Measurement of water fluxes and potentials in a single root-soil system

The usefulness of a tensiometer-potometer system in investigations of water flow in the, vicinity of a plant root has been demonstrated. Measurements were made of the root-soil interface water potential, xylem potential and the distribution of water fluxes and root resistance along the length of a maize root. For a root growing in sand, the rhizosphere resistance was 3.5 to 8 times the radial resistance of the root at average rhizosphere, potentials of −250 m bars. For a root growing in sandy loam such rhizosphere resistance was not achieved until the average rhizosphere potential is approximately −2 bars.