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The development of new high-yielding and stable sunflower hybrids based on interspecific hybridization requires information on the heterotic effects for agronomically important traits in the F, generation. Heterotic effects for seed yield, plant height and head diameter were studied in interspecific sunflower hybrids developed by the line x tester method. The female inbred lines were developed by interspecific hybridization, while the male restorer inbreds with good combining abilities were used as testers in the form of fertility restorers. F, hybrids were obtained by crossing each tester with each female inbred. The inbred lines and their F, hybrids differed significantly in their mean values of the traits under study. Heterosis values for seed yield per plant were positive and highly significant relative to both the parental mean (98.4-274.1%) and the better parent (54.8-223.2%). Significantly less heterosis was recorded in the case of plant height relative to parental mean (19.0-66.0%) and better parent (-3.9-51.6%). With head diameter, the heterotic effect ranged from 19.0 to 55.6% (parental mean) and from 7.8 to 36.6% (better parent). The results of this study may be used for the development of new high-yielding and stable sunflower hybrids based on interspecific hybridization. Stvaranje visoko prinosnih i stabilnih hibrida suncokreta na bazi interspecijes hibridizacije zahteva posedovanje informacije o efektu heterozisa za agronomski važna svojstva u F, generaciji. Efekat heterozisa za prinos semena. visinu biljke i prečnik glave proučavan je kod interspecijes hibrida nastalih ukrštanjem primenom linija x tester metoda. Inbred linije majke nastale su interspecijes hibridizacijom, a restorer inbred linije oca dobrih kombinacionih sposobnosti korišćene su kao testeri u formi restauratora fertilnosti. Hibridi F1 generacije nastali su ukrštanjem svakog testera sa svakom inbred linijom majke. Vrednosti heterozisa za prinos semena po biljci bile su pozitivne i visoko značajne u odnosu na roditeljski prosek (98.4-274.1%) i u odnosu na boljeg roditelja (54.8-223.2%). Znatno niži efekat heterozisa ustanovljen je za visinu biljke (19.0-66.0%) u odnosu na roditeljski prosek i u odnosu na boljeg roditelja (6.1-51.6%). Kod prečnika glave vrednosti heterozisa su se kretale od 19.0% do 74.7% u odnosu na roditeljski prosek i od 11.6-36.6% u odnosu na boljeg roditelja.

The main goals of sunflower breeding in Yugoslavia and abroad are increased seed yield and oil content per unit area and increased resistance to diseases, insects and stress conditions via an optimization of plant architecture. In order to determine the mode of inheritance, gene effects and correlations of total leaf number per plant, total leaf area and plant height, six genetically divergent inbred lines of sunflower were subjected to half diallel crosses. Significant differences in mean values of all the traits were found in the F1 and F2 generations. Additive gene effects were more important in the inheritance of total leaf number per plant and plant height, while in the case of total leaf area per plant the nonadditive ones were more important looking at all the combinations in the F1 and F2 generations. The average degree of dominance (Hi/D)1/2 was lower than one for total leaf number per plant and plant height, so the mode of inheritance was partial dominance, while with total leaf area the value was higher than one, indicating super dominance as the mode of inheritance. Significant positive correlation was found: between total leaf area per plant and total leaf number per plant (0.285*) and plant height (0.278*). The results of the study are of importance for further sunflower breeding work. Oplemenjivanje suncokreta u svetu i kod nas usmereno je na povećanje prinosa semena i sadržaja ulja po jedinici površine, otpornosti prema bolestima insektima i stresnim. uslovima optimalizacijom arhitekture biljke. U cilju utvrđivanja načina nasleđivanja, efekta gena i međuzavisnosti ukupnog broja listova po biljci, ukupne lisne površine po biljci i visine biljke, izvršena su dialelna ukrštanja isključujući recipročna sa šest genetski divergentnih inbred linija suncokreta. Dobijene su signifikantne razlike u srednjim vrednostima za sva ispitivana svojstva F1 i F2 generaciji. Aditivni efekat gena je bio od većeg značaja u nasleđivanju ukupnog broja listova po biljci i visini biljke dok je neaditivni efekat gena bio značajniji kod ukupne lisne površine po biljci uzevši u obzir sve kombinacije ukrštanja u F1 i F2 generaciji. Prosečan stepen dominacije (H1/D)1/2 je kod ukupnog broja listova po biljci i visine biljke manji od jedinice iz toga se može zaključiti da je način nasleđivanja parcijalna dominacija, a kod ukupne lisne površine je veći od jedinice što ukazuje na superdominaciju. Značajna pozitivna međuzavisnost ustanovljena je između ukupne lisne površine po biljci i ukupnog broja listova po biljci (0.285*), visine biljke (0.278*). Rezultati ovih istraživanja imaće značaja u daljem radu na oplemenjivanju suncokreta.

Sunflower is the main crop species for the production of edible oil in many countries of the world, including ours. Plant height and head size, form and position on the stem as well as the number of leaves, their size, duration and distribution on the plant all play an important role in defining optimal plant architecture in sunflower hybrids (Škorić, 1975, 1989, 2002). In order to monitor the mode of inheritance and gene effects for head diameter in the F1 and F2 generations, half diallel crosses were made in six genetically divergent sunflower inbreds. The mean values of the trait in question differed significantly. The mode of inheritance of head diameter in the F1 generation was superdominance in all but four crosses, which had dominance instead. In the F2 generation, on the other hand, the prevailing mode was dominance, while superdominance was recorded in four cases. The dominant component accounted for the bulk of genetic variance, and the mode of inheritance of head diameter taking into account both the F1 and F2 generations was superdominance. These findings may prove valuable for developing high-yielding sunflower genotypes. Suncokret je u mnogim zemljama u svetu i kod nas osnovna biljka za proizvodnju jestivog ulja. Visina biljke, veličina, forma i položaj glave na stablu, broj listova, njihova veličina, trajanje i raspored na biljci imaju važnu ulogu u definisanju optimalne arhitekture hibrida suncokreta (Škorić 1975; 1989; 2002). U cilju praćenja načina nasleđivanja i efekta gena prečnika glave suncokreta u F1 i F2 generaciji izvršena su dialelna ukrštanja isključujući recipročna sa šest genetski divergentnim inbred linijama suncokreta. Dobijene su značajne razlike u srednjim vrednostima za ispitivano svojstvo. Prečnik glave se u F1 generaciji nasleđivao superdominantno jedino se u četiri ukrštanja javila dominacija, dok se u F2 generaciji nasleđivao dominantno, a superdominacija se zadržala u četiri kombinacije. Glavni deo genetske varijanse čini dominantna komponenta, a način nasleđivanja prečnika glave je superdominacija uzevši u obzir sve kombinacije ukrštanja u obe generacije (F1 i F2). Ova istraživanja mogu biti od značaja u stvaranju visoko prinosnih genotipova suncokreta.