1: Environ Pollut. 1994;83(1-2):155-89. Related Articles, Links
Click here to read
Plant responses to atmospheric CO2 enrichment with emphasis on roots and
the rhizosphere.
Rogers HH, Runion GB, Krupa SV.
National Soil Dynamics Laboratory, ARS-USDA, PO Box 3439, Auburn, Alabama
36831, USA.
Empirical records provide incontestable evidence of global changes: foremost among these changes is the rising
concentration of CO(2) in the earth's atmosphere. Plant growth is nearly always stimulated by elevation of CO(2).
Photosynthesis increases, more plant biomass accumulates per unit of water consumed, and economic yield is enhanced. The
profitable use of supplemental CO(2) over years of greenhouse practice points to the value of CO(2) for plant
production. Plant responses to CO(2) are known to interact with other environmental factors, e.g. light, temperature,
soil water, and humidity. Important stresses including drought, temperature, salinity, and air pollution have been shown
to be ameliorated when CO(2) levels are elevated. In the agricultural context, the growing season has been shortened for
some crops with the application of more CO(2); less water use has generally, but not always, been observed and is under
further study; experimental studies have shown that economic yield for most crops increases by about 33% for a doubling
of ambient CO(2) concentration. However, there are some reports of negligible or negative effects. Plant species respond
differently to CO(2) enrichment, therefore, clearly competitive shifts within natural communities could occur. Though of
less importance in managed agro-ecosystems, competition between crops and weeds could also be altered. Tissue
composition can vary as CO(2) increases (e.g. higher C: N ratios) leading to changes in herbivory, but tests of crop
products (consumed by man) from elevated CO(2) experiments have generally not revealed significant differences in their
quality. However, any CO(2)-induced change in plant chemical or structural make-up could lead to alterations in the
plant's interaction with any number of environmental factors-physicochemical or biological. Host-pathogen relationships,
defense against physical stressors, and the capacity to overcome resource shortages could be impacted by rises in CO(2).
Root biomass is known to increase but, with few exceptions, detailed studies of root growth and function are lacking.
Potential enhancement of root growth could translate into greater rhizodeposition, which, in turn, could lead to shifts
in the rhizosphere itself. Some of the direct effects of CO(2) on vegetation have been reasonably well-studied, but for
others work has been inadequate. Among these neglected areas are plant roots and the rhizosphere. Therefore, experiments
on root and rhizosphere response in plants grown in CO(2)-enriched atmospheres will be reviewed and, where possible,
collectively integrated. To this will be added data which have recently been collected by us. Having looked at the
available data base, we will offer a series of hypotheses which we consider as priority targets for future research.
PMID: 15091762 [PubMed]
[permaculture] Entrez PubMed Plant responses to atmospheric CO2 enrichment with emphasis on roots and the rhizosphere.,
Lawrence F. London, Jr., 03/16/2006