W. L. Bauerle

Transpiration, leaf temperature and stomatal resistance of a greenhouse cucumber crop☆

Abstract Transpiration, leaf temperature and stomatal resistance for a greenhouse cucumber crop were determined by simultaneously measuring solar radiation, air flow, transpiration rate, dew point, and air and leaf temperature profiles. Transpiration rate varied with solar radiation and was not uniformly distributed within the canopy. Leaf temperature was lower than air temperature on clear summer days owing to high transpiration rates. Stomatal resistance was computed and was exponentially related to solar energy. No significant correlations between stomatal resistance and other climatic variables were found.

Plant architectural parameters of a greenhouse cucumber row crop

Abstract A group of parameters which describe the plant architecture of a greenhouse cucumber row crop were experimentally quantified. Leaf area index was found to be linearly related to plant height. Spatial distributions of the foliage area were described by a beta and a periodic cosine distribution function in the vertical and cross-row direction, respectively. The parameters of the distribution functions were also determined as functions of plant height. Each architectural parameter was chosen to be useful in greenhouse microclimate studies, especially in modeling the radiation transfer in a row crop canopy.

Implementing a decision and expert system model for individual nutrient selection

Abstract 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 together with intuitive modeling for the derivation of a plant growth function through the use of expert systems provided a flexible and adaptable model. The model was assembled using a decision tree as the core with three rulebases providing inputs into the tree. The decision tree was comprised of a decision node (which nutrients?), a chance node (probabilities of solar irradiance ranges) and an outcome (plant growth function). The rulebase for the plant growth function was derived by growing a cucumber crop in a greenhouse at the Ohio Agricultural Research and Development Center, Wooster, Ohio. The expected value of each recipe was determined by computing the cross-products of the probabilities of irradiance levels and the plant growth function.