Optimal Regulation of Gas Exchange: Evidence from Field Data

Since the work of Cowan in 1977 it has been assumed that plants regulate their stomata in a way that maximizes photosynthesis at a constant average rate of transpiration. The approach was further developed by Hari et al. (1986) by introducing additional assumptions which enabled the mathematical solution of the optimization problem using the Lagrangian method. The solution is tested for Scots pine seedlings against field data. The results support the optimization hypothesis.