Plant Ethanol Content as an Index of the Soil-Oxygen Status

The feasibility of using the plant ethanol content as a measure of the soil-oxygen status was investigated. No satisfactory correlation between the oxygen status of the growth media and the plant ethanol content was found. The plant ethanol content was related to the plant's morphological age and development as well as the oxygen treatments imposed. The results of these experiments appear to rule out this method as a diagnostic method of characterizing the oxygen status of the growth medium. The findings have considerable implication when one considers the use of the plant ethanol content as a measure of the soil oxygen status. First, plants grown under continuous low root zone oxygen conditions for an extended length of time do not exhibit the high ethanol content which plants grown under an adequate oxygen supply in the root zone do after suddenly being subjected to a low root zone oxygen supply for short periods of time. This means that this method would not be suitable for detecting prolonged periods of unfavorable oxygen conditions, but may, under certain instances, be useful in detecting periods of short adverse oxygen conditions. Second, the dependency of the plant ethanol content on the plant's morphological age overshadows the effects of the oxygen stresses imposed on the plant grown continuously under conditions of adverse oxygen supply, thus making the selection of individual plants selected for measurements extremely critical. Third, the large variability in the values of ethanol content obtained from individual plants apparently at the same morphological age, when grown continuously under a given set of oxygen stresses, makes the use of this method for predicting the soil oxygen status from measurements of the plant ethanol content very doubtful.