Title: Corn-soybean rotation systems in the Mississippi Delta, implications on mycotoxin contamination and soil populations of Aspergillus flavus Authors
Submitted to: International Journal of Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 19, 2012
Publication Date: October 1, 2012
Citation: Abbas, H.K., Bellaloui, N., Zablotowicz, R.M., Bruns, H.A., Gillen, A.M. 2012. Corn-soybean rotation systems in the Mississippi Delta, implications on mycotoxin contamination and soil populations of Aspergillus flavus. International Journal of Agronomy. 2012, Article ID 935463, 7 pages doi:10.1155/2012/935463. Interpretive Summary: Crop rotation or alternating crops planted in the same field each year can be of benefit in several ways including reduction of plant diseases. The fungus Aspergillus flavus grows on corn and soybeans produces a toxin that can cause mortality in mammals. This study was designed to see if rotating corn and soybeans can reduce levels of the toxic fungus in specific fields. After four years of rotation. The results showed that levels of toxic fungus were lower in soybeans than in corn. This is useful information for both growers and researchers.
Technical Abstract: In many crop production systems corn (Zea mays L.) is followed by soybean (Glycine max L. Merr.), however the implication of this rotation on mycotoxin contamination has not been fully evaluated. A four-year field experiment was initiated in 2005 to determine the effects of eight corn– soybean rotation schemes on aflatoxin and fumonisin contamination of the grain and colonization by Aspergillus flavus under furrow irrigated conditions. No significant effect of rotation was observed. However, aflatoxin levels in soybean averaged 2.3, < 0.5, 0.6, and 6.8 ng/g in 2005, 2006, 2007, and 2008, respectively, while significantly (p= 0.05) higher levels were found in corn 16.7, 37.1, 2.4, and 54.8 ng/g (2005, 2006, 2007, and 2008, respectively). Aspergillus flavus colonization was significantly greater (p=0.05) in corn (log 1.9, 2.9, and 4.0 cfu/g compared to soybean (< 1.3, 2.6, and 2.7 cfu/ g in 2005, 2007 and 2008, respectively. In 2006 similar colonization was observed among both crops (log 3.3 cfu/g). A higher frequency of aflatoxigenic A. flavus isolates were associated with corn compared to soybean in all four years. Higher levels of fumonisin contamination were found in corn (3.6, 0.9, 0.2, and 3.5 µg/g in 2005, 2006, 2007, and 2008, respectively), compared to soybean < 0.2 µg/g in four years. These results demonstrated that soybean grain is less susceptible to aflatoxin contamination compared to corn because of a lower level of colonization by A. flavus and a greater colonization by non-aflatoxigenic isolates.