持续施用缓/控释尿素条件下水田土壤NH3挥发与N2O排放特征

以持续9年施用不同缓／控释尿素的水田棕壤为试验对象,以普通大颗粒尿素为对照,研究了持续施用不同缓／控释尿素条件下水田土壤NH₃挥发与N₂O排放特征.结果表明: 与普通大颗粒尿素(U)相比,除1% 3,4－二甲基吡唑磷酸盐(DMPP)+U处理 NH₃挥发增加了25.8%外,其他缓／控释尿素肥料处理对NH₃有明显的减排效果.树脂包膜尿素(PCU)对NH₃减排效果最明显,为73.4%,硫包膜尿素(SCU)为72.2%,0.5% N-丁基硫代磷酰三胺(NBPT)+1% DMPP+U为71.9%,1% 氢醌(HQ)+3% 双氰胺(DCD)+U为46.9%,0.5% NBPT+U为43.2%,1% HQ+U为40.2%,3% DCD+U为25.5%, 1% DMPP均与施用普通大颗粒尿素差异显著;所有缓／控释尿素处理与对照相比均可显著减少N₂O排放.1% DMPP+U对N₂O减排效果最明显,为74.9%,PCU为62.1%,1% HQ+3% DCD+U为54.7%,0.5% NBPT+1% DMPP+U为42.2%,3% DCD+U为35.9%,1% HQ+U为28.9%,0.5% NBPT+U为17.7%,SCU为14.5%,均与施用普通大颗粒尿素差异显著.比较0.5% NBPT+1% DMPP+U、SCU、PCU对NH₃和N₂O减排的综合效果,3种肥料作用相近,且均明显优于其他处理,但包膜材料的成本较抑制剂高数倍.因此,同时添加脲酶和硝化抑制剂的缓释尿素是减少水田氮素损失及环境污染的首选氮肥.     

不同地貌背景下民族村农户生计脆弱性及其影响因子

基于2014年贫困户实地调查数据,运用集对分析和障碍度模型对宁夏海原县农户生计脆弱性及其胁迫因子进行实证分析.结果表明: 海原县农户生计脆弱性总体较高且呈现地貌和民族差异化,平原区、河谷川地山间洼地农户生计脆弱性低于土石山区、黄土梁区和中山地貌区;回汉混居村农户生计脆弱性高于纯回族与纯汉族村.农户自身必要资产的缺乏和外部地理环境敏感性的胁迫是海原县农户生计脆弱的深层原因.生计结构不合理与生计方式单一导致生计脆弱性长期积累;地理环境的不易改变使扶贫资源的地区可进入性降低.农户生计应对能力的提高需建立明确的村级水权分配制度,实施教育贫困户对口帮扶,加大生计方式多元化转型的成本投入,开发村域连锁综合商品市场.农户生计脆弱性的治理应把“公路村村通”建设放在“村村通工程”更突出的位置,坚持气象防灾和保险企业减灾相结合,开发农业生产保险系统.     

长白山白桦林不同演替阶段土壤有机碳组分的变化

为了解长白山天然针阔混交林群落恢复演替土壤碳储量的变化,采用空间代替时间的方法,选取白桦幼龄林、白桦中龄林、白桦成熟林、阔叶红松成熟林和阔叶红松过熟林5个不同演替序列,研究其土壤总有机碳(SOC)、易氧化有机碳(ROC)、微生物生物量碳(MBC)及颗粒有机碳(POC)含量。结果表明:随着白桦林从早期到晚期的演替,SOC、MBC、ROC、POC以及土壤全氮、全磷和碳氮比(C/N)均呈现先逐渐增加后保持稳定的规律。随着土层深度的增加,SOC、MBC、ROC和POC含量均显著降低(P0.05),5个演替序列内ROC/SOC和POC/SOC的变化范围分别为12.91%~47.95%和14.21%~69.46%。相关分析表明:MBC、ROC和POC含量与土壤总有机碳(SOC)含量呈极显著正相关(P0.01),SOC、MBC、ROC和POC含量与全氮、全磷及碳氮比呈极显著正相关(P0.01)。研究结果为了解白桦林在演替过程中土壤有机碳的稳定性变化和固碳潜力提供数据支持。     

Genomewide analysis of <Emphasis Type="Italic">MATE</Emphasis>-type gene family in maize reveals microsynteny and their expression patterns under aluminum treatment

Multidrug and toxic compound extrusion (MATE) proteins are a group of secondary active transporters, which widely exist in all living organisms and play important role in the detoxication of endogenous secondary metabolites and exogenous agents. However, to date, no systematic and comprehensive study of this family is reported in maize. Here, a total of 49 MATE genes (ZmMATE) were identified and divided into seven groups by phylogenetic analysis. Conserved intro–exon structures and motif compositions were investigated in these genes. Results by gene locations indicated that these genes were unevenly distributed among all 10 chromosomes. Tandem and segmental duplications appeared to contribute to the expansion and evolution of this gene family. The K_a/ K_s ratios suggested that the ZmMATE has undergone large-scale purifying selection on the maize genome. Interspecies microsynteny analysis revealed that there were independent gene duplication events of 10 ZmMATE. In addition, most maize MATE genes exhibited different expression profiles in diverse tissues and developmental stages. Sixteen MATE genes were chosen for further quantitative real-time polymerase chain reaction analysis showed differential expression patterns in response to aluminum treatment. These results provide a useful clue for future studies on the identification of MATE genes and functional analysis of MATE proteins in maize.     

还原亚硒酸盐产生红色单质硒光合细菌菌株的筛选与鉴定

从实验室保藏的光合细菌中筛选出一株对亚硒酸钠还原效率较高的菌株S3,其亚硒酸钠还原产物通过透射电子显微镜及EDX(Electron-Dispersive X-ray)分析确定为红色单质硒。菌株S3的形态学特征、生理生化特征及光合色素扫描结果与固氮红细菌(Rhodobacter azotoformans)的特征基本一致;16S rDNA序列(GenBank登录号为DQ402051)在系统发育树中与固氮红细菌同属一个类群,序列同源性为99%。根据上述结果将菌株S3鉴定为固氮红细菌。初步研究了该菌株还原亚硒酸钠的特性,首次报道固氮红细菌具有还原亚硒酸盐产生红色单质硒的能力,为今后利用微生物方法治理环境中硒污染、利用微生物方法获得活性红色单质硒以及对微生物还原亚硒酸盐产生红色单质硒的机理研究奠定了良好的基础。     

Characterization of Genome and Chromosomes in Octoploid Wheat wheatgrass Amphiploid Zhong 2 Using Fluorescence in situ Hybridization and Chromosome Pairing Analysis

Genomic constitution of octoploid wheat-wheatgrass amphiploid Zhong 2 was analyzed by chromosome pairing and fluorescence in sim hybridization techniques. The results indicated that the octoploid wheatwheatgrass chromosomes in Zhong 2 were derived from the distant homologous genomes of wheatgrass ( Agropyron intermedium (Host) P.B. = Elytrigia intermedia (Host) Nevski = Thinotopyrum intermedium (Host) Barkworth and Dewey, and thew distant homologous genomes were not from the E geaome of T. elongatum 2x. Zhong 2 contained 12 wheatgrass chromosomes in which a pair of chromosomes was involved in translocation between wheatgrass and wheat chromosomes.     

子午沙鼠生态学的初步研究

子午沙鼠的数量消长与季节变化有着密切的关系,数量高峰在9-11月。雌鼠妊娠率、繁殖指数均以夏季7月较高,冬季繁殖休止。雌雄性比为1:0.94。夏季以植物茎叶为主食,冬、春、秋三季均以种籽为主食。年龄结构呈金字塔形,老年鼠最少,成年鼠次之,幼年鼠和亚成年鼠数量最高。     

Systematic Position of the Rhoipteleaceae: Evidence from Nucleotide Sequences of rbc L Gene

Systematic position of the Rhoipteleaceae was investigated using nucleotide sequences of the chloroplast gene rbcL. Two sets of parsimony analyses were conducted, one using Bauera as the outgroup and the other using Cercidiphyllum-Liquidambar as outgroups. The results of these analyses are consistent. Rhoiptelea is allied with sampled Jug-landaceous genera in the rbcL phylogeny, suggesting its close relationship with the Juglandaceae.     

60Co事故受照人员远期细胞遗传学效应观察

对三例钴源事故受照人员照后6(7)年和11(12)年两次细胞遗传学随访结果表明,两次随访受照者染色体畸变率分别为4.29%和3.63%,均显著高于对照组(P<0.01),但两次随访间未见显著差异(P>0.05),而且第一次随访染色体畸变是以双+环和无着丝粒断片为主,第二次随访是以易位、缺失和倒位为主;两次随访受照者微核率分别为4.17‰和1.17‰,第二次随访微核率明显下降(P<0.01)。提示随着照后时间推移, 非稳定性染色体畸变逐渐丢失,稳定性染色体畸变仍保持在较高水平。