Palazzo Antonio J, Cary Timothy J, Hardy Susan E, Lee C Richard
U.S. Army Engineer Research and Development Center, Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover, NH 03755, USA.
J Environ Qual. 2003 May-Jun;32(3):834-40. doi: 10.2134/jeq2003.8340.
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.
根系深度和面积对于生长在金属污染陡坡土壤上的植物长期存活至关重要。我们在温室中评估了四种冷季型草在高锌土壤上的地上部和根系生长以及金属吸收情况。将生物固体、粉煤灰和熟石灰的混合物直接置于锌污染土壤上，或置于干净的细粒表土上，然后再覆盖锌污染土壤；对照组为干净的表土。这些草分别是“信赖”硬羊茅（Festuca brevipila R. Tracey）、“奥阿希”中间偃麦草[Elytrigia intermedia (Host) Nevski subsp. intermedia]、“鲁本斯”加拿大早熟禾（Poa compressa L.）和“K - 31”高羊茅（Festuca arundinacea Schreb.）。在干净土壤和生物固体中的根系生长与每个物种的特征生根能力相对应，而在锌污染土壤中的生根情况则与物种对锌的耐受性有关。虽然偃麦草和高羊茅在干净土壤或生物固体的表层（0 - 5厘米）根系生长最强，但在锌污染土壤的第二层（5 - 27厘米），偃麦草的根系密度至少是其他草的两倍。当在第二层锌污染土壤上生长时，硬羊茅（锌含量为422毫克/千克）是地上部锌含量未达到植物毒性水平的唯一物种；高羊茅的锌吸收量最高（1553毫克/千克）。因此，在高锌土壤中，长期存活最好的应该是偃麦草，因为它能够深入扎根于锌污染土壤，以及硬羊茅，因为它能够有效排除有毒锌的吸收。
