Progress 11/01/10 to 04/30/12
Outputs
Progress Report Objectives (from AD-416): To identify appropriate plant genotypes and soil pH levels for maximal annual phytoextraction of Cd from the subject soils. Approach (from AD-416): Improved methods of phytoextraction of Cd from soils containing excessive Cd are needed for U.S. soils. The Thlapsi caerulescens that we previously developed and patented does not survive in rice soils in Asia, but might do well in the IL location with excessive soil Cd. Rice genotypes have also been identified in Japan that accumulate much higher Cd when grown in aerobic soils than common food type rice cultivars. Thus the study will evaluate relative yield and Cd, Zn, Cu and other nutrients and metals in genotypes of Thlaspi caerulescens and rice grown on a highly metal enriched soil from the MWRDGC field location in Fulton Co., IL. Rice will be grown in the greenhouse, while Thlaspi caerulescens will be grown in a growth chamber to provide the needed temperature range. Shoot yields will be obtained at an appropriate growth stage before flowering, and the shoots analyzed for metals and nutrients. Results will be statistically evaluated and a report prepared, then a manuscript for a peer-reviewed journal will be prepared. Plant performance will be photographed as well. Excessive Cd in some historically biosolids amended soils requires remediation before alternative land use may be permitted. ARS scientists tested phytoextraction of Cd from soils from the Metropolitan Water Reclamation of Greater Chicago. Swiss chard grown on the soils accumulated Cd levels which highly exceeded international standards for Cd in leafy vegetable crops, especially if the soils were acidified. Phytoextraction with Cd-accumulating rice cultivars was unsuccessful under aerobic soil management needed for useful Cd phytoextraction. Three newly identified Chinese Cd hyperaccumulator herbaceous species were grown on the test soils, but either did not phytoextract useful levels of Cd, or suffered phytotoxicity from other metals in the soils than Cd and Zn for which these species were tolerant. A corn inbred, B37, shown to accumulate much more Cd than other corn inbreds was also tested in these soils and this plant grew well on the high metal soils. Because useful phytoextraction requires harvestable plant biomass rich in Cd, corn appears to offer more effective annual Cd removals than the other species tested. Thlaspi accumulated up to 900 mg Cd/kg shoots, but has low yields and is short making biomass harvest difficult. Even corn inbreds with 40 mg Cd/kg Dry Weight, grown as double-crop when shoot biomass is maximum, would offer higher annual Cd removal than other plants tested, although breeding to improve Thlaspi may offer more effective Cd phytoextraction technology. Growth of corn inbred B37 on acidified soils is being undertaken, including a treatment where normal subsoil is included below the high metal topsoil so that roots can obtain adequate Fe using roots below the metal rich depth. A report on the funded studies was submitted to the sponsor. Opportunities to continue work to demonstrate Cd phytoextraction in the field or additional greenhouse testing are being discussed.
Impacts
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Publications
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