Enhancing biomass production and yield by maintaining enhanced capacity for CO<inf>2</inf> uptake in response to elevated CO<inf>2</inf>

Using four model plants, two members of the Gramineae, rye and wheat, and two Brassicaceae, Brassica napus and Arabidopsis thaliana, two fundamental approaches were exploited to determine how regulating source-sink development would alter photosynthesis, productivity and yield during long-term acclimation to elevated CO2. In one approach we exploited the cold acclimation response of winter wheat, rye and B. napus. In the other approach we modified the dark respiration in A. thaliana to alter availability of respiratory substrates required for anabolic processes, such as fatty acid metabolism, thus reducing sink limitations on canopy photosynthesis at elevated CO2. Taken together, the data show the importance of maintaining strong demand from active sinks when the aboveground canopy is being exposed to elevated levels of the primary substrate of photosynthesis, CO2.