Abstract
Bt ( Bacillus thuringiensis ) corn ( Zea mays L.) accounted for 74.5% of the corn acreage in eastern Canada in 2009. Reports that Bt corn has greater yield and lignin concentrations than unmodified corn have raised questions about its effect on the soil ecosystem. Our objectives were to evaluate the biomass of field‐grown Bt and non‐Bt corn, the chemical composition of different corn components that remain as residues in the field after harvest, and the effect of the Bt modification on residue decomposition. Nine Bt corn hybrids and their near isolines were field‐grown in 2008 and 2009. Grain and stover yields were measured and leaves, stems, and roots were collected and analyzed for lignin, C, and N concentrations. Stem sections from a Bt/non‐Bt corn pair were buried in the field and sampled periodically during 1 yr. No difference in yield or lignin concentrations due to the Bt gene was noted; however, N concentration in Bt stems was significantly greater than in non‐Bt stems in 1 yr of the 2‐yr study. Leaves had less lignin and a lower C/N ratio than stems and roots in both years. In buried field litterbags, the decline in C/N ratio and mass loss suggests that Bt stems were decomposing more rapidly than non‐Bt stems. We conclude that the Bt gene does not affect the agronomic performance or the chemical composition of corn in fields without herbivory, and that Bt corn residue may be more susceptible to decomposition than non‐Bt corn residue.
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Claims 7
Claim · model-written summary
The Bt gene did not change corn yield or lignin concentration.
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Bt ( Bacillus thuringiensis ) corn ( Zea mays L.) accounted for 74.5% of the corn acreage in eastern Canada in 2009”
e2“No difference in yield or lignin concentrations due to the Bt gene was noted”
Claim · model-written summary
N concentration in Bt corn stems was significantly greater than in non-Bt stems in one of the two study years.
- Organ / stage
- stemse3
- Treatment
- Bte3
- Outcome
- N concentratione3
- Direction
- greatere3
- Qualifier
- in 1 yr of the 2‐yr studye3
- Comparator
- non‐Bt stemse3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Bt ( Bacillus thuringiensis ) corn ( Zea mays L.) accounted for 74.5% of the corn acreage in eastern Canada in 2009”
e3“however, N concentration in Bt stems was significantly greater than in non‐Bt stems in 1 yr of the 2‐yr study”
Claim · model-written summary
Corn leaves had less lignin than stems and roots in both years.
- Organ / stage
- Leavese4
- Outcome
- lignine4
- Direction
- lesse4
- Qualifier
- in both yearse4
- Comparator
- stems and rootse4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Bt ( Bacillus thuringiensis ) corn ( Zea mays L.) accounted for 74.5% of the corn acreage in eastern Canada in 2009”
e4“Leaves had less lignin and a lower C/N ratio than stems and roots in both years”
Claim · model-written summary
Corn leaves had a lower C/N ratio than stems and roots in both years.
- Organ / stage
- Leavese4
- Outcome
- C/N ratioe4
- Direction
- lowere4
- Qualifier
- in both yearse4
- Comparator
- stems and rootse4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Bt ( Bacillus thuringiensis ) corn ( Zea mays L.) accounted for 74.5% of the corn acreage in eastern Canada in 2009”
e4“Leaves had less lignin and a lower C/N ratio than stems and roots in both years”
Claim · model-written summary
Bt corn stems appear to decompose more rapidly than non-Bt stems in buried field litterbags.
- Organ / stage
- stemse5
- Treatment
- Bte5
- Outcome
- decomposinge5
- Direction
- more rapidlye5
- Comparator
- non‐Bt stemse5
- Setting
- buried field litterbagse5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Bt ( Bacillus thuringiensis ) corn ( Zea mays L.) accounted for 74.5% of the corn acreage in eastern Canada in 2009”
e5“In buried field litterbags, the decline in C/N ratio and mass loss suggests that Bt stems were decomposing more rapidly than non‐Bt stems”
Claim · model-written summary
The Bt gene does not affect agronomic performance or chemical composition of corn in fields without herbivory.
- Treatment
- Bt genee6
- Outcome
- agronomic performance or the chemical compositione6
- Direction
- does not affecte6
- Qualifier
- in fields without herbivorye6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Bt ( Bacillus thuringiensis ) corn ( Zea mays L.) accounted for 74.5% of the corn acreage in eastern Canada in 2009”
e6“We conclude that the Bt gene does not affect the agronomic performance or the chemical composition of corn in fields without herbivory”
Claim · model-written summary
Bt corn residue may be more susceptible to decomposition than non-Bt corn residue.
- Treatment
- Bt corn residuee7
- Outcome
- susceptible to decompositione7
- Direction
- moree7
- Comparator
- non‐Bt corn residuee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Bt ( Bacillus thuringiensis ) corn ( Zea mays L.) accounted for 74.5% of the corn acreage in eastern Canada in 2009”
e7“Bt corn residue may be more susceptible to decomposition than non‐Bt corn residue”
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See all 5 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.