Modelling nitrogen content and distribution in cauliflower (Brassica oleracea L. botrytis)

A model of nitrogen uptake and distribution is presented which describes these processes in relation to the amount of available soil nitrate and the rate of plant growth. Nitrogen uptake is either sink or source limited. Sink limitation is based on maximum N-concentrations of plant compartments. The N-uptake model is combined with a photosynthesis model based on the productivity-nitrogen relationship at the single-leaf level. The model is parameterized using cauliflower as an example crop. Applied to an independent data set, the combined model was able to predict leaf, stem and inflorescence nitrogen concentrations with correlation coefficients between predicted and simulated values of 0.89, 0.66 and 0.86, respectively. The influence of nitrogen supply and light intensity on leaf nitrate-N could also be predicted with good accuracy (r(2) = 0.87). Dry matter production based on the productivity-N relationship and the partitioning into leaf, stem and inflorescence was also reproduced satisfactorily (r(2) = 0.91, 0.93 and 0.92, respectively). (C) 2000 Annals of Botany Company.