Characteristics of Coatings formed on Rice Roots as Affected by Iron and Manganese Additions

Abstract

Rice plants (Oryza sativa ‘Brazos’) were grown with varying rates of application of Fe and Mn. Solution concentration of Fe ranged from 0.5 to 50.5 ppm and Mn from 0.1 to 12.5 ppm in an experiment designed to study the coatings formed on rice roots grown under anaerobic conditions. Root coatings were removed for analysis with citrate‐bicarbonate‐dithionite solution. Chemical analysis inidcated that the coatings were composed primarily of Fe. Manganese was present in detectable amounts only when solution concentrations were > 1.0 ppm.Scanning electron micrographs of the coatings showed a precipitate on the surface of the rice root. X‐ray diffraction analysis of coatings identified the iron oxide mineral lepidocrocite (γ‐FeOOH) as the only crystalline component of the coatings.