Oxygen Transport and Root Respiration of Maize Seedlings

Abstract
Oxygen uptake and ATP/ADP ratio were simultaneously monitored during incubation of excised maize (Zea mays L. INRA 508) root tips under varying O2 partial pressure. Both variables were independent of O2 tension until a critical O2 pressure was reached. Below this pressure, ATP/ADP ratio and respiratory rate declined. However, in tissues having a high glycolytic capacity, the correlation between the ATP/ADP ratio and the respiratory rate breaks down as O2 tension decreases, due to the increasing contribution of fermentative processes.