Growth responses of barley exposed to SO₂

Barley (Hordeum vulgare ev. Schooner) plants were exposed to 4, 42, 121, 256 or 517 nl 1^-l SO₂ to investigate the relationship between the exposure concentration of SO² and growth. The plants were exposed from 14 days old, in open-top chambers for 4 h day^-1 (10.00-14.00 h) for 79 days. The concentration-response curves established illustrated a small growth stimulation (approx. 10%) at 42 nl 1^-1 and a growth inhibition at 121 nl 1^1- or greater. The growth reduction was generally proportional to the exposure concentration at concentrations above 42 nl 1^-1 Sulphur concentration in the shoot increased linearly with ambient SO₂ concentration.