Carbon dioxide rhizosphere

Root products, as defined by Uren and Reisenauer (17), represent a wide range of compounds. Only secretions are deemed to have a direct and immediate functional role in the rhizosphere. Carbon dioxide, although labeled an excretion, may play a role in rhizosphere processes such as hyphal elongation of vesicular-arbuscular mycorrhiza (39). Also, root-derived CO2 may have an effect on nonphotosynthetic fixation of CO2 by roots subject to P deficiency and thus contribute to exudation of large amounts of citrate and malate, as observed in white lupins (40). The amounts utilized are very small and, in any case, are extremely difficult to distinguish from endogenous CO2 derived from soil and rhizosphere respiration. 

M. C. Rillig, K. M. Scow, J. N. Klironomos, and M. F, Allen, Microbial carbon-substrate utilisation in the rhizosphere of Cutierrezia sarothrae grown in elevated atmospheric carbon dioxide. Soil Biology and Biochemistry 29 1387 (1997). 

Schortemeyer, M., U.A. Hartwig, G.R. Hendrey, and M J. Sadowsky (1997). Influence of free air carbon dioxide enrichment (FACE) on microbial communities in the rhizosphere of white clover and perennial ryegrass. Soil Biol Biochem., 28 1717-1724. 

The rhizosphere is complex and heterogeneous. It contains exudates, lysates, mucilage, secretions, dead cell material and carbon dioxide all of which affect substrate flow to the root (Lynch and Whipps, 1991). Moreover, certain soil micro-... 

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... 

Gorissen, A., Cotrufo, M.E., 1999. Elevated carbon dioxide effects on nitrogen dynamics in grasses, with emphasis on rhizosphere processes. Soil Sci. Soc. Am. J. 63,1695-1702. 

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