I was able to learn that many articles define rhizosphere as a thin soil layer near the root and quite few articles, like a recent nature education article, define it as the root soil interface and is the root cortex (endorizosphere) and the thin soil near the root (ectorhizosphere) together called rhizosphere. Which one is the best definition?
I find this discussion highly interesting as I try to measure compounds in the rhizosphere (my definition: the soil/space around the roots -never knew the cortex is considered part of it by some). As a chemical ecologist, I would say that we could also define the rhizosphere as the 'chemical space' around the roots. So how far do root exudates 'reach' or have an effect on the organisms (microbes, arthropods, nematodes) that live in the soil. Thus more as a 'sphere of influence' than as a certain distance from the root.
In 1904 the German agronomist and plant physiologist Lorenz Hiltner first coined the term "rhizosphere" to describe the plant-root interface, a word originating in part from the Greek word "rhiza", meaning root (Hiltner, 1904; Hartmann et al., 2008).
For Further details see the following link: http://www.nature.com/scitable/knowledge/library/the-rhizosphere-roots-soil-and-67500617
Thavasi but many articles define it as only the SOIL and not including the root cortex.what would be the rational to include root cortex as part of rhizosphere?if it is the presence of endophytes,i think endophytes are also found in the stem,flower...
I think i have to stick to the concept rhizosphere as being only the SOIL
Rhizosphere is a concept, not an object and is indeed only composed of soil. That is all soil under plant root influence. Now, that is indeed a conceptual definition and method to analyze this specific part of a soil can vary a lot.
I don't like that idea of a distinction between endo and ecto rhizosphere. A plant root is also a natural drill foraging in soil while scrapping it's plant tissue to mineral particles sharp like razors, releasing plant root cells and eventually endophytes in soil...
How is this idea of endo / ecto lasting here ?
Is the concept of soil under plant roots influence ever contested though? Such term should be defined in the most broad sense and for sure not take for granted a definition based on last century knowledge of soil microscale structure and living organisms interactions.
Joseph what will be your reaction to this article.see the illustration of rhizosphere
https://www.researchgate.net/go.Deref.html?url=http%3A%2F%2Fwww.nature.com%2Fscitable%2Fknowledge%2Flibrary%2Fthe-rhizosphere-roots-soil-and-67500617
Yes my answer is linked to this article. Two comments: it's a pretty good article with a lot of informations. But it is a "text book" and not a research paper. It stands only to the extent current knowledge.
More in science than anywhwere else, definitions are bound to evolve and change in meaning in order to refine it to reflect our knowledge status.
My second comment is about the need if precise definition like this. Writing town lines on what you hear by this or that term throughout a paper, a defense, you'll save precious time on quite sterile debates (science wise).
My real statement here, and I'm though a word lover, is that we must refrain as much as possible strict definitions.
Dear Fisseha,
"rhizosphere" is a term that is strictly used for the narrow soil area around the root that interactions between plant root and soil borne microorganisms take place. Hence the rhizosphere is a very narrow regions at which plant root exudates and microbial compounds can influence microorganisms and plant roots, respectively. The rest of the soil is just soil and the roots are roots. It's the interface area that can be called the rhizosphere.
I hope this helps,
Vasileios
Then can we define rhizobacteria to be bacteria that lives in(exophytes) or originates from(endophytes) the rhizosphere??
Rhizobacteria are soil-borne bacteria that live in the rhizosphere and can colonize roots, forming a (usually) mutually beneficial relationship with the plant, resulting in organic nutrient uptake for the bacteria from the root exudates and inorganic nutrient availability (usually nitrogen) for the plant.
There are, of course, case of detrimental rhizobacteria but most of the times the term is used to described plant beneficial microorganisms.
I find this discussion highly interesting as I try to measure compounds in the rhizosphere (my definition: the soil/space around the roots -never knew the cortex is considered part of it by some). As a chemical ecologist, I would say that we could also define the rhizosphere as the 'chemical space' around the roots. So how far do root exudates 'reach' or have an effect on the organisms (microbes, arthropods, nematodes) that live in the soil. Thus more as a 'sphere of influence' than as a certain distance from the root.
Thanks Nicole for sharing us your idea.now i m more convinced on excluding the cortex
Rhizosphere is a combination of two words. The first part originating from Greek word "Rhiza" meaning root, and the second part "Sphere" meaning zone. Yhe combination of these two words make the word rhizosphere. So, rhizosphere can be defined as an interface btn roots and the surrounding soils including all microorganisms.
As Agustín Probenza said to you, I think you already have the answer. I just want to mention that Lorenz Hiltner was the first scientist to introduce the term "rhizosphere" in 1904, as the part of soil influenced by roots. You can read about Lorenz Hiltner and his rhizosphere definition in the interesting article of Anton Hartmann (www.researchgate.net/publication/225405556_Lorenz_Hiltner_a_pioneer_in_rhizosphere_microbial_ecology_and_soil_bacteriology_research)
Article Lorenz Hiltner, a pioneer in rhizosphere microbial ecology a...
The enhancement of the growth of a soil microorganism resulting from physical and chemical alteration of the soil and the contribution of excretions and organic debris of roots within a rhizosphere.
The soil region subject to the influence of plant roots. It is characterized by a zone of increased microbiological activity and is an example of the relationship of soil microbes to higher plants.
A sharp boundary cannot be drawn between the rhizosphere and the soil unaffected by the plant (edaphosphere). At the root surface the rhizosphere effect is most intense, falling off sharply with increasing distance.
Growth of a plant markedly changes the microbial population of soil within its influence. In the rhizosphere there are more microorganisms than in soil distant from the plant. This increase is most pronounced with bacteria but is evident with other groups. The rhizosphere effect is seen in seedling plants; it increases with the age of the plant and usually reaches a maximum at the stage of greatest vegetative growth. Upon death of the plant the microbial population reverts to the level of the surrounding soil. Leguminous plants support higher rhizosphere populations than nonlegumes. The stimulation of microorganism growth in the rhizosphere results chiefly from the liberation of readily available organic substances by the growing plant. See also Soil microbiology.
Read more: http://www.answers.com/topic/rhizosphere-2#ixzz32pPQ0I7M
Surrounding of roots or the zone where root and other organisms interact.
The rhizosphere can be divided into several distinct zones (Lynch, 1987). These include the endorhizosphere (root tissue including the endodermis and cortical layers), the rhizoplane (the root surface with the epidermis and mucilaginous polysaccharide layer), and the ectorhizosphere (the soil immediately adjacent to the root). In addition, plants that are colonized by mycorrhizal fungi have a zone termed the mycorrhizosphere (Lindermann, 1988). As mycorrhizal fungi can extend for some distance out from the plant root, this region can be significant. In soils that are well colonized by plants, the plant roots may affect all the soil present in a particular area, and little non-rhizosphere soil (bulk soil) may be present. Even horticultural plants growing hydroponically possess a rhizosphere, and the layer of solution close to the root surface may differ substantially from the bulk solution (Vanpeer and Schippers, 1989).
The biosphere is the functional area of the roots, microorganisms and the chemical and physical conditions that favor the positive and negative interactions in soil.
The agroecological approach should be favoring positive functional interactions by increasing the organic matter, microorganisms to promote efficient and quality health rhizosphere soil resilient to climate change
In your opinion , the soil which l
is found at 30cm far from plant is rhizosphere ???
It is not that easy to make the decission of what the rhizosphere is when working with it. The term was frist coined by the german biologist (I think that he was a biologist) Hiltner, described the rhizosphere as the area around a plant root that is inhabited by a unique population of microorganisms influenced, he postulated, by the chemicals released from plant roots. Today, the rhizosphere definition has been refined to include three zones according to their relative proximity to, and thus influence from, the root. The endorhizosphere includes portions of the cortex and endodermis in which microbes and cations can occupy the "free space", between cells (apoplastic space); so the cortex is part of the rhizosphere. The rhizoplane: medial zone directly adjacent to the root including the root epidermis and mucilage. The outermost zone is the ectorhizosphere which extends from the rhizoplane out into the bulk soil.
- Badges
- Science topic
- Similar topics
- Agriculture
- Soil Science
- Soil