In order to study the drought tolerance in sunflower an experiment was conducted with 65 sunflower entries including cms -lines R-lines inbred hybrids and varieties grown in temporary cement root structures. During the active vegetative growth several physiological parameters were recorded. As flowering plants were harvested the observations on root traits were recorded. Results showed a wide and significant genetic variability for leaf area specific leaf area plant height chlorophyll content root length root dry weight root volume and total dry matter (TDM). Δ13C a surrogate approach to quantify water use efficiency also showed a significant variability. Since our major objective was to look for genetic variability for drought tolerant traits and to select lines with superior drought tolerant lines the entries were grouped into high and low root TDM and Δ 13 C types. Promising sunflower entries were selected based on high TDM with better root system and low Δ 13 C to be used for heterosis breeding to develop drought tolerant hybrids. In all screened entries it was examined how the TDM and its components are related to each other by correlating many growth parameters with TDM. The results revealed that a positive and significant relationship between total leaf area and TDM was found. Similarly root dry weight also showed a significant positive relationship with TDM. However Δ 13 C values neither related to TDM nor to root dry weight.

Sunflower in vitro culture regeneration is highly dependent on the genotypic context and culture conditions. However, there is insufficient information about the effect of the cytoplasm on the regeneration ability of this species. The aim of this experiment was to evaluate the effect of different cytoplasmic background on the regeneration ability of HA89, a well known recalcitrant inbred line. Cotyledons of seven HA89-alloplasmic lines and the fertile HA89 inbred line were used as explants on four different culture media. After 36 days of incubation, the regeneration percentage, as well as the productivity and proliferation rates, was recorded. Genotype × culture media interaction was detected in order to obtain regeneration percentage. Further analysis of this interaction demonstrated that the effect of the cytoplasm and the resulting interactions with the culture medium are key factors to be taken into account for better understanding of the in vitro culture performance of this species. Furthermore, non-nuclear genome could be considered as another source of variability modifying the regeneration ability of recalcitrant sunflower genotypes.

Immature sunflower ( Helianthus annuus L.) zygotic embryos of sunflower fertility restorer line R 2574 were treated with ultrasound before planting on the embryo culture medium. As a result some chlorophyll leaf and inflorescence mutations were observed. New sunflower forms with inherited morphological biochemical and phytopatological changes were obtained through selection and self-pollination. The line R 12003 subjected to investigation in this study was characterized with significant changes concerning most of the studied characters. The contribution of the present research connected to the investigated mutation was the appearance of resistance to the parasite broomrape. The increased number of seeds per head in line R 12003 increased oil content in seed and 100% resistance to the parasite Orobanche are the desired combination in the breeding programme of sunflower.

Information on the performance and gene action of sunflower traits is still scarce in southern Africa despite the crop’s increasing importance and the growing demand for adapted cultivars. To generate this information 30 malesterile lines were cross-bred to a restorer line generating 30 experimental hybrids. The hybrids and three check varieties were evaluated in South Africa Zambia and Zimbabwe. Data was analysed using REML procedure in GenStat®. Significant differences (P<0.05) were observed for grain yield traits oil content and days to 50% flowering. Grain yield ranged between 1700 kg ha -1 and 4278 kg ha -1 1000-seeds weight between 59.4 g and 89.3 g oil content between 36.6% and 44.6% and days to 50% flowering between 55.5 and 68.0 for the hybrids but going up to 70 for the control varieties. Five hybrids were ranked above the highest performing check variety for grain yield. Two hybrids HV9120 and HV9132 significantly outperformed the highest check variety by up to 19.6% and the lowest check variety by up to 91.6%. Oil content showed similar trends with eight hybrids having up to 6.8% yield advantage over the highest check variety and 19.3% over the lowest check variety. The high yields were attributed to heterosis and indicated the high potential for grain yield and oil content from the current germplasm set. The presence of high yielding hybrids with shorter days to 50% flowering such as HV9132 HV9127 HV9128 and HV9135 showed that it was possible to breed for the short growing season characteristics of most southern African areas without compromising grain yield. General combining ability (GCA) effects were significant for all the traits indicating the importance of additive gene action for the traits. Parental lines KP1235 KP1304 and KP1290 that showed desirable GCA effects for at least three of the important traits were selected for inclusion in the breeding programme for cultivars adapted to the region.

This study took into account the protein content in the kernel of ten lines derived from interspecific hybrids Helianthus annuus (line 2607) × Helianthus resinosus and Helianthus annuus (line 2607) × Helianthus salicifolius . The amino acid composition of storage protein was also studied. The protein in the new lines exceeded the protein in the parental forms with up to 10.6%. The essential amino acids lysine valine threonine and phenylalanine had higher amounts. With regard to sulfur-containing amino acids (cystine and methionine) the new lines had lower content than the line 2607. From the nonessential amino acids mainly asparagine and glycine exceeded the parental lines.

Hybrid Yana was developed with simple cross of Bulgarian line cms 2607 and mutant line R12003. Mutant line was produced after treatment of immature sunflower ( Helianthus annuus L.) zygotic embryos of fertility restorer line R 2574 with ultrasound. In 2004 2006 and 2007 years hybrid Yana was presented for testing at State Variety Testing Commission. The hybrid considerably exceeded the mean standard (the Bulgarian commercial hybrid Albena and French commercial hybrid Diabolo) by seed yield. The seed yield of hybrid Yana was significantly higher with 31 kg/dka or 9.8%. The correlations of the cross cms 2607 × R12003 with the mean values of the parental lines (h1) and with the mean value of the parent with higher indices (h2) were statistically significant. In h1 the variation was from 152.4% to 1471.2%; in h2 the variation was within 149.5-1052.9%. The evaluation of the heterosis effect parameters proved that the parent with the higher values of the indices was superdominant. This was markedly expressed for indices total seeds number per head and seed yield per head. Hybrid Yana possessing immunity to the Orobanche cumana population of races A-F and immunity to Plasmopara helianhi- races 300 700 and 731.

Breeding for downy mildew resistance is one of the major goals in sunflower breeding programmes. In the last few decades new sources of resistance have been discovered and the position of 11 resistance genes was established on the genetic map of sunflower. For most of these resistance genes sequence specific markers have been developed which facilitate their detection and make the selection process faster and more reliable. By combining the partial resistance provided by minor genes with specific resistance genes durable resistance could be achieved.

Sclerotia of S. sclerotiorum are surviving structures and the most important source of inoculum in sunflower fields. There are few studies about sclerotia survival in uncultivated soil and in accordance to that our objective was to establish the effect of burial depth on sclerotia longevity and the ability of carpogenic germination. In the trial (2009-2011) sclerotia were buried at the depth of 5 10 and 30 cm and recovered every year in June. In laboratory sclerotia survival and carpogenic germination were examined. Our results showed that a large percentage of sclerotia survive at least three years under suitable conditions of temperature and moisture. In the case of continuous flooding (2011) sclerotia placed shallow in the soil (5 cm) were completely destroyed. Achieved results suggest that in undesturbed soil sclerotia placed deeper in the soil (10 and 30 cm) stay alive longer than those in upper soil (5 cm). Regardless of the burial depth sclerotia were able to produce apothecia under laboratory conditions. Resident saprofitic soil fungi ( Aspergillus sp. Fusarium sp. Mucor sp. and mycoparasitic Conyothirium sp.) have been isolated equally from alive and deceyed sclerotia but still less from the viable one.

Broomrape is one of the most critical biotic constraints to sunflower crop production. In the most extended sunflower crop area of the world, distributed across Black sea region, this parasitic weed shows a high occurrence. The weed, originally from the Caucasus region, has progressively migrated to the South of the Eurasia continent. The actual invaded area reaches Spain, Israel, Kazakhstan, China, Mongolia and Iran. Due to the usual seed exchange between macro-regions it is not clear why this weed is absent in other extended sunflower crop area located in South America. It is possible that the invasive process could be limited by abiotic restrictions. With the aim to estimate the influence of environmental factors on the actual broomrape geographic distribution, we evaluated 14 sunflower habitats of Serbia with different levels of natural infection and nine natural habitats of wild sunflower in Argentina. The altitude, latitude, longitude, mean hottest month temperature, mean coolest month temperature, and average rainfall of 10 habitats from Serbia showed no differences between infected and non-infected soils. The natural initial infection of four soils from Serbia did not influence the Orobanche attack intensity in a greenhouse experiment with artificial inoculation. Soil texture, total N, humus and calcareous content, as well as pH, had no effect on Orobanche attack intensity. In the greenhouse experiment, Principal Components Analysis showed that Orobanche attack intensity (expressed as parasite plant number per sunflower plant) was inversely associated only with P availability (ALP2O5), but the linear relationship between both variables was not significant. When Argentinean habitats were included in the database, strong differences between invaded and not invaded areas were found regarding geographic localization, as expected. The invaded habitats differed by the coolest month mean temperature, but no significant differences were found for the remaining climatic parameters. Soil fertility and the texture of 13 soils with different natural Orobanche infection showed no differences between invaded and non-invaded habitats. A better understanding of the abiotic determinants of Orobanche geographic distribution could help to design management tools to prevent the continuous increase of the invaded area and to limit damage to sunflower in the regions presently affected by the weed.

Broomrape ( Orobanche cumana Wallr.) presents a serious problem in sunflower production in a number of countries it reduces sunflower seed yield and negatively affects other sunflower traits in sunflower production. Continued work on creating new sunflower hybrids resistant to broomrape requires testing of breeding materials in both field conditions and controlled conditions of a greenhouse. The best solution is to do the testing simultaneously in order to verify the congruence of the evaluation of the broomrape resistance achieved by these two methods. The screening of chosen new 15 sunflower hybrids for broomrape resistance was done in 2009 and 2010 in infected field on two locations in Vojvodina Province and in 2010 in greenhouse. Both field and the greenhouse tests rated the hybrids exclusively on the basis of presence or absence of the parasite. The infection of hybrids with broomrape has shown that out of 15 hybrids tested 9 hybrids were resistant. These hybrids were fully resistant in both years in field conditions and controlled greenhouse conditions during one year. Fully resistant hybrids in field conditions and in greenhouse conditions NS-H-6385 and NS-H-6396 had significantly higher seed yield seed oil content and oil yield in relation to standard.

In the tubercle of O. cumana of high-virulent populations from Rostov region of Russian Federation some changes were found which helped to improve the seed productivity and to decrease the development period of fruiting shoots. The maintenance of high level of seed productivity can be realized by setting multiple meristematic zones in a tubercle and simultaneous development of several adventive shoots from them. The maintenance of viability of tubercle and the formation of new shoot apexes after the seed ripening on one or several stems grown out of it and finished in the vegetation period also go in the favour of the improvement of seed productivity. The development of the apexes of tubercle rudimentary roots into adventive shoots was observed in this paper. The polymorphism of inflorescence in the quantity of the setting flowers and their distribution along the stem and even below the soil level was observed. The flowering ability of flowers hidden in the soil and the seed formation in them was defined. All that leads to the improvement of seed productivity of individual plant. On the whole the described peculiarities of the development of O. cumana show that there is an accumulation of traits which goes in the favour of the high potential of reproductive function in parasite’s ontogenesis.

Sunflower is a plant species with a prominent period of seed dormancy. Physiological maturation period can be accelerated under laboratory conditions using methods for breaking seed dormancy such as: previous cooling at 5-10°C previous heating at 30-35°C gibberellic acid treatment KNO 3 ethrel etc . The aim of this study was to determine the duration of seed dormancy period of different sunflower hybrids and parent lines produced in Serbia and to determine which of the methods for breaking seed dormancy gives the best results. Studies were carried out on five commercial sunflower hybrids and their parental components. Seed germination was determined after harvesting using standard laboratory methods and tetrazolium tests. The following methods were used for seed dormancy breaking: low temperature treatment of 5- 10°C high temperature treatment of 30-35°C and treatment with gibberellic acid. The tests were performed in the period of 30 50 and 90 days after harvesting. The application of gibberellic acid method gave the lowest values of seed germination while statistical significant differences between the control and method of low and high temperatures were not found. Sunflower hybrids Sremac Duško NS-H-111 Velja and Branko as well as the female lines of hybrid NS-H-111 and male lines of hybrids Sremac and Velja had no prominent seed dormancy 30 days after harvesting. Seed dormancy in female lines of hybrids Sremac Duško Velja and Branko and male lines of hybrids Duško NS-H-111 and Branko was decreased 90 days after storage but it was not completely removed.

Seed aging and deterioration affect seed vigor and viability. The characteristics of the chemical composition of oil crops seed are related to specific processes occurring in the seed during storage. This study was performed to examine the changes in seed vigor of different sunflower and soybean genotypes under controlled and conventional (uncontrolled) conditions of natural aging for six and twelve months. Obtained results show that the degree of seed damage and the ability of seed to resist the negative effects of aging were influenced by duration and type of storage as well as seed characteristics of the tested genotypes. The most valuable vigor test for both sunflower and soybean was cold test.