YIELD RESPONSES OF DIFFERENT CROP SPECIES TO LONG-TERM FUMIGATION WITH SULFUR-DIOXIDE IN OPEN-TOP CHAMBERS

Potted plants of commercial cultivars of rape (Brassica napus L., cv. 'callypso'), summer barley (Hordeum vulgare L., cvs. 'arena' and 'hockey') and bush beans (Phaseolus vulgaris L., cvs. 'rintintin' and 'rosisty') were continuously exposed in open-top chambers to sulphur dioxide (SO2) for the whole growing season in order to assess effects of this pollutant on growth and various yield parameters. Treatments consisted of charcoal-filtered air (CF) and CF supplemented with four levels of SO2, resulting in mean exposure concentrations (μg m-3) of approximately 8, 50, 90, 140 and 190. With the exception of the 1000 seeds weight, which was slightly reduced, dry matter production and yield parameters of rape remained unaffected by all SO2 concentrations or were even stimulated. Compared to CF vegetative growth of both bean cultivars was reduced by 10-26% at all SO2 levels; however, with significant effects only for cv. 'rintintin'. While all SO2 additions reduced significantly the yield (dry weight of pods) of the bean cultivar 'rosisty' between 17% and 32%, cv. 'rintintin' showed a significant reduction of up to 42% only at the two highest pollutant concentrations. Dry matter production of the barley cultivars was mainly impaired at SO2 concentrations > 100 μg m-3 with a reduction of 30-52%. While nearly all yield parameters of cv. 'hockey' reacted similar to the dry matter production, the yield of cv. 'arena' was reduced already at the low SO2 levels. At a treatment concentration of 90 μg SO2 m-3 a significant yield loss of 30% was recorded. A reduction of the 1000 grains weight mainly contributed to these yield losses observed for both barley cultivars. From these results, it may be assumed that SO2 concentrations within the range 50-90 μg m-3 are potentially phytotoxic to some crop species. © 1990.