Fig. 4.

Rates of radial oxygen flow (J_O2) along the root when perfused with 20.3% O₂ at overpressures of 10, 20, and 30 kPa at the entrance of the segments (reference atmospheric pressure 100 kPa=0.1 MPa). Assuming a linear drop in pressure along the segments for the three different pressures, average values of 105, 110, and 115 kPa were used to calculate P_O2 and the actual O₂ concentration. For each distance from the root apex, radial oxygen flows increased with increasing overpressures, but increases were not significantly different. Measurements were taken at 25 °C in a temperature-controlled room. Data given are means ±SE (n=8).