Improvement of nitrogen use efficiency in European winter oilseed rape

Plant science seminar

Fertilization with nitrogen is one of the most important factors contributing to maintenance of the high seed yields needed to match food and non-food demand for a strongly increasing world population. At the same time, nitrogen that is not taken up by the plants can escape from the agricultural production system, causing severe damage in other ecosystems. Therefore, increasing nitrogen use efficiency is becoming a major global megatrend in agricultural production and a key challenge for crops used as a biofuel source. Besides more exact fertilizer applications the use of genetic diversity to breed for nitrogen use efficiency (NUE) is a promising strategy towards a more sustainable agriculture.

The recent allopolyploid oilseed rape (Brassica napus L.), the third-most important oil crop worldwide, has multiple uses in food and non-food products and is part of a sustainable crop rotation. Compared to other crops, however, oilseed rape releases a high nitrogen balance surplus. 

We assessed the genetic improvement of NUE in 30 elite inbred and hybrid varieties, spanning 25 years of breeding progress, at six locations and two years across Germany. The varieties were cultivated under two distinct nitrogen fertilization levels (120 and 220 kg N/ha including Nmin). A second set of 30 highly diverse B. napus genotypes, including older and more recent varieties and resynthesized lines, was investigated in Mitscherlich pots and large scale containers filled with 150 kg soil at a high and low N level. By separating plant biomass at flowering (BBCH 67-69) and seed maturity into leaves, stems and siliques the trait interrelationship for N uptake (NupE) and utilization efficiency (NutE) was studied in detail. 

Analysis of inter-trait relationships among more than 30 morpho-physiological traits enabled us to elucidate key factors contributing to superior NUE. Furthermore, the experiments indicated a huge phenotypic variation for NupE until flowering, based on different N quantities in plant organs. While the genotypes also differ in their NutE during the generative phase, both trait complexes seem to be completely independent inherited. Therefore, our results suggest a great potential to genetically improve total NUE. 

Dr Andreas Stahl 

Andreas has a Bachelor degree in Agriculture (2007-2010) and completed a Master degree in Crop Production (2010-2012) at the Justus Liebig University Giessen, Germany. From 2012 to 2016 he was a PhD student at the department for plant breeding, focusing on detection of genetic variation for nitrogen uptake and utilization efficiency traits in oilseed rape (B. napus). Currently Andreas continues his career as a postdoctoral researcher at the same department. His particular research interest is the understanding of phenotypic characteristics and genetic determinants that lead to superior agronomic performance of hybrids in oilseed rape.