GENETIC AND REPRODUCTIVE CHARACTERISTICS OF A CHEMICALLY-INDUCED SEMIDWARF MUTANT IN TRITICALE

The difference in height between a chemically-induced (EMS) semidwarf mutant of hexaploid triticale (X Triticosecale Wittmack) and its tall parent (6TA204) was found to be controlled by a single recessive gene. The pedigree of the 6TA204 parent involved the combination of two hexaploid triticales, one octoploid triticale, and one dwarf hexaploid wheat (Triticum aestivum L. em. Thell). The dwarfness of the hexaploid wheat (P4160 3 E ), itself known to be conditioned by one or more recessive genes, was masked in the 6TA204 parent. In the derivation of the semidwarf 6TA204, it is postulated that either (1) a dominant gene for tallness was mutated to the recessive state, or (2) that a suppressor gene closely linked with a recessive gene for semidwarfism was impaired by EMS treatment, thereby allowing the expression of the semidwarf condition. Spike length of the semidwarf remained comparable to that of the tall parent; however, its cytological stability and fertility were significantly lower.