Ecological distribution and species diversity of Aegilops L. genus in Bulgaria

The genus Aegilops has an important potential utilization in wheat improvement because of its resistance to different biotic and abiotic stresses and close relation with the cultivated wheat. Therefore, a better knowledge of the eco-geographical distribution of Aegilops species and their collection and conservation are required. A total of 297 Aegilops accessions representing nine (five tetraploid and four diploid) species were collected in different regions of Bulgaria, and the ecological characteristics of the 154 explored sites were recorded. The distribution of the diploid species (Ae. caudata L., Ae. speltoides Tausch, Ae. umbellulata Zhuk. and Ae. comosa Sibth. and Sm.) was limited to specific environments in south-central Bulgaria. Tetraploid species were present in harsher environments than diploid species and showed wider adaptation and distribution. Species-environment relationships were analysed by considering the worldwide distribution of the species and their physiological resistance to abiotic stress. Aegilops cylindrica Host was more frequently found in northern Bulgaria and at high altitudes. Its distribution was closely related to its tolerance to low temperatures. Aegilops geniculata Roth and Ae. neglecta Req. ex Bertoi. were absent in the north of Bulgaria, but widely distributed in low rainfall areas. Aegilops neglecta, more frost resistant than Ae. geniculata, was present at higher altitude. Aegilops biuncialis Vis. and Ae. triuncialis L. showed adaptation to a wide range of climatic conditions. The study of Aegilops species ecology and distribution in Bulgaria provided useful information for the future collection and for the genetic resource management in this region.