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 ar ea, 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 t he canopy is calculated with respect to daily growth rate. By comparison wi th 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 diff erent nitrogen and light treatments. The amount of super-optimal N accumula ted in cauliflower depends on N-supply and can exceed 80 kg N ha(-1). (C) 2 000 Annals of Botany Company.