The first sterile plants were produced in M, from 'Progres' cultivar during 1983 (Table 1). Sterile plants were observed in various varieties and doses of gamma rays Their total number for the whole period of study is 18, with an average percent below 0.01%. There were cultivars and lines in which this percent was considerably higher, and other which did not produce sterile plants (Tab 1). Untill now two new sources of cytoplasm ic male sterility (CMS) were developed by gamma rays treatment of 'Stadion1 (70 Gy) and 'Hemus1 (150 Gy) cultivars ('CMS-Stadion', 1984 and 'CMSHemus',1986).