短期培养下抑制剂烯丙基硫脲对土壤硝化作用及微生物的影响

硝化抑制剂烯丙基硫脲（ATU）对土壤硝化作用及温室效应的影响及机理尚不清楚。本研究采集典型旱地土壤,进行21天室内微宇宙培养,探究了氮肥与不同剂量ATU（分别为氮素用量的1%, 5%, 10%, 15%和20%）配施对土壤硝化作用及N2O和CO2排放通量的影响,并通过实时荧光定量PCR和高通量测序16S rRNA基因技术监测硝化微生物群落变化,同时与传统硝化抑制剂双氰胺（DCD）进行了保氮减排效果的对比。结果表明,与未施加氮肥的对照相比（CK）,单施氮肥（N）显著提高了土壤硝化强度并促进了N2O排放。DCD能显著抑制硝态氮和N2O的积累,抑制效率分别为68.6%和93.3%。而低浓度ATU对土壤硝化作用无影响,仅在高浓度具有抑制效应,且抑制效率最高仅为14.7%。所有ATU处理N2O排放量均显著降低,降幅为60.3～68.2%,仍远高于DCD处理。处理间N2O和CO2的综合温室效应强弱顺序为N>ATU+N>DCD+N≈CK,且不同ATU施用量处理之间差异不显著。相关分析发现氨氧化细菌（AOB）,而不是氨氧化古菌（AOA）和全程氨氧化细菌（Comammox）,与土壤硝态氮积累和N2O排放显著正相关,与土壤pH显著负相关。高通量测序结果表明Nitrosovibrio tenuis类型AOB对氮肥诱导的硝化过程起主导作用。除此之外,ATU和DCD还能显著提高Cupriavidus,并降低Patulibacter、Aeromicrobium、Actinomycetospora、Defluviicoccus和Acidipila等微生物属在群落中的相对丰度。该研究为深化土壤碳氮循环理论,合理使用硝化抑制剂以及减缓温室气体排放提供科学依据。     

10份菠萝种质资源的描述和评价

对收集的10份菠萝种质资源植株的芽、叶片及其果实性状进行描述和评价.结果表明:徐台品种的可溶性固彤物含量最高,其余指标接近于巴厘品种但无刺,是巴厘品种较好的一个替代品种;上海2号品种果型端正,果肉橙黄色,品质中上,Vc含量高,是较好的鲜食和加工皆宜品种;ST品种风味好,口感好,是一个优良的鲜食品种.     

氨基甲酸酯类杀虫剂及其与阿维菌素的混配制剂对美洲斑潜蝇(Diptera:Agromyzidae)的防治效果

测定了扑蚜威、速灭威、灭蚜威、间乙威等9个氨基甲酸酯类化合物及其 与阿维菌素混剂对美洲斑潜蝇的田间药效，结果发现，当施用有效量0.75 kg/hm2时，氨 基甲酸酯类单剂对美洲斑潜蝇的防效在75%～92%之间，而扑蚜威、速灭威、灭蚜威与阿维菌 素混剂对该蝇的防效可达85%～92%。表明，氨基甲酸酯类化合物与阿维菌素混配对美洲斑潜 蝇田间防效、速效性均较好，且成本显著降低。     

三种藏药成分复方抗ORFV体内外药效学实验研究

将岩青、轮叶棘豆等3种藏药材成分按一定比例配成复方,采用水提醇沉法提取,将浓缩药液用细胞维持液配制成1g·L-1的药液,并根据对兔肾细胞(PRK)安全浓度的测定结果,稀释成不同梯度浓度,分别将脓疱皮炎病毒(ORFV)加入到已培养24h的单层PRK中,通过MTT法测定OD值,分析其对ORFV病毒增殖的影响;并通过复制ORFV感染小鼠建立动物模型,观察药液对ORFV感染小鼠的保护作用。结果表明:复方药液的浓度在7.81mg·mL-1～62.5mg·mL-1范围内,经回归分析,药物浓度与活细胞存在线性关系,P<0.05,对病毒增势有显著的抑制作用;复方药液可明显延长ORFV感染小鼠存活天数和存活率,与阳性对照组比较具有显著性差异(P<0.05)。说明藏药材复方药液具有抗脓疱皮炎病毒感染的作用,为临床试验提供理论依据。     

A solar-powered wireless cell for dynamically monitoring soil water content

In various agricultural activities, such as irrigation scheduling, tillage operation and nutrient management, soil water content is regarded as an essential parameter. For the demand of monitoring soil water dynamics at field scale, this study presents a solar-powered wireless cell that contained a water content sensor, two temperature sensors, an optical sensor, a communication module and a data-logger. To evaluate its feasibility in the field, three cells were independently installed in a bare plot, a maize plot and a sugarbeet plot in the summer of 2008. By a heavy rain event (20 mm, 6 h) during the experimental period, different responses of soil water content sensors were dynamically recorded and then analyzed under each canopy condition. In addition, to explore the possibility of reducing the dimensions of the cell under the condition of sufficient energy supply, various sizes of the solar panel were tested. The experimental results showed that the cell is promising to become a node of wireless network in the field.     

脐橙次生果黄化的生理原因初探

在罗伯逊脐橙花后至次生果黄化(脐黄)发生期间,对其果实进行解剖观察及生理测定。结果表明,脐黄果实多为次生果生长停止、花柱残留物多且褐变或次生果由离生心皮发育而成并产生大量粘性分泌物的果实。脐黄果实呼吸强度显著高于正常果实。过氧化物酶在果实内随维管束走向分布,其活性随果实发育而下降。但脐黄高峰期,脐黄果实中过氧化物酶活性异常增高。     

不同绵羊品种脂肪组织中挥发性脂肪酸的组成分析

【目的】研究绵羊品种对其脂肪组织中挥发性脂肪酸(C4~C10)组成的影响,为深入研究羊肉膻味的形成机理奠定基础。【方法】采用同时蒸馏萃取和气相色谱技术,对小尾寒羊、滩羊和同羊皮下脂肪组织中的挥发性脂肪酸进行了定量分析。【结果】采用同时蒸馏萃取和气相色谱技术可在绵羊脂肪组织中检测到对羊肉膻味贡献较大的4-甲基辛酸和4-甲基壬酸。小尾寒羊、滩羊和同羊的总挥发性脂肪酸含量分别为261.109,169.124和271.898mg/kg;其中直链脂肪酸含量分别为217.792,143.036和229.059 mg/kg,支链脂肪酸含量分别为43.317,26.088和42.839 mg/kg。4-甲基辛酸和4-甲基壬酸是对羊肉膻味贡献较大的挥发性脂肪酸,其在小尾寒羊、滩羊、同羊脂肪组织中的含量分别为20.317和9.772,14.150和5.597,12.835和6.403 mg/kg。【结论】应用此方法可以检测到对羊肉膻味有主要作用的挥发性脂肪酸,且不同绵羊品种对其脂肪组织中挥发性脂肪酸的组成有一定影响,小尾寒羊脂肪组织中4-甲基辛酸和4-甲基壬酸含量有大于滩羊和同羊的趋势。     

单端孢菌素对几种作物病原菌的室内毒力及田间防效

为明确单端孢菌素对主要作物病原菌的抑菌活性和田间防效,采用孢子萌发抑制测定法、菌丝生长速率法和田间药效常规试验方法,测定了单端孢菌素在不同质量浓度下对作物病原菌的室内毒力及田间药效。结果表明:单端孢菌素对供试16个病原菌的MIC为1.9~15.5mg/L,对辣椒炭疽病菌、番茄早疫病菌、水稻恶苗病菌、水稻稻瘟病菌、番茄灰霉病菌、玉米小斑病菌和马铃薯晚疫病菌等7个病原菌的EC50分别为5.93、7.90、9.27、10.78、13.34、14.95和16.50mg/L,500mg/L质量浓度对番茄灰霉病、番茄早疫病、辣椒炭疽病、马铃薯晚疫病、玉米小斑病和水稻稻瘟病的防治效果分别为78.98%、81.29%、85.28%、72.42%、78.99%和72.74%。单端孢菌素具有较强的抑菌活性和较广的抑菌谱,对几种主要作物真菌和卵菌病害具有较好的田间防治效果,应用前景广。     

赤霉酸及矮壮素对苦瓜性别表现的影响

以兰山大白、株洲长白和英引３个苦瓜品种为材料进行外源激素处理对苦瓜植株性别表现影响的试验．结果表明，苗期进行ＧＡ３２５～１００ｍｇ／Ｌ处理有明显的促雌效果；ＣＣＣ５０～２００ｍｇ／Ｌ处理则有促雄效果，但促雄程度因品种而异，ＣＣＣ５００ｍｇ／Ｌ处理对兰山大白有适度的促雌作用．外源激素处理对苦瓜植株性别分化的影响可持续８０ｄ以上．苦瓜第一雌花形成与茎尖ＧＡ３含量达到峰值有关，２５ｍｇ／Ｌ的ＧＡ３处理使茎尖ＧＡ３含量的峰值提前出现而使第一雌花形成提早，而１００ｍｇ／ＬＣＣＣ处理使茎尖ＧＡ３含量先下降再逐渐回升而使植株第一雌花形成滞后     

Changes in VP2 gene during the attenuation of very virulent infectious bursal disease virus strain Gx isolated in China

Very virulent (vv) infectious bursal disease virus (IBDV) Gx strain with high pathogenicity was attenuated through replication in specific-pathogen-free (SPF) chicken embryos and in chicken embryo fibroblast (CEF) cell cultures. The changes in VP2 nucleotide and the deduced amino acid sequences were obtained during attenuation of vvIBDV in CEF culture. Sequence analysis of selected passages from numbers 0 to 20 in CEFs (designated here Gx to CEF-20) showed that no changes were detectable in the VP2 gene before CEF-7. There were a few changes in the nucleotide sequence of the VP2 gene but no amino acid substitutions at CEF-8. The virus of CEF-9 was an intermediate with some amino acid changes that possibly were related to virulence. CEF-10 virus had become similar to CU-1 strain. The VP2 gene sequence remained the same from CEF-10 to CEF-20. The results of pathogenicity tests showed that the mortalities of Gx, CEF-5, CEF-8, and CEF-9 in 4-wk-old SPF chickens were 64%, 60%, 60%, and 32%, respectively; whereas CEF-10, CEF-15, and CEF-20 were nonpathogenic. Virus neutralization tests with Gx strain showed that the antigenicities are similar from Gx to CEF-20.