生物肥对冬枣根际土壤微环境特征的影响

通过保绿法和萝卜子叶增重法,从6年生冬枣根际土壤中筛选出具有促生作用的优势细菌,以发酵鸡粪（DCM）为吸附载体制成冬枣生物有机肥（DBF）,研究了DBF、普通生物有机肥（NBF）和DCM对冬枣根际土壤微生态环境特征的影响。结果表明:同NBF处理相比,DBF降低了冬枣根际土壤的pH值,提高了根际土壤的电导率和阳离子代换能力;DBF显著提高了冬枣根际土壤中的磷、钾及部分微量元素的有效性,但对碱解氮含量影响较小;不同肥料对冬枣根际土壤的有机碳及其组分产生了很大影响,DBF显著增加了根际土壤中有机碳和胡敏酸的含量,提高了胡/富,对富里酸含量影响差异不显著;DBF显著提高了根际土壤中根系分泌物的含量,同NBF处理相比,DBF可使冬枣根际土壤中的氨基酸、有机酸和总糖含量分别提高40.70%、32.54%和59.14%;此外,DBF显著降低了根际土壤中的氯氰菊酯含量。施用普通生物肥料和发酵鸡粪并未对冬枣根际土壤微生态环境特征产生显著影响。综合分析认为,从冬枣根际土壤中筛选出的微生物有效地改善了冬枣根际土壤的微生态环境。      

切花葱的再生

切花葱种球价格昂贵,目前通常一个种球的市场售价在20~38元之间。为了建立切花葱高效再生体系,以Lucy Ball和His Excellency两个切花葱品种为试验材料,研究了灭菌时间及灭菌剂浓度、外植体的选择、不同激素配比等因素对切花葱再生的影响。结果表明,最佳的灭菌方法为4%次氯酸钠处理20 min,污染率仅为18.2%,利用率达到了81.8%;最佳外植体为幼叶尖端,平均诱导率为92.6%;诱导不定芽直接再生效果最好的培养基为MS+NAA 1.0 mg/L+6-BA 0.2 mg/L,两个切花葱品种的诱导率分别为His Excellency85.71%,Lucy Ball 90.00%;最佳的生根培养基为1/2MS+0.2 mg/L NAA+0.2 mg/L IBA,生根率为41.67%。通过该方法即可利用切花葱幼叶尖端经直接再生途径诱导出新植株。     

Soil moisture and soil-litter mixing effects on surface litter decomposition: A controlled environment assessment

Recent studies suggest the long-standing discrepancy between measured and modeled leaf litter decomposition in drylands is, in part, the result of a unique combination of abiotic drivers that include high soil surface temperature and radiant energy levels and soil-litter mixing. Temperature and radiant energy effects on litter decomposition have been widely documented. However, under field conditions in drylands where soil-litter mixing occurs and accelerates decomposition, the mechanisms involved with soil-litter mixing effects are ambiguous. Potential mechanisms may include some combination of enhanced microbial colonization of litter, physical abrasion of litter surfaces, and buffering of litter and its associated decomposers from high temperatures and low moisture conditions. Here, we tested how soil-litter mixing and soil moisture interact to influence rates of litter decomposition in a controlled environment. Foliar litter of two plant species (a grass [Eragrostis lehmanniana] and a shrub [Prosopis velutina]) was incubated for 32 weeks in a factorial combination of soil-litter mixing (none, light, and complete) and soil water content (2, 4, 12% water-filled porosity) treatments. Phospholipid fatty acids (PLFAs) were quantified one week into the experiment to evaluate initial microbial colonization. A complementary incubation experiment with simulated rainfall pulses tested the buffering effects of soil-litter mixing on decomposition.Under the laboratory conditions of our experiments, the influence of soil-litter mixing was minimal and primarily confined to changes in PLFAs during the initial stages of decomposition in the constant soil moisture experiment and the oscillating soil moisture conditions of the rainfall pulse experiment. Soil-litter mixing effects on CO₂ production, total phospholipid concentrations, and bacterial to total PLFA ratios were observed within the first week, but responses were fairly weak and varied with litter type and soil moisture treatment. Across the entire 32-week incubation experiment, soil moisture had a significant positive effect on mass loss, but soil-litter mixing did not. The lack of strong soil-litter mixing effects on decomposition under the moderate and relatively constant environmental conditions of this study is in contrast to results from field studies and suggests the importance of soil-litter mixing may be magnified when the fluctuations and extremes in temperature, radiant energy and moisture regimes common dryland field settings are in play.     

不同栽培基质对温室茭白幼苗生长及光合特性的影响

为筛选出以椰糠为基础并适合茭白幼苗的栽培基质,以茭白浙茭2号为试材,以普通土壤、粗粒椰糠、细粒椰糠、珍珠岩为基质原料,按照不同体积配比设置5种栽培基质:普通土壤(CK)、粗粒椰糠(T1)、V粗粒椰糠:V珍珠岩=3:1(T2)、细粒椰糠(T3)、V细粒椰糠:V珍珠岩=3:1(T4),探究不同栽培基质对茭白幼苗生长及光合特性的影响。结果表明,T2处理茭白幼苗株高可达130.28 cm、叶长可达99.89 cm;总叶绿素质量分数为5.28 mg·g^-1,较CK处理提高7.32%;净光合速率为17.75μmol·m^-2·s^-1,较CK高出35.91%;光化学淬灭系数较CK高17.65%,非光化学淬灭系数较CK低63.33%;T2处理茭白幼苗植株地上部鲜质量可达107.97 g,较CK高205.52%;地下部鲜质量可达102.82 g,较CK高263.45%。综上所述,选用V粗粒椰糠:V珍珠岩=3:1基质处理的茭白幼苗植物学性状和叶片光合参数整体表现最优,可作为适合茭白幼苗的推荐基质。     

Urban-rural and temporal differences of woody plants and bird species in Harbin city,northeastern China

Urbanization has been greatly accelerated by the economic growth in China, while its possible effects on woody plants, bird species and their associations are not well defined yet. Here, we analyzed urban-rural gradients (landscape level: urban-farmland-forest-natural reserves; city level: ring road and urban build-up history) and temporal data (1955–1980–2014 for woody plants; 1980s–2010 s for birds) in Harbin city, China, to investigate the changes in the composition and diversity of woody plants and birds during urbanization. Both landscape gradient and temporal data confirmed that urbanization had the function of species conservations with sharp increases of alien species and tropical type plants. In the case woody species, 60-yr urbanization in Harbin had induced increases of 9 families and 17 genera, and there were 7–20 more families, 12–35 more genera, 1.6–2.6 higher Margalef richness in urban areas than those in nature reserves and local forest farms; Increases in alien species (4-fold in 60-yr urbanization; 21% in urban area vs <2% for non-urban region) and tropical type plants (1.6-fold in 60-yr urbanization; temperate/tropical ratio at 1.2 in urban area vs >1.6 in non-urban area) were mainly responsible for these compositional changes, which can be proved by their significant correlations. Moreover, moderate disturbance had peak values in alien species, tropical type plants, Shannon-wiener diversity, Margalef richness index and Pielou evenness index, and both ring road- and buildup history gradients showed the similar tendency. Compared with those in 1980s, forest- and eurytopic-habitats birds increased 9–11 species (23–39%), and omnivorous, insect-eating, and phytophagous bird increased 5–9 species (14.1–29.4%) in those in 2010s, indicating that bird temporal changes were closely related with the changes in urban forests owing to food supply and habitat provision. Our findings could provide data for biodiversity evaluation of urbanization effects, and is also useful for ecological re-construction of local cities in China.     

猪伪狂犬病病毒流行株gE蛋白表达及其多克隆抗体制备

本研究旨在获得重组伪狂犬病病毒（PRV）gE蛋白及其多克隆抗体。利用PCR方法从PRV感染猪的肺脏、脑和扁桃体混合组织中扩增PRV gE基因,连接至克隆载体pMD18-T（pMD-gE）后进行测序与进化树分析。以pMD-gE为模板,利用PCR方法扩增其膜外结构域部分基因（gE-outside）,将其连接至原核表达载体pET-30a（+）,转化大肠杆菌DH5α感受态细胞,构建重组质粒pET-gE-outside。将重组质粒pET-gE-outside转化大肠杆菌Rosetta^TM（DE3）pLysS感受态细胞,经IPTG诱导后,通过SDS-PAGE和Western blotting进行表达产物的分析与鉴定。经亲和层析技术纯化重组PRV gE蛋白并免疫小鼠,通过间接ELISA和Western blotting分别进行三免3周血清中鼠抗PRV gE多克隆抗体效价的测定和鉴定。PCR和测序结果表明,本研究成功克隆了PRV gE基因,与国内2011年以后流行毒株属于相同分支。SDS-PAGE和Western blotting结果证实,PRV gE-outside基因在原核表达系统获得正确表达,分子质量约为55 ku,且可与猪抗PRV多克隆抗体发生免疫反应。经亲和层析纯化的gE-outside蛋白浓度为1.23 mg/mL。将其免疫小鼠,三免3周的小鼠血清中鼠抗PRV gE-outside多克隆抗体效价为1：204 800,并可与gE-outside蛋白发生免疫反应。综上,本研究制备了重组PRV gE蛋白和鼠抗PRV gE蛋白多克隆抗体,可为PRV感染机制研究及建立快速、高效免疫学检测技术提供技术指导和材料。     

土壤固化剂集流面不同施工工艺比较

土壤固化剂以土壤为固结对象，具有就地取材、减少砂石量和节省工程造价等优点，在集雨工程特别是集流面建设中具有广阔的应用前景。该文在提出固化剂集流面施工工艺分类的基础上，阐述了干硬性－整体施工－固化剂浆液收光、干硬性－整体施工－自然收光、干硬性－砌块施工、塑性－整体施工－自然收光等4种不同施工工艺的技术要求。通过测定集流面的集流效率和粗糙系数，认为固化剂集流面的集流效率达到90％以上，表面粗糙系数在0.011～0.014之间。与混凝土集流面比较，固化剂集流面的建造成本可节约40％以上。试验结果表明：砌块施工工艺在未来固化剂集流面的发展应用中具有重要的地位和价值；单一用途的集流面应考虑塑性施工工艺；表面采用固化剂浆液收光有利于降低集流面的粗糙系数和表面干缩裂缝。     

北京地区下凹式绿地土壤渗透能力及蓄水对土壤物理性质的影响

采用自制的模拟下凹式绿地,通过模拟不同设计暴雨强度条件下下凹式绿地的进水负荷,动态监测下凹式绿地在蓄水过程中土壤水分的渗透量和平均入渗速率,研究北京地区下凹式绿地在蓄积周边外来雨水径流过程中土壤水分的渗透规律以及蓄积雨水径流后对土壤孔隙及土壤密度的影响。结果表明:1)在土壤含水率基本相同的条件下,下凹式绿地土壤渗透性能在1、3、5年一遇暴雨情况下会随着暴雨强度的增加而增大;2)在设计暴雨强度一致时,土壤水分的渗透量和平均入渗速率没有明显差异,土壤密度小、总孔隙度大的渗透量和平均入渗速率更大;3)随着绿地蓄水次数的增多,土壤密度和总孔隙度变化较大,蓄水试验后,土壤密度由最初的1.33 g/cm3变为1.65g/cm3、总孔隙度由原来的50.06%变为39.18%。     

Relationships between soil biota,nitrogen and phosphorus availability,and pasture growth under organic and conventional management

Legume-based pastures generally rely on soil biological activity to provide nitrogen (N) for plants. This study examined seasonal pasture growth in nine adjacent hill pastures, under sheep or beef, with different long-term managements, including certified organic, no fertilizer, and conventional fertilizer application, that formed a soil-fertility sequence. We determined relationships between net N mineralization, as a measure of soil biological activity and N availability, and microbial biomass, soil organic matter, and fauna. Net N mineralization generally explained differences in pasture production (r = 0.87). On an areal basis, net N mineralization was strongly related (r = 0.93) to total soil N (0–200 mm depth) and negatively related (r = −0.92) to soil C:N ratio, but not to soil C. Total N and C:N ratios were related to soil phosphorus (P) status and probably past N fixation by legumes. Where labile P was low, the N:P ratios of both soil microbes and enchytraeids were wide, and the organisms appeared to be P limited, possibly competing with plants for P. Faunal grazing on soil micro-organisms appeared to release P. We could find no convincing evidence that net N mineralization, pasture growth or soil biological diversity increased under organic farming. Rather, the data from organic pastures followed similar trend lines to data from pastures under conventional management.