Tolerance of seven perennial grasses to high nickel in sand culture

Although grasses are commonly used to revegetate disturbed areas, comparatively little is known regarding the tolerance of perennial grasses to toxic levels of trace metals. A sand culture experiment was conducted to investigate the tolerance of seven perennial grasses to high concentrations of Ni. The activity of Ni(2+) in solution that resulted in a 50% reduction in shoot growth ranged from 50 mu M for Sabi grass (Urochloa mosambicensis (Hack.) Dandy cv. Saraji) to 13 mu M for curly Mitchell grass (Astrebla lappacea (Lindl.) Domin). In most grasses, growth in the high-Ni(2+) treatments resulted in shoot Ni concentrations at or above the toxicity threshold for consumption by cattle (100 mu g Ni g (1)). Based upon their tolerance to Ni, and the extent to which they translocate Ni to the shoots, Sabi grass, signal grass (Brachiaria decumbens Stapf. cv. Basilisk) and buffel grass (Cenchrus ciliaris (L.) cv. Biloela) appear well suited for the phytostabilisation of Ni-contaminated sites in subtropical and tropical regions.