Observations on the effects of pressure differences between the bathing media and exudates of excised maize roots

Observation of the water fluxes from excised maize roots at various levels of suction showed significant differences between control roots and those which have been subjected to an evacuation pre-treatment. This involved placing excised lengths of root in bathing medium in a flask which was evacuated (1 cmHg) for 10 min; during this time air bubbles emerged from the cut ends. This pre-treatment has been shown to result in an increase in the density of the root, which is ascribed to the replacement of air in the cortical intercellular spaces by bathing medium. This observed differences in the response to suction in the two groups of roots is therefore explained as a decrease in the resistance to water flow of the cortex of the treated roots.