O2 dynamics in the rhizosphere of young rice plants (Oryza sativa L.) as studied by planar optodes

• DOI: 10.1007/s11104-015-2382-z
• Publication Date: 2015-02-05T15:08:42Z
• Authors: Morten Larsen; Jakob Santner; Eva Oburger; Walter W. Wenzel; Ronnie N. Glud
• Keywords: iron plaque-formation; 0301 basic medicine; MARINE-SEDIMENTS; PH; ph; Planar optode; planar optode; Soil Science; Plant Science; SUBMERGED RICE; 7. Clean energy; ZOSTERA-MARINA; SOLUTION CULTURE; 03 medical and health sciences; Radial oxygen loss; IRON PLAQUE-FORMATION; ROOT AERATION; RADIAL OXYGEN LOSS; AERENCHYMA FORMATION; Plaques imaging; plaques imaging; 0303 health sciences; submerged rice; Rice (Oryza sativa L.); root aeration; stagnant solution; Regular Article; 15. Life on land; solution culture; aerenchyma formation; Oxygen; zostera marina; 13. Climate action; Rhizosphere; STAGNANT SOLUTION; rhizosphere; oxygen; marine sediments; rice (Oryza sativa L); radial oxygen loss

Radial O2 loss (ROL) strongly affect the O2 availability in the rhizosphere of rice. The ROL create an oxic zone around the roots, protecting the plant from toxic reduced chemical species and regulates the redox chemistry in the soil. This study investigates the spatio-temporal variability in O2 dynamics in the rice rhizosphere.Applying high-resolution planar optode imaging, we investigated the O2 dynamics of plants grown in water saturated soil, as a function of ambient O2 level, irradiance and plant development, for submerged and emerged plants.O2 leakage was heterogeneously distributed with zones of intense leakage around roots tips and young developing roots. While the majority of roots exhibited high ROL others remained surrounded by anoxic soil. ROL was affected by ambient O2 levels around the plant, as well as irradiance, indicating a direct influence of photosynthetic activity on ROL. At onset of darkness, oxia in the rhizosphere was drastically reduced, but subsequently oxia gradually increased, presumably as root and/or soil respiration declined.The study demonstrates a high spatio-temporal heterogeneity in rhizosphere O2 dynamics and difference in ROL between different parts of the rhizosphere. The work documents that spatio-temporal measurements are important to fully understand and account for the highly variable O2 dynamics and associated biogeochemical processes and pathways in the rice rhizosphere.