Silicon is Deposited in Leaves of New Guinea Impatiens

Authors: Frantz, Jonathan; DHARMALINGAM, D - UNIVERSITY OF TOLEDO; Locke, James; Horst, Leona; Krause, Charles

Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2004
Publication Date: 2/15/2005
Citation: Frantz, J., Dharmalingam, D.S., Locke, J.C., Horst, L., Krause, C.R. 2005. Silicon is deposited in leaves of New Guinea Impatiens. Plant Health Progress. Available: http://www.plantmanagementnetwork.org/php.

Interpretive Summary: Silica (Si) is not considered to be an essential plant nutrient because most plants can be grown from seed to seed without its presence, but many investigations have shown a positive growth effect if Si is present, including increased dry mass and yield, enhanced pollination, alleviation of micronutrient toxicity, and most commonly, increased disease resistance. In modern plant culture, these plants are no longer exposed to Si from mineral soil, so if there are benefits of Si uptake and root exposure, Si must be added to the fertilizer solutions or mineral soil should be incorporated into the media mix. 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 low doses of Si. Using scanning electron microscopy and elemental analysis, we detected Si deposits on the leaf margins in unique Si-filled cells. We did not detect Si in the stem. This report is the first documentation of Si uptake or accumulation in any ornamental dicot species. Further research needs to determine if the observed uptake has an effect on growth, alleviating micronutrient toxicities, or enhanced fungal pathogen resistance, but the work is significant because since Si is taken up in the plant and can therefore potentially stimulate disease resistance and alleviate micronutrient toxicity.

Technical Abstract: Silica (Si) is not considered to be an essential plant nutrient because most plants can be grown from seed to seed without its presence, but many investigations have shown a positive growth effect if Si is present, including increased dry mass and yield, enhanced pollination, alleviation of micronutrient toxicity, and most commonly, increased disease resistance. The effect of Si on many ornamental and greenhouse crop species has not been extensively studied. In modern plant culture, these plants are no longer exposed to Si from mineral soil, so if there are benefits of Si uptake and root exposure, Si must be added to the fertilizer solutions or mineral soil should be incorporated into the media mix. 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 ornamental dicot species. Further research needs to determine if the observed uptake has an effect on growth, alleviating micronutrient toxicities, or enhanced fungal pathogen resistan.