COLD HARDINESS IN Triticum AND Aegilops SPECIES

Abstract

A total of 237 Triticum and Aegilops accessions were cold-acclimated and screened for cold hardiness. These included 90 A genome accessions (T. monococcum L. and T. beoticum Boiss.), 26 AG genome accessions of T. timopheevi (Zhuk.) Zhuk., 44 D genome accessions of Ae. squarrosa L., and 77 accessions made from 22 Aegilops species. The greatest degree of cold hardiness was found in the polyploid Aegilops species; particularly Ae. cylindrica Host (CD genome). One Ae. cylindrica accession was equal to the hardy winter wheat cultivar Norstar (T. aestivum L., ABD genome). Triticum timopheevi accessions possessed only poor levels of cold hardiness. Two of the diploid progenitor species of common wheat, T. monococcum and Ae. squarrosa, had poor to intermediate levels of cold hardiness. The D genome species was, on average, more hardy than the A genome species. Several polyploids have achieved a level of cold hardiness greater than that found in any of the diploid species. It is speculated that these hardiness levels have been achieved, in part, by the chance incorporation of hardy diploids in the original hybridization. However, the evolution of new genie forms or an integrated genetic system between the genomes of the polyploid was probably equally important to the development of highly cold hardy types. The utility of related species for the improvement of cold hardiness in common wheat is discussed.Key words: Triticum, Aegilops, cold hardiness, winter wheat, interspecific hybridization