M. Drumeva*, P. Yankov
Department of Plant Production, Faculty of Shipbuilding, Technical University Varna, 1 Studentska, 9010 Varna, Bulgaria (Manuscript received 6 March 2017; accepted for publication 3 July 2017)
Abstract. For accelerated development of fertility restorer lines with imidazolinone tolerance in sunflower (Helianthus annuus L.), the gamma-induced parthenogenesis, which combines classical breeding approaches and in vitro techniques, was applied. As initial materials six imidazolinone-tolerant hybrid combinations (F1203, F1216, F1246, F1248, F1295 and F1332), obtained from Dobrudzha Agricultural Institute, General Toshevo, were used. To initiate parthenogenetic development mixed pollen from different fertility restorer lines was applied. The mixed pollen was irradiated with a dose of 600 Gy. A total of 166 parthenogenetic immature embryos were obtained, and 84 young plants developed from them, 42 of the plants were fertile. Best parthenogenetic response, expressed as a number of embryos obtained, was observed by hybrid combination F1295, followed by hybrid combination F1332. The lowest parthenogenetic responsiveness is reported in hybrid combinations F1246 and F1248, where the total number of parthenogenetic embryos obtained was 5. In hybrid combinations F1295 and F1332, as well as in F1216, the method of gamma-induced parthenogenesis can be efficiently used for accelerated production of parental lines for heterosis breeding in sunflower. In hybrid combinations F1203, F1246 and F1248, which showed low parthenogenetic responsiveness, conventional methods for developing lines from these hybrids are recommended.