INHERITANCE OF THRESHABILITY IN SYNTHETIC HEXAPLOID (TRITICUM-TURGIDUM X TRITICUM-TAUSCHII) BY TRITICUM-AESTIVUM CROSSES

Triticum tauschii provides breeders with a valuable source of resistan ce and tolerance genes. Elucidation of the inheritance of traits in th is species that hinder its use in breeding programmes is therefore of interest to wheat breeders. Inheritance of threshability was investiga ted in the crosses of four non-free-threshing (NFT) synthetic hexaploi ds (Triticum turgidum x T. tauschii) and two free-threshing(FT) T. aes tivum cultivars during four crop seasons over 3 years at El Batan and Ciudad Obregon, Mexico. The parents, their F-1 hybrids and individual F-2 plant-derived F-3 progenies of the crosses revealed that 'Altar 84 '/T. tauschii (219), 'Chen'/T. tauschii (205), 'Chen'/T. tauschii (224 ), and 'Duergand'/T. tauschii (214) have independently segregating loc i with two dominant alleles controlling threshability. Intercrosses am ong the synthetics, except 'Altar 84'/T. tauschii(219), showed the gen es to be allelic to each other. The cross between the FT cultivars sho wed no segregation in the F-3 generation, indicating common recessive genes. Based on these findings, population sizes of the synthetic-deri ved breeding materials should be increased to improve the chances of s electing FT desirable plants in the programme.