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

A model of nitrogen uptake and distribution is presented which describes th ese processes in relation to the amount of available soil nitrate and the r ate 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 produc tivity-nitrogen relationship at the single-leaf level. The model is paramet erized using cauliflower as an example crop. Applied to an independent data set, the combined model was able to predict leaf, stem and inflorescence n itrogen concentrations with correlation coefficients between predicted and simulated values of 0.89, 0.66 and 0.86, respectively. The influence of nit rogen 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 produc tivity-N relationship and the partitioning into leaf, stem and inflorescenc e was also reproduced satisfactorily (r(2) = 0.91, 0.93 and 0.92, respectiv ely). (C) 2000 Annals of Botany Company.