Inheritance of the efficiency of nitrogen uptake and utilization in winter wheat (Triticum aestivum L.) under diverse nutrition levels

The effects of contrasting soil nitrogen (N) levels on the inheritance of the efficiency of N uptake and N utilization in grain mass formation were examined in winter wheat. Parents of various origins and their diallel F-2-hybrids were evaluated in field and pot experiments under varying levels of soil N. The range of additive variance in the components of N efficiency was narrow, especially under N shortage. The soil N-treatments imposed had a substantial influence on gene actions responsible for the efficiency components and modes of inheritance. Genotype x nutrition interactions were common. Under high N-fertilization, the efficiency components were inherited in a manner favourable for wheat selection (preponderance of additive effects). However, the enhanced contribution of non-additive gene effects and increased dominance under N-limited conditions could impede wheat selection to improve the N efficiency and adaptation to less luxurious fertilization regimes. Selection methods that eliminate masking non-additive influences and take advantage of the additive variance should be employed to improve these traits.