Optimal nitrogen content and photosynthesis in cauliflower (Brassica oleracea L. botrytis). Scaling up from a leaf to the whole plant

A simple model of photosynthesis is described which is dependent on leaf area, organic nitrogen content and distribution within the canopy as well as on the light and temperature environments. The model is parameterized using a cauliflower crop as an example. The optimized protein-N profile within the canopy is calculated with respect to daily growth rate. By comparison with measured protein-N contents, the amount of super-optimal N-uptake, i.e. the N-uptake which does not increase productivity, is assessed for two different nitrogen and light treatments. The amount of super-optimal N accumulated in cauliflower depends on N-supply and can exceed 80 kg N ha^-1. (C) 2000 Annals of Botany Company.