玫烟色棒束孢耐热菌株的筛选及对麦长管蚜的致病力测定

采用48℃恒温水浴热胁迫法对玫烟色棒束孢7个菌株进行了耐热性测定。结果表明,热胁迫45 min后,不同菌株的残存活孢率差异显著,其中IF-502、IF-904和IF-9606菌株耐热性较强,残存活孢率均达50%以上;IF-7606菌株耐热性最差,残存活孢率仅为28.70%;IF-14、IF-511和IF-609菌株耐热性居中,残存活孢率34.72%～36.00%。对耐热性强的IF-502、IF-904和IF-9606三个菌株对麦长管蚜若蚜的致病力测定表明, IF-904菌株在1×10~7孢子/mL时对麦长管蚜的致病力最高,校正死亡率达88.20%,致死中时最短,为2.67 d。     

土地规模化经营能否促进农业社会化服务获取?——基于全国3类农户样本的实证分析

土地流转和农业社会化服务是经营规模化和服务规模化的根本途径,研究二者关系对农业供给侧结构性改革、农业现代化发展乃至乡村振兴具有重要意义。基于第二期"全国新型农业经营主体发展指数调查"数据,运用负二项回归模型实证分析土地流转及转入不同特征土地对普通农户、专业大户和家庭农场农业社会化服务获取的影响。结果表明,单纯的土地转入对不同类型农户农业社会化服务获取均不具有显著影响。但如果转入土地有利于规模化经营、农业基础设施较好,则能显著促进社会化服务获取。另外,农户经营能力越强,对不同类型社会化服务的应用程度也越高。因此,政府应推动更有效率的土地流转,实现农业适度规模经营;加强农业社会化服务供给,提升农户生产经营效率;强化经营主体培训,增强联结带动能力。     

不同发酵条件对荔枝产香菌发酵茶品质的影响

经过长时间的工艺优化,国内不同地区的黑茶风味已趋于稳定,为了进一步改善发酵茶品质,生产更具特色的发酵茶,利用课题组前期已筛选出的一株适用于茶叶发酵的优良产香菌ZYF3单菌发酵青砖茶原料(一芽四五叶)。在实验室条件下,以灭菌后青砖茶为发酵原料,探究该菌株在不同接菌量、不同茶坯含水量、不同发酵温度和不同发酵时间下对发酵茶感官品质和理化品质的影响。结果表明:在不同发酵条件下,产香菌ZFY3发酵茶品质差异显著,当接种量为1.2%～1.3%(mL/g)、茶坯含水率为45%、发酵温度为32℃、发酵时间为20 d时,发酵茶综合品质最佳。不同发酵条件能明显改善荔枝产香菌发酵茶品质,并且促进发酵茶特殊风味的形成。     

Protective efficacy of an H5/H7 trivalent inactivated vaccine produced from Re-11, Re-12, and H7-Re2 strains against challenge with different H5 and H7 viruses in chickens

We developed an H5/H7 trivalent inactivated vaccine by using Re-11, Re-12, and H7-Re2 vaccine seed viruses, which were generated by reverse genetics and derived their HA genes from A/duck/Guizhou/S4184/2017(H5 N6)(DK/GZ/S4184/17)(a clade 2.3.4.4 d virus), A/chicken/Liaoning/SD007/2017(H5 N1)(CK/LN/SD007/17)(a clade 2.3.2.1 d virus), and A/chicken/Guangxi/SD098/2017(H7 N9)(CK/GX/SD098/17), respectively. The protective efficacy of this novel vaccine and that of the recently used H5/H7 bivalent inactivated vaccine against different H5 and H7 N9 viruses was evaluated in chickens. We found that the H5/H7 bivalent vaccine provided solid protection against the H7 N9 virus CK/GX/SD098/17, but only 50–60% protection against different H5 viruses. In contrast, the novel H5/H7 trivalent vaccine provided complete protection against the H5 and H7 viruses tested. Our study underscores the importance of timely updating of vaccines for avian influenza control.     

小贯小绿叶蝉在5个茶树品种（系）上的蜜露排泄量与茶树叶片结构比较

为明确茶树叶片组织结构与小贯小绿叶蝉抗性之间的相关性,在确定小贯小绿叶蝉不同龄期和虫态蜜露排泄量的基础上,比较研究了小贯小绿叶蝉雌成虫在不同茶树品种（系）上取食24 h后蜜露排泄量的差异,进而通过比较不同茶树品种（系）叶片的组织结构和色泽,分析了5个茶树品种（系）叶片的组织结构与茶树对小贯小绿叶蝉抗性能力强弱的关系。研究结果表明,小贯小绿叶蝉4龄若虫的蜜露排泄量显著高于1~3龄;雌、雄成虫的蜜露排泄量之间不具显著差异;取食中选10号的雌成虫蜜露排泄量显著低于取食其他品种;不同品种（系）茶树的叶面积、叶片总厚度、上表皮厚度、下表皮厚度以及色差等指标与雌成虫的蜜露排泄量之间无显著相关性,而叶片茸毛密度与雌成虫蜜露排泄量呈显著负相关,叶片茸毛长度与蜜露排泄量呈显著正相关。     

Wild Bonelli’s eagles (Aquila fasciata) as carrier of antimicrobial resistant Salmonella and Campylobacter in Eastern Spain

Wild birds have repeatedly been found to be involved in the dissemination of enteric bacterial pathogens in the environment. The aim of this study was to determine the occurrence of Salmonella and Campylobacter as well as the antimicrobial resistance in wild Bonelli’s eagles nestlings in Eastern Spain. In addition, we compared the efficiency of two sampling methods (fresh faecal samples from nest and cloacal swabs from nestlings) for detection of both bacteria. A total of 28 nests with 45 nestlings were analysed. In the nest, Salmonella occurrence was 61 ± 9.2%, while Campylobacter occurrence was 11 ± 5.8% (p < 0.05). In the nestlings, Salmonella occurrence was 36 ± 7.1%, while Campylobacter occurrence was 11 ± 4.7% (p < 0.05). Eight Salmonella serovars were identified, and the most frequently isolated were S. Enteritidis, S. Typhimurium, S. Houston, and S. Cerro. Only one Campylobacter species was identified (C. jejuni). Regarding antimicrobial resistance, the Salmonella strains isolated were found to be most frequently resistant to ampicillin and to tigecycline; however, the sole Campylobacter strain recovered was multidrug resistant. In conclusion, this study demonstrated that wild Bonelli’s eagles nestlings are greater carriers of Salmonella than of Campylobacter. Both Salmonella and Campylobacter isolates exhibited antimicrobial resistance. In addition, faecal samples from nests were most reliable for Salmonella detection, while cloacal swab from nestlings were most reliable for Campylobacter detection.     

北京市蔬菜专业村产业集聚测度实证研究

以北京蔬菜专业村为研究对象,选取2012—2018年北京蔬菜专业村及蔬菜产业相关数据,运用区位商指数测算方法,从时间和空间两个层面对北京市蔬菜专业村产业集聚度进行测算;运用集中度指数测算方法,从专业村主导产业总产值和从业农户数两方面对集聚度进行测算。结果显示,北京市蔬菜专业村出现了集聚现象,但存在不稳定上下波动的问题,顺义区、通州区和平谷区总体集聚程度较高,并保持稳定集聚状态,集聚区域主要集中在顺义区和房山区。研究建议完善蔬菜专业村基础设施建设,打造蔬菜专业村区域品牌效应,发挥蔬菜示范村辐射带动作用,推进专业镇、基地及园区建设。     

贫困地区基于农民专业合作社的土地流转模式及选择——以贵州、四川、甘肃三省为例

基于贵州、四川、甘肃三省贫困连片区的调研,采用问卷调查、关键人访谈和统计分析相结合的方法,总结出农户与农民专业合作社间土地流转模式主要有转包、转让、出租、入股、出租-入股5种,同时分析了每种模式的运作机制和利弊,并在此基础上为不同类型农户的土地流转模式选择提出建议。     

猪流行性腹泻病毒灭活疫苗的制备及攻毒保护研究

为研究现用猪流行性腹泻病毒(PEDV)CV777疫苗毒株对流行毒株的免疫保护效果,以RTPCR进行PEDV CV777疫苗株、JS12流行株S基因克隆测序,进行PEDV S基因核酸序列分析与氨基酸序列分析。分别以转瓶工艺与细胞悬浮培养工艺培养Vero E6细胞,制备PEDV CV777株转瓶灭活苗与悬浮灭活苗。分别以PEDV转瓶灭活苗、悬浮灭活苗、PEDV流行株组织灭活苗(JS12株)产前30d免疫经产母猪;母猪产仔后14d进行仔猪攻毒保护试验。核酸序列分析显示,PEDV CV777株S基因与流行毒株的相似性在96.4%~99.7%之间,氨基酸序列相似性在96.7%~99.5%之间。转瓶工艺制备PEDV抗原效价为107.0 TCID50/mL,悬浮培养制备PEDV抗原效价为108.5 TCID50/mL。攻毒保护试验显示,悬浮灭活苗免疫母猪后,仔猪有2/10发病,保护率为8/10,转瓶灭活苗组发病率为8/10,保护率仅为2/10;组织灭活苗组9/10发病;对照组10头全部发病。该试验证明,提高PEDV CV777株的抗原含量,能够有效提高疫苗对PEDV流行毒株的保护效果。     

核桃优良早实新品系云新9030l、云新90303的选育

选用我国南方著名的晚实良种“三台核桃”与北方新疆早实核桃优株“新早13号”进行种间杂交,培育出云新90301、云新90303两个核桃新品系。新品系综合了双亲优势性状,具有早实、丰产、优质、树体矮化、适应性广等优良特点,推广前景广阔。