Responses of rice to Fe²⁺ in aerated and stagnant conditions: Growth, root porosity and radial oxygen loss barrier

• Main Authors: Jenjira Mongon, Dennis Konnerup, Timothy D. Colmer, Benjavan Rerkasem
• Format: Journal
• Published: 2018
• Online Access: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84906222642&origin=inward; http://cmuir.cmu.ac.th/jspui/handle/6653943832/45718
• Institution: Chiang Mai University

Lowland rice (Oryza sativa L.) encounters flooded soils that are anaerobic and chemically reduced. Exposure of the roots to high soil Fe 2+ concentrations can result in toxicity. Internal aeration delivering O 2 to submerged roots via the aerenchyma is well understood, but the effect of Fe 2+ on O 2 transport in roots is less studied. We aimed to evaluate the effects of Fe 2+ on growth and root aeration. O. sativa var. Amaroo was grown in aerobic and deoxygenated solutions with 0mM, 0.18mM, 0.36mM, 0.54mM or 0.72mM Fe 2+ using FeS O4 .7H 2O and a control with 0.05mM Fe-EDTA. The treatments were imposed on 14-day-old plants (28-30 days old when harvested). Dry mass, shoot Fe concentration, root porosity and patterns of radial O 2 loss (ROL) along roots were determined. In the aerobic solution, where Fe 2+ was oxidised in the bulk medium, root dry mass increased with higher Fe 2+ ; this was not the case in stagnant solutions, which had no significant root growth response, although Fe oxidation near the root surface was visible as a precipitate. In the highest Fe 2+ treatment, shoot Fe concentrations in aerobic (667mgkg -1 ) and stagnant (433mgkg -1 ) solutions were below the level for toxicity (700mgkg -1 ). Rice responded to high Fe 2+ in aerobic conditions by increasing root porosity and inducing strong barriers to ROL. In stagnant conditions, root porosity was already high and the ROL barrier induced, so these root aeration traits were not further influenced by the Fe 2+ concentrations applied. © CSIRO 2014.