Effects of nitrogen and sulfur fertilizer on protein composition, mixing requirements, and dough strength of four wheat cultivars

Two field trials using four New Zealand wheat cultivars were undertaken to observe the effects of nitrogen and sulfur fertilization on protein composi tion, mixing requirements, and dough strength and to compare the results wi th that observed with a single cultivar, Otane. The results confirmed that adequate sulfur fertilization was necessary to ensure lower dough mixing re quirements. The existence of a nexus between mixing requirements and dough strength was confirmed and genotype has significant effects on it. Variatio n in the content of HMW-GS in the protein corresponded to changes in dough mixing requirement of Otane. Across the four cultivars, dough mixing requir ements (mechanical dough development work input and mixograph development t ime) and dough strength (Extensigraph resistance to extension) depended on different aspects of protein composition. As the content of polymeric prote ins increased, MDD work input increased, but mixograph development time dec reased, while the effect on Rmax was small. Rmax, however, was more affecte d by either the content of small monomerics in the flour or the ratio betwe en HMW-GS peak area to total gliadin peak area. The ratio of MDD work input to Rmax was largely explained by the gliadin content of the flour. Thus, d epending on the genetic background, it should be possible to adjust dough m ixing requirements by modifying overall HMW-GS, LMW-GS, or gliadin content while maintaining dough strength.