Yield Evaluation of a Glyphosate-Tolerant Soybean Line after Treatment with Glyphosate

Transformation of soybean [Glycine max (L.) Merr.] with a gene encoding a glyphosate-tolerance 5-enolpyruvylshikimate-3-phosphate synthase enzyme from Agrobacterium sp. strain CP4 resulted in the development of glyphosate-tolerant line 40-3-2. Glyphosate (N-phosphonomethyl glycine) is the active ingredient of Roundup herbicide. Line 40-3-2 was yield tested at 17 locations in 1992, 23 locations in 1993, and 18 locations in 1994. At those locations, broadcast applications of glyphosate at various rates were made over 40-3-2 or its derivatives from early vegetative growth to pod fill. No significant yield reduction was observed as a result of the glyphosate treatment at any of the locations. Development of glyphosate-tolerant soybean promises to provide the farmer with access to a new weed control system that should result in lower production costs and reliable weed control under a wide range of conditions.