Managing irrigation and nitrogen fertility of hard spring wheats for optimum bread and noodle quality

End-uses of hard wheat (Triticum aestivum L.) are increasingly diverse. However, limited understanding of crop management system interactions with genotype exists to tailor production systems for both bread and Asian noodle production. Therefore, we evaluated the bread quality and alkaline noodle color of four hard spring wheat genotypes differing in end-use quality at four nitrogen fertilizer levels and three irrigation levels. The trials were grown for 2 yr at Aberdeen, ID, using the hard red cultivar 'Westbred 936', the hard white cultivars 'Idaho 377s' and 'Lolo', and the hard white breeding line 'IDO523'. The main effects of genotype, nitrogen fertilizer, and irrigation affected grain protein concentration, which led to significant differences among treatments for mixograph characteristics and loaf volume. Genotypes differed significantly in their optimum nitrogen levels for grain yield, yet grain protein concentration of all four genotypes increased linearly with increasing nitrogen fertilizer application. Reducing the amount of irrigation elevated grain protein concentration; however, it also reduced milling yield. By contrast, increasing nitrogen fertility did not affect milling yield. Reducing the amount of irrigation also increased grain polyphenyl oxidase (PPO) activity, generally undesirable for Asian noodles. In this study, it was preferable to increase grain protein concentration by increasing fertilization rather than by reducing irrigation. Nitrogen fertilizer did not affect alkaline noodle brightness, except at the lowest irrigation level where increasing nitrogen fertilizer decreased initial brightness. Increased nitrogen fertilizer increased both peak flour pasting viscosity and final flour pasting viscosity. The increase in viscosity occurred at all irrigation levels but with different slopes among the genotypes. The flour pasting properties of Lolo were most affected by nitrogen fertilization.