BACKGROUND: Optimization of nitrogen (N) and sulfur (S) nutrition of wheat influences the bread-making quality of grain. This study was conducted to determine whether the application of N and S in winter wheat at anthesis stage during two field trials could influence the absorption and distribution of N and S in grain and flour bread-making quality

Nitrogen (N) and sulfur (S) supplies have a strong influence on the quality and quantity of wheat storage proteins, which play an important role in the breadmaking process. Nitrogen derived from urea, S from micronized elemental sulfur, and a mixture of both (N+S) were applied at anthesis stage on wheat by foliar spray. To relate N and S incorporation in storage proteins to the quality of dough, their incorporation into each storage protein fraction was measured: monomers, low molecular weight glutenin subunits (LMW‐GS), and high molecular weight glutenin subunits (HMW‐GS). Then protein fraction quantities, molecular weight distribution (MWD), polymerization index (PI), and molecular dimensions of unextractable polymeric protein (UPP), as well as dough mixing properties were determined. Fertilizers N and S were differentially incorporated into each storage protein fraction, influencing protein synthesis. Moreover, after the N+S fertilization, the increase of the polymeric proteins induced an increase in molecular weight and compactness, as well as in dough strength and consistency. These results provide evidence that N and S fertilizers applied by foliar spray route at anthesis, simultaneously, play an important role in controlling the storage protein synthesis and the degree of polymerization, which in turn influence dough mixing properties.

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Nitrogen (N) and sulphur (S) supplies have a strong influence on the quality and quantity of wheat storage proteins, which play an important role in the bread-making process. In order to relate the incorporation and distribution of foliar N and S fertilisers at the post-anthesis stage to the quality of wheat, 15N and 34S isotopes were used as tracers. The incorporation of these tracers in different plant parts (leaves, stems, ears) and in each storage protein fraction (gliadins, HMW and LMW glutenin subunits) was determined by isotopic ratio mass spectrometry coupled with an elemental analyser (EA-IRMS). By this means, the true recovery coefficient of N and S (TRCNfertiliser and TRCSfertiliser) and the N and S derived from fertilisers (Ndff and Sdff) could be determined. The TRCNfertiliser and TRCSfertiliser values of the different plant parts provide evidence of the applied N and S assimilation and translocation from wheat leaves to the seeds. The determination of Ndff and Sdff incorporated into storage proteins shows the efficiency and the influence of N and S incorporation into each storage protein fraction. Moreover, a favourable stage for fertiliser application can be determined by the TRCNfertiliser values in the grain and in the whole plant. The fertilisers enriched in stable isotope used in the culture techniques can be a means of understanding the effectiveness of fertilisers in the expression of wheat quality.

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