Simulation model for maize crop growth based on acquisition and allocationprocesses for carbohydrate and nitrogen

A population model for maize growth and development driven by temperature, solar radiation, soil water and soil nitrogen is presented. A time-varying distributed delay model is used to describe the dynamics of the attributes number, biomass and nitrogen belonging to leaf, root, stem, grain, rachys a nd husk populations. Photosynthate production as well as water and nitrogen acquisition was simulated with a demand-driven ratio-dependent functional response model. Carbohydrate, water and nitrogen supply-demand ratios were calculated to control the growth of different populations of plant. The met abolic pool model was used to allocate carbohydrates to plant subunits. The model was validated with published observations and field data from a 95- and a 120-day variety grown at the Research Station of the International In stitute of Tropical Agriculture in Calavi, in the southern part of the Repu blic of Benin (West Africa). It was concluded to satisfactorily represent c rop phenology and growth patterns. Moreover, the model permitted the assess ment of drought stress, soil nitrogen, and planting density effects on maiz e growth and development. (C) 1999 Elsevier Science B.V. All rights reserve d.