The effect of the Rht1 gene on grain protein content in tetraploid wheat Triticum turgidum

The relationship between plant height and grain protein content was studied in an F₂ population of a cross between a high protein line and a semi-dwarf cultivar segregating for the dwarfing gene Rht1 and for grain protein percentage. Samples of this population were sown at the normal sowing time and at a later date. Plants sown later were shorter than those sown earlier, and no differences in height between the dwarfing genotypes were observed. This enabled the direct relationship between the Rht1 gene and grain protein content to be studied in the absence of any possible effects due to culm length. At both sowing dates, grains of plants homozygous for Rht1 had on average 1·2% less protein than grains of plants homozygous for rht1, while there was no correlation between culm length and protein content within the Rht1 and rht1 groups.