title: Root growth and metal uptake in four grasses grown on zinc-contaminated soils.
abstract: Depth and area of rooting are important to long-term survival of plants on metal-contaminated, steep-slope soils. We evaluated shoot and root growth and metal uptake of four cool-season grasses grown on a high-Zn soil in a greenhouse. A mixture of biosolids, fly ash, and burnt lime was placed either directly over a Zn-contaminated soil or over a clean, fine-grained topsoil and then the Zn-contaminated soil; the control was the clean topsoil. The grasses were 'Reliant' hard fescue (Festuca brevipila R. Tracey), 'Oahe' intermediate wheatgrass [Elytrigia intermedia (Host) Nevski subsp. intermedia], 'Ruebens' Canada bluegrass (Poa compressa L.), and 'K-31' tall fescue (Festuca arundinacea Schreb.). Root growth in the clean soil and biosolids corresponded to the characteristic rooting ability of each species, while rooting into the Zn-contaminated soil was related to the species' tolerance to Zn. While wheatgrass and tall fescue had the strongest root growth in the surface layers (0-5 cm) of clean soil or biosolids, wheatgrass roots were at least two times more dense than those of the other grasses in the second layer (5-27 cm) of Zn-contaminated soil. When grown over Zn-contaminated soil in the second layer, hard fescue (with 422 mg/kg Zn) was the only species not to have phytotoxic levels of Zn in shoots; tall fescue had the highest Zn uptake (1553 mg/kg). Thus, the best long-term survivors in high-Zn soils should be wheatgrass, due to its ability to root deeply into Zn-contaminated soils, and hard fescue, with its ability to effectively exclude toxic Zn uptake.
authors.affiliation: U.S. Army Engineer Research and Development Center, Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover, NH 03755, USA. antonio.j.palazzo@erdc.usace.army.mil
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Palazzo
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Cary
authors.forename: Susan E
authors.initials: SE
authors.lastname: Hardy
authors.forename: C Richard
authors.initials: CR
authors.lastname: Lee
mesh_terms: D018517:Plant Roots / Q000737:chemistry / Q000254:growth & development; D006109:Poaceae / Q000254:growth & development*; D012989:Soil Pollutants / Q000009:adverse effects* / Q000493:pharmacokinetics*; D016019:Survival Analysis; D015032:Zinc / Q000009:adverse effects* / Q000493:pharmacokinetics*
chemical_list: D012989:Soil Pollutants; D015032:Zinc