A dynamic one–dimensional model, PSCLIMATE, was developed to simulate microclimate on and around leaf
surfaces for greenhouse cucumbers. Based on an energy balance of plant leaves and heat and mass transfer among air strata
and leaves, the model predicts climate profiles within a plant canopy and the microclimate within a leaf surface boundary
layer. The simulated in–canopy and leaf–surface climate profiles can be used to improve the prediction of pest outbreaks and
their control for greenhouse cucumbers. Validation of the model with data collected from a glass greenhouseindicated that
air temperature (Ta) and relative humidity (RHa) within the canopy were accurately predicted (RMSDs < 0.6
C and 2.9%
at night andRMSDs < 0.2
C and 3.9% in the daytime). Leaf surface temperature (Tl) was predicted with an RMSD < 1.3
C for shaded leaves and < 2.7
C for sunlit leaves. Leaf wetness incidence, as measured by a leaf wetness sensor, was predicted
correctly for a sunlit leaf but not for a shaded leaf. Predicted vapor pressure deficit within the leaf surface boundary layer
provides information that cannot be measured directly by sensors. This model can be used for other crop canopies or
greenhouse structures once the specific characteristics of the greenhouse structure and the plant canopy are defined.Further
improvements to the model are discussed.