Does the wild‐caught Chinese mitten crab megalopae perform better than the hatchery‐produced seed during the juvenile culture?

Although wild Yangtze Eriocheir sinensis juveniles (coin‐sized seed) have better culture performance than the pond‐reared juveniles during the adult crab culture stage, the culture performance of wild‐caught megalopae (WC) remains unknown. Therefore, this study was designed to compare the growth, survival rate, crab yield, feed conversion rate (FCR), precocity, final weight and size distribution between WC and hatchery‐produced megalopae (HP) during the juvenile culture stage. Wild‐caught megalopae had significantly higher body weight, weight gain rate (WGR) and specific growth rate (SGR) during 0–4 weeks but lower WGR and SGR than HP during 4–8 weeks (p < .05). Although WC had a significantly lower survival rate and yield of normal juvenile crabs than HP, total yields of normal juveniles and precocious crabs were similar. Wild‐caught megalopae had a significantly higher precocious rate and yield of precocious crabs than HP (p < .05). Regardless of sex, no significant differences were found in the gonadosomatic index (GSI), hepatosomatic index (HSI) and final weight of normal juveniles and precocious crabs between WC and HP. As for the size distribution of normal crabs, WC had a higher percentage of small female juveniles (<3 g) but a lower proportion of middle size ranges (3–5.99 g and 6–8.99 g) than HP for females (p < .05), and there was no significant difference for males. In conclusion, wild megalopae of the Yangtze E. sinensis had worse culture performance than the hatchery‐produced seeds; therefore, wild megalopae would not be recommended for commercially juvenile culture of E. sinensis.     

庐山常绿落叶阔叶混交林土壤AM真菌资源及其分布特征

【目的】探究庐山常绿落叶阔叶混交林土壤AM真菌群落多样性及分布特征,为推动其地下AM真菌资源的开发利用提供理论基础。【方法】以庐山典型常绿落叶阔叶混交林5种常见树种［（杜鹃（Rhododendron simsii）、蜡瓣花（Corylopsis sinensis）、山橿（Lindera reflexa）、女贞（Ligustrum lucidum）、榆树Ulmus pumila）］根际土壤丛枝菌根真菌（AM真菌）为材料,通过孢子形态学鉴定方法研究其多样性特征、影响因素及分布特征。【结果】从庐山常绿落叶阔叶混交林中鉴定、分离出55个AM真菌类群,其中包括2个广布种、10个常见种与43个稀有种（按优势度水平划分）,其中无梗囊霉属（Acaulospora属,24种）和球囊霉属（Glomus属,18种）为优势属。此外,不同树种根际AM真菌孢子密度、物种丰富度、Shannon指数、Pielou均匀度指数等指标差异总体上不显著（P>0.05）,且群落相似度系数较高,其中山橿（L.reflexa）与蜡瓣花（C.sinensis）根际AM真菌群落相似度系数最高（73.85%）。不同树种根际AM真菌种属分布存在差异,其中稀有内养囊霉（Entrophospora infrequens,稀有种之一）只在山橿根际有所发现,稀有种球囊霉17（Glomus.17）只在杜鹃（R.simsii）根际发现,稀有种亮色盾巨孢囊霉（Scutellospora fulgida）只在女贞（L.lucidum）根际发现,稀有种扭形伞房囊霉（Corymbiglomus tortuosum）只在蜡瓣花根际发现。不同树种根系侵染率水平存在显著差异（P<0.05）,从高到低依次为蜡瓣花（45.72%）、榆树（U.pumila）（38.60%）、杜鹃和女贞（31.67%）、山橿（29.73%）。通过典范对应分析（CCA）发现土壤因子（全磷、全氮、氨态氮、硝态氮、有机质、pH和含水率）对土壤AM真菌群落变异的解释度为7.29%,而消除趋势对应分析（DCA）分析发现植物种类对土壤AM真菌群落变异的解释度为15.72%。【结论】庐山常绿落叶阔叶混交林土壤AM真菌是以稀有种为主的分布模式,该模式下的AM真菌及分布受宿主植物与土壤养分影响较小。     

云南古茶园土壤化学成分研究

通过实地采样和实验室化验分析,研究云南古茶园土壤化学成分含量状况。结果表明,古茶园土壤含有机质4.66%、碱解氮167.48 mg/kg、速效磷13.57 mg/kg和速效钾81.46 mg/kg,有效硼1.07 mg/kg、有效钙292.93 mg/kg、有效镁47.2 mg/kg、有效铁85.99 mg/kg、有效锰20.72 mg/kg、有效铜0.93 mg/kg和有效锌1.33 mg/kg,全铬74.28 mg/kg、全铅96.67 mg/kg和全汞0.13 mg/kg。有机质含量高于中国目前一等土壤生产水平和高产优质高效茶园土壤含量水平,速效磷、速效钾、有效铜和有效锌含量均低于高产优质高效茶园土壤含量水平。     

国内外农产品物流模式对比

农产品物流模式已成为决定我国农业经济整体水平的重要因素,我国农产品物流发展缓慢始终是我国农业可持续发展的瓶颈。当前在国际市场上已经形成了3种典型的农产品物流模式,其成功的管理模式与经验都值得我国借鉴与学习。该文主要分析国内外农产品物流模式,针对我国当前国情,建议建立起中国式的农产品物流组织。      

Modeling waterbird diversity in irrigation ponds of Taoyuan, Taiwan using an artificial neural network approach

The study develops an approach adopted by artificial neural networks (ANN) to model the relationship between pondscape and waterbird diversity. Study areas with thousands of irrigation ponds are unique geographic features from the original functions of irrigation converted to waterbird refuges. The model considers pond shape and size, neighboring farmlands, and constructed areas in calculating parameters pertaining to the interactive influences on avian diversity, among them the Shannon–Wiener diversity index. Results indicate that irrigation ponds adjacent to farmland benefited waterbird diversity. On the other hand, urban development leads to the reduction of pond numbers, which reduces waterbird diversity. By running the ANN model, the resulting index shows a good-fit prediction of bird diversity against pond size, shape, neighboring farmlands, and neighboring developed areas with a correlation coefficient (r) of 0.72, in contrast to the results from a linear regression model (r < 0.28).     

基于高光谱与在线序列极限学习机确证大米产地方法

为满足快速无损的大米产地确证需求,采集吉林省梅河口市水稻主产区及松原、大安、辉南等其他水稻产区共990个大米样本的高光谱图像（400~1 000 nm）作为研究对象,利用多元散射校正（MSC）处理方法对光谱进行预处理。采用多层感知机（MLP）、极限学习机(ELM)与在线序列极限学习机(OS-ELM)算法,分别基于全波段高光谱数据以及经多维尺度分析（MDS）方法降维后的数据建立产地确证模型。结果表明,基于全波段高光谱数据的OS-ELM模型分类性能最好,准确率达到98.3%。经MDS处理后,输入的数据变量减少了96.6%,MDS-OS-ELM模型准确率稳定在97.4%。对三种模型的训练时间进行对比分析,OS-ELM训练时间明显优于MLP,在分批次获取数据时训练时间优于ELM。为大米产地确证提供了一种高效、准确、稳定的方法。     

急性感染猪瘟病毒猪体外排毒规律的观察

为研究CSFV感染后在体外的传播途径、排毒规律,针对CSFV基因组设计了一对引物和一条探针,建立了一套CSFV荧光定量PCR(FQ-PCR)检测方法,并以质粒为标准品得到扩增标准曲线.对18个CSFV阳性质控样本检测全阳性,6个CSFV阴性质控样本检测全阴性,显示良好敏感性和特异性.应用此方法对石门株感染的16头60日龄长白猪和1头阴性对照猪的粪便、尿液、眼分泌物和唾液中病毒含量进行了动态测定,结果表明从感染后第1天到频死前第8天,粪便中均能检测出病毒;尿液和眼分泌物至少能从第3天,唾液从第4天开始检测出病毒,且病毒含量呈增加趋势.本研究对急性感染猪瘟病毒猪体外排毒规律进行了系统研究,为弄清CSFV感染病程、致病机理及临床诊断奠定了重要理论基础.     

广东优质稻粤农丝苗的衍生品种及其特征特性研究

粤农丝苗既是一个丰抗优综合性状优良的常规水稻品种,同时也是一个优质稻育种亲本,分析其衍生品种的特征特性,可以为优质稻育种提供理论依据。以粤农丝苗(R1212)作亲本,育成通过审定或授权的水稻品种有53个,其中通过国家、省级审定的43个,这些品种类型丰富,包括常规稻、杂交稻、香稻等。为阐明粤农丝苗衍生品种的特征特性,选取审定的衍生品种,以它们参加国家、省级区域试验的产量、米质、抗病及抗逆性表现进行比较分析。结果表明,这些品种区域试验产量均比对照种增产,增幅为0.46%～10.98%;品质指标除Q两优粤农丝苗未定级外,常规稻、杂交稻都可达到优质标准;在抗病性方面,部分衍生品种表现为抗稻瘟病和白叶枯病,但较多衍生品种对这两个主要水稻病害抗性表现较弱;在抗倒力、耐热性鉴定上,粤农丝苗衍生品种均表现抗倒力强,除徽两优粤农丝苗外,其他品种对耐热性表现为较强或强。粤农丝苗衍生品种普遍具有丰产稳产性好、稻米品质优、抗倒性和耐热性较强等特点,充分体现了粤农丝苗作为优质稻亲本的“芯”片作用。粤农丝苗主要衍生品种粤禾丝苗、粤金农占、隆晶优1212、晶两优1212、隆两优1212、荃优粤农丝苗、徽两优粤农丝苗...     

图书馆针对突发公共事件的应急情报研究

介绍了突发公共事件的类型与特点、情报研究的定义以及目前国内外突发公共事件情报研究的概况,并针对当前形势提出了我国图书馆对突发公共事件情报研究的具体措施。