THE EXPRESSION OF COLD HARDINESS IN TRITICUM SPECIES AMPHIPLOIDS

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Abstract
A total of 18 amphiploids were produced from interspecific crosses involving T. durum Desf., T. dicoccum Shrank., T. araraticum Jakubz., T. ventricosum Ces., T. aestivum L. em. Thell. and T. tauschii (Coss.) Schmal. The amphiploids and their parents were evaluated for cold hardiness to determine its expression in the synthetic hexaploid reconstituting the ABD genome of common wheat and in other genomic combinations. Cold hardiness of the parents was not additive in the artificially produced amphiploid; rather, the expression of cold hardiness was dependent upon the specific combining ability of the parents. None of the amphiploids exceeded the most hardy T. durum parents in cold hardiness. The poor general combining ability of the synthetic amphiploids suggests that the addition of the D genome of T. tauschii to the AB genome of tetraploid wheat would not have given the original hexaploid wheats a significant initial cold hardiness advantage. The high level of cold hardiness present in the hexaploid wheats apparently evolved through genetic mutation and/or recombination followed by selection at the hexaploid level.