GENOTYPIC AND CYTOLOGICAL INFLUENCES ON THE MEIOSIS OF HEXAPLOID TRITICALE

Two groups of hexaploid triticale were synthesized from the crosses of two cultivars of diploid rye (Secale cereale L.) with (a): two cultivars of tetraploid macaroni wheat (durum-group of Triticum turgidum L.), and (b): extracted AABB tetraploids of three cultivars of hexaploid bread wheat (T. aestivum L. em. Thell.).The extracted triticales, as a group, showed the greater chromosome regularity in the division of their PMC's. This was attributed to the prior adaptation of the extracted AABB component to the hexaploid meiosis of bread wheat. There was much variation in chromosome behaviour among triticales which had in common the same parental cultivars of wheat and rye. This genetic variability most likely came from the heterogeneity of gametes that were contributed by the two outbred cultivars of rye.AI was delayed in PMC's in which there was a low level of synapsis at MI. This effect was related to the total number of chromosome arms that were paired in each cell (arm pairs), regardless of how many univalents each cell contained. Non-randomness in the distribution of paired chromosome arms suggested that some chromosomes (possibly derived from rye) were less likely to pair than others.The rate at which univalents were formed in cells with a particular number of arm pairs was clearly influenced both by the genotype and by the environment of the triticale in question.