Simple, Robust Method for Quantifying Silicon in Plant Tissue

• Published in: Communications in Soil Science and Plant Analysis Vol. 41; no. 16-19; pp. 2075 - 2085
• Main Authors: Kraska, Joseph E, Breitenbeck, Gary A
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group 01.01.2010; Taylor & Francis; Taylor & Francis Ltd
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Colorimetric; Fundamental and applied biological sciences. Psychology; ICP-OES; silicate; silicon; tissue analysis; Plant tissue; Optical spectrometry; Emission spectrometry; silicate; Colorimetry; Silicon; Silicates; Inductive coupling plasma spectrometry; tissue analysis; ICP-OES; Colorimetric
• ISSN: 0010-3624; 1532-2416; 1532-4133
• DOI: 10.1080/00103624.2010.498537

Low silicon (Si) content in rice, sugarcane and other Si-accumulating crops can adversely affect crop performance because it creates reduced tolerance to both abiotic and biotic stresses. Assessing the Si status of a crop typically depends upon accurately measuring Si accumulation in plant tissue. Methods involving wet digestion of plant tissue followed by colorimetric determination of Si have proven attractive because they are both rapid and do not require costly, specialized instrumentation. Some popular wet-digestion methods are reported to provide highly variable and inconsistent results. A systematic study to identify and address the sources of variability associated with wet digestion for Si analysis found that modifications that reduce excessive foaming during wet digestion of plant tissue in strong alkali and peroxide significantly reduce variability. Unstable and variable color development associated with the molybdenum blue reaction is a concern in the colorimetric determination of Si in digests. Experiments showed that the inclusion of ammonium fluoride to facilitate the release of polysilicic acid prior to colorimetric determination results in reproducible readings that stabilize within 60 min and remain stable for at least 5 h. With this modification, the accuracy and precision of values obtained colorimetrically are comparable or superior to those obtained by inductively coupled plasma-optical emission spectroscopy (ICP-OES) analysis. A two-phase wet-digestion procedure is described for Si tissue analysis that is robust, accurate, and precise and requires equipment commonly found in most agricultural laboratories.