Nitrogen Assimilation and Growth of Wheat under Elevated Carbon Dioxide

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 99; no. 3; pp. 1730 - 1735
• Main Authors: Bloom, Arnold J., Smart, David R., Nguyen, Duy T., Searles, Peter S.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 05-02-2002; National Acad Sciences; The National Academy of Sciences
• Subjects: Biological Sciences; Carbon dioxide; Carbon Dioxide - pharmacology; Chloroplasts; Chloroplasts - drug effects; Chloroplasts - metabolism; Nitrates - metabolism; Nitrites - metabolism; Nitrogen; Nitrogen - metabolism; Nutrient solutions; Nutrition; Peas; Photosynthesis; Plant growth; Plant Leaves - growth & development; Plant Roots - growth & development; Plant Shoots - growth & development; Plant Stems - growth & development; Plants; Triticum - drug effects; Triticum - growth & development; Triticum aestivum; Wheat
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.022627299

Simultaneous measurements of CO2and O2fluxes from wheat (Triticum aestivum) shoots indicated that short-term exposures to elevated CO2concentrations diverted photosynthetic reductant from NO3
-or NO2
-reduction to CO2fixation. With longer exposures to elevated CO2, wheat leaves showed a diminished capacity for NO3
-photoassimilation at any CO2concentration. Moreover, high bicarbonate levels impeded NO2
-translocation into chloroplasts isolated from wheat or pea leaves. These results support the hypothesis that elevated CO2inhibits NO3
-photoassimilation. Accordingly, when wheat plants received NO3
-rather than NH4
+as a nitrogen source, CO2enhancement of shoot growth halved and CO2inhibition of shoot protein doubled. This result will likely have major implications for the ability of wheat to use NO3
-as a nitrogen source under elevated CO2.