1,720,982 research outputs found
The cropping system matters – Contrasting responses of winter faba bean (Vicia faba L.) genotypes to drought stress
No full textPost-harvest N 2 O and CO 2 emissions related to plant residue incorporation of oilseed rape and barley straw depend on soil NO 3 - content
No full textThe sustainable production of bioenergy from crops like oilseed rape, barley, and maize presents a significant option to mitigate climate change by reducing fossil CO2 emissions. Greenhouse gas emissions (specifically N2O) during the energy crop production need to be quantified precisely for reliable life cycle analysis of bioenergy cropping systems. Energy crops (specifically oilseed rape) have a very high N demand, which results in a higher N-fertilizer application and thus higher risk of N2 O emissions not only during the vegetation period but also after crop harvest due to i) incorporation of N rich plant residue to soil and/or ii) residual N. An incubation experiment was conducted under conditions favoring denitrification (80% water-holding capacity), to study the drivers of N2O emissions specifically during the post-harvest period. Here we compared two different plant residues varying in C/N ratio (oilseed rape (RST) and barley straw (BST)) with or without N supply and measured
CO2, and N2O emissions. Stable isotope labeling (15N) was used to quantify soil- and residue-born N2O. Incorporation of both plant residues alone induced significant increases in CO2 emissions compared to control
soil without straw addition (p < .05). However, the increase in CO2 emissions was less pronounced when straw was incorporated in conjunction with mineral N. There was a clear increase in cumulative N2O emissions (p < .05) when soil amended with BST or RST (6- and 9-fold) was compared to control, however, the increase of
cumulative N2O emissions was drastic when mineral N was added (15- and 23-fold). No significant differences in N2O emission were observed when comparing residue types (p > .05). Stable isotope labeling of barley straw clearly showed that the share of residue-born N2O was very low (1.35 or 0.4%) in the overall N2O fluxes in BST and BST+N. The present study suggests that N fertilization in autumn should be avoided to minimize N2O fluxes regardless of type of straw
Maize root and shoot litter quality controls short-term CO<sub>2</sub> and N<sub>2</sub>O emissions and bacterial community structure of arable soil
No full textOpen-Access-Publikationsfonds 202
Extraction of Total DNA and RNA from Marine Filter Samples and Generation of a Universal cDNA as Universal Template for Marker Gene Studies
No full textExtraction of Total DNA and RNA from Marine Filter Samples and Generation of a cDNA as Universal Template for Marker Gene Studies
No full textMicrobial communities play an important role in marine ecosystem processes. Although the number of studies targeting marker genes such as the 16S rRNA gene has been increased in the last few years, the vast majority of marine diversity is rather unexplored. Moreover, most studies focused on the entire bacterial community and thus disregarded active microbial community players. Here, we describe a detailed protocol for the simultaneous extraction of DNA and RNA from marine water samples and for the generation of cDNA from the isolated RNA which can be used as a universal template in various marker gene studies
Complete Genome Sequence of Alkalihalobacillus sp. Strain LMS39, a Haloalkaliphilic Bacterium Isolated from a Hypersaline Lake
No full textHere, we report the complete genome sequence of a haloalkaliphilic bacterium (Alkalihalobacillus sp. strain LMS39) isolated from Lake Magadi, a hypersaline lake in Kenya. The genome comprised 4,850,562 bp with a GC content of 37%
Leaf litter is the main driver for changes in bacterial community structures in the rhizosphere of ash and beech
No full textThe rhizosphere and the surrounding soil harbor an enormous microbial diversity and a specific community structure, generated by the interaction between plant roots and soil bacteria. The aim of this study was to address the influences of tree species, tree species diversity and leaf litter on soil bacterial diversity and community composition. Therefore, mesocosm experiments using beech, ash, lime, maple and hornbeam were established in 2006, and sampled in October 2008 and June 2009. Mesocosms were planted with one, three or five different tree species and treated with or without litter overlay. Cluster analysis of DGGE-derived patterns revealed a clustering of 2008 sampled litter treatments in two separated clusters. The corresponding treatments sampled in 2009 showed separation in one cluster. PCA analysis based on the relative abundance of active proteobacterial classes and other phyla in beech and ash single-tree species mesocosm indicated an effect of sampling time and leaf litter on active bacterial community composition. The abundance of next-generation sequencing-derived sequences assigned to the Betaproteobacteria was higher in the litter treatments, indicating a higher activity, under these conditions. The Deltaproteobacteria, Nitrospira and Gemmatimonadetes showed an opposite trend and were more active in the mesocosms without litter. The abundance of alphaproteobacterial sequences was higher in mesocosms sampled in 2009 (P = 0.014), whereas the Acidobacteria were more active in 2008 (P=0.014). At the family level, we found significant differences of the litter vs. non-litter treated group. Additionally, an impact of beech and ash as tree species on soil bacterial diversity was confirmed by the Shannon and Simpson indices. Our results suggest that leaf litter decomposition in pH-stable soils affect the soil bacterial composition, while tree species influence the soil bacterial diversity. (C) 2013 Elsevier B.V. All rights reserved.Ministry of Science and Culture of Lower Saxony; Niedersachsisches Vora
Maize root and shoot litter quality controls short-term emissions and bacterial community structure of arable soil
No full textChemical composition of root and shoot litter controls decomposition and, subsequently, C availability for biological nitrogen transformation processes in soils. While aboveground plant residues have been proven to increase emissions compared to fresh maize shoot litter, (2) to assess whether emissions. To obtain root and shoot litter, maize plants (Zea mays L.) were cultivated with two N fertilizer levels in a greenhouse and harvested. A two-factorial 22 d laboratory incubation experiment was set up with soil from both N levels (N1, N2) and three litter addition treatments (control, root, root + shoot). We measured fluxes, analyzed soil mineral N and water-extractable organic C (WEOC) concentrations, and determined quality parameters of maize litter. Bacterial community structures were analyzed using 16S rRNA gene sequencing. Maize litter quality controlled ^−_3 emissions. Emissions induced by maize root litter remained low, while high bioavailability of maize shoot litter strongly increased emissions when both root and shoot litter were added. We identified a strong positive correlation between cumulative emissions, supporting our hypothesis that litter quality affects denitrification by creating plant-litter-associated anaerobic microsites. The interdependency of C and N availability was validated by analyses of regression. Moreover, there was a strong positive interaction between soil ^−_3 emissions, when both ^−_3 and and $ emissions from crop residues, especially when soil mineral N is limited
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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