EFFECTS OF SULFUR-DIOXIDE AND HYDROGEN-FLUORIDE, SINGLY AND IN COMBINATION, ON GROWTH AND YIELD OF WHEAT IN OPEN-TOP CHAMBERS

Wheat (Triticum aestivum cv. 'Eradu') growing in open-top chambers was exposed to the factorial combination of two concentrations of HF (<0.03 and 0.30 μg m-3) and three concentrations of SO2 (< 14, 133 and 266 μg m-3). Each combination was tested in duplicate chambers. Exposure was for 8 h day-1 from emergence to the onset of grain hardening, 120 days later. Exposure to 133 μg SO2m-3 had little effect, but 266 μg m-3 substantially reduced growth and yield. It reduced dry weights of shoots, ears and grain by about 25%, and concentrations of leaf chlorophyll a and ascorbic acid by about 60 and 40%, respectively, while slightly increasing grain protein concentrations. HF reduced shoot surface area and grain protein concentration, and increased leaf fluoride concentrations. In addition to main effects there were interactive effects of SO2 and HF on shoot surface area and grain protein concentration, the effects of HF being larger when SO2 concentrations were low. © 1990.