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Transgenic Bt ‐Cotton Affects Enzyme Activity and Nutrient Availability in a Sub‐Tropical Inceptisol
Author(s) -
Sarkar B.,
Patra A. K.,
Purakayastha T. J.
Publication year - 2008
Publication title -
journal of agronomy and crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.095
H-Index - 74
eISSN - 1439-037X
pISSN - 0931-2250
DOI - 10.1111/j.1439-037x.2008.00312.x
Subject(s) - bt cotton , inceptisol , rhizosphere , loam , agronomy , soil water , crop , nutrient , sowing , panicum miliaceum , biology , horticulture , ecology , genetics , bacteria
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 (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.