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

Abstract

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. 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. 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. 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.