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. Minn-pro 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 ind'') 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 x 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.