Moisture stress influences both yield and end‐use quality of wheat (Triticum aestivum L.). Previous studies assessed stability of yield and yield components to moisture stress. This study evaluated the stability of spring wheat quality parameters relative to the stability of grain yield and its components under moisture stress. Sixteen spring wheat cultivars were produced under two moisture‐deficit regimes in 1995 and 1996 to determine the effects of moisture‐deficit severity on grain yield and its components, test weight, flour protein, flour extraction, dough‐mixing characteristics, and alkaline noodle color. Moisture deficit differentially and significantly influenced cultivar test weight and yield. The overall moisture‐deficit‐induced reduction in yield was due primarily to reduction in kernel weight; effects of moisture deficit on yield of specific cultivars were due largely to effects on kernels per spike. Drought‐sensitivity indices (DSIs) for yield were correlated to cultivar yield potential. Yield reduction by moderate moisture deficit was not predictive of yield reduction by severe moisture deficit. Effects of moisture‐deficit severity on flour extraction and mixograph peak time varied with cultivar. Moisture deficit reduced initial noodle brightness and enhanced noodle yellowness. However, the color of noodles produced by the cultivars included in this study responded similarly to moisture deficit, suggesting that evaluation of noodle color may not require testing across moisture‐deficit environments. Test weight and flour extraction DSIs were correlated with DSIs for grain yield. Therefore, identifying drought‐tolerant genotypes based on yield stability under moisture stress also will identify genotypes having stable test weight and flour extraction.

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Although some quality characteristics for the two categories of wheat products are similar, the relative effects End-uses of hard wheat (Triticum aestivum L.) are increasingly of genotype and crop management variables on the two diverse. However, limited understanding of crop management system interactions with genotype exists to tailor production systems for both product categories need better definition. bread and Asian noodle production. Therefore, we evaluated the bread Both protein quantity and quality are required for opquality and alkaline noodle color of four hard spring wheat genotypes timum bread performance. Nitrogen fertilization strongly differing in end-use quality at four nitrogen fertilizer levels and three influences the quantity of protein in wheat flour (Dubetz irrigation levels. The trials were grown for 2 yr at Aberdeen, ID, using Gauer et al., 1992). Studies have demonthe hard red cultivar 'Westbred 936', the hard white cultivars 'Idaho strated the importance of N application timing for opti-377s' and 'Lolo', and the hard white breeding line 'IDO523'. The main mal wheat yield, increased grain protein concentration, effects of genotype, nitrogen fertilizer, and irrigation affected grain proand reductions in N loss from the soil-plant system (Fowtein concentration, which led to significant differences among treat- ler et al., 1989;Hucklesby et al., 1971;Altman et al., 1983; ments for mixograph characteristics and loaf volume. Genotypes dif- Miezan et al., 1977). Nitrogen applications later in the fered significantly in their optimum nitrogen levels for grain yield, yet grain protein concentration of all four genotypes increased linearly season, near anthesis, when coupled with irrigation, inwith increasing nitrogen fertilizer application. Reducing the amount creased grain protein concentration more than earlier of irrigation elevated grain protein concentration; however, it also reapplications (Wuest and Cassman, 1992;Strong, 1982). duced milling yield. By contrast, increasing nitrogen fertility did not Bread loaf volume is positively and directly correlated affect milling yield. Reducing the amount of irrigation also increased with flour protein concentration (Bushuk, 1985; Finney grain polyphenyl oxidase (PPO) activity, generally undesirable forand Barmore, 1948). Therefore, protein quantity and Asian noodles. In this study, it was preferable to increase grain protein quality have received considerable attention in wheat concentration by increasing fertilization rather than by reducing irriimprovement programs. However, simultaneously ingation. Nitrogen fertilizer did not affect alkaline noodle brightness, excreasing both grain yield and grain protein content has cept at the lowest irrigation level where increasing nitrogen fertilizer been difficult because of the widely documented negadecreased initial brightness. Increased nitrogen fertilizer increased both peak flour pasting viscosity and final flour pasting viscosity. The