Genotypic and fertilization effect on grain protein content in wild and cultivated tetraploid wheats

Five lines of tetraploid wheat were tested for their grain protein content at 10 levels of fertilization ranging from 90 to 2610 mg pure nitrogen per plant. The low levels yielded, in all genotypes,
the protein percentage normally obtained under agricultural practice or in the natural habitat. The five lines included: two high protein accessions of the wild wheat, 'l'riticu1n i'ltrgidmn var. dicoccoicles, one clitr1t1n cultivar (Inbar), and the F1 and F6 derivatives of a cross between one of the var. clicoccoides accessions and Inbar. Protein percentage of all genotypes was strongly affected by fertilization, although to a different degree; a significant genotype x fertilization interaction was observed. As a result of that interaction the genetic estimate of dominance ("cl") for protein percentage was found to be significantly affected by the fertilization level: at low levels of fertilization the low protein parent (Inhar) was partially dominant, whereas at high levels - the high protein parent (var. clicoccoicles). At the low levels of fertiliz,ttion, the differences between genotypes were more pronounced than at high levels. Hence, the commonly applied agricultural levels are recommended for any genotypic evaluation of
germplasm for protein percentage. Heterosis was observed in protein weight per grain and grain weight. Protein ·weight per grain was almost unaffected by the level of fertilization and is therefore suggested as a gootl parameter for breeding wheat with high protein content.