Complementary diversity for nitrogen uptake and utilisation efficiency reveals broad potential for increased sustainability of oilseed rape production

Abstract

Aims: Nitrogen use efficiency (NUE) has become a major global megatrend for sustainable agricultural production, particularly in association with the reduced release of nitrogen-derived greenhouse gases from soils and nitrate contamination of waterways. Oilseed rape (Brassica napus L.), the second most important oilseed crop worldwide, requires relatively high N fertilisation but releases an N balance surplus after harvest. The use of genetic variation to breed more efficient varieties is a promising option to improve agricultural sustainability. Methods: We assessed 30 diverse winter oilseed rape accessions at contrasting nitrogen fertilisation levels for 33 physiological traits associated with N uptake and utilisation efficiency. Relationships among traits across the diversity panel were used to identify key complementary factors contributing to overall NUE. Results: Trait correlations revealed considerable variation for NUE parameters, including positive effects of early flowering and high leaf N concentration on enhanced N utilisation under low N input. Furthermore, seed yield per se was found to be more important than the seed N concentration for simultaneously achieving both high N utilisation and reduced N balance surplus. Conclusion: Independent inheritance of N uptake and N utilisation traits suggests potential for further improvement of NUE in oilseed rape by targeted combination of contributing factors in new, high-yielding varieties.