Transgenic Bt-cotton affects enzyme activity and nutrient availability in a sub-tropical inceptisol

Sarkar, B. and 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. ISSN 0931-2250

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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-6301Bt) 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 (NH 4+-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.

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Journal of Agronomy and Crop Science
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27 Jan 2020 09:55
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22 Nov 2022 08:40