水钾耦合对苜蓿根颈抗氧化特性及越冬率的影响

为探究不同水钾耦合处理对科尔沁沙地生境下种植苜蓿（Medicago sativa）抗寒生理特性的影响，以‘骑士T’和‘公农1号’苜蓿品种为试验材料，采用两因素裂区随机区组设计，水分处理为主区：灌水时间间隔分别为4 d，8 d和12 d（用W₁，W₂，W₃表示）；钾肥施用量水平为副区，具体施用量分别为50 kg·hm^-2 K₂O，100 kg·hm^-2 K₂O和150 kg·hm^-2K₂O（用K₁，K₂，K₃表示），并设置不施钾肥为对照（CK），于越冬前期挖取苜蓿根颈材料测定丙二醛（Malondialdehyde，MDA）、可溶性蛋白含量和抗氧化酶活性，翌年测定越冬率。结果表明：在W₃灌水时间间隔处理下，‘骑士T’和‘公农1号’品种苜蓿根颈的过氧化氢酶、过氧化物酶和超氧化物歧化酶活性、越冬率以及可溶性蛋白含量均明显高于W₁和W₂处理，其中以K₂施用量处理下的数值与CK差异最显著（P<0.05），且此施肥量下的MDA含量也显著低于CK（P<0.05）。因此在科尔沁沙地生境下生产苜蓿，灌水时间间隔为12 d、钾肥施用量在100 kg·hm^-2K₂O有利于提高苜蓿抗寒性。     

Identification of an H1N1 subtype of swine influenza virus and serological analysis

To investigate the epizootic of swine influenza virus(SIV), 60 nasal swabs were collected from a clinical cases of pig farm in Tai'an City, Shandong Province of China in April 2017. SIV was isolated by inoculating into 10-day-old Special Pathogen Free embryonated eggs and the whole genome was sequenced. An H1N1 subtype SIV was isolated and designated as A/swine/Shandong/TA04/2017(H1N1). Phylogenetic analysis showed that apart from the polymerase A(PA) fragment belonging to the 2009 pandemic H1N1 branch, seven genome segments belonged to avian-like H1N1 influenza virus lineage. The cleavage site sequence of the hemagglutinin(HA) protein was PSIQSR↓G, which is a typical molecular biological characteristic. Five potential N-glycosylation sites(N14, N26, N277, N484 and N543) were found in the HA gene. To further investigate the epidemiology of SIV in this farm, the 995 serum samples were assessed with EAH1N1 2009 pandemic H1N1 and H3 N2 antigens. The results showed that the total positive rate was 65.43%. The positive rates of single virus infection detected by EAH1N1, 2009 pdmH1N1 and H3 N2 for serum HI(Hemagglutination inhibition) were 48.35, 30.85 and 7.47%, respectively. The results showed that SIV in Shandong Province has been reassorted in some segments and the SIV-positive rate was high on the SIV outbreak farm. These data provide evidence of an epizootic of SIV.     

Identification,characterization and full-length sequence analysis of a novel endornavirus in common sunflower (Helianthus annuus L.)

To identify the possible quarantine viruses in seven common sunflower varieties imported from the United States of America and the Netherlands, we tested total RNAs extracted from the leaf tissues using next-generation sequencing of small RNAs. After analysis of small RNA sequencing data, no any quarantine virus was found, but a double-stranded RNA(dsRNA) molecule showing typical genomic features of endornavirus was detected in two varieties, X3939 and SH1108. Full-length sequence and phylogenetic analysis showed that it is a novel endornavirus, temporarily named as Helianthus annuus alphaendornavirus(HaEV). Its full genome corresponds to a 14 662-bp dsRNA segment, including a 21-nt 5′ untranslated region(UTR), 3' UTR ending with the unique sequence CCCCCCCC and lacking a poly(A) tail. An open reading frame(ORF) that encodes a deduced 4 867 amino acids(aa) polyprotein with three domains: RdRP, Hel and UGT(UDP-glycosyltransferase). HaEV mainly distributed in the cytoplasm but less in the nucleus of leaf cells by fluorescence in situ hybridization(FISH) experiment. This virus has a high seed infection rate in the five varieties, X3907, X3939, A231, SH1108 and SR1320. To our knowledge, this is the first report about the virus of the family Endornaviridae in the common sunflower.     

沙地生境不同播期对紫花苜蓿生产性能及其越冬率的影响

为确定科尔沁沙地种植苜蓿（Medicago sativa）的适宜播期，本研究于2017年在内蒙古阿鲁科尔沁旗，选择骑士T、公农1号、擎天柱3个紫花苜蓿品种，7月1日开始播种，每5天播种1期，共10个播期，分析播期、生产性能、越冬率之间的关系。结果表明：建植当年苜蓿播种越晚干草产量越低，骑士T干草产量在7月21日播期显著降低（P<0.05），公农1号干草产量在7月16日播期显著降低（P<0.05），擎天柱干草产量在7月11日播期显著降低（P<0.05）；随播种时期的推迟，苜蓿株高、单枝条重呈降低的变化趋势，单位面积株数和枝条数呈先增加后降低的变化趋势；苜蓿越冬率从播期7月16日开始显著降低，公农1号在7月16日以前播种越冬率显著高于骑士T和擎天柱（P<0.05）；播种翌年第1茬苜蓿干草产量和株高随着播期的推迟而逐渐降低，2，3茬则无明显变化；苜蓿单位面积株数和枝条数都随播期的推迟呈降低的变化趋势，随着刈割茬次的增加，苜蓿的株数逐渐降低。因此，在科尔沁沙地种植紫花苜蓿最佳播期为7月1日—7月16日。     

Impact of fluxapyroxad on the microbial community structure and functional diversity in the silty-loam soil

The aim of this work was to assess the effect of applying three different doses of fluxapyroxad on microbial activity, community structure and functional diversity as measured by respiration, microbial biomass C, phospholipid fatty acid(PLFA) and community-level physiological profiles(CLPPs). Our results demonstrated that substrate-induced respiration(on day 15) and microbial biomass C(on days 7 and 15) were inhibited by fluxapyroxad, but stimulation was observed thereafter. In contrast, fluxapyroxad addition increased the basal respiration and metabolic quotients(q CO2) and respiratory quotients(QR). Analysis of the PLFA profiles revealed that the total and bacterial biomass(both Gram-positive bacteria(GP) and Gram-negative bacteria(GN)) were decreased within the initial 15 days, whereas those as well as the GN/GP ratio were increased at days 30 and 60. F luxapyroxad input decreased the fungi biomass but increased the bacteria/fungi ratio at all incubation time. Moreover, high fluxapyroxad input(75 mg fluxapyroxad kg–1 soil dry weight) increased the microbial stress level. A principal component analysis(PCA) of the PLFAs revealed that fluxapyroxad treatment s ignificantly shifted the microbial community structure, but all of the observed effects were transient. Biolog results showed that average well color development(AWCD) and functional diversity index(H′) were increased only on day 60. I n addition, the dissipation of fluxapyroxad was slow in soil, and the degradation half-lives varied from 158 to 385 days depending on the concentration tested.     

Human capital agglomeration,institutional barriers,and internal migration in China

This paper investigates how human capital agglomeration interplays with institutional factors to affect migration destination choice in China. Over the last decades, China has experienced massive internal migration, substantial human capital investment, and the relaxation of its hukou system, thus providing us with a valuable opportunity to examine the role of human capital externality in migration choice. Based on rich data on province-to-province migration flows for different education and hukou groups, we find that migrants in China, especially highly educated and urban-to-urban migrants, have a strong preference to move to provinces with a high agglomeration of human capital. Further examination reveals that low-skilled migrants in China are less likely to benefit from human capital agglomeration because of their lower ability to overcome hukou restrictions. Our findings raise the concern that labor migration under the skill-biased hukou system would enlarge China's regional disparities in human capital and economic development.     

黄芪不同采收期有效成分含量比较

以黄芪为试材,采用紫外-可见分光光度法,分析了5个不同采收期的3年生蒙古黄芪的多糖、总皂苷、总黄酮含量,探讨蒙古黄芪的适宜采收期。结果表明:10月上旬采收的黄芪多糖含量最高,达7.79%,8月上旬采收的黄芪黄酮含量、皂苷含量最高,分别为3.18%和0.568%。3年生蒙古黄芪的适宜收获期为9月上旬至10月初,此期间采收的黄芪品质较佳。     

绿色木霉Fn10-1纤维素酶的分离纯化及酶学特性测定

试验研究了绿色木霉Fn10-1纤维素酶的初步纯化及酶学性质开展研究。结果表明,该纤维素酶的最适催化温度为70℃,最适pH 7.6,在温度为4~50℃下均能保持较稳定的酶活,高于50℃以后,热稳定性变差,酶活力开始急剧下降。pH在5.6~7.6时该酶有较好的稳定性。Na+、Mn2+、Fe2+、Mg2+、Co2+、Ca2+、Ba2+、Al3+对纤维素酶具有一定的激活作用,Ag+、Fe3+、Cu2+、Zn2+、K+对该酶有一定的抑制作用,其中Cu2+的抑制作用尤为明显。     

苋菜试管开花初探

以苋菜试管苗为材料,研究多种因子对苋菜试管开花的影响.结果表明:(1)基本培养基MS和1/2MS对苋菜试管开花的影响不大.(2)单独添加NAA,可促进苋菜试管开花；苋菜试管开花对IBA含量的变化较敏感；6-BA含量为1.0 mg.L-1时的开花率最高,培养50 -60 d时可达58.7％.(3)不同单色光处理时,绿光与...