Nonlinear Dynamic Lettuce Growth Model: Parameter Selection and Estimation for N-Limited Experiments

Regulations of European Commission have imposed upper limits of nitrate in lettuce due to possible health hazards for consumers. These nitrate limits create problems for growers in Northern countries. Therefore an effective modeling tool for lettuce growth is necessary. A parameter estimation for a nonlinear three-state model for N-limited lettuce growth in greenhouses is presented in this paper. The variable structural nitrogen concentration and water content are included in the model. The experimental data collected for identification does not allow to readily estimate all parameters of the model, and a recently proposed Dominant Parameter Selection (DPS) method [8], [9] is used to select the set of parameters to be effectively estimated. The calibrated model was perfectly fitted to existing experimental data.