Transpiration of container-grown Acer rubrum under conditions of high evaporative demand

This study was preliminary to developing feed-forward computer control algo rithms to irrigate Acer Rubrum (Red Maple) trees in proportion to predicted transpiration. Transpiration rates of Acer Rubrum and related climate vari ables were measured continuously in a very high, evaporative demand greenho use environment and compared independently to solar radiation and vapor pre ssure deficit (VPD), Measured transpiration rates were further compared to predicted transpiration based on the combination equation. Based on regress ion analyses and the coefficient of determination (R-2), the single variabl e VPD predicted transpiration equally as well as the combination model with an R squared value for both equal to 0.861. Meanwhile, using the single va riable solar radiation to predict transpiration resulted in an R squared va lue of 0.652.