Roots rhizosphere

Plexiglas box divided by nylon gauze into various vertical compartments differently proximate to roots Rhizosphere and bulk soil initially compartmentalized. Soil-root interface scarcely resolved. Apparatus time expensive and difficult to build up. No particular constraints for root growth. 94, 95, 130-132... 

Table II. Sources and Action of Secondary Plant Compounds on Root - Rhizosphere Interactions...

In the soil close to the roots (rhizosphere) there is much greater release of potassium, phosphorus and nitrogen than in the soil that is a long way... 

Various writers have from time to time emphasized the importance as a plant nutrient of the carbon dioxide released from roots, and by the microorganisms living on the roots (rhizosphere microorganisms) and on the organic matter. The amount of carbon dioxide in the upper air is fairly constant at 0.03% by volume. However, where a crop is grown... 

The intensity and capacity of soil reduction also influence plant functions in wetland ecosystems. As soil reduction intensifies, demand for oxygen in the root rhizosphere also increases. Under some reducing conditions, with high soil reduction capacity, plant roots may not be able to create an oxidized rhizosphere, which helps in neutralizing sulfide and other plant toxicants. 

How is iron plaque formed on the surface of roots of wetland plants List the processes the iron plaque can impact in the root rhizosphere. 

Wetland plants growing in flooded soil possess well-developed aerenchyma (airspace tissue) systems that act as conduits for the diffusion of oxygen from the atmosphere through the plant leaves and stems to the roots. The root rhizosphere contains an oxidized area where reduced sulfide can be oxidized to snlfafe or elemenfal snlfnr (Fignre 11.20). Sulfide can be oxidized either chemically or microbiologically to elemental snlfnr. Beggiatoa organisms that oxidize H2S to elemental sulfur are abundant in the root zone. 

Methane oxidation cannot occur in the absence of oxygen therefore, in wetland soils the process is only important in the surface oxic-anoxic boundary or within the plant root rhizosphere. However, aerated soil regions or oxic layers have been demonstrated to consume as much as... 

Clonal differences in Cd uptake are independent of whether the plant is cultivated in nutrient solution or soil however, the relation between clones in accumulation of other metals, such as Cu and Zn, may differ depending on these two media (Greger et al., 2001). In the case of Cu and Zn, the presence of soil may trigger roots to initiate rhizosphere processes (Stoltz and Greger, 2002), which is absent in solution culture. It is therefore important to investigate differences in root rhizosphere mechanisms between Salix clones. 

Cushman, J.H., 1984. Nutrient transport inside and outside the root rhizosphere generahzed model. Soil Sci. 138, 164-171. 

The soil solution is extremely dilute and generally contains 0.3-3.0 ppm of P (10 -10 M of phosphate). This concentration is usually a good deal less than that of the other major nutrient ions. Plant roots can nevertheless absorb sufficient phosphate from the very dilute soil solution. Inside the roots and in sap, the phosphate concentration is generally 10 -10 higher than in soil solution. Species present are pH dependent. The pH in the immediate vicinity of the plant roots (rhizosphere) is not necessarily the same as that of the soil solution a little further away. 

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