Comparisons of GM and Non-GM Soybean Cultivars and Weed Management Systems

With the adoption of glyphosate-resistant crops and the use of glyphosate, evolution of glyphosate-resistant weeds also took place. Scientist M. D. K. Owen and colleagues at the Iowa State University conducted a study to investigate yield and weed management systems of genetically modified (GM) and non-GM soybean at three different locations in Iowa for two years (2007-2008).

Yield of glyphosate-resistant, glufosinate-resistant, and non-GM cultivars were recorded in all the sites, and it was found out that the non-GM cultivar produced 315 and 265 kg/ha less than the glyphosate-resistant and the glyfosinate-resistant cultivars, respectively. No yield differences were observed between the GM cultivars. Weed management systems (WMS) varied among the cultivars but had comparable weed control. WMS in non-GM cultivars caused higher degree of toxic effect on plant growth, and the non-GM cultivars also produced the lowest yields. There were no differences in the WMS of GM cultivars. The experiment areas did not have high weed population densities, however the untreated controls produced 48% less weeds than the other WMS included in the studies.

The study reveals that acceptable and equivalent options to glyphosate-resistant soybean exist to manage glyphosate-resistant weeds in maturity groups 2 and 3, which represent most of the U.S. soybean production.

The abstract of this study is available at https://www.crops.org/publications/cs/abstracts/50/6/2597.