Measurement and modeling of the transpiration of a temperate red maple container nursery

This study was designed to estimate transpiration in a container nursery under both irrigated and water stressed conditions using a biologically based canopy model. The model, MAESTRA, was parameterized with a suite of physiological measurements and an explicit response function for soil moisture deficit was incorporated. The model was validated against transpiration measurements monitored by the stem heat balance method in both irrigated and non-irrigated plots. Distinct disconnects between estimated and measured values were found at high soil moisture deficits. The data justify the incorporation of a soil moisture component to simulate transpiration of plants with root zones in limited soil volumes. The agreement between measured and modelled canopy transpiration separated at a soil moisture deficit of 0.85 or greater, however, estimates of daily transpiration simulated by the model were in agreement with sap-flow measurements when water was not limiting. The data indicate that cuticular conductance at soil moisture deficits ≤0.85 may explain the separation in model estimates and actual plant water loss.