SOIL AERATION AS A FACTOR IN WATER ABSORPTION BY THE ROOTS OF TRANSPIRING PLANTS

Abstract

Soil aeration as a factor directly influencing passive water absorption by the roots of transpiring, soil-grown tomato plants was studied using atmospheres of N2 and CO2. The influence of these gases on the rate of water absorption by the roots of transpiring plants was measured by observing the time required for equally wilted, paired plants to recover turgor following irrigation under controlled soil-atmosphere conditions in a constant-environment room. The ratio of the time of recovery for N2-treated plants to that for the aerated check plants had a mean value of 1.4 [plus or minus] 0.08 (s. e. of mean) and for CO2-treated plants of 2.6 [plus or minus] 0.17. These ratios were independent of the severity of the initial wilting and of the period of gas saturation up to several hours prior to irrigation. Readily detectable differences in recovery were sometimes apparent after a total exposure of less than 1 hr., particularly with CO2. The effects of these gases appear to be reversible within short periods of time. Deficient aeration, presumedly by controlling metabolic activities which influence cell permeability, may affect the rate of passive water absorption directly and very rapidly. Over a longer period of time, poor aeration may indirectly retard passive water absorption further by causing a reduction in absorbing root surface.