Search results for "soil"
showing 10 items of 3493 documents
Influence of arbuscular mycorrhizal colonisation on cadmium induced Medicago truncatula root isoflavonoid accumulation.
2012
Cadmium is a serious environmental pollution threats to the planet. Its accumulation in plants affects many cellular functions, resulting in growth and development inhibition, whose mechanisms are not fully understood. However, some fungi forming arbuscular mycorrhizal symbiosis with the majority of plant species have the capacity to buffer the deleterious effect of this heavy metal. In the present work we investigated the capacity of Rhizophagus irregularis (syn. Glomus irregularis) to alleviate cadmium stress in Medicago truncatula. In spite of a reduction in all mycorrhizal parameters, plants colonized for 21 days by R. irregularis and treated by 2 mg kg(-1) cadmium displayed less growth…
Variations in the concentrations of macro- and trace elements in two grasses and in the rhizosphere soil during a day
2019
The aim of the research was to study short-term variations in concentrations of 17 elements in two widely distributed natural plant species (couch grass and plantain) and in the rhizosphere soil of the plants. The plant and soil samples were collected in a field from a small site over a daytime. In the course of the day, the variations of the total amounts of C, N, and H in the rhizosphere soil were rather marked and different for the soils taken from roots of plantain and couch grass. The concentrations of some other elements in the rhizosphere soil of the plants varied in a similar way. The short-term variations of element concentrations in roots and leaves of the plants were also rather …
Root-induced tree species effects on the source/sink strength for greenhouse gases (CH4, N2O and CO2) of a temperate deciduous forest soil
2013
Through their leaf litter and throughfall water, tree species can have a pronounced influence on soil chemistry. However, there is little knowledge of species-specific root effects on greenhouse gas fluxes between forest soils and the atmosphere. By growing saplings of beech (Fagus sylvatica) and ash (Fraxinus excelsior) in monoculture or mixture at defined atmospheric and soil conditions in rhizotrons, we tested four hypotheses related to potential root-induced tree species effects on the uptake of CH4 and the emission of N2O and CO2 from the soil. This design excluded putative effects of leaf litter mineralisation on trace gas fluxes. Gas fluxes were measured biweekly using the closed cha…
Implication of pyoverdines in the interactions of fluorescent pseudomonads with soil microflora and plant in the rhizosphere
2007
Soils are known to be oligotrophic environments whereas soil microflora is mostly heterotrophic in such way that microbial growth in soil is mainly limited by the scarce sources of readily available organic compounds (Wardle 1992). Therefore, in soils, microflora is mostly in stasis (fungistasis/bacteriostasis) (Lockwood 1977). In counterpart, plants are autotrophic organisms responsible for the primary production resulting from the photosynthesis. A significant part of photosynthetates are released from plant roots to the soil through a process called rhizodeposition. These products, i.e. the rhizodeposits, are made of exudates, lysates, mucilage, secretions and dead cell material, as well…
Root-induced decomposer growth and plant N uptake are not positively associated among a set of grassland plants
2007
Abstract It is known that plant species can induce development of different soil decomposer communities and that they differ in their influence on organic matter decomposition and N mineralization in soil. However, no study has so far assessed whether these two observations are related to each other. Based on the hypothesis that root-induced growth of soil decomposers leads to accelerated decomposition of SOM and increased plant N availability in soil, we predicted that (1) among a set of grassland plants the abundance of soil decomposers in the plant rhizosphere is positively associated with plant N uptake from soil organic matter. To test this, we established grassland microcosms consisti…
ITS region of the rDNA of Pythium rhizosaccharum sp. nov. isolated from sugarcane roots: taxonomy and comparison with related species.
2003
Pythium rhizosaccharum (F-1244) was isolated from soil samples taken in the rhizosphere of sugarcane (Saccharum officinarum) in the north-eastern India. This species is characterized by its smooth-walled, spherical sporangia and rarely formed sexual structures. When formed, the antheridial branches wrap around the oogonia and soon disappear after fertilization. The internal transcribed spacer (ITS) region of its rDNA is comprised of 904 bases. The taxonomical description of this new species and its comparison with related species are given here, together with the nucleotide sequences of the ITS1 and ITS2, and the 5.8S gene of its ribosomal nuclear DNA.
Cadmium-induced changes in soil biochemical characteristics of oat (Avena sativa L.) rhizosphere during early growth stages
2011
A microcosm was assembled to physically separate soil from roots and was used to study both the impact of living roots on the soil–plant system during early stages of growth and plant responses to abiotic stress. Oat (Avena sativa L.) seedlings were grown in the microcosm unit for 44 days. Twenty-three days after planting, 0.154 mg CdSO4/g dry soil was added. Plants grown in Cd-treated microcosms showed considerable inhibition of shoot growth rates, and leaf chlorophyll content. Soil microbial biomass C and respiration increased with plant age, and most of the measured biochemical indicators decreased with increasing distance from the soil–root interface, thus demonstrating the rhizosphere …
Do interactions with soil organisms mediate grass responses to defoliation?
2008
Abstract Defoliation-induced changes in grass growth and C allocation are known to affect soil organisms, but how much these effects in turn mediate grass responses to defoliation is not fully understood. Here, we present results from a microcosm study that assessed the role of arbuscular mycorrhizal (AM) fungi and soil decomposers in the response of a common forage grass, Phleum pratense L., to defoliation at two nutrient availabilities (added inorganic nutrients or no added nutrients). We measured the growth and C and N allocations of P. pratense plants as well as the abundance of soil organisms in the plant rhizosphere 5 and 19 d after defoliation. To examine whether defoliation affected…
Impact of wheat straw decomposition on successional patterns of soil microbial community structure
2009
International audience; The dynamics of indigenous bacterial and fungal soil communities were followed throughout the decomposition of wheat straw residue. More precisely, such dynamics were investigated in the different soil zones under the influence of decomposing wheat straw residue (i.e. residues, soil adjacent to residue = detritusphere, and bulk soil). The genetic structures of bacterial and fungal communities were compared throughout the decomposition process long by applying B- and F-ARISA (for bacterial and fungal-automated ribosomal intergenic spacer analysis) to DNA extracts from these different zones. Residue decomposition induced significant changes in bacterial and fungal comm…
Impact of inoculation with the phytostimulatory PGPR Azospirillum lipoferum CRT1 on the genetic structure of the rhizobacterial community of field-gr…
2009
International audience; The phytostimulatory PGPR Azospirillum lipoferum CRT1 was inoculated to maize seeds and the impact on the genetic structure of the rhizobacterial community in the field was determined during maize growth by Automated Ribosomal Intergenic Spacer Analysis (ARISA) of rhizosphere DNA extracts. ARISA fingerprints could differ from one plant to the next as well as from one sampling to the next. Inoculation with strain CRT1 enhanced plant-to-plant variability of the ARISA fingerprints and caused a statistically significant shift in the composition of the indigenous rhizobacterial community at the first two samplings. This is the first study on the ecological impact of Azosp…