Partial amphiploids from wheat (Triticum aestivum) × rye (Secale cereale) crosses

Two groups of three-way hybrids were produced by crossing F1 hybrids of 'Petkus' × 'Prolific' rye (2n = 14) and 'Prolific' × 'Puma' rye (2n = 14) onto 'Chinese Spring' wheat (2n = 42). Meiosis was studied in 89 plants from 29 families from the first combination and in 36 plants from 11 families in the second cross. In three families from the first combination ('Petkus' × 'Prolific') five partial amphiploids with chromosome numbers of 2n = 35, 36, 36, 38, and 41 were identified. The mean bivalent frequencies in five hybrids were 6.71, 7.73, 8.10, 9.94, and 13.00, suggesting that the number of bivalents was generally equal to the number of chromosomes in excess of the expected chromosome number of 2n = 28. These five plants were partial or incomplete amphiploids and their origin was attributed to duplication of a portion of the wheat complement after fertilization.Key words: partial amphiploids, hybrids (intergeneric), Triticum, Secale, chromosome pairing.