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Effect of nitrogen fertilization on nitrogen dynamics in oilseed rape using ¹⁵N-labeling field experiment
- Gombert, Julie, Le Dily, Frédérik, Lothier, Jérémy, Etienne, Philippe, Rossato, Laurence, Allirand, Jean-Michel, Jullien, Alexandra, Savin, Alexandre, Ourry, Alain
- Zeitschrift für Pflanzenernährung und Bodenkunde 2010 v.173 no.6 pp. 875-884
- Brassica napus var. napus, environmental impact, field experimentation, flowering, leaves, nitrogen, nitrogen content, nitrogen fertilizers, pods, stem elongation, stems
- In order to optimize nitrogen (N) fertilization and to reduce the environmental impact of oilseed rape without decreasing yield, a clearer understanding of N dynamics inside the plant is crucial. The present investigation therefore aimed to study the effects of different N-application rates on the dynamics of N uptake, partitioning, and remobilization. The experiment was conducted on winter oilseed rape (Brassica napus L. cv. Capitol) under three levels of N input (0, 100, and 200 kg N ha⁻¹) from stem elongation to maturity using ¹⁵N-labeling technique to distinguish between N uptake and N retranslocation in the plant. Nitrogen fertilization affected the time-course of N uptake and also the allocation of N taken up from flowering to maturity. Most pod N came from N remobilization, and leaves accounted for the largest source of remobilized N regardless the N-application rate. However, the contribution of leaves to the remobilized N pool increased with the N dose whereas the one of taproot decreased. Stems were the main sink for remobilized N from stem elongation to flowering. Leaves remained longer on N200 than on N0 and N100 plants, and N concentration in fallen leaves increased with the N treatment and in N100 plants along an axial gradient from the basal to the upper leaves. Overall, these results show that the timing of N supply is more crucial than the N amount to attain a high N efficiency.