EVAPOTRANSPIRATION MEASUREMENT AND MODELING FOR A POTTED CHRYSANTHEMUM CROP

A crop of chrysanthemums was grown on a lysimeter in a variable shade greenhouse. Measurements were made of evapotranspiration (ET), air vel ocity, air temperature, air dew point temperature, carbon dioxide conc entration, leaf temperature, leaf area, and photosynthetically active and global solar radiation. Comparisons were made between the evapotra nspiration of the crop and the predicted water use from a computer mod el that used temperature, relative humidity, and solar irradiance leve ls as inputs (the combination model). The ET was studied as a function of vapor pressure deficit (VPD) and solar irradiance levels both sepa rately and together. A relationship between stomatal resistance and so lar irradiance levels for chrysanthemums was established.