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Title: Review of Potential Environmental Impacts of Transgenic Glyphosate-Resistant Soybean in Brazil

Author
item CERDEIRA, ANTONIO - EMBRAPA-BRAZIL AG. DEPT.
item GAZZIERO, DIONSIO - EMBRAPA-BRAZIL AG. DEPT.
item Duke, Stephen
item MATALLO, MARCUS - BIOLOGICAL INST.-BRAZIL
item SPADOTTO, CLAUDIO - EMBRAPA-BRAZIL AG. DEPT.

Submitted to: Journal of Environmental Science and Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2007
Publication Date: 6/15/2007
Citation: Cerdeira, A.L., Gazziero, D.L., Duke, S.O., Matallo, M.B., Spadotto, C.A. 2007. Review of Potential Environmental Impacts of Transgenic Glyphosate-Resistant Soybean in Brazil. Journal of Environmental Science and Health. 42(5):539-549.

Interpretive Summary: Transgenic glyphosate-resistant soybeans (GRS) have been commercialized and grown extensively in the Western Hemisphere, including Brazil. Worldwide, several studies have shown that previous and potential effects of glyphosate on contamination of soil, water, and air are minimal, compared to that caused by the herbicides that they replace when GRS are adopted. In the USA and Argentina, the advent of glyphosate-resistant soybeans resulted in a significant shift to reduced- and no-tillage practices, thereby significantly reducing environmental degradation by agriculture. Similar shifts in tillage practiced with GRS might be expected in Brazil. Transgenes encoding glyphosate resistance in soybeans are highly unlikely to be a risk to wild plant species in Brazil. Soybean is almost completely self pollinated and is a non-native species in Brazil, without wild relatives, making introgression of transgenes from GRS virtually impossible. Probably the highest agricultural risk in adopting GRS in Brazil is related to weed resistance. Weed species in GRS fields have shifted in Brazil to those that can more successfully withstand glyphosate or to those that avoid the time of its application. Four weed species, Conyza bonariensis, Conyza Canadensis, Lolium multiflorum, and Euphorbia heterophylla, have evolved resistance to glyphosate in GRS in Brazil.

Technical Abstract: Transgenic glyphosate-resistant soybeans (GRS) have been commercialized and grown extensively in the Western Hemisphere, including Brazil. Worldwide, several studies have shown that previous and potential effects of glyphosate on contamination of soil, water, and air are minimal, compared to that caused by the herbicides that they replace when GRS are adopted. In the USA and Argentina, the advent of glyphosate-resistant soybeans resulted in a significant shift to reduced- and no-tillage practices, thereby significantly reducing environmental degradation by agriculture. Similar shifts in tillage practiced with GRS might be expected in Brazil. Transgenes encoding glyphosate resistance in soybeans are highly unlikely to be a risk to wild plant species in Brazil. Soybean is almost completely self pollinated and is a non-native species in Brazil, without wild relatives, making introgression of transgenes from GRS virtually impossible. Probably the highest agricultural risk in adopting GRS in Brazil is related to weed resistance. Weed species in GRS fields have shifted in Brazil to those that can more successfully withstand glyphosate or to those that avoid the time of its application. Those weeds are Chamaesyce hirta (erva-de-Santa-Luzia), Commelina benghalensis (trapoeraba), Spermacoce latifolia (erva-quente), Richardia brasiliensis (poaia-branca), and Ipomoea spp. (corda-de-viola). Four weed species, Conyza bonariensis, Conyza Canadensis (buva), Lolium multiflorum (azevem), and Euphorbia heterophylla (amendoim-bravo), have evolved resistance to glyphosate in GRS in Brazil and have great potential to become problems.