PETUNIA CULTIVAR SENSITIVITY TO OZONE AND SULFUR-DIOXIDE

Ozone (O3) and sulphur dioxide (SO2) are widespread pollutants in many of the areas in which petunias are grown as bedding-plants. Controlled environment experiments were conducted to evaluate the sensitivity of 'Capri', 'White Magic' and 'White Cascade' to separate or combined O3 and SO2 at 2 growth stages. Relative cultivar sensitivity was the same for O3, SO2 or O3 + SO2, with 'Capri' leaves least injured and 'White Cascade' leaves most injured. Visible injury symptoms were similar in all cultivars. Leaves of intermediate age were most sensitive, but early vegetative plants were more sensitive to O3 than plants in immediate prefloral stage. Severity of leaf injury was generally greater from the combined gases than from the single gases, and the combination treatment at the early vegetative stage significantly reduced plant growth and flower weight 4 weeks later. © 1979.