Accumulation of Oxygen Gas in Excised Maize Root on Aging in Water, and Water Uptake by the Root

Transfer of excised maize root from wet sawdust to water causeda considerable reduction in the exudation rate of the root.After 1-day aging in water, the exudation rate increased about8-fold and the exudation continued for 3 days. Osmotic pressureof the exudate from the root decreased with time after excisionreaching almost zero in 2 days in spite of a high exudationrate. Concentrations of sugars, acids, Ca²⁺ and Mg²⁺ in theexudate decreased with the decrease of osmotic pressure, whilethe decrease in K⁺ concentration delayed and P₁ concentrationincreased. The gas content of the root, especially of O₂, increased duringaging in water. The accumulated O₂ gas may promote water uptake,because degasification of the root by evacuation induced a decreaseof water uptake. Also, the longitudinal gradient of the O₂ contentin the root coincides with the gradient of water uptake intensity. (Received February 7, 1982; Accepted July 2, 1983)