Influence of nitrogen supply on macro- and micronutrient accumulation during growth of winter wheat

The understanding of the dynamics of nutrient accumulation in crops is essential to obtain optimal yield and high qtiality food products. Modern crop production is characterized by high nitrogen (N) rates, which can influence the uptake and concentrations of other nutrients. The aim of this study was to investigate the influence of N fertilization on the temporal accumulation pattern and concentrations of nutrients during the life cycle of a winter wheat crop grown in a cool temperate climate. Seven field trials involving four N treatments (0-240 kg N ha(-1)) in southern and central Sweden were sampled over one growing cycle. Above-ground plant parts were sampled at tillering, stem elongation, flowering and full maturity; and the samples were analyzed for macronutrients (N, S, P, K, Ca, and Mg) and micronutrients (Fe, Zn, Mn, Cu, and B). Temporal accumulation pattern of some elements (P, Mg, Zn, Cu, Mn and B) followed biomass accumulation, while other elements (K, Ca, N, S and Fe) accumulated faster than biomass, especially at the early developmental stages and at high N fertilization rates. Low uptake early in the growing season could, at least partly, be compensated by late season uptake with possible implications for nutrient management. In vegetative tissues, the total amounts and concentrations of most macro- and micronutrients (except P, Mn and B) increased with N uptake. In grains, high N rate resulted in increased concentrations of S and Fe, but decreased concentration of K. Enhanced N supply did not generally result in the dilution of other elements in the grain. Results suggest that the high N accumulation rates in high-yielding crops (here winter wheat) are associated with increased demands also of other nutrients, in terms of both increased amounts and tissue concentrations. Nutrient management plans for these crops should accommodate not only the enhanced demand for N, but also other nutrients. Critical threshold concentrations for the avoidance of nutrient deficiencies should be considered in relation to the crop N concentrations.