Tolerance of perennial grasses to high copper in sand culture

Abstract

Environmental context. Copper (Cu) is an essential element for the growth of plants, but various anthropogenic activities such as mining, smelting, disposal of wastes, and the use of Cu-containing fungicides have resulted in substantial Cu contamination at sites throughout the world. We used a sand-culture system to investigate the tolerance of seven perennial grasses to toxic levels of Cu. This study provides information to assist in the selection of grasses for the revegetation and stabilisation of Cu-contaminated sites. Abstract. Although perennial grasses are commonly used to revegetate and stabilise disturbed sites, comparatively little is known of their tolerance to Cu. High Cu in solution reduced growth in all grasses, with the critical solution Cu concentration (corresponding to a 50% reduction in shoot fresh mass) ranging >5-fold, from 1.7 μM in Queensland blue grass (Dichanthium sericeum (R.Br.) A. Camus) to 10 μM in Sabi grass (Urochloa mosambicensis (Hack.) Dandy cv. Saraji). An increase in Cu in solution resulted in elevated Cu concentration in shoots of all but one species, increasing from 6 to 11 μg g–1 at 0 μM Cu to 13 to 25 μg g–1 at 11 μM Cu. The comparatively small magnitude of this increase to a concentration below the animal toxicity threshold suggests that phytotoxicity is likely to be of more environmental concern than is the uptake of Cu into the shoots (and its subsequent consumption by fauna).