IMPLEMENTING A DECISION AND EXPERT-SYSTEM MODEL FOR INDIVIDUAL NUTRIENT SELECTION

A decision analysis and expert system model was applied to the problem of individual nutrient selection for cucumber growth in a controlled environment. The ability to use a decision tree with probabilities tog ether with intuitive modeling for the derivation of a plant growth fun ction through the use of expert systems provided a flexible and adapta ble model. The model was assembled using a decision tree as the core w ith three rulebases providing inputs into the tree. The decision tree was comprised of a decision node (which nutrients?), a chance node (pr obabilities of solar irradiance ranges) and an outcome (plant growth f unction). The rulebase for the plant growth function was derived by gr owing a cucumber crop in a greenhouse at the Ohio Agricultural Researc h and Development Center, Wooster, Ohio. The expected value of each re cipe was determined by computing the cross-products of the probabiliti es of irradiance levels and the plant growth function.