SCREENING RESISTANCE SOURCES IN AEGILOPS SPECIES AND THEIR UTILIZATION IN THE GENETIC IMPROVEMENT OF BREAD WHEAT Thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Agriculture (M.Sc. agr.) at the Faculty of Agriculture, Georg-August-Universität Göttingen. submitted by: Solomon Assefa Supervisor: Prof. Dr. H. Fehrmann Co-supervisor: Dr. H. Lehmann-Danziger Institut of Plant Pathology and Plant Protection Göttingen, February 1998