Search results for "soil"

Phenotypic traits and establishment speed of 44 turf bermudagrass accessions

2014

Breeding of turf bermudagrass (Cynodon (L.) Rich.) has made available a broad range of turf varieties with unique morphological and growth traits. Rapid establishment is necessary in order to provide the performance of a mature turf cover in the shortest time possible. The aims of the research were: (1) to determine variation of growth, morphological and biomass traits in bermudagrass accessions belonging to different phenotypic groups during establishment and (2) to relate such variations to establishment speed in order to assess whether contrasting phenotypic traits could induce different establishment patterns in bermudagrass or if a general establishment predictor can be identified for …

Biomarker responses of the earthworm Aporrectodea tuberculata to copper and zinc exposure: differences between populations with and without earlier m…

2003

Biomarkers in the earthworm Aporrectodea tuberculata (Eisen) were measured to find out their possible induction under Cu and Zn exposure and differences in the responses between two populations with different exposure history. The biomarkers applied were concentration of metallothioneins (MT), and cytochrome P4501A (CYP1A) monooxygenase and glutathione-S-transferase (GST) activities. These were measured from earthworms sampled at three distances from a steel smelter in Finland and from the individuals from two populations, one with and another without earlier metal exposure, exposed to three combined Cu/Zn concentrations in the laboratory. In the field, MT concentration, and cytochrome CYP1…

Fluorine adsorption by volcanic soils at Mt. Etna, Italy

2012

Abstract Fluorine adsorption experiments were performed on 28 samples of the first 5 cm of topsoil collected on the flanks of Mt. Etna. The soil samples were equilibrated with F-rich rainwater (3.25 mg/L) at a soil/water weight ratio of 1/25. Aliquots of the supernatant were collected after 1, 7, 72, 720 and 5640 h and analysed for F content. The soil samples could be subdivided into three groups based on their F-adsorption behaviours after 1 h and at the end of the experiment: (1) negative adsorption (F released from the soil to the solution) after 1 h and negative or moderately positive adsorption at the end, (2) from negative after 1 h to strongly positive adsorption at the end, and (3) …

INDAGINE SPERIMENTALE SULLA DISTRIBUZIONE SPAZIALE DELLA DENSITÀ RADICALE DI PIANTE DI OLIVO (OLEA EUROPEA, L.) IRRIGATE A GOCCIA

2009

Taxonomic and functional diversity of atrazine‐degrading bacterial communities enriched from agrochemical factory soil

2010

Aims: To characterize atrazine-degrading potential of bacterial communities enriched from agrochemical factory soil by analysing diversity and organization of catabolic genes. Methods and Results: The bacterial communities enriched from three different sites of varying atrazine contamination mineralized 65–80% of 14C ring-labelled atrazine. The presence of trzN-atzBC-trzD, trzN-atzABC-trzD and trzN-atzABCDEF-trzD gene combinations was determined by PCR. In all enriched communities, trzN-atzBC genes were located on a 165-kb plasmid, while atzBC or atzC genes were located on separated plasmids. Quantitative PCR revealed that catabolic genes were present in up to 4% of the community. Restricti…

Direct conjugal transfers of Ti plasmid to soil microflora

2002

The bacterial species in soil that can receive a Ti plasmid by conjugation from Agrobacterium spp. were investigated. In order to have direct access to the potential reservoir of Ti plasmid amongst soil microflora, the conjugal system consisting of a multiply auxotrophic derivative of C58 (ST-96-4) and a derivative of pTiC58Delta(acc)R (pSTiEGK) containing a triple antibiotic-resistance cassette in traM was used to transfer the Ti plasmid in a complex soil microflora used as the recipient. Numerous transconjugants were obtained by this method but none was identified as Agrobacterium. This could be explained by the low density of Agrobacterium in the tested soil. As indicated by analysis of …

Long-term effects of crop management on Rhizobium leguminosarum biovar viciae populations.

2004

Little is known about factors that affect the indigenous populations of rhizobia in soils. We compared the abundance, diversity and genetic structure of Rhizobium leguminosarum biovar viciae populations in soils under different crop managements, i.e., wheat and maize monocultures, crop rotation, and permanent grassland. Rhizobial populations were sampled from nodules of pea- or vetch plants grown in soils collected at three geographically distant sites in France, each site comprising a plot under long-term maize monoculture. Molecular characterization of isolates was performed by PCR-restriction fragment length polymorphism of 16S-23S rDNA intergenic spacer as a neutral marker of the genomi…

Role of plant residues in determining temporal patterns of the activity, size and structure of nitrate reducer communities in soil

2010

ABSTRACT The incorporation of plant residues into soil not only represents an opportunity to limit soil organic matter depletion resulting from cultivation but also provides a valuable source of nutrients such as nitrogen. However, the consequences of plant residue addition on soil microbial communities involved in biochemical cycles other than the carbon cycle are poorly understood. In this study, we investigated the responses of one N-cycling microbial community, the nitrate reducers, to wheat, rape, and alfalfa residues for 11 months after incorporation into soil in a field experiment. A 20- to 27-fold increase in potential nitrate reduction activity was observed for residue-amended plot…

Estimation of atrazine-degrading genetic potential and activity in three French agricultural soils

2004

The impact of organic amendment (sewage sludge or waste water) used to fertilize agricultural soils was estimated on the atrazine-degrading activity, the atrazine-degrading genetic potential and the bacterial community structure of soils continuously cropped with corn. Long-term application of organic amendment did not modify atrazine-mineralizing activity, which was found to essentially depend on the soil type. It also did not modify atrazine-degrading genetic potential estimated by quantitative PCR targeting atzA, B and C genes, which was shown to depend on soil type. The structure of soil bacterial community determined by RISA fingerprinting was significantly affected by organic amendmen…

Molecular analysis of the catechol-degrading bacterial community in a coal wasteland heavily contaminated with PAHs

2010

International audience; A PCR-based molecular tool was developed to estimate the diversity of the catechol-degrading bacterial community in a coal wasteland heavily contaminated with PAHS. A degenerate primer pair specific to catA sequences was designed by multiple alignment of known sequences coding a key intermediate of the β-ketoadiapate pathway degrading catechol, namely catechol 1,2-dioxygenase. The specificity of this primer pair was assessed in 21 pure strains by PCR and sequencing. Comparison of the 16S rDNA and catA phylogenies revealed an absence of congruence between these two genes. The primer set was able to amplify catA sequences in DNA extracts from an industrial soil highly …