PARENT SESSION
Contributed Oral Session 67: Modeling: Nutrient Cycling; Food Webs
Tuesday, August 9, 1:30 PM - 5:00 PM, Meeting Room 520 C, Level 5, Palais des congrès de Montréal

Modeling the effects of elevated CO₂ on plant stoichiometry.

Loladze, Irakli^*,1, Zea, Eduardo², ¹ University of Nebraska - Lincoln, Lincoln, NE² Princeton University, Princeton, NJ

ABSTRACT- One of the most certain aspects of global change is the increase in the concentrations CO₂of atmospheric CO₂ - the major nutrient for plants. Numerous field experiments showed that elevated CO₂ generally enhance photosynthesis but reduces transpiration. Enhanced photosynthesis leads to increased carbon (C) assimilation, while decreased transpiration can lead to reduced mass flow of nutrients to roots. This raises a question of how elevated CO₂ affects C:Micronutirent content in plants. The importance of this question is underscored by the fact that chemical elements such as iron (Fe), iodine (I), and zinc (Zn) are already deficient in the diets of the half of human population, which derives 84% of its calories from plant products. Apart from an overall decline in nitrogen (N) concentration, however, little is known about the effects of high CO₂ on other chemical elements. One of the ways (and, perhaps, the least inexpensive way) to narrow this gap in our knowledge is to construct a mathematical model of an individual plant that reflects both enhanced C assimilation and reduced transpiration in elevated CO₂ atmosphere. We present such a minimal, in our view, model consisting of the system of ordinary differential equations that tracks nutrient concentrations in soil, rhizosphere, and inside of a plant. Simulations of the model show important differences in elevated CO₂ effect on stoichiometry of plants grown in flooded (e.g. rice) and non-flooded (e.g. wheat) conditions. The results of the model experiments will be compared with all published albeit very limited data.

Key words: elevated CO2, mathematical model, stoichiometry, plant quaility