵法(CTAB)对其基因组DNA的提取效果,并通过简单序列重复区间—聚合酶链式反应(ISSR-PCR)扩增反应体系分析其群体内遗传多样性。结果表明,CTAB-2法通过适当提高CTAB浓度,添加聚乙烯吡咯烷酮(PVP)和酚—氯仿—异戊醇,获得的基因组DNA纯度和质量较好;筛选的11条ISSR引物共扩增85个条带,其中多态性条带61条,占71.76%;NTSYS 2.10e软件设定阈值(GS)为0.78,该山枇杷样品归为4个类群,样品遗传相似系数介于0.588-0.929,平均为0.779,说明该群体的遗传基础较宽;利用STRUCTURE 2.2软件将样品分为4个类群,结合后验概率(Q值)分布表表明部分个体之间存在较丰富的遗传信息交流。  相似文献   

分根法研究连作条件下大豆根系的生长   总被引：1，自引：0，他引：1  

阮维斌  李晓鸣  王玉峰  王敬国  张福锁 《大豆科学》2001,20(3):183-186

盆栽条例上利用分室法研究大豆根系等分后处于不同介质条件下根系的生长发育情况。结果表明，在重茬灭菌土中根系发育良好，重茬土中根系的发育因另一室中的介质不同而表现不同。  相似文献   

Enzyme activities in agricultural soils fumigated with methyl bromide alternatives     

Susanne Klose  Husein A. Ajwa 《Soil biology & biochemistry》2004,36(10):1625-1635

Pre-plant fumigation of agricultural soils with a combination of methyl bromide (MeBr) and chloropicrin (CP) to control nematodes, soil-borne pathogens and weeds has been a common practice in strawberry (Fragaria X ananassa Duchesne) production since the 1960s. MeBr will be phased out by 2005, but little is known about the impacts of alternative fumigants on soil microbial processes. We investigated the response of microbial biomass and enzyme activities in soils fumigated over two years with MeBr+CP and the alternatives propargyl bromide (PrBr), InLine, Midas and CP. Results were compared to control soils, which were not fumigated for the last 4-5 years for Watsonville and Oxnard, respectively, but had a 10 year history of MeBr+CP fumigation (history soils). Soil samples (0-15 cm) were taken from two sites in the coastal areas of California, USA, in Watsonville and Oxnard, at peak strawberry production after two years of repeated application. In addition to the soil enzymes, the activities of purified reference enzymes of β-glucosidase, acid phosphatase and arylsulfatase were assayed before and after fumigation with MeBr+CP and alternative biocides. At the Oxnard site, microbial respiration significantly decreased in soils fumigated with MeBr+CP (P=0.036), while microbial biomass C and N showed no response to fumigation at both sites. These results may indicate that fumigation promotes the growth of resistant species or that soil microorganisms had recovered at the time of sampling. Repeated soil fumigation with MeBr+CP significantly decreased the activities of β-glucosidase and acid phosphatase at the Watsonville site, and dehydrogenase activity at the Oxnard site. Although, enzyme activities in soils fumigated with PrBr, InLine, Midas and CP were lower compared to the control soil, effects were, in general, not significant. Fumigation with MeBr+CP and alternatives reduced the activities of purified reference enzymes by 13, 76 and 28% for acid phosphatase, β-glucosidase and arylsulfatase, respectively. Mean enzyme protein concentrations in fumigated agricultural soils were 2.93, 0.105, and 2.95 mg protein kg⁻¹ soil for acid phosphatase, β-glucosidase and arylsulfatase, respectively, all lower than in control soils. Organic matter turnover and nutrient cycling, and thus, the long-term productivity of agricultural soils seem unaffected in soils repeatedly fumigated with PrBr, InLine, Midas and CP.  相似文献   

溴甲烷在土壤及作物(黄瓜)中的消解动态     

乞永艳  焦淑贞  姚建仁  邵向东 《农业环境科学学报》1997,(3)

用衍生气相色谱法测定了溴甲烷熏蒸大棚土壤后土壤及作物（黄瓜）中残留的Ｂｒ－，用顶空法测定土壤吸附的溴甲烷。在０．４－４０ｍｇ／ｋｇ的添加范围内，Ｂｒ的平均回收率为８３．７％－９４．８％，相对标准偏差为±２．５％－１４．７％。Ｂｒ在土壤和黄瓜中的半衰期为１５．０和１４．２ｄ（北京）、２４．７和１０．３ｄ（沈阳）。土壤吸附的溴甲烷量较少，其半衰期和Ｂｒ的嵪嘟５陀冢罚担埃纾恚驳氖┯眉亮靠杀Ｖせ乒现胁辛舻模拢虿怀畲蟛辛粝蘖勘曜肌  相似文献   

基于数值模拟的微型溴化锂屏蔽泵的性能分析   总被引：2，自引：2，他引：0  

孔繁余  邱宁  高翠兰  周水清 《农业工程学报》2011,27(10):56-60

针对现有单级溴化锂屏蔽泵存在效率低、能耗高的缺点,研究开发了两级叶轮微型溴化锂屏蔽泵。设计两级微型溴化锂屏蔽泵机泵一体结构以及两级屏蔽泵的水力部件,包括叶轮设计、径向导叶和螺旋形涡室组合设计等。利用CFD软件FLUENT,对两级屏蔽泵进行流场模拟,得到了内部流场的分布情况。由此分别以溴化锂和清水为介质进行了性能预测,与设计值进行比对,结果符合设计要求。经样机试验验证,在相同流量下,两级微型溴化锂屏蔽泵比现有单级微型溴化锂屏蔽泵扬程高约1 m,机组效率高约1.6%。设计的两级屏蔽泵的扬程和机组效率模拟值与试验值比较接近,初步验证了模拟可信,设计方法可行。  相似文献   

Electroencephalographic recordings in dogs: Prevention of muscle artifacts and evaluation of two activation techniques in healthy individuals     

Christina Brauer  Sabine B.R. Kästner  Henning C. Schenk  Julia Tünsmeyer 《Research in veterinary science》2011,90(2):306-311

This study was performed to improve a standard anesthetic protocol for electroencephalography (EEG) in dogs and to evaluate the effect of photic stimulation and hyperventilation on the EEG of healthy dogs. Ten clinically and neurologically normal beagle dogs were anesthetized with propofol given intravenously with average doses of 7.5 mg/kg for induction and 0.37 mg/kg/min constant rate infusion for maintenance. Rocuronium bromide (0.4 mg/kg IV) was used as a peripheral muscle relaxant in order to prevent muscle artifacts. EEGs were recorded digitally using five subdermal needle electrodes. Photic stimulation and hyperventilation were performed to evaluate two activation techniques commonly used in human EEG recording methods. Monopolar and bipolar montages were analyzed visually and quantitatively. The use of rocuronium produced muscle artifact-free EEG recordings during the given recording procedure which indicates that rocuronium is a valuable adjunct to anesthesia during EEG recording. Photic stimulation and hyperventilation did not provoke paroxysmal discharges in the EEG of healthy dogs. Analysis of quantitative EEG data showed that background activity did not differ significantly between periods with and without stimulation. This data are important basic values and will further help to compare the effects of photic stimulation and hyperventilation of healthy dogs and those suffering from epilepsy.  相似文献   

不同熏蒸剂处理防治黄瓜根结线虫效果及经济效益分析     

曹坳程  郭美霞  颜冬冬  毛连纲  赵海滨  谢红薇  李为  王秋霞  李园  郑建秋  吴振美 《中国蔬菜》2011,(Z1)

选用93%1,3-二氯丙烯乳油(EC)、62%1,3-二氯丙烯胶囊、42%威百亩水剂(AS)、98%棉隆微粒剂(MG)、99%硫酰氟原药(TC)、93%1,3-二氯丙烯EC+98%棉隆MG、93%1,3-二氯丙烯EC+42%威百亩AS防治黄瓜根结线虫,以98%溴甲烷为对照。结果表明:不同熏蒸剂对根结线虫均有良好的防治效果。各熏蒸处理黄瓜产量均显著高于不施药对照,以50g·m-298%溴甲烷处理产量最高,其次为9g·m-293%1,3-DEC+25g·m-298%棉隆MG、9g·m-293%1,3-DEC+21g·m-242%威百亩AS;混用的溴甲烷替代品与溴甲烷相比,经济效益更好。9～18g·m-293%1,3-DEC、9～18g·m-262%1,3-D胶囊和25～50g·m-299%硫酰氟TC处理也有很好的增产效果和良好的经济效益。  相似文献   

采用粉末微电极循环伏安法估测锂离子电池炭负极材料的循环性能     

徐仲榆杨小飞  王其坤 《湖南农业大学学报(自然科学版)》2004,31(3)

阐明了采用粉末微电极循环伏安法估测锂离子电池(LIB)炭负极材料的循环性能的原理．采用该法研究了经高温热处理后具有良好贮锂结构的石油焦试样在1mol／L LiClO4／EC DEC(1：1)电解液中的循环性能．实验结果表明，该试样是一种循环性能优越的LIB负极材料：充、放电到第500循环时，放电容量仍保持了最大放电容量的85．02％，充、放电效率为94．96％；同时也证明了粉末微电极循环伏安法用于估测LIB炭负极材料的循环性能的可行性．  相似文献   

土传病害防治技术进展及面临的挑战     

曹坳程  张大琪  方文生  宋兆欣  任立瑞  李青杰  李文静  王秋霞  颜冬冬  李园  靳茜  郝征 《植物保护》2023,49(5):260-269

近10年来, 随着人们对环境的关注, 绿色发展成为农业生产的主流。在土传病害的防治中, 要尽可能减少对环境和生态的影响, 同时保证取得更好的经济效益。因而, 一些环境友好的防治技术受到重视。农业防治技术如抗性品种利用和嫁接、阻截传播、深翻、轮作和无土栽培; 生物防治技术如生物熏蒸、厌氧消毒、生物防治制剂等; 物理防治技术如太阳能消毒、火焰消毒、微波消毒、电消毒、射频消毒也在不断地创新; 化学防治技术主要依赖土壤熏蒸剂, 一些新型的环境友好的熏蒸剂如异硫氰酸烯丙酯、二甲基二硫、乙二腈、乙蒜素等也在不断发展。熏蒸剂新剂型、新的施药机械也在不断创新。土壤熏蒸剂在防治土传病害时, 也会对土壤中的微生态造成不同程度的影响。此外, 我们也应该清醒地认识到任何技术都有两面性, 并正视不同防治技术中的不足。土传病害作为一类难以防治的病害, 也面临着巨大的挑战, 高传染性要求有高质量的种苗和高效的防治和阻隔技术, 土传病害的定量检测技术, 土壤中的病原菌数量与发病的关系、土壤微生态对发病的影响都是亟待研究和解决的问题。在防控土传病害时, 如何减少温室气体的排放、减少防治投入以及塑料薄膜的污染均为面临的环境和经济学挑战。  相似文献