| Summary: | A demographic canopy model for a photosensitive cowpea [Vigna unguiculata (L.) Walp.] variety, whose growth and development is driven by temperature, solar radiation, soil phosphate, and water is presented. The dynamics of age-structured populations of leaves, shoots, roots, peduncles, and other reproductive organs having numbers and dry matter attributes is simulated by a time-varying distributed delay model with attrition. A modified functional response model from predation theory is used to estimate the daily photosynthates acquisition. Dry matter allocation is simulated by a metabolic pool model. Growth and yield formation of the plant are driven by the computed ratio between carbohydrates supply and demand. Simulation results are compared with four sets of field data. Further, the model has been used to evaluate the effect of drought stress and different levels of available phosphate in the soil. The model is designed for research purposes, to be used as a tool for further studies of the cowpea agro-ecosystem.
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