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item Rogers, Alistair
item Gibon, Yves
item Morgan, Patrick
item Bernacchi, Carl
item Ort, Donald
item Long, Stephen

Submitted to: Plant Cell and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2006
Publication Date: 5/1/2006
Citation: Rogers, A., Gibon, Y., Morgan, P.B., Bernacchi, C.J., Ort, D.R., Long, S.P. 2006. Increased carbon availability at elevated carbon dioxide concentration improves nitrogen assimilation in legumes. Plant Cell and Environment. 29:1651-1658.

Interpretive Summary: Carbon dioxide in the world’s atmosphere is on the rise. In the last century it has risen 20% and this geologically unprecedented pace will continue resulting in an atmosphere in 2050 containing 50% more CO2 than it did in 1900. While this enrichment of the atmosphere CO2 promises the potential of increase crop yield the inability of crops to acquire enough nitrogen often prevents the expected increase. Our results show that in the case of soybean, which has the ability to fix atmospheric nitrogen if it is supplied with adequate resources from the plant; nitrogen does not limit the response of yield to CO2. This outcome indicates that legume in general will respond favorably to rising CO2.

Technical Abstract: The atmospheric carbon dioxide concentration ([CO2]) has risen by 30% in the last 250 years and is predicted to rise an additional 50% by 2050. This extremely rapid rise in [CO2] portends critical uncertainty over both carbon uptakes by terrestrial ecosystems, and food production. Although photosynthesis and growth are typically stimulated when plants are grown at elevated [CO2] the stimulation often disappears with time. The observed and modelled attenuation are nearly always associated with the inability of plants to acquire sufficient nitrogen, resulting in the commonly observed reduction in leaf nitrogen content. Here we show, in two consecutive seasons, that unfertilized fields of soybean grown at elevated [CO2] were able to overcome an early season reduction in leaf nitrogen content because additional carbohydrate from increased photosynthesis at elevated [CO2] resulted in improved nitrogen assimilation in subsequent growth. Results from this model field system suggest that nitrogen limitation may not restrict increases in soybean production with rising [CO2] and may not prevent increased carbon uptake into terrestrial ecosystems that include legumes.