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United States Department of Agriculture

Agricultural Research Service

Research Project: Alternatives to Methyl Bromide: Mitigation of the Threat from Exotic Tropical and Subtropical Insect Pests

Location: Subtropical Horticulture Research

Title: Screening ornamentals for their potential as As Accumulator Plants

Authors
item Reed, Stewart
item Ayala-Silva, Tomas
item Dunn, Christopher
item Gordon, Garry -
item Meerow, Alan

Submitted to: World Journal of Agricultural Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 28, 2013
Publication Date: September 15, 2013
Citation: Reed, S.T., Ayala Silva, T., Dunn, C.B., Gordon, G. 2013. Screening ornamentals for their potential as As Accumulator Plants. World Journal of Agricultural Sciences. doi:10.5539/jas.v5n10p20 http://dx.doi.org/10.5539/jas.v5n10p20.

Interpretive Summary: Arsenic-based chemicals are used in horticultural operations resulting in soil contamination around greenhouse structures. Phytoremediation uses plants to remove toxic substances from the soil. Phytostabilization prevents substances from moving from contaminated sites to uncontaminated adjacent areas. These are two techniques for treating arsenic contaminated soil. Several ornamental plant species, iris (Iris virginica), switchgrass (Panicum virgatum), tithonia (Tithonia rotundifloa), coreopsis (Coreopsis lanceolata), sunflower (Helianthus annuus), and marigold (Tagetes erecta), were evaluated in a hydroponic medium for their potential to remove arsenic from soil. Based on dry weight, tithonia and coreopsis were most sensitive to arsenic. Tithonia had an 85% reduction in dry weight at 0.75 ppm arsenic and coreopsis a 65% reduction at 2.25 ppm arsenic solution concentration. Iris dry weight increased with increasing solution concentrations but arsenic did not accumulate to a great extent in above ground plant tissue. The uptake ratio, concentration of plant arsnic divided by the concentration of arsenic in the hydroponic tank, is a measure of how effective a plant is at removing arsenic from soil. Values at one or above are considered best. At the high arsenic rate (5.25 ppm), marigold and sunflower had uptake ratios of 0.7 and 1.7, respectively, and transported about half of that arsenic to harvestable plant parts. Both show little effect of arsenic toxicity on growth and therefore, they are appealing candidates for phytostabilazion. Switchgrass and iris can be harvested multiple times a year, making them candidates for phytostabilization.

Technical Abstract: Arsenic-based pesticides, herbicides and insecticides are used in horticultural operations resulting in soil contamination around greenhouse structures. Phytoremediation and phytostabilization are two techniques for treating arsenic (As) contaminated soil. Several ornamental plant species, Iris (Iris virginica), switchgrass (Panicum virgatum), (Tithonia rotundifloa)), (Coreopsis lanceolata), Sunflower (Helianthus annuus), and Marigold (Tagetes erecta), were evaluated for their potential use as accumulator plants. Based on dry weight, tithonia and coreopsis were most sensitive to As. Tithonia had an 85% reduction in dry weight at 0.75 mg As L-1 and coreopsis a 65% reduction at 2.25 mg As L-1 solution concentration. Iris dry weight increased with increasing solution concentrations but As did not accumulate in tissue. At the high As rate, marigold and sunflower had uptake ratios of 0.7 and 1.7, respectively, and translocation factors near one. Both show little effect of As toxicity on dry weights production, therefore, are appealing candidates for phytostabilazion. Switchgrass and iris can be harvested multiple times a year, making them candidates for phytostabilization.

Last Modified: 9/1/2014
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