Studies on the Effect of Sulphur Dioxide on Perennial Ryegrass (Lolium perenneL.): II. EVOLUTION OF SULPHUR DIOXIDE TOLERANCE

The response to SO₂ fumigation was examined in long-establishedperennial ryegrass populations from the same climatic region,which had experienced widely different ambient SO₂ concentrations.The results provide strong evidence of the evolution of SO₂tolerance in populations from the high SO₂ areas. Populationsfrom these areas exhibited greater tolerance to SO₂ and showedreduced clonal variability in response. Furthermore, the degreeof tolerance exhibited appeared to depend on the severity ofSO₂ pollution experienced by the populations in the field.