Rising demand for grain crops and an expanding biofuel industry are vastly
increasing pressure to maximize productivity on agricultural land. Rising atmospheric [CO2] is increasing global temperature and altering precipitation patterns, which will challenge agricultural productivity in the future. Yet, rising [CO2] also provides a unique opportunity to markedly increase the productivity of C3 crops, but the average yield stimulation observed to date is well below the potential theoretical gains. This suggests there is significant room for improving productivity. There are tens of thousands of lines of wheat, rice, soybean and other crops available, but only a fraction of these have been
tested for CO2 responsiveness in a production environment. Yield is a complex
phenotypic trait determined by the interactions of a genotype with the environment.
Selection of promising genotypes and characterization of physiological mechanisms will
only be effective if the crop improvement and systems biology approaches are closely
linked to actual production environments, i.e., on the farm within the major growing
regions. Free Air Carbon dioxide Enrichment (FACE) experiments can provide the
platform upon which to conduct genetic screening as well as to elucidate the inheritance
and mechanisms that underlie cultivar differences in productivity under elevated [CO2].
We propose a new generation of large scale, low-cost per unit area, FACE facilities and
experiments to identify the most CO2-responsive genotypes and provide starting lines for
future breeding programs. This is necessary if we are to realize the potential yield gains
n the future.