JXB Advance Access originally published online on July 1, 2003
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Journal of Experimental Botany, Vol. 54, No. 389, pp. 1951-1955,
August 1, 2003
© 2003 Oxford University Press
Short-term exposure to elevated atmospheric CO2 benefits the growth of a facultative annual root hemiparasite, Rhinanthus minor (L.), more than that of its host, Poa pratensis (L.)
Received 10 April 2003; Accepted 16 April 2003
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School of Biological Sciences, Department of Plant and Soil Science, University of Aberdeen, Aberdeen AB24 3UU, UK
* Present address: Radiation Application Research Team, Korea Atomic Energy Research Institute, Taejeon, Korea.
To whom correspondence should be addressed. Fax: +44 (0)1224 272703. E-mail: w.e.seel{at}abdn.ac.uk
The effects of elevated CO2 (650 ppm) on interactions between a chlorophyllous parasitic angiosperm, Rhinanthus minor (L.) and a host, Poa pratensis (L.) were investigated. R. minor benefited from elevated CO2, with both photosynthesis and biomass increasing, and transpiration and tissue N concentration remaining unaffected. However, this did not alleviate the negative effect of the parasite on the host; R. minor reduced host photosynthesis, transpiration, leaf area and biomass, irrespective of CO2 concentration. Elevated CO2 resulted in increased host photosynthesis, but there was no concomitant increase in biomass and foliar N decreased. It appears that the parasite may reduce host growth more by competition for nitrogen than for carbon. Contrary to expectation, R. minor did not reduce the productivity of the hostparasite association, and it actually contributed to the stimulation of productivity of the association by elevated CO2.
Key words: Elevated CO2, nitrogen, parasitic angiosperm, photosynthesis, Poa pratensis, Rhinanthus minor.