| Abstract: | Lettuce was grown in nutrient solution in a climate chamber under varied levels of temperature and radiation and in the greenhouse under fluctuating climatic conditions. A model to calculate maximum nitrate inflow (Imax) in relation to relative growth rate (RGR) and root:shoot ratio (RSR) was used for computing total-N uptake. For doing this, developing of submodels to calculate RGR and RSR was necessary. The good agreement between calculated N uptake and measured total-N taken up by the plants supports the assumption that Imax reflects the inflow necessary to meet the demand of plants. |
