Oxygen Diffusion in the Soil-Plant System IV. Oxygen Concentration Profiles, Respiration Rates, and Radial Oxygen Losses Predicted for Rice Roots1
- R. J. Luxmoore,
- L. H. Stolzy and
- J. Letey2
Oxygen concentration profiles, mean respiration rates, and the percent radial oxygen losses (proportion of the oxygen diffusing into the top of the root that is lost radially from the root) were obtained from an analysis of steady state oxygen diffusion in rice (Oryza sativa L.) root models under simulated paddy field conditions.
An increase in root radius and water layer thickness results in an increase in the oxygen concentration within the root and at the root wall at all positions along the root. These higher oxygen concentrations resulted in higher mean respiration rates, however the percent radial oxygen loss (PRL) was reduced. The mean respiration rate and PRL were both decreased with increase in root length. Under paddy conditions it seems that oxygen concentration is a factor limiting respiration rate since the mean respiration rate is much less than the maximum rate for mature root tissue. A 20-cm root with 0.05-cm radius is predicted to radially lose about 5 to 7% of the oxygen diffusing into the top of the root. This has considerable ecological significance for roots growing in an anaerobic medium.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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