Effects of nickel and copper on Acer rubrum, Cornus stolonifera, Lonicera tatarica, and Pinus resinosa

Abstract

Red maple (Acer rubrum), yellow-stem dogwood (Cornus stolonifera 'Flaviramea'), and tartarian honeysuckle (Lonicera tatarica) cuttings and red pine (Pinus resinosa) seedlings were grown in a controlled environment in aerated liquid culture with 2 or 10 mg∙L−1 Ni2+ or 4 or 20 mg∙L−1 Cu2+ singly or in combination (2 and 4 mg∙L−1 or 10 and 20 mg∙L−1). Injury symptoms included marginal and interveinal chlorosis, alteration of leaf pigmentation, severe leaf drop, and abnormally small leaves. With increasing metal levels, root tissues became severely discoloured, lateral roots were few in number, stunted, and thickened, and bulbous root tips developed. Growth and development of plants were retarded in most metal treatments compared with control plants. Tissue accumulation of metals generally increased with increasing Ni and Cu concentrations in the nutrient solutions, but tissue concentrations varied according to species, metal, and tissue analyzed. Pine needles did not accumulate added Cu, while roots of all species contained very high concentrations of Cu. In the combination treatments, the presence of elevated levels of Cu reduced Ni accumulation in the root tissues of all four species and pine stems and leaves and stems of dogwood, compared with the single Ni treatments. In contrast, honeysuckle stems and pine needles had greater Ni accumulation from a combined Ni and Cu treatment than from the corresponding single treatment.