%0 Research article
%T Optimal stomatal control in relation to leaf area and nitrogen content
%A Farquhar, Graham D.
%A Buckley, Thomas N.
%A Miller, Jeffrey M.
%D 2002
%J Silva Fennica
%V 36
%N 3
%R doi:10.14214/sf.530
%U https://silvafennica.fi/article/530
%X We introduce the simultaneous optimisation of water-use efficiency and  nitrogen-use efficiency of canopy photosynthesis. As a vehicle for this  idea we consider the optimal leaf area for a plant in which there is no  self-shading among leaves. An emergent result is that canopy  assimilation over a day is a scaled sum of daily water use and of  photosynthetic nitrogen display. The respective scaling factors are the  marginal carbon benefits of extra transpiration and extra such nitrogen,  respectively. The simple approach successfully predicts that as  available water increases, or evaporative demand decreases, the leaf  area should increase, with a concomitant reduction in nitrogen per unit  leaf area. The changes in stomatal conductance are therefore less than  would occur if leaf area were not to change. As irradiance increases,  the modelled leaf area decreases, and nitrogen/leaf area increases. As  total available nitrogen increases, leaf area also increases. In all the  examples examined, the sharing by leaf area and properties per unit  leaf area means that predicted changes in either are less than if  predicted in isolation. We suggest that were plant density to be  included, it too would further share the response, further diminishing  the changes required per unit leaf area.