Optimal control of gas exchange.

A major difficulty in evaluating the optimization theory of leaf gas exchange under conditions of water deficit has been that of obtaining suitable experimental data. Mathematical solutions to three formulations of optimal stomatal control are presented which can be tested experimentally. First, it is assumed that the movement of stomata and changes in environmental factors are slow compared to changes in the internal CO(2) concentration. The optimization problem is solved under this assumption, and the procedures for testing the solution experimentally are described. Second, instantaneous stomatal response is postulated and the solution suggests that very rapid oscillations provide optimal CO(2) uptake. Third, variable stomatal dynamics are postulated and the mathematical solution shown to be similar to that of the second case. The second and third cases can also be tested empirically.