Soybean (Glycine max (L.) Merr.) cultivar tolerance to sulfentrazone

Sulfentrazone has excellent soil activity on many small-seeded broadleaf we eds, however, soybean injury in field experiments has been noted under cert ain environmental conditions. Injury levels in these field experiments have appeared to differ in severity among soybean cultivars. Growth chamber stu dies were initiated with the objective of examining the suspected differenc es in tolerance among soybean cultivars. Over 40 soybean cultivars, selecte d from the USDA Soybean Germplasm Collection, were tested for tolerance to sulfentrazone. The soybean cultivars were grown under constant conditions i n a growth chamber in a soil mix treated with sulfentrazone at 0.28 kg ai h a (-1) preemergence. Ratings of plant injury and measurement of height and biomass reduction were made 14 days after treatment and compared to the res pective untreated check plants of each cultivar. Notable differences in tol erance to sulfentrazone across the cultivars were observed. The cultivars w ere divided into three groups based on plant response and classified as hav ing either high, medium, or low tolerance to sulfentrazone. Results of this study suggest that cultivar selection may lower the risk of early season i njury to soybean and potential yield reductions. (C) 2001 Elsevier Science Ltd. All rights reserved.