Assessment of Grain Protein Deviation in Hard Winter Wheat Germplasm.

Assessment of grain protein deviation in hard winter wheat germplasm. Hard winter wheat producers maximize profits by growing high yielding varieties with adequate grain protein concentration (GPC) to satisfy marketing and end-use standards. Breeder selections for both traits are confounded by the commonly observed antagonism between high grain yield and high GPC. Genotype by environment effects are substantial for both traits and reduce the effectiveness of simultaneous selection schemes. To compensate for this negative relationship, research studies have shown that strategically applied nitrogen fertilizer enhances GPC. The practice is not commonly done in Colorado due to increased input costs coupled with inconsistent precipitation patterns, along with potential environmental damage. The wheat ideotype that would account for these constraints would produce high yields of high protein grain with limiting or moderate nitrogen supply. Several recent studies report on genetic factors that have either independent or antagonistic effects on grain yield and grain protein across environments, offering evidence that the negative association between the traits can be modified through breeding, over a range of nitrogen supply. We report on an assessment of 399 lines developed by Colorado State University Wheat Breeding Program between 2006 and 2012 for deviation from the negative relationship between these traits. We calculated the residuals of the regression of GPC on grain yield across environments. Fifty three sites over 7 years were evaluated, providing a total of 107 environments. All lines had trait values for at least 4 environments in the 2012 growing season, with additional trait values contributed by varying numbers of environments in earlier seasons.