Search

Since northern European agricultural practices are likely to go toward systems with lower inputs of N fertilizers, it is desirable to develop cultivars with increased yield potential associated with higher nitrogen use efficiency (NUE). This study determined the extent of variation in NUE‐related parameters, specifying the primary traits contributing to the difference in nitrogen remobilization efficiency (NRE) on four spring cereal crops, two‐ and six‐row barley (Hordeum vulgareL.), oat (Avena sativaL.), and wheat (Triticum aestivumL.). Field experiments were conducted in Finland during 2001, 2002, and 2003 under two N regimes (0 and 90 kg N ha−1). Wheat had relatively high N content at maturity even though NUE was low, whereas oat and barley had higher NUE. A comparison of nitrogen harvest index (NHI) and NRE revealed that both were low for wheat, linking this with high N uptake after anthesis, suggesting that in wheat the proportion of the assimilated N used immediately in the developing grain is greater than in barley and oat. There was no strong N translocation from vegetative parts of the main shoots in wheat, which exhibited higher competition for N between vegetative and reproductive organs. Plant breeders could use these findings to their advantage in breeding spring cereal crops that not only produce high yield but also efficiently use available N in northern growing conditions.

Spring cultivars of barley (Hordeum vulgareL.), oat (Avena sativaL.), and wheat (Triticum aestivumL.) are the most important crops in Finnish agricultural systems. The increasing need to reduce pollution from N fertilizer is concomitantly strengthening the importance of improving the understanding of nitrogen use efficiency (NUE) of these crops. The aim of this work was to study the differences in NUE, defined as the crop's ability to produce yield with one available N unit, among spring cereal cultivars, and to determine the achievements of plant breeding in NUE under northern European growing conditions. Field experiments were conducted in Finland during 2003 and 2004. Samples from matured plants of 17 to 18 cultivars of each of the three cereal species released between 1909 and 2002 were studied. There were no clear differences in NUE among modern spring cultivars. However, there were cultivar differences within species and significant NUE improvements on wheat and particularly for oat across time. There was no clear trend of NUE and year of release of cultivars in two‐row spring barley, probably because breeding for malting barley involves consistent selection for low‐protein cultivars. The study revealed that most breeding effects on NUE were associated with changes in nitrogen uptake efficiency (UPE).