Decomposition Bt Cotton Residues affecting Soil microbial activity under varied Soils

摘要

The effect of transgenic Bacillus thuringiensis (Bt) cotton residues on soil microbiological activity was investigated. Greenhouse study was carried out during the 2011 wet season (March to August) at Institute of Agricultural Sciences, Banaras HinduUniversity. It was experimented on three different soil orders that included entisol, inceptisol and alfisol. Bt cotton (var.NCS-138) and its non-transgenic isoline (var.NCS-138) were grown until maturity along with one control treatment. Microbial population count, Dehydrogenage activity and Microbial Biomass Carbon (MBC) were estimated following standard protocols. The decomposition of cotton crop residues resulted increased micro-flora populations and microbial biomass carbon (MBC). When residue wasretained, non- Bt cotton showed higher populations of micro-flora as well as MBC that of Bf-cotton. Results from the study revealed that a significant reduction (7.5%) of the dehydrogenase activity was there in case of Bf-cotton. The interaction effect between soil type and varieties was found to be non significant for the soil micro-flora populations for different sampling stages throughout the incorporation period.These results suggest that Bf-transgenic cotton tissues have no apparent effect on soilmicrobial activity.