Journal or Publishing Institution: Journal of Agronomy and Crop Science
Study: http://onlinelibrary.wiley.com/doi/10.1111/j.1439-037X.2008.00312.x/abstract
Author(s): Sarkar, B., Patra, A.K. and Purakayastha, T.J.
Article Type: Peer Reviewed Study
Record ID: 2272
Abstract: We investigated the dynamics of N and P availability in the rhizosphere of Bt and non‐Bt cotton crops during their growth. In a net‐house pot culture experiment at the Indian Agricultural Research Institute, New Delhi, Bt‐cotton (cv. MRC‐6301 Bt) and its non‐transgenic near‐isoline (MRC‐6301) were grown on a sandy loam soil until maturity. A control (no‐crop) treatment was also included. Rhizosphere soil and root samples were collected at 60, 90, and 120 days after sowing (DAS). Soil samples were analysed for dehydrogenase activity, soil respiration, mineral‐N and Olsen‐P. Results have revealed a significant reduction in dehydrogenase activity (−17%) and soil respiration (−3.5%) in the rhizosphere of Bt‐cotton over non‐Bt isoline. Total mineral‐N (NH4+‐N + 
‐N) in soil was reduced by 14%, whereas Olsen‐P was increased by 8% because of Bt‐cotton. Root biomass yields were not different (P>0.05), but root volume was significantly higher in Bt than non‐Bt isoline. Time of sampling strongly (P<0.05) affected the above parameters, showing their highest values at 60 or 90 DAS. A significant interactive effect of sampling time and treatments was also indicated. Our results suggest that Bt‐cotton may constrain the availability of N, but enhances P‐availability in these soils.
Keywords: Gossypium hirsutum, cotton, transgenic plants, Bacillus thuringiensis, crystal proteins, enzyme activity, soil enzymes, rhizosphere, nutrient availability, soil fertility, sandy loam soils, root systems, soil respiration, nitrogen, phosphorus, dry matter accumulation, India
Citation: Sarkar, B., Patra, A.K. and Purakayastha, T.J., 2008. Transgenic Bt‐Cotton Affects Enzyme Activity and Nutrient Availability in a Sub‐Tropical Inceptisol. Journal of Agronomy and Crop Science, 194(4), pp.289-296.
