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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT OF SOYBEAN GENEOTYPES AND MANAGEMENT SYSTEMS FOR EARLY SEASON AND STRESS ENVIRONMENTS

Location: Crop Genetics Research Unit

Title: Comparisons of Herbicide Treated and Cultivated Herbicide-Resistant Corn

Authors
item BRUNS, HERBERT
item ABBAS, HAMED

Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 7, 2010
Publication Date: July 1, 2010
Citation: Bruns, H.A., Abbas, H.K. 2010. Comparisons of Herbicide Treated and Cultivated Herbicide-Resistant Corn. Field Crops Research. doi:10.1155/2010/798127.

Interpretive Summary: Large acreages of corn grown today have been genetically modified to be resistant to the herbicides, Round-up, Liberty, or both products. The impact these herbicides have on growth, yield, and possible contamination by aflatoxin of these genetically modified corns is not clear. An experiment on irrigated corn resistant to these herbicides and to atrazine was done at Stoneville, MS, between 2005 to 2007, and compared herbicide treated plots with those that received no herbicide but were cultivated for weed control. No differences in leaf area development, dry matter accumulation during the season, or grain yield at harvest due to weed control method were found. Analysis for aflatoxin and fumonisin found differences in contamination over the three years of the study but no differences due to the type of weed control used to grow the corn. Round-up, Liberty, and atrazine herbicides do not affect development, yield, or mycotoxin contamination of corn when applied to hybrids that are resistant to them.

Technical Abstract: Four glyphosate resistant corn (Zea mays L.) hybrids, a glufosinate-ammonium resistant hybrid, and a conventional atrazine resistant hybrid grown at Stoneville, MS in 2005, 2006, and 2007 with furrow irrigation were treated with thier respective herbicides and their growth, yeild, and mycotoxin incidence was compared with untreated cultivated plots. Leaf area index (LAI) and dry matter accumulation (DMA) were collected on a weekly basis beginning at groth stage V3 and terminating anthesis. Crop growth rate (CRG) and relative growth rates (RGR) were calculated. Plots were later harvested, yield and yield component data collected, and kernel samples analyzed for aflatoxin and fumonisin. Leaf area index, DMA, CRG, and RGR were not different among the herbicide treated plots and those that were cultivated. Curves for LAI and DMA were similiar to those previously reported. Aflatoxin and fumonisin were relatively low in all plots. Herbicide application or the lack there of had no negative impact on the incidence of kernal contamination by these two mycotoxins. Herbicides, especially glyphosate on resistant hybrids, has no negative effects on corn yields or kernel quality in corn produced in humid sub-tropical enviroment.

Last Modified: 9/10/2014