No abstract

A comparative study was carried out on the parthenogenetic reaction of Helianthus annuus L. lines and hybrids used as initial female material for parthenogenetic induction. It was established that the mean parthenogenetic responsiveness of the hybrids was considerably higher than that of the lines. The mean parthenogenetic responsiveness of the lines used as initial female material (2607 A, 2607 B, 1607 A, 1607 B, 1234 A and 1234 B) was lower than the mean responsiveness of the hybrids (Albena, Viki, Euroflor, Perla and San Luka). Within the investigated lines, no specific genotype reaction with regard to parthenogenetic induction was ascertained; such reaction was observed in the hybrids. The hybrids San Luka and Perla had the relatively highest parthenogenetic responsiveness. The analysis of the results showed that the optimal expression of the parthenogenetic responsiveness of the female genotype depended mainly on the interaction with the pollen source. The pollen source Rf 673 induced on average 3.4 times better parthenogenetic reaction in the hybrids Perla, San Luka and Viki that the line Rf 147. The γ-irradiation influenced the expression of parthenogenetic responsiveness of the female genotype through its effect on the parthenogenesisinducing ability of the pollen source.

Anthers from the He/ianthus mollis (M-020) species and from the hybrid combination H.mollis (Jvf-020) x H.annuus and H.annuus x H.mollis (lv/-020) were isolated. Different variants of nutrient media were tested. The most suitable medium for plant regeneration proved to be the B5 medium without hormones and with reduced sucrose content. Regeneration was obtainedji•om the H.mollis (M-020) as well asji•om the hybrid combination H.mollis (M-020) x H.annuus. On~y well formed embryos were obtained from the reciprocal crosses. Investigation on the ploidity level of the regenerants are still in progress.

Using microsatellite markers (SSR), the doubled haploid origin of diploid plants develo

Basic in vitro techniques, linked with the increase of genetic variability and acceleration of the breeding process, have been mastered and applied in sunflower breeding programs at Dobroudja Agricultural Institute, Bulgaria.The method of direct organogenesis has been succesfully used for genetic modifications of fertility restorer lines RHA-857, 147 R and Z-8-A and for overcoming the inability for crossing between H. annuus (hybrid Albena) and Helianthus tuberosus, Helianthus salicifolius, Helianthus maximiliani, Helianthus silphioides, Verbisina helianthoides and between H. mollis and H. annuus.The method of γ-induced parthenogenesis has been successfully applied to the cultivated sunflower (H. annuus L.) for obtaining doubled haploid lines. The parthenogenetic ability of both maternal and paternal parents and the gamma-irradiation effect on parthenogenic embryo development have been studied.A number of researches have been focused on the genetic potential of wild species from the genus Helianthus. Our studies investigated the possibilities of the methods for cultivation of embryos and anthers from interspecific origin. They included the use of the embryo cultivation technique under in vitro conditions until the production and testing of finished lines that could directly participate in the breeding process. Embryos were isolated from interspecific hybrids (cultural x wild and wild x cultural) with the participation of the species H. resinosus M-046, H. strumosus M-059, H. salicifolius M-045, H. ciliaris M-092, H. giganteus M-030, H. maximiliani M-087 and H. glaucophylus M-012. The studies included and investigated 51 new lines which originated from embryos of the above interspecific crosses.A number of lines obtained from embryos of the above interspecific crosses exibited valuable economic indices and high combining ability. They were included as components in highly productive hybrids.