Hybridization of Thinopyrum distichum and Secale cereale

An attempt was made to determine whether the salt tolerance genes of Thinopyrum distichum would be expressed in the presence of the rye genomes and if it would be possible to improve and utilize its hybrid with rye as a salt-tolerant fodder crop. Th. distichum florets were pollinated with diploid and tetraploid rye but hybrids were obtained only with tetraploid rye. The F₁ had 28 chromosomes and expressed high levels of salt tolerance. Fertility could not be induced through colchicines treatment but the plants produced some apomictic seeds during the summer months. The F₂ had 20-22 chromosomes and retained two complete or near-complete rye genomes. The F₂ plants responded better to colchicine treatment, however, the doubled hybrids remained male sterile. In summer, one F2 plant produced many apomictic seeds with chromosome numbers ranging from 14 to 16 (primarily rye chromosomes). The mechanism that caused the preferential loss of Thinopyrum chromosomes in each apomictic cycle remains unknown. The F₃ phenotypically resembled rye, had primarily reductional male meioses and produced seemingly functional pollen, but were self-sterile.