OPTIMIZATION MODEL OF STOMATAL REGULATION IN C-3-PLANTS .1. DESCRIPTION OF THE MODEL

A model is suggested to verify the assumption that stomatal regulation ensures maximum efficiency of plant costs (materials and energy) during C-3 photosynthesis. Plant costs were subdivided into two groups: water transport and photosynthetic apparatus reproduction (in the broad sense of the term), Each of these components was presented as a function of CO2 concentration in the leaf intercellular space (c(i)). We obtained an optimization statement, describing c(i) dependency on environmental factors. An invariant of the stomatal regulation was defined and predicted by the optimization statement to be independent of changes in ambient CO2 concentration and water vapor deficit in ambient air. Realization of this prediction was demonstrated by the approximate constancy of the invariant in two plant species upon variation of these factors. With assumptions adopted, the efficiency of plant costs (the ratio of photosynthesis to total costs) typically decreased by about 1% in the cases considered.