Silicon differentially influences Cu toxicity response in silicon-accumulator and non-accumulator species

Authors: Frantz, Jonathan; KANDAHAR, SUSHANT - University Of Toledo; LEISNER, SCOTT - University Of Toledo

Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2011
Publication Date: 9/21/2011
Citation: Frantz, J., Kandahar, S., Leisner, S. 2011. Silicon differentially influences Cu toxicity response in silicon-accumulator and non-accumulator species. Journal of the American Society for Horticultural Science. 136:329-338.

Interpretive Summary: Copper (Cu) is commonly used as a pesticide in both traditional and organic systems, and it is present in high concentration in some manures. The likelihood of Cu toxicity increases as Cu and manure use expand. Some researchers have successfully demonstrated that supplemental silicon (Si) can counteract micronutrient toxicities on a few species. There is currently considerable debate as to the value of widely supplying supplemental Si in fertility programs and as such, it is not a typical management practice in floriculture crop production in the United States. We investigated the potential for Si to help decrease Cu toxicity in both a Si-accumulating (Zinnia elegans Jacq.) and a Si-non-accumulating (snapdragon, Antirrhinum majus L.) species. Using visible stress symtoms like yellow or brown discoloration in leaves and roots and dry weight analysis, it initially appeared that Si was a significant benefit to only zinnia under Cu toxicity. Measuring activity of stress enzymes and tissue analysis of leaves, stems, and roots revealed that both species responded to supplemental Si. This provided evidence that both species had reduced stress and nutrient concentrations more similar to healthy, control plants than plants receiving toxic amounts of Cu. While there appear to be differences in the extent of stress reduction caused by Si between these two plants, both responded to supplemental Si. This adds to the growing body of evidence that most, if not all, plants have Si-mediated responses to stress, and its inclusion into fertility programs should be more broadly considered than current practices.

Technical Abstract: The use of Cu in agriculture is widespread as a pesticide, and it is present in high concentrations in certain types of manures. As the use of Cu continues and manure management in incorporated into sustainable systems, the likely occurrence of Cu toxicity increases. Some have successfully used supplemental Si to counteract potential micronutrient toxicity. There is currently considerable debate as to the value of widely including Si as a nutrient in fertility programs and as such, it is not a typical management practice in floriculture crop production in the United States. We investigated the potential for Si to ameliorate the effects of Cu toxicity in both a Si-accumulating (Zinnia elegans Jacq.) and a Si-non-accumulating (snapdragon, Antirrhinum majus L.) species. Using visible stress indicators and dry weight analysis, it initially appeared that Si was a significant benefit to only zinnia under Cu toxicity. Enzymatic assays and elemental analysis of leaves, stems, and roots revealed that both species responded to supplemental Si, showing evidence of reduced stress and nutrient concentrations more similar to healthy, control plants than Cu-toxicity. While there appear to be differences in the extent of Si-mediated amelioration of Cu toxicity between these two plants, both responded to supplemental Si. This adds to the growing body of evidence that all plants have Si-mediated responses to stress, and its inclusion into fertility programs should be more broadly considered than current practices.