Leaf Water Potentials of Sorghum and Corn, Estimated with the Pressure Bomb1

The pressure bomb method for rapid field measurements of water stress in sorghum and corn was evaluated with the thermocouple psychrometer technique. A bomb was used to measure the sap pressures in the vascular bundles of the leaf blades. These values formed acceptable estimates of the leaf water potentials as measured with the thermocouple psychrometer. The osmotic potentials of the xylem sap, measured periodically with the psychrometer, were shown to be relatively small and therefore unimportant.