LEAFC3-N: a nitrogen-sensitive extension of the CO2 and H2O gas exchange model leafc3 parameterised and tested for winter wheat (Triticum aestivum L.)

Abstract The generic steady-state flux model ‘LEAFC3’ [Nikolov, N.T., Massman, W.J., Schoettle, A.W., 1995. Coupling biochemical and biophysical processes at the leaf level: an equilibrium photosynthesis model for leaves of C-3 plants. Ecol. Model. 80, 205–235], that couples major processes of CO 2 and H 2 O gas exchange with stomatal function and the energy and mass transfer in the leaf-boundary layer was extended to account for effects of leaf nitrogen content. Relationships between nitrogen mass per unit leaf area, N a , and key model parameters were derived from field measurements of CO 2 exchange rate ( A ) and transpiration rate ( E ) carried out on leaves of winter wheat at different stages of development. Maximum carboxylation rate V c,max , maximum quantum yield of photosynthetic electron transport, φ a , and the ratio of mitochondrial respiration R dark to V c,max , C dr , were correlated linearly with N a . The parameter m that determines the composite sensitivity of leaf stomatal conductance g s to net photosynthesis rate, air humidity, and ambient CO 2 concentration, showed a non-linear decline with increasing N a . The maximum rate of electron transport, J max , was assumed proportional to V c,max and hence only indirectly related to N a . The proposed nitrogen-sensitive LEAFC3-N model was validated based on an independent set of data obtained from diurnal time course measurements of A and E . Although the parameterisation of the model has to be verified with more data from different growth conditions, the model can be used as a submodel in modelling plant and canopy-scale gas exchange of winter wheat.