Nitrogen and water rate effect on winter wheat dough quality

Nitrogen and water stress might have different impacts on winter wheat bread quality. Using the 13C discrimination (Delta) method, N and water stress (YLNS and YLWS) impacts on yield can be separated. Relating stresses (YLNS and YLWS) and crop reflectance and ultimately dough quality may provide opportunity to identify problems and correct solutions. The objective of this study were: 1) to quantify the nitrogen and water stress and their effect on winter wheat grain yield and quality and; 2) to assess the feasibility of using remote sensing to predict wheat quality characteristics.;Field experiments were conducted in 2007 and 2008 at Dakota Lake Research Farm. The design was a randomized split block, which contained 5 N-rates (0, ¼, ½, 1, 1½- rate of recommendation ), 2 water levels (adequate and deficient) and 4 replication. Dough quality was measured with farinograph. Yield loss due to N stress (YLNS) and water stress (YLWS) were calculated using the 13C isotopic discrimination (Delta) technique. Reflectance indices were developed on data collected at Haun GS5 and GS6 by MSR Cropscan unit.;Grain yield, harvest biomass, grain protein and flour protein increased with higher nitrogen rate. Grain yield and biomass increased with increasing water amount while grain protein was not affected by water in 2007 but decreased in 2008. Grain yield was higher in 2008 but grain and flour protein values were lower than 2007. N Applied in excess of the N recommendation had a minimal impact on wheat yield in 2007. Protein concentration generally decreased with increasing yield potential. Correlation analysis suggested that nitrogen stress (YLNS) was the primary factor controlling yield in 2007 while water stress (YLWS) was the primary factor controlling yield in 2008. N stress (2007) decreased arrival, departure, peak, stability and time to breakdown, while with water stress (2008) opposite results were observed. These results were expected because water and N stress have opposite impacts on protein.;The Cred and Cgreen crop reflectance indices provided the "best" indirect measures of stress. Values for both indices increased with N in the adequate water treatment. In the water deficient treatment, the first increment of N increased the indices values. The Cgreen and Cred indices provided good estimates of wheat grain yield, protein, quality parameters and YLNS in 2007 and grain yield and YLWS in 2008. Grain protein and quality prediction in 2008 were best estimated using multiple indices.