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 F 4 ‐ derived F 7 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 F 4 ‐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.