Interaction between nitrogen and sulfur by foliar application and its effects on flour bread‐making quality

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 RESULTS: The incorporation of 15 N and 34 S tracers in various plant parts (leaves, stems, spikes) was determined by isotopic ratio mass spectrometry coupled with an elemental analyser (EA‐IRMS). The effects of foliar fertilization on percentage of 15 N and 34 S recovery in various plant parts, grain yield, flour protein content, and dough properties were investigated after a combination of treatments: N (urea), S (micronized elemental S) and NS (both urea and micronized elemental S). Nitrogen (70–80%) and S (35–55%) were quickly assimilated during the days following application. Sixty days after application, 42–68% N and 6–12% S were recovered in the grain. When N and S fertilizers were applied simultaneously, N and S recoveries (68% and 12%), N/S ratios (11–14), flour protein content (115 g kg −1 ) and dough strength (310 × 10 −4 J), swelling (21.8 mmH 2 O) and extensibility (96.4 mm) were increased. CONCLUSION: A synergistic effect between the foliar applied N and S fertilizers appears to increase N and S assimilation in grain and may improve bread‐making qualities. Copyright © 2007 Society of Chemical Industry