Oxidizing power of plant roots

Although we presented evidence for oxygen release by roots and subsequent oxidation of reduc-tants in the root zone, a fundamental question is whether the amount of oxygen released by roots is adequate to maintain oxidized rhizosphere to support aerobic respiration. As discussed earlier, oxygen released from roots will be first consumed during chemical oxidation of Fe, Mn +, and S , followed by heterotrophic and autotrophic oxidation by bacteria. The kinetics of chemical oxidation are much more rapid than biological oxidation. 

FIGURE 7.29 Methane and Oj flux in selected emergent macrophytes cultured in flooded organic soil in Florida. (Reddy, K. R., Unpublished Results, University of Florida.) 

Once the reductants present in the oxidized root zone are depleted, subsequent oxidation of these compounds will depend on the diffusive resupply across the aerobic-anaerobic interface. The ability of wetland plants to transport oxygen has attracted biologists and engineers to include this process into designing constructed wetlands for wastewater treatment. 

Oxidizing power of wetland plant roots depends on 

---