Technical summary

Immature sunflower (Helianthus annuus L.) zygotic embryos belonging to R and B sunflower lines were treated with ultra sound and gamma rays before planting in an embryo culture medium. In those circumstances new mutant lines with the altered architecture, increased oil content, 1000-seed weight, number of seed per head, as well as seed yield were developed. Some mutant lines showed very good combining abilities. Line 12004 R (developed trough Embryo culture method in immature zygotic embryos in combination with gamma irradiation at dose 8 Gy), paternal component of hybrid Goryanin, line 12002 R (developed trough Embryo culture method in immature zygotic embryos in combination with gamma irradiation at dose 8 Gy), paternal component of the commercial hybrid Rada and line 12003 R (developed trough Embryo cluture method in immature zygotic embryos in combination with ultra sound at dose 25.5 W/cm2 for 1 min) and paternal component of the commercial hybrid Yana were realized. Hybrid Goryanin con-siderably exceeded the average standard (the Bulgarian commercial hybrids Mercury, Perfect and S-205) by seed yield with 15.2%. Hybrid Rada considera-bly exceeded the average standard of seed yield by 2.3-7.7 % (in relation to Bul-garian commercial hybrid Albena and French commercial hybrid Diabolo). The vegetation period was 115 days. The hybrid Yana considerably exceeded the average standard of seed yield by 7.6%-14.4 % (in relation to Bulgarian com-mercial hybrid Perfect and French commercial hybrid Diabolo). Its vegetation period is 110 days. The hybrids Rada and Yana possess the immunity to the parasite Orobanche cumana race G, immunity to Plasmopara helianhi-race