Glyphosate-resistant soybean response to various salts of glyphosate and glyphosate accumulation in soybean nodules

Journal or Publishing Institution: Weed Science

Study: https://web.archive.org/web/20180824191146/https://www.ars.usda.gov/research/publications/publication/?seqNo115=136330

Author(s): Reddy, K.N. and Zablotowicz, R.M.

Article Type: Peer Reviewed Study

Record ID: 2040

Abstract: A field study was conducted during 2000 and 2001 at Stoneville, MS to determine the effects of isopropylamine (Ipa), trimethylsulfonium (Tms), diammonium (Dia), and aminomethanamide dihydrogen tetraoxosulfate (Adt) salt formulations of glyphosate on weed control, growth, chlorophyll content, nodulation, nitrogen content, and grain yield in glyphosate-resistant soybean, and to assess potential glyphosate accumulation in soybean nodules. Glyphosate was applied early postemergence (EPOST) at 0.75 kg ae ha-1 at one-trifoliate leaf or EPOST followed by late postemergence (LPOST) at 0.75 kg ae ha-1 at three- to four-trifoliate leaf to glyphosate-resistant soybean. Glyphosate-Tms and glyphosate-Adt injured soybean and visible injury ranged from 29 to 38% at 2 d after LPOST, however, soybean recovered from injury by 14 d after LPOST. Glyphosate salts had no effect on chlorophyll content of fifth- (9 d after LPOST) and ninth-trifoliate (23 d after LPOST) leaves, and soybean root and shoot dry weights at 14 d after LPOST. Glyphosate formulations had no effect on nodule number, but reduced nodule biomass at 14 d after LPOST compared to untreated control. Two applications of glyphosate-Ipa, glyphosate-Tms, glyphosate-Dia, and both applications of glyphosate-Adt reduced leghemoglobin content 8 to 10% compared to untreated control. Glyphosate levels in nodules from treated plants ranged from 39 to 147 ng g-1 (dry weight). The highest nodule glyphosate concentration was found with two applications of glyphosate-Ipa. Control of five predominant weed species at 14 d after LPOST was > 83% with one application and > 96% with two applications regardless of glyphosate salts. Soybean yields were generally higher with two applications compared to one application regardless of glyphosate formulation. Nitrogen content of fifth- and ninth-trifoliate leaves was similar among glyphosate formulations. Nitrogen content of soybean grain was slightly lower with two applications of Glyphosate-Ipa, glyphosate-Tms, and glyphosate-Dia compared to untreated control. These results indicate that soybean injury and inhibition of nodule development with certain glyphosate formulations can occur, but soybean has the potential to recover from glyphosate stress.

Keywords: Glyphosate, Glycine max (L.) Merr. ‘DP 5806 RR’, Chlorophyll, formulation, injury, leghemoglobin, nodules, weed control, transgenic soybean, pesticide formulations, field experimentation, nodulation, nitrogen content, grain yield, herbicide resistance, postemergent weed control, plant damage, roots, shoots, pesticide application, Mississippi

Citation: Reddy, K.N. and Zablotowicz, R.M., 2003. Glyphosate-resistant soybean response to various salts of glyphosate and glyphosate accumulation in soybean nodules. Weed Science, 51(4), pp.496-502.