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The creation of new sunflower hybrids with high genetic potential for seed yield on the basis of interspecies hybridization requires a possession of the information about the mode of inheritance and the combining abilities of the created inbreed lines for the total seed number per head and the mass of 100 seeds. Apart from this the research of interdependence between yield components and seed yield allows the defining of traits which have the biggest influence on the yield formation. Significant differences were found among the A lines, Rf testers and their F1 hybrids in total seed number per head and the mass of 100 seeds. Analysis of variance of the combining abilities revealed highly significant differences for GCA and SCA. Highly significant positive value GCA was demonstrated by A-line NS-GS-5 for both traits. Hybrid NS-GS-5xRHA-R- PL-2/1 has the highest significant value SCA for both traits. The main role in inheritance of the total seed number per head and the mass of 100 seeds is played by non additive component of the genetic variance which is confirmed by the GCA/SCA relation in F1 generation that is less than one (0.11, 0.24). Rf-testers had the highest average contribution in the expression of the total seed number per head (55.8%) while for the mass of 100 seeds a more significant contribution was given by A-line (70.6%). A strong positive interdependence has been determined between seed yield and total seed number per head (0.376*) and a very strong positive interdependence was determined between seed yield and the mass of 100 seeds (0.823). These research can be significant for the creation of new high-yielding sunflower hybrids on the basis of interspecies hybridization. Stvaranje novih hibrida suncokreta sa visokim genetskim potencijalom za prinos semena na osnovu interspecijes hibridizacije zahteva posedovanje informacija o načinu nasleđivanja i kombinacionim sposobnostima stvorenih inbred linija za ukupan broj semena po glavi i masu 100 semena. Pored ovoga, istraživanja međuzavisnosti komponenti prinosa i prinosa semena omogućavaju definisanjae svojstava koja imaju najveći uticaj na formiranje prinosa. Pronađene su značajne razlike između A linija, Rf testera i njihovih F1 hibrida u ukupnom broju semena po glavi i masi od 100 semena. Analizom varijanse kombinacionih sposobnosti uočene su visoko značajne razlike za OKS i PKS. Visoko značajnu pozitivnu vrednost OKS pokazala je A-linija NS-GS-5 za obe ispitivane osobine. Hibrid NS-GS-5xRHA-R-PL-2/1 ima visoko značajnu vrednost PKS za ukupan broj semena po glavi i masu 100 semena. Glavnu ulogu u nasleđivanju ukupnog broja semena po glavi i mase 100 semena igra neaditivna komponenta genetske varijanse, što je potvrđeno odnosom OKS/PKS u F1 generaciji koji je manji od 1 (0.11, 0.24). Najveći prosečan doprinos u ekspresiji ukupnog broja semena po glavi (55.8%) imali su Rf testeri, dok je za masu od 100 semena mnogo važniji doprinos A-linija (70.6%). Jaka pozitivna međuzavisnost utvrđena je između prinosa semena i ukupnog broja semena po glavi (0.376*) i vrlo jaka pozitivna međuzavisnost utvrđena je između prinosa semena i mase 100 semena (0.823). Ova istraživanja mogu biti značajna za stvaranje novih visoko prinosnih hibrida suncokreta na bazi interspecijes hibridizacije.

One of the primary tasks of sunflower breeding is the development of inbred lines by interspecific hybridization for the purpose of obtaining high-yielding, stable hybrids that are characterized by altered plant appearance and the ability to produce a higher number of plants per unit area under intensive agriculture conditions. Studied in this paper by the line x tester method were seven new divergent cms inbred lines (A) lines, three Rf restorers utilized as testers, and 21 F1 hybrids developed. Significant differences in the mean values of all the traits studied were observed. Highly significant GCA and SCA values were obtained for petiole length (PL) and total leaf area per plant (TLA). The nonadditive component of genetic variance played the main role in the inheritance of both these traits. This was confirmed by the GCA/SCA ratios for PL and LA in the F1 generation, which were below the value of one (0.43 and 0.07, respectively). The greatest average contribution to the expression of PL (49.9%) and TLA (57.1%) was found in the female A lines. A positive correlation was found between seed yield (SY) and PL (0.374*) and TLA (0.630**), while seed oil content (SOC) and TLA were found to be negatively correlated (-0.520**). The findings of this study can be used in the development of new high-yielding sunflower hybrids with high yields based on interspecific hybridization. Jedan od primarnih zadataka oplemenjivanja suncokreta je stvaranje inbred linija putem interspecijes hibridizacije radi dobijanja visokoprinosnih i stabilnih hibrida promenjenog izgleda koji u uslovima intenzivne agrotehnike omogućavaju povećanje broja biljaka po jedinici površine. Za linija x tester analizu korišćeno je sedam novih divergentnih (A) citoplazmatski muško sterilnih inbred linija nastalih interspecijes hibridizacijom, tri Rf-restorer linije kao testeri i 21 hibrid F1 generacije. Dobijene su značajne razlike u srednjim vrednostima za sva ispitivana svojstva. Izračunate su visoko značajne vrednosti OKS i PKS za dužinu lisne drške (DLD) i ukupne lisne površine po biljci (ULP). Glavnu ulogu u nasleđivanju oba svojstva ima neaditivna komponenta genetske varijanse. To potvrđuje i odnos OKS/PKS u F1 generaciji koji je manji od jedinice i iznosi 0.43 za DLD i 0.07 za ULP. Najveći prosečan doprinos u ekspresiji ovih svojstava imale su A-linije majke i to (49.9%) za DLD i (57.1%) za ULP. Ustanovljena je pozitivna međuzavisnost prinosa semena (PS) sa DLD (0.374*) i ULP (0.630**). Između sadržaja ulja u semenu (SU) i ULP ustanovljena je značajna negativna međuzavisnost (-0.520**). Ova istraživanja mogu biti od značaja za stvaranje novih visoko prinosnih genotipova suncokreta na bazi interspecies hibridizacije.

Study of inbreeding and heterosis in sunflower has been taking place for over 80 years now. Practical application of the phenomenon of heterosis in this species began after the discovery of a suitable source of cytoplasmic male sterility in 1969 and that of restorer genes. Many authors have reported significant manifestation of heterosis for seed yield and yield components as well. Also, the mode of inheritance of agronomically important traits in the F1 and F2 generations has been thoroughly examined. Positive correlations for yield have been established between parental lines and F1 hybrids. The GCA and SCA for yield and yield components have been well studied. Solutions have been suggested on how to increase the harvest index and sink capacity as well as the contributions of individual physiological parameters in the process of yield augmentation. In order to increase heterotic effects for seed yield and oil yield and direct and indirect yield components, it is necessary to increase the genetic variability of pre-breeding materials, achieve improved efficacy at the inbreeding stage, and streamline and accelerate the process of GCA and SCA evaluation using molecular markers and other biotechnology methods in order to achieve breeding goals. Seed oil content should be increased to over 55% using recurrent selection methods. Special focus in breeding programs should be placed on the development of high-oleic hybrids (>95%) with a high genetic potential for oil yield, resistance to the dominant diseases, and wide environmental adaptability that would be used for industrial purposes (production of biodiesel, or hydrogen). In order to extent the duration of sunflower oil stability, beta, gamma and delta tocopherols should be incorporated instead of alpha ones alongside the Ol genes. The exiting genetic variability of the cultivated sunflower makes it possible to develop hybrids with a genetic potential for seed yield of over 6 t/ha and seed oil content of over 55%. Most often, however, sunflower yields obtained in large-scale commercial sunflower production are in the 1.5-3.0 t/ha range. There are multiple limiting factors preventing the realization of the high genetic potential of this crop. Their removal will enable commercial sunflower yield to stabilize at levels of 4 t/ha and above. Diseases are the main limiting factor affecting sunflower production in all sunflower-growing parts of the world. Development of exotic germplasm through further use of wild sunflower species, distant hybridization and genetic transformations should be used to provide genes for resistance to all dominant pathogens and broomrape. Efficient breeding methods should be employed to increase sunflower tolerance of air and soil drought and salinity and to attain wider resistance to herbicides.

Plant height and head diameter are important parameters which effect on a yield in sunflower. Six restorer Rf lines, three tester A lines and their 18 Fl hybrids were studied, using line x tester method. Significant differences were found between restorer lines and testers and their Fl hybrids for plant height and head diameter. Regarding the inheritance of examined characteristic, super dominance and dominance of better parent occurred, and the intermediary too. Tester line HA-48A (188.25 cm) and Fl hybrid HA-48A x RHA-SELEUS (245.10 cm) had the highest mean value for plant height, and the lowest value had line RHA-BRE-1 (105.35 cm) and hybrid L-19A x RHA-BRE-1 (147.9 cm). For head diameter, the highest mean value had line L-19A (19.02 cm) and Fl hybrids HA-48A x RHA-TR-20 and L-19A x RHA-TR-20 (24.55 cm), and the lowest line RHA-BRE-1 (13.10 cm) and hybrid HA-26A x RHA-M-72 (20.25 cm). Based on the results, the following conclusion is that lines RHA-BRE-1 for plant height and RHA-SELEUS for head diameter have the best GCA, and the best SCA have hybrids L-19A x RHA-BRE-1 for plant height and HA-26A x RHA-SELEUS for head diameter. Analyzing components of genetic variance, the nonadditive component played the main role in the inheritance of plant height and the additive of head diameter. The largest average contribution in the expression of plant height had the tester A-lines (83.17%) and for head diameter Rf lines had the greatest influence (58.13%). Visina biljke i prečnik glave su značajni parametri koji utiču na visinu prinosa kod suncokreta. Metodom linija x tester ispitano je šest restorer linija, tri tester A linije i njihovih 18 F1 hibrida. Utvrđene su značajne razlike između restorer linija i testera i njihovih F1 hibrida za visinu biljke i prečnik glave. U nasleđivanju ispitivanih svojstava ispoljile su se superdominacija i dominacija boljeg roditelja, ali i intermedijarnost. Najveću srednju vrednost za visinu biljke su imali tester linija HA-48 A (188,25 cm) i Fj hibrid HA-48A x RHA-SELEUS (245,1 cm), a najmanju linija RHA-BRE-1 (105,35 cm), odnosno hibrid L-19A x RHA-BRE-1 (147,9 cm). Kod prečnika glave najveću srednju vrednost su imali tester linija L-19A (19,95 cm) i F, hibridi HA-48 A x RHA-TR-20 i L-19A x RHA-TR-20 (24,55 cm), a najmanju linija RHA-BRE-1 (13,10 cm) i hibrid HA-26A x RHA-M-72 (20,25 cm). Na osnovu dobijenih rezultata može se zaključiti da najbolje OKS imaju linije RHA-BRE-1 za visinu biljke i RHA-TR-20 za prečnik glave, a najbolje PKS, hibridi L-19A x RHA-BRE-1 za visinu biljke i HA-26A x RHA-SELEUS za prečnik glave. Analiziranjem komponenti genetske varijanse, neaditivna komponenta je imala najveći uticaj na nasleđivanje visine biljke, a aditivna na prečnika glave. Najveći prosečni doprinos u ekspresiji visine biljke dale su A-tester linije 83,17%, a za prečnik glave najveći uticaj su imale restorer linije 58,13%.

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.

Western European and especially German-based multinational food processing companies tend to grow confectionery sunflower hybrids and varieties in Hungary. This commercial product is highly preferred as substitute for walnuts, as filling in chocolate, bread and other bakery products, or as seasoning. In the early 1990s, German companies rejected several trucMoads of confectionery sunflower due to "greening of the kernel in the achene". Almost 90% of the rejected consignments originated from a sandy terrace in the region between the rivers Danube and Tisza, which at the time was severely infected with the Asclepias syrlaca L. Field investigations revealed unambiguously that the greening of the kernel in the achene had been caused by the red spotted bug (Spilostethus [=Lygaeus] equestris L). This species is able to cause extensive damage and discontinuity in the so-called shoulder part of the achene with its powerful stinging-suctorial mouth organ. Intensive chlorophyll synthesis begins in the damaged area due to the solar effect, which is undoubtedly the cause for the greening of the kernel in the achene. In this investigation, we studied confectionery sunflower fields in two neighboring areas (Bâcsalmâs and Katyrnâr) for extent of damage caused by Spuostethus !=Lygaeus! equestris L. While in Bâcsalmâs (that district less infected with the Asclepias syriaca L) we found a damage of decreasing intensity (8.85 damaged achenes per sunflower disc) as advancing towards the centre of the field, this value was almost three times as high, reaching 31.71 of damaged achenes per disc, in the area of Katymâr (the area severely infested with Asclepias syriaca L). Though the numbers are not very high in themselves - assuming that a well-developed disc contains 1100 to 1200 seeds - the damage may result in significant reduction of kernel quality. Our extensive research into the causes of the greening of the sunflower kernels made it clear that Spilostethus [=Lygaeusl equestris L. had a significant influence on the chemical composition of the damaged achenes: it Increased the proportion of linoleic acid (C-18:2) by about 2.5%. That affects the lasting quality of the achene unfavorably (Horvâth and Bujâki, 1991). For this reason, a comprehensive study of the biology of Spiloslethus [=Lygaeus] equestrls L. was undertaken in order to develop effective protection methods. This study was a pioneer investigation of exogenous and endogenous factors that might obstruct the use of confectionery sunflower hybrids and varieties In food industry.

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.

Although the wild sunflower species Helianthus laevigatus has not been extensively studied, it may be considered for sunflower breeding as a potential source of desirable genes for Sclerotinia stalk rot resistance and high contents of proteins and linoleic acid in the seed. A set of six H. laevigatus populations was crossed to cultivated sunflower lines and produced nine F 1 (2-14 plants) and 66 BC 1 F 1 hybrid combinations (1-13 plants). Male sterility occurred in F 1 and BC 1 F 1 hybrid combinations and pollen viability was lower in the progenies than in the parents (51.6-77.2% in F 1 and 4.8-34.0% in BC 1 F 1 ). Meiosis was normal in the H. laevigatus populations. It was found that this tetraploid species also occurred in a hexaploid form. Numerous irregularities were observed in the meiosis of the F 1 interspecific hybrids. During diakinesis, quadrivalents and hexavalents were recorded in addition to bivalents. Dislocated chromosomes and chromosome bridges were present in the other phases. The chromosome number in F 1 was 68 (tetraploid). Irregularities in chromosome pairing were observed in the interspecific hybrids at BC 1 F 1 . There were many univalents, and trivalents, quadrivalents and hexavalents were also present. The chromosome number in the BC 1 F 1 generation ranged from 34 to 60. The occurrence of meiotic irregularities in the F 1 and BC 1 F 1 interspecific hybrids indicates that H. laevigatus and the cultivated sunflower differ in genome constitution.

The development of sunflower hybrids with high genetic potential for seed and oil yields requires information on the general combining ability (GCA) and specific combining ability (SCA) for plant height and head diameter in the F1 generation. Used in this study were thirteen new divergent cms inbred lines (A), three Rf restorers utilized as testers, and their F1 hybrids. The inbred A-lines, Rf-testers and F1 hybrids differed significantly in the mean values for plant height and head diameter. The mode of inheritance for plant height was superdominance of the better parent and for head diameter it was dominance and superdominance of the better parent. Highly significant positive values of GCA for both traits were found in cms inbred line NS-G-7 and restorer line RHA-N-49. Based on the GCA values chosen were lines with the best GCA for plant height (NS-G-9, NS-G-7) originating from PRA-RUN and head diameter (NS-G-13, NS-G-12) originating from DES. The greatest highly significant positive SCA value was found in NS-G-1xRHA-N-49 for plant height and in NS-G-8xRUS-RF-OL-168 for head diameter. Non-additive genetic variance played the main role in the inheritance of both traits as confirmed by the GCA/SCA ratios in the F1 generation, which were invariably smaller than unit. The female A lines had the highest contribution to the expression of head diameter and plant height. [Projekat Ministarstva nauke Republike Srbije, br. TR 31025]

SUMMARY Four interspecies populations, originating from three annual (H. debilis, H. praecox, H. deserticola) and one perennial (H. resinosus) wild species, were used to produce 13 new (cms) inbred lines with cytoplasmic male sterility, three Rf restorer lines with good general combining ability used as testers and their F1 hybrids. A two-year trial with three replicates was set up using the line × tester method. The inbred A-lines, Rf-testers and F1 hybrids differed significantly in the mean values for both studied traits. The mode of inheritance for leaf area was dominance and superdominance of the better parent and for plant height it was superdominance of the better parent. Highly significant positive values of general combining ability for both traits were found in inbred lines NS-G-7, NS-G-8, NS-G-9. The greatest highly significant positive specific combining ability value was found in NS-G-6 × RUS-Rf-OL-168 for the total leaf area per plant and in NS-G-6 × RHA-N-49 for plant height. The non-additive gene effect had greater influence on both traits. A significant heterotic effect was found for both traits in relation to the parental average so as in relation to the better parent.

Discovery of tribenuron-methyl resistant wild Helianthus annuus L. population (ANN-KAN) created an opportunity for expansion of sunflower herbicide resistance breeding program. The aim of this study was development of sunflower hybrids resistant to tribenuron-methyl. Creation of tribenuron-methyl resistant hybrids would enable the use of a wider palette of herbicides for sunflower, more efficient chemical control of Cirsium arvense and more economically profitable post-emergence control of some annual broad-leaves weeds in sunflower. Original populations SURES-1 and SURES-2 are homozygous for resistance to tribenuron-methyl. F1 generations produced from the crossings are completely resistant to tribenuron-methyl, pointing out to dominant way of inheritance of this trait. Studies on the exact number of genes controlling the resistance are in progress. Tribenuron-methyl resistance was transferred from original populations into a number of female and male inbred lines of cultivated sunflower. These inbred lines could enable creation of a number of hybrids resistant to tribenuron-methyl. Hybrids SUMO-1-PR, SUMO-2- OR and SUMO-3 are resistant to doubled application dose of tribenuron-methyl. Agronomical characteristics of these hybrids are on the level with the leading conventional sunflower hybrids. Otkrićem populacije divljeg Helianthus annuus L. (ANN-KAN) otporne prema tribenuron-metilu stvorena je mogućnost proširenja programa oplemenjivanja suncokreta na tolerantnost na herbicide. Cilj ovog rada je bio stvaranje hibrida suncokreta tolerantnih na tribenuron-metil. Stvaranje hibrida tolerantnih na tribenuron-metil proširilo bi paletu herbicida u suncokretu, omogućilo efikasnije suzbijanje palamide (Cirsium arvense) i ekonomski povoljnije suzbijanje nekih jednogodišnjih širokolisnih korova posle nicanja u suncokretu. Izvorne populacije SURES-1 i SURES-2 su homozigotno tolerantne na tribenuron-metil. Dobijene F1 generacije su u potpunosti tolerantne na tribenuron-metil što ukazuje na dominantan način nasleđivanja. Istraživanja tačnog broja gena koji kontrolišu ovu otpornost su u toku. Otpornost prema tribenuron-metilu je iz izvornih populacija preneta u veći broj majčinskih i restorer samooplodnih linija suncokreta. Na osnovu ovih linija moguće je stvaranje većeg broja hibrida tolerantnih na tribenuron-metil. Hibridi SUMO-1- PR, SUMO-2-OR i SUMO-3 su tolerantni na dvostruku praktičnu koncentraciju po hektaru tribenuron-metila. Ovi hibridi su po svojim agronomskim karakteristikama na nivou vodećih hibrida koji se nalaze u širokoj proizvodnji.

The hexaploid species of Helianthus tuberosus is a potential source of resistance to several sunflower pathogens. But crossed with cultivated sunflower, it produces F, hybrids which have low values of fertility or even full sterility. Pollen viability and meiotic features were studied in 17 populations of the species H. tuberosus and in F1 hybrids. Significant differences in pollen viability existed between populations (47.1–98.8%). In the 15 FI hybrids, plant fertility ranged from 0 to 100 per combination, while pollen viability ranged from 12.4 to 57.1. Meiosis was almost normal in the analyzed species, and irregular in the F, hybrids. The highest percentage of meiocytes was with bivalents (85.9), but univalents (0.3) and multivalents (13.8) occurred as well. In metaphase and anaphase, the percentage of meiocytes with fast and lagging chromosomes was high. In anaphase, chromosome bridges were detected in 9.9 of the meiocytes.

Path coefficient analysis was used to separate direct and indirect effects of studied traits on seed oil content and seed yield, and to identify traits that could be used as selection criteria in sunflower breeding. Significant and highly significant correlations were found between most of the examined traits. Highly significant negative correlations have been established between stem diameter, total leaf area per plant, head diameter and 1,000-seed weight on one side and seed oil content on the other. Highly significant positive correlations have been established between seed yield on one side and stem diameter, total leaf area per plant, head diameter, total number of seeds per head, and the 1,000-seed weight on the other. The weight of 1,000 seeds had a highly significant direct negative effect on seed oil content and a highly significant direct positive effect on seed yield. The total number of seeds per head has demonstrated a highly significant direct positive effect on seed yield and oil content. The total leaf number per plant has demonstrated a significant direct positive effect on seed yield. A path coefficient analysis of seed yield at phenotypic level indicated that maximum direct effects were shownby the weight of 1,000 seeds, total number of seeds per head and total leaf number per plant. The total number of seeds per head was the most important trait that determined seed yield and oil content. The obtained results can be used in sunflower breeding programs aimed at the development of sunflower hybrids that combine high genetic potentials for seed yield and seed oil content.

Sunflower (Helianthus annuus L.) is among the most important oil crops in the world. Due to its low to moderate production requirements, high oil quality, protein content, and utilization of all plant parts, it is grown on about 14 million ha. The major sunflower-producing countries in the world are the Soviet Union, Argentina, China, the United States, France, Spain, Romania, Turkey and Hungary. Sunflower became an oil crop around the end of the 19th century, when ‘popular selection’ was practiced in several parts of Russia to improve sunflower populations grown at that time. The most important contributions to the development of sunflower were made by Pustovoit and Jdanov in the Soviet Union, who increased the oil concentration in sunflower seed above 500 g kg−1. Leclercq of France discovered the first usable sourccytoplasmic male sterility in a cross H. petiolaris Nutt. × H. annuus L. and Kinman of the United States developed fertility restorer lines RHA 265 and RHA 266 which allowed practical development of sunflower hybrids. When starting a breeding program, it is useful to design a model of the desired hybrid and then strive to develop the envisaged model as closely as possible. It is also advisable to direct breeding efforts toward a limited number of economically important traits. These should include: (1) components of seed and oil yield: the number of seeds per plant, test weight, 1000-seed weight, low husk content and high oil concentration in the seed; (2) architecture of the sunflower plant: plant height, head size and shape, angle of the head, leaf area and leaf canopy; (3) increased harvest index: oil quality, protein concentration and quality, early maturation, short stem and uniform height; and (4) resistance to diseases and drought using wild sunflower species. Mass selection, a method of selecting desirable plants from a population on the basis of phenotypic traits, is still in effective method in sunflower breeding. Recurrent selection appears to be a promising method of increasing the frequency of desirable genotypes in a source population. Genetic variability of the cultivated sunflower may be increased by interspecific hybridization with wild sunflower species. The inclusion of wild species programs is difficult because of differences in chromosome number (2n, 4n, 6n) and incompatibility. These obstacles have been overcome by embryo culture and other tissue culture techniques. Generally, the use of new technologies in sunflower breeding is imperative, particularly in regard to the introduction of resistance genes to diseases and insect pests.

One of the directions in sunflower breeding is the selection for resistance to broomrape. The population of broomrape has been stable in Serbia for a long period of time, but the racial composition has changed in recent years, with race E being predominant in the regions of north Backa and Banat. Cultivated sunflower is genetically narrow and deficient in many desirable genes. Its genetic variability can be increased by the use of wild sunflower species and interspecific hybridization. The resistance to broomrape in 15 new experimental hybrids was tested on locations in Serbia (Pacir) during three years (2006, 2007 and 2008) and in Romania (Baragan, Braila) during 2008. These hybrids were produced by crossing female inbred lines (Ha-26PR-A, PH-BC2-92-A and Ha-98-A) susceptible to broomrape race E and new Rf inbred lines (RHA-D-2, RHA-D-5, RHA-D- 6, RHA-D-7, RHA-D-8), developed from interspecific populations originating from H. deserticola and resistant to race E. All examined hybrids were resistant to broomrape in both locations. Since broomrape race F is present in the location in Romania, it is expected that the new Rf inbred lines - male components of the examined hybrids, possess the resistance gene for race F also.

The cultivated sunflower (Helianthus annuus L.) is one of most important oil crops of the world. Although sunflower is primarily grown for extraction of its seed oil there is a limited production of non-oilseed sunflower types which are used in confections industry or as bird feed. The objective of this research was development of hybrids with high and stable oleic acid content and modified tocopherol composition, with high values for the two most important agronomic characters (seed yield and oil yield) and high tolerance to Phomopsis. The incorporation of the gene Ol+tph1 into these genotypes has led to the development of high-oleic hybrids with altered tocopherol profiles. Oil of these hybrids has a much longer shelf-life than standard sunflower oil. The process of incorporating the genes Ol+tph2 and Ol+tph1tph2 into highly productive sunflower genotypes is under way. The most important results of this line of research are the newly developed female lines with the oleic acid content in oil over 90% and the male lines (restorers) with an oleic acid content in the 89-93% range. Using these lines, hybrids will be developed whose oleic acid content in oil will exceed 90%.

SUMMARY Significant manifestation of heterosis for agronomically important traits is the main precondition for obtaining productive sunflower hybrids (Skoric et al., 2006). Development of high-yielding and stable sunflower hybrids based on interspecific hybridization requires knowledge of heterotic effects occurring in the F1 generation. Heterosis for seed yield per plant, total seed number per head and 1,000-seed weight was studied in interspecific hybrids obtained by the line × tester method. The seven female inbred lines used in the study had been developed by interspecific hybridization, while the three male restorer inbreds with good combining abilities were used as testers in the form of fertility restorers. Twenty-one F1 hybrids were obtained by crossing each tester with each female inbred line. A trial with the lines and F1 hybrids was set up at Rimski Sancevi. Experiment Field of Institute of Field and Vegetable Crops in Novi Sad using a randomized block design with three replications. Our study found significant differences in the mean values of all the traits under investigation. Heterosis values for seed yield were positive and highly significant relative to parental average (98.4-274.1%) as well as better parent (55.8-223.2%). Considerably less heterosis was found for total seed number per head (69.6-203.7%) relative to parental average and better parent (47.6-183.3%). With 1,000-seed mass, the values ranged between 26.5% and 48.8% relative to parental average and from -42.4% to 30.9% relative to better parent. This study could prove useful in the development of new high-yielding sunflower hybrids based on interspecific hybridization.

The sunflower is one of the four most important oil crops in the world. The common sunflower oil predominantly contains linoleic acid, followed by oleic, palmitic and stearic ones as well as some others that are found only in traces. As far as tocopherols are concerned, the predominant type are alpha tocopherols. Using sources for a high oleic acid content (Ol genes) and sources with genes tph1 (50% alpha + 50% beta tocoph.), tph2 (0–5% alpha + 95–100% gamma), and tph1tph2 (8–40% alpha + 0–25% beta + 25–84% gamma + 8–10% delta), the highly Phompsis-tolerant parental lines of the hybrids NS-H-45, NS-H-626, and NS-H-680 were translated into three isogenic forms. These have taken the following forms: a) Ol+tph1; b) 01+tph2; and c) 01+tph1tph2. In other words, three types of high-oleic oil with different tocopherol type and content have been obtained. Besides these isogenic lines, a number of oleic and linoleic B-lines with a different tocopherol composition have been developed as well. Also, we have developed a large number of high-oleic, high-oil restorer lines with different tocopherols. Some of these have a high level of tolerance to Phomopsis. The newly developed B- and Rf-lines can be used to develop new hybrids with different oil quality. Due to a synergy between Ol and tph genes, the oil oxistability of these new hybrids can be up to 20 times higher than in the common sunflower oil.