SENSITIVITY OF 20 SOYBEAN CULTIVARS TO SIMULATED ACID-RAIN

Efforts to assess the effect of acid rain on soybean [Glycine max (L.) Merr.] have shown variable results. Simulated acid rain has been reported to cause increases, decreases, and no significant effect on yield. Although few parameters were identical among the diverse studies reported in the literature, one common difference was the choice o cultivar. In this study, 20 soybean cultivars were screened to determine their relative sensitivity to simulated acid rain. Soybean was grown in 1984,1985, and 1986 in field plots ineast central Illinois. Plots were protected from ambient rain and treated twice weekly with simulated rain of pH 5.6 (control) or pH 3.0. Early in each growing season visible leaf injury was noted for all 20 cultivars, and level of injury was significantly higher for plants receiving the more acidic treatment (pH 3.0). Average yield for the 20 cultivars was approximately the same when plants were treated with simulated rain of pH 3.0 as when plants were treated with stimulated rain of pH 5.6. Over all 3 yr, the group V cultivars Essex and Forrest yielded more grain and had more chaff dry matter, pods per hectare, and pods per plant with the more acidic pH treatment than with the control treatment. Only 'Williams 82' yielded significantly less with the more acidic pH treatment than with the control treatment. The results suggest soybean cultivars may respond differently to applications of highly acidified rainfall, but none of the cultivars tested were extremely sensitive to growth and yield reduction.