Grant: Discovery Grants Program - Individual

The effects of rising atmospheric CO2 concentrations on plant growth have been studied intensively. In spite of these efforts, there are still relatively few generalizations we can make concerning these effects. Elevated CO2 generally increases growth, but the magnitude of this effect varies widely. In particular, the effect of elevated CO2 on plants grown as individuals differs dramatically from its effects when plants are grown in competition. Work from my laboratory has demonstrated that in addition to its effects on growth, CO2 also interacts with light to control development. We have shown that the effect of CO2 on germination, stem elongation, branching, and flowering can vary in magnitude and direction depending on light quality and photoperiod. These effects in turn, can have a dramatic effect on the growth response. An understanding of how and why atmospheric CO2 affects development will clearly be useful in explaining the confusing and often complex effects of CO2 on plant growth. To this end, the proposed research will examine two aspects of the effect of CO2 on development. First, we will use the developmental mutants of Arabidopsis to explore which developmental pathways are impacted by CO2. This will provide a framework for understanding and predicting the effects of CO2 on development under different environmental conditions. Second, we will examine the possibility that the contrasting effects of CO2 on growth of individually versus competitively grown plants are related to the changes in light quality associated with competition. We will grow species differing in shade tolerance and Arabidopsis mutants differing in their capacity to respond to light quality at ambient versus elevated CO2 as individuals and in competition. Results will be useful in helping us predict how rising atmospheric CO2 concentrations will affect plant populations and communities and will be of interest to foresters and agronomists, as well as to ecologists.