The spatially and temporally upscaled version of the process based Farquahar’s photosynthesis model of Chen et al.,1999, was used to simulate a winter wheat  crop at different levels of nitrogen treatments, at ambient CO2 concentration.  The simulated growth was compared with continuous measurements taken at the Indian Agricultural research Institute farm in 2000-2001. The model was able to simulate the biomass as well as grain yield with reasonable accuracy (r2= 0.81 and 0.83). The main controls on biomass production were attributed to soil moisture, which controls the stomatal dynamics and the leaf area index, LAI. Nitrogen status affected the magnitude of Vcmax, which directly affect photosynthesis in C3 plants. We  used sun lit and shaded LAI  fractions to explicitly upscale  the leaf level photosynthesis using respective stomatal conductance.  The ability of this process model, which runs at daily time step, to realistically simulate wheat growth is encouraging because of its direct applicability for  regional scale applications, using remote sensing products.