Morphological diversity and potential interest for wheat improvement of three Aegilops L. species from Bulgaria

A collection of fifty-two Aegilops accessions belonging to three tetraploid, self-pollinated species (Ae. cylindrica Host, Ae. geniculata Roth and Ae. neglecta Req. ex Bertol.) and sampled from different eco-geographical regions of Bulgaria was evaluated during three successive years on the basis of morphological descriptors and agronomical characters. Morphological diversity was analysed using a set of thirteen quantitative traits. Significant differences between populations were noted for most morphological traits, highest variation being observed in the three species for thousand kernel weight, grain weight per spike, plant height and earliness. There was not strong relation between the morphology of the studied accessions and their eco-geographical region of origin what was obviously due to marked differences between populations from the same region. The most important characters contributing to the eco-geographical differentiation were those related to vegetative growth in Ae. cylindrica and to grain production and earliness in Ae. geniculata. Considerable variability was found among and within species in response to biotic and abiotic stresses. Ae. cylindrica accessions exibited high frost resistance, but were the most susceptible to rusts and powdery mildew. At the opposite Ae. neglecta and Ae. geniculata were characterized with high level of foliar diseases resistance. Moreover, Ae. geniculata accessions appeared to be the best adapted to drought conditions. Promising accessions were identified and are presently used to introgress potentially useful traits into wheat.