INTERACTION OF COPPER AND SULFUR-DIOXIDE IN PLANT INJURY

Barley cultivars were assessed for relative sensitivity to SO2. The most SO2-sensitive cultivar, Laurier, was used to study the effects of Cu in the rooting medium on plant growth. Copper stunted growth, especially of the roots, and induced leaf injury starting at the leaf tips. The cultivar Laurier, grown in a medium watered with 0, 10, 50 and 100 ppm Cu as CuSO4 5H2O, was exposed to 1.0 ± 0.1 ppm SO2 for 6 and 7 h on 2 consecutive days. Less injury due to SO2 was observed at the higher Cu concentration. The higher levels of Cu greatly increased stomatal resistance, thereby reducing SO2 uptake.