Extractable soil lipids and microbial activity as affected by Bt and non Bt maize grown on a silty clay loam soil.
Pyrolysis-gas (Py-GC) chromatography was used to characterize extractable lipids from Bt and non-Bt maize shoots and soils collected at time of harvesting. Py-GC-MS (mass spectrometry) showed that the concentrations of total alkenes identified in non-Bt shoots and soils were 47.9 and 21.3% higher than in Bt maize shoots and soils, respectively. N-alkanes identified were of similar orders of magnitude in Bt and non-Bt maize shoots, but were 28.6% higher in Bt than in non-Bt soils. Bt maize shoots contained 29.7% more n-fatty acids than non-Bt maize shoots, whereas the concentrations of n-fatty acids in Bt soils were twice as high as those in non-Bt soils. Concentrations of unsaturated fatty acids in Bt maize shoots were 22.1% higher than those in non-Bt maize shoots, while concentrations of unsaturated fatty acids were 22.5% higher in non-Bt than in Bt soils. The cumulative CO2-C evolved from soils under Bt and non-Bt crops was 30.5% lower under Bt as compared to non-Bt crops, whereas when maize shoots were added to Bt and non-Bt soils, the decrease in CO2-C evolved were 16.5 and 23.6%, respectively. Our data showed that the cultivation of Bt maize significantly increased the saturated to unsaturated lipid ratios in soils which appeared to negatively affect microbial activity.
Dinel
Henri
H
Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, Ottawa, Canada. denise.drd@sympatico.ca
Schnitzer
Morris
M
Saharinen
Maritta
M
Meloche
François
F
Paré
T
T
Dumontet
S
S
Lemee
Laurent
L
Ambles
André
A
D001413:Bacillus thuringiensis / Q000235:genetics; D001427:Bacterial Toxins / Q000235:genetics; D002849:Chromatography, Gas / Q000379:methods; D005231:Fatty Acids, Unsaturated / Q000032:analysis* / Q000494:pharmacology*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D007300:Insect Control / Q000379:methods; D018520:Plant Shoots / Q000737:chemistry; D030821:Plants, Genetically Modified / Q000737:chemistry*; D012987:Soil / Q000032:analysis*; D012988:Soil Microbiology; D003313:Zea mays / Q000737:chemistry*
D001427:Bacterial Toxins; D005231:Fatty Acids, Unsaturated; D012987:Soil