Carbon Cycle Science

Plant Physiology and Phenotyping

Plants, and terrestrial ecosystems, are not simply passive respondents to rising carbon dioxide (CO₂) concentration.  They play an important role in determining the rate of global change, and are subsidizing our use of fossil fuels by absorbing approximately 30% of anthropogenic CO₂ emissions.  The CO₂ released when plants are used as biofuels is balanced by the CO₂ they take up during growth, therefore plants can off set fossil fuel use and provide fuels that are close to carbon neutral.  If the CO₂ released from biofuels could be captured and stored, biofuels could provide an alternative energy source, and remove CO₂ from the atmosphere.  In many ecosystems, and on our farms, plant productivity is limited by CO₂.  Therefore, rising CO₂ concentrations offer a potential boon for crop production, which, if fully exploited, could offset many of the projected negative impacts of global change on crop productivity.  Understanding plants & ecosystems is central to the major challenges at the intersection of climate, energy and food security, our research touches all these areas.

We are attempting to improve understanding of the mechanisms that underlie whole plant and ecosystem responses to global change.  Research has focused on the long-term response of plants to rising CO₂concentration in large field experiments where Free Air CO₂ Enrichment (FACE) technology has been used to expose vegetation to the levels of CO₂ predicted to occur in the middle of the century.  We have found that a sustained stimulation in photosynthesis and growth is dependent on the capacity to utilize the extra photosynthate produced at elevated CO₂ and on an adequate nitrogen supply.  Signals for the carbon and nitrogen status of a plant, and to an extent the ecosystem, are brokered in the leaf and we focus on understanding and elucidating the interactions between carbon and nitrogen metabolism that underlie many of the commonly observed responses of plants to global change.

FACE experiments have shown that the few lines of crops that have been tested in their production environment had a less than maximal responses to CO₂.  Given the 10-15 year timeline to move from discovery to commercial application, there is an urgent need to evaluate current germplasm for CO₂responsiveness.  Meeting this challenge will require the combination of quantitative genetics with molecular and biochemical phenotyping and general agronomic and biochemical understanding of CO₂ responsive germplasm.  To help meet this challenge we are developing a platform for high throughput biochemical phenotyping that focuses on parameters associated with central metabolism.  We plan to use this platform to help identify CO₂ responsive crops and highly productive, but sustainable biofuels.