On the nature of hybrid dwarfness

In studies of the hybrid combination ((F₄ Khar’kovskaya 46 × Triticum dicoccum) × Khar’kovskaya 46), a short-stemmed line, whose progeny exhibited traits of hybrid dwarfism, segregated with a frequency close to 1: 15. Analysis of this line in F₃ and hybrids from crosses of the short-stemmed line from this combination with the long-stemmed accession T. turgidum L. (c-38097) showed that the stem size variability curves of the both lines have two peaks. Since these results cannot be explained by complementary interaction of D genes, hybrid dwarfism is probably controlled by pleiotropic action of two genes that have multiple pleiotropic effect on the D ₂ D ₂ D ₃ D ₃ genes. Two or three rounds of selection performed on the progeny of plants higher than 80–100 cm produces stable lines without hybrid dwarfism traits, i.e., the pleiotropic effect disappears.