Dr. Manuele Tamo
International Institute of Tropical Agriculture (IITA) -BCCA
Republic of Benin
Fax : +229-30-14-66
Growth and development of a photosensitive cowpea variety are studied with the help of a demographic canopy model. The major driving variables are abiotic factors such as temperature, solar radiation, soil phosphate and water. 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. The delay subroutine is used to emulate stochasticity in growth, aging, and loss of population attributes. A modified functional response model from predation theory is used to estimate the daily photosynthates aquisition. Dry matter allocation is simulated by a matabolic pool model. Growth and yield formation of the plant are driven by the computed ratio between carbohydrates supply and demand. Demand parameters were estimated from detailed dry matter data of developing plant organs. 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.
This model has been designed for research purposes, to be used as a tool for the exploration of the cowpea egro-ecosystem. It demostrates the suitability of the demographic approach for the analysis of cowpea growth and development. The model also permits the assessment of yield limiting factors, which is of great value as herbivory will be added to the model in the future.
Source of the Abstract:
Joergensen S.E., B. Halling-Soerensen and S.N Nielsen (Edts.) 1996: Handbook of Environmental and Ecological Modelling. CRC Press Boca Raton et al. 672 pp.