Dry Matter and Nitrogen Partitioning Patterns in Bt and Non-Bt Near-Isoline Maize Hybrids
- K. D. Subedi * and
- B. L. Ma
While maize (Zea mays L.) hybrids with the Bt transgene from Bacillus thuringiensis have been gaining popularity, their dry matter (DM) production, N uptake, and whole-plant N dynamics have not been assessed to justify their added cost. A field experiment conducted for 2 yr in Ottawa, Canada, studied DM and N partitioning patterns, and N-use efficiency (NUE) of a conventional (Pioneer 3893) and its near-isoline transgenic hybrid (Pioneer 38W36 Bt). The hybrids were grown with two N treatments (0 kg N [N0] or 150 kg N ha−1 with 15N-labeled source [N150]). Plant samples were analyzed for DM, N concentration, and the fate of 15N at the V7, silking, and physiological maturity (PM) stages. Both hybrids were similar in harvest index, leaf chlorophyll content, and N concentrations and contents at the V7, silking, and PM stages. The Bt hybrid produced greater DM in leaves (42.1 vs. 37.5 g plant−1) and kernels (134 vs. 121 g plant−1) than its non-Bt counterpart, it also accumulated about 11% more N in kernels and on a whole-plant basis. Both hybrids had a similar partitioning of N and NUE in different plant parts. About 47% of the applied N was recovered at harvest, 70% of which was accumulated in the kernels of both hybrids. There was no indication that the Bt hybrid accumulated more N than its non-Bt near-isoline until the silking stage; the greater N content of the Bt hybrid at the PM stage was associated with greater DM in the kernels and leaves.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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