Silicon is Deposited in Leaves of New Guinea Impatiens

Abstract

Although silicon (Si) is not considered to be an essential plant nutrient because most plants can complete their life cycle without it, many investigators have shown a positive growth effect, such as increased disease resistance, if Si is present. The effect of Si on many ornamental and greenhouse crop species has not been extensively studied. In greenhouse culture, plants are not exposed to Si from mineral soil, so Si should be added to the fertilizer solutions with mineral soil or soil amendments if there are benefits of Si. The initial step in determining potential benefits of Si requires the documentation of Si uptake and localization within the plant. We grew New Guinea impatiens for four weeks and exposed them to 2.0 mM Si in the form of K2SiO4. Using scanning electron microscopy and energy dispersive X-ray analysis, we detected Si deposits on the leaf margins in unique, Si-filled cells, primarily near hydathodes. We did not detect Si in the xylem. This report is the first documentation of Si uptake or accumulation in any species of the Balsaminaceae family. Accepted for publication 12 January 2005. Published 17 February 2005.