Grain Protein Inheritance and Nitrogen Uptake and Redistribution in a Spring Wheat Cross

Grain‐protein concentration in hard red spring wheat (Triticum aestivum L.) is important to bread‐making quality and human nutrition, and for its economic impact in marketing. The inheritance of high protein concentration in Minnpro, a cultivar released in 1989, was studied because progeny from its previous crosses in the breeding program appeared to have segregated in a qualitative fashion. Minnpro was crossed to MN7570, a lower‐protein line, and 88 and 84 F4‐ derived F7 lines were grown in a simple lattice design at two locations in Minnesota in 1984. Traits measured were grain yield, grain‐protein concentration, and the physiological traits (biological yield, harvest index, plant N concentration, N concentration index, total plant N, and N harvest index) associated with N uptake and redistribution. The latter traits were measured in order to determine their associations and the possible physiological relationship with the increased grain protein. For grain‐protein concentration, the data fit a bimodal distribution at each location and across locations with a monogenic ratio (9 high:7 low) expected for randomly selected F4‐derived lines. As further evidence of probable qualitative inheritance of grain protein concentration, the genotype × location interaction was nonsignificant, and the correlation of the lines between locations for grain protein concentration was positive and high (r = 0.8, P < 0.01). Grain‐protein concentration was positively associated with N concentration in the aerial vegetation on a per unit area basis but not with total aerial biomass. Thus, grain‐protein concentration was associated with more efficient N redistribution per unit of aerial biomass, but not with the redistribution of a greater quantity of N per unit area.