Differences in N use efficiency, N translocation and N immobilization capacity of their residues of oilseed rape varieties due to N fertilization

ABSTRACT

Winter oilseed rape (OSR) is known to poorly utilize nitrogen (N), thus increasing the risk of N losses. In five environments in Germany, eight OSR varieties were grown in combination with five fertilizer N treatments enabling to fit N response curves for each variety separately. At Hohenschulen, additional plant sampling after flowering and at harvest allowed to calculate N translocation from the vegetative plant parts into the seeds and to estimate the potential of the residues to immobilize N after harvest. Nitrogen fertilization increased seed and N yield. Varieties differed significantly in their yields and consequently in their NUE, however, without any significant interaction with the N supply. Total N accumulation at harvest, (N) harvest index and N translocation after flowering into the seeds as well as the N immobilization potential (I_pot) of the residues followed a similar pattern. Without N, the low amount of residues reduced I_pot despite the wide C/N ratio, while a high N fertilization only slightly increased the amount of residues, but clearly decreased their C/N ratio resulting in a lower I_pot. Our results support the approach that breeding for increased seed yields seems to be the most promising way to also improve NUE.

KEYWORDS:

• Winter oilseed rape
• N use efficiency
• Apparent fertilizer N recovery
• N immobilization

Acknowledgments

We gratefully acknowledge the excellent technical assistance provided by the staff of the laboratories at Giessen and Kiel and at the experimental stations in Groß-Gerau, Hohenschulen and Rauischholzhausen: Karlheinz Balzer, Petra Degen, Gunda Schnack, Rüdiger Ströh, Katharina Tyson.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Supplemental data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/03650340.2023.2228257.

Additional information

Funding

The work was funded by the Federal Ministry of Food and Agriculture (Federal Office for Agriculture and Food, grant no. 281B2003-16)