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Effect of Foliar Sulfur and Nitrogen Fertilization on Wheat Storage Protein Composition and Dough Mixing Properties

¹Ecole Supérieure d'Agriculture de Purpan, Laboratoire d'Agrophysiologie, UMR INRA-1054, 75 voie du T.O.E.C, 31076 Toulouse cedex 03, France. ²Corresponding author. Phone: 00 (33) 56 115 3076. Fax: 00 (33) 56 115 3060. E-mail: tea@esa-purpan.fr ³Grande Paroisse S.A., 12 place de l'Iris, 92062 Paris La Défense cedex, France. ⁴Université de Nantes, Faculté des Sciences, LAIEM, UMR CNRS-6006, 2 rue de la Houssinière, 44322 Nantes cedex, France.

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.