CRISP (crayfish and rice integrated system of production): 1. Modelling crayfish (Oryza sativa) growth and production

A ecological sub-model for rice growth, adapted to the culture processes us ed in the lower Mondego river valley (Portugal), is presented. The structur e of the model is based on the production of carbohydrates by the photosynt hesis. Parallel structures were used to simulate the development stage of t he crop, and the tillering process. The model is composed of 11 state varia bles, 14 forcing functions, 22 rate processes, 9 parameters and 17 switches , regulatory processes and calculated values. Simulations were performed fo r periods ranging from January 1995 to October 1996. During this period the simulation results were compared with data on aerial rice biomass and also on the tiller density. In addition, the simulated final rice production pa rameters were compared with the observed values for both years. It can be s tated that the model performs well in what regards prediction of final prod uction parameters but it underestimated rice biomass during the growth peri od. Although at this stage the model is mainly directed towards research, t he final purpose is the management of crayfish and rice production. In orde r to achieve this aim, it will be necessary to couple several sub-models. ( C) 1999 Elsevier Science B.V. All rights reserved.