A Colorimetric Method for Assaying Dissolved Oxygen Loss from Container‐Grown Rice Roots

Abstract

AbstractAlthough not easily measured measured, oxygen release from rice (Oryza sativa L.) roots determines the plant's ability to survive reducing conditions. Our main objective was to test titanium‐citrate complex for its potential to quantify dissolved O2 concentrations in solutions bathing the whole root system of container‐grown rice cultivars. Influences of aeration status on root aerenchyma formation and radial oxygen loss from roots were also evaluated. Seven rice cultivars were grown in sand culture fertilized with nutrient solution under well drained and hypoxic conditions. Oxygen concentration was measured colorimetrically 6 h after placing plant roots in the Ti3+ ‐citrate solution. Plants were harvested for root porosity and radial oxygen loss estimates at 14 and 35 d after transplanting. Estimates of radial oxygen loss with the Ti3+‐citrate technique were comparable to those obtained with a polarographic oxygen electrode. Both radial oxygen loss and root porosity were enhanced by hypoxia. Rapid formation of aerenchyma at early growth stages coupled with correspondingly high O2 leakage from roots may explain why some rice cultivars cope with the adverse effects of anaerobiosis better than other cultivars.