Microbial biomass and diversity in roundup-ready corn rhizosphere
The effects of Roundup-Ready (RR) corn, grown in monoculture or in rotation with canola, on microbial biomass and diversity in corn rhizosphere were investigated at Lethbridge from 2002 to 2004. In monoculture, weeds in RR corn or conventional corn were controlled by applying either Roundup or other herbicides. In rotations, RR corn rotated with RR canola or Liberty-Link (LL) canola was compared with conventional corn rotated with conventional canola. Microbiological properties in corn rhizosphere were measured at tasseling stage. In monoculture, RR corn affected microbial biomass only in 2003, when application of Roundup increased microbial biomass in RR corn rhizosphere, but not in conventional corn rhizosphere. The diversity of bacteria in RR corn rhizosphere was greater than that in conventional corn rhizosphere, regardless of Roundup application, only in 2002. RR corn in rotation did not affect microbial biomass or bacterial diversity. Therefore, RR corn affected microbial biomass or diversity in only one of three years when it was grown in monoculture, but there were no effects when corn was grown in rotation with canola. When effects were significant, the rhizosphere of RR corn had greater microbial biomass or diversity that that of conventional corn.
genetically-modified (GM) crops
soil microbial communities
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