Sunflower broomrape (Orobanche cumana Wallr.) is currently regarded as one of the most important constraints in sunflower (Helianthus annuus L.) production. In the last fifteen years, efforts to introduce genetic sources of resistance to this parasite in sunflower hybrids have been rapidly followed by the appearance of new virulent races that have overcome all known resistance genes. Due to this situation, most of the research efforts have focused on the development and characterization of new sources of genetic resistance to the most virulent races and also to investigate the genetic structure and variability of O. cumana populations and their evolution in order to develop long-term strategies for sunflower broomrape management. Results of evaluation of sunflower germplasm for resistance to different races have demonstrated that wild Helianthus species constitute the major reservoir of genes conferring resistance to new virulent races. Cultivated germplasms are also valuable sources of resistance genes. Most of the resistant sources have been found to be controlled by major genes, although quantitative resistance and epistatic effects have also been reported. Different dominance reactions depending on the race of broomrape, the source of resistance, and the susceptible parental line used for the cross have been observed. Molecular studies have shown that phenotypic variance for race E resistance was mainly explained by a major QTL associated with the resistance or susceptibility character, while race F resistance was explained by several QTLs with a small to moderate effect, mainly associated with the number of broomrapes per plant, suggesting the existence of a quantitative component in the resistance to race F. The relevance of these findings for sunflower breeding for resistance to broomrape is discussed.

It is widely known that Orobanche cumana seeds need a conditioning phase of several days under suitable temperatures and wet conditions before being able to germinate in response to germination stimulants. In a series of experiments we showed that O. cumana seeds respond to the synthetic germination stimulants Nijmegen-1 and GR24 even without prior conditioning. These results are consistent with our hypothesis that, under certain field circumstances, non-conditioned Orobanche seeds may also germinate when a host root comes close to them.

The climatic changes during the recent years and the general usage in the agricultural practice of resistant varieties and hybrids are the main reasons for the limited distribution of downy mildew on sunflower (Plasmopara halstedii Farl. Berlese ét de Toni) in Bulgaria. The disease has occurrence only in separate locations, with a low percentage of attack - up to 10%. Our investigations showed that the current situation stimulated the pathogen to develop new races. Thus, for example, during 1988-2000, i.e., over a period of 12 years, only two downy mildew races were identified in Bulgaria. Now, however, there are five: 300, 330, 700, 721, and 731. Race 700 has the largest area of occurrence. This race has been isolated from 20 samples with origin from northern Bulgaria during the years of investigation. Its percentage in the downy mildew population was 45.5%, and it is of the greatest economic significance for sunflower production in this part of the country. Races 721 and 731 were isolated in the last two years. They had equal percentages in the population - 15.9% each, but their area of occurrence was quite different. Race 721 was distributed in south-east Bulgaria, its range of occurrence was large, and it is the most significant race in this region in economic terms. The other new race, 731, was localized only in the region of the Dobroudja Agricultural Institute (DAI) and has currently no economic significance for sunflower production. Race 330 is also a new one for Bulgaria. It was isolated in 2006 in single fields in north Bulgaria and its percentage in the population was 13.6%. Race 300 had the most limited distribution during the last two years - 9.1%. This tendency has been observed for the last few years and most probably race 300 will soon disappear from the downy mildew population.

blishment rate and yield in the rotation crops soft winter wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), winter oil seed rape (WOSR) (Brassica napus L.), maize (Zea mays L.) and sugar beet (Beta vulgaris L.) following Intervix® (33g Imazamox + 15g Imazapyr) spraying in Clearfield® (CL) sunflower (Helianthus annuus L.) production. The experiments were conducted at the Trakya Agricultural Research Institute in Edirne between 2007 and 2009 using a randomized complete block design (stripe plots) with three replications. Five crops were evaluated in crop rotation after spraying Intervix® on Clearfield® sunflower. As the experiment materials, we used the sunflower hybrid Sanay-CL and the cultivars Gelibolu (soft winter wheat, SWW), Bolayir (barley), Elvis (winter oil seed rapeseed, WOSR), Brasco (maize), and Leyla (sugar beet). Nitrogen and phosphorus fertilization were applied according to soil analysis recommendations. Observations were made of the number of plants emerged per m2, stand establishment, yield, time to flowering, time to physiological maturity, plant height, root length, head diameter, etc., according to plants included in crop rotations. Based on statistical analysis of the data from crop rotation experiments, CL sunflower plots followed by wheat, barley, and maize were not negatively affected to a significant degree by Intervix® residues in terms of stand establishment and seed yield in either year. In the first year of crop rotation, however, when planting WOSR four months after Intervix® application on CL sunflower plots, stand establishment and seed yield decreased significantly, by 35.7 and 23.7%, respectively. When planting sugar beet nine months after Intervix® application on CL sunflower plots, stand establishment and beet yield decreased by 26.7 and 11.6%, respectively. However, in the second year in the same crop rotations plots, stand establishment and yield of WOSR and sugar beet planted after CL sunflower were not affected significantly by Intervix® residues.

Nyírség, in northeast Hungary, is one of the most important cultivation regions of confectionery sunflower used for toasting in Europe. The production area in this part of the country is over 20,000 ha. The importance of the crop keeps increasing due to its favorable nutritional properties. Apart from the hybrids suitable for husking produced on large scale, the cultivation area of the traditional open pollinated confectionery varieties is extending too. Kisvárda, an open pollinated variety, is the most widely produced. The abiotic and biotic stress resistance of this variety is excellent; however, it is susceptible to sun flower moth attack. The development of phytomelanin layer that would result in a decrease of susceptibility cannot be implemented without a change of the husk color, which in its turn is highly important on the market. The experiments carried out between 2006 and 2008 had three objec tives: first, it included a comparative study of two varieties belonging to the cul tivar Kisvárda and two standard hybrids (one confectionary and one oil type) regarding their resistance to moth infestation; second, we wished to determine the effect of sowing time on the extent of moth contamination; and third, we searched for differences, if detectable, between the varieties with respect to the above mentioned aspects. The experiments showed that it is the flowering time, determined by the growing period of the variety and the sowing time, that basically influences the extent of moth infestation.

Wild Helianthus annuus naturalized in Argentina could be a valuable germplasm source for cultivated sunflower. Five wild populations collected in different environments and with different phenotype expression were evaluated as a genetic resource in a common garden study. The populations showed nor mal meiosis and produced a good seed set when their plants pollinated the male-sterile inbred line A09 (cms PET1). The wild populations restored more than 80% fertility of the HA89 (cms PET1) and A10 (cms PET1) inbred lines in the F1 generation. The fertility of one male sterile source from Mendoza was restored (>95%) by the maintainer line B10. The fatty acid composition differ entiated a population from Entre Ríos with a high saturated fatty acid content (>107 g kg-1). Another population from La Pampa showed a high level (>50%) of resistance to the Sunflower Chlorotic Mottle Virus (SuCMoV). No wild popu lations showed tolerance to imazaphyr sprayed at 2× doses (×=80 g i.a. ha-1). A population collected in the coolest environment showed high tolerance to low temperature (15/5°C, neutral day) in the initial grow stages (80%) under water stress (-0.4 MPa) imposed by polyethylene glycol 6000. This population and a second one from southern Buenos Aires showed the lowest leaf temperature increase (<10%) and the highest foliar specific den sity under artificial drought during the R4 to R6 reproductive stages. It was concluded that wild H. annuus naturalized in central Argentina can supply some useful traits for sunflower breeding.

Wild Helianthus annuus is native to North America but it naturalized in other parts of the world as well. Although the origin of exotic populations is uncertain, they have probably evolved very differently in different countries. To unravel the origin of invasive populations from Argentina and Spain, morpho logical and agro-ecological data of nine populations from central Argentina, six from Andalusia and one from Gerona were collected in their natural habitats during three exploration trips in 2007 and 2008. In Argentina wild H. annuus was found mainly in disturbed areas between roads and fences. In a few cases the populations were located on the margins of cultivated fields. The Argen tinean populations are spread across more than 50,000 m2 at a density of about 25 plants m-2. In Spain, the populations were found mainly in crop lands. The largest population covered about 1,500 m2 and comprised no more than 200 plants. The Argentinean populations had taller plants with a higher number of heads of small size, while the Spanish populations were character ized by bigger heads with wider ligules and bracts. Plants were shorter and leaf size was larger in Gerona than in Andalusia. Multivariate analysis differenti ated populations from Argentina and Spain by many traits. Wild-crop gene flow is likely the source of genetic variation among them. In Argentina, the popula tions keep the appearance of early wild introductions, while the Spanish popu lations are weedier and probably originated from pollen contamination of commercial seed with wild plants or crop-wild hybrids.

The primary objective of this research was to determine differences among investigated sunflower genotypes and whether the analysed hybrids could be sources of phenols and tocopherols important for storage stability of sunflower seeds and their derived products. DPPH• radical scavenging activity, the content of phenolic components and tocopherols (α-, β-, γ-, and δ-) in seeds and kernels of three sunflower hybrids were analysed. In the present study, six different phenolic compounds were separated by the HPLC analysis. Chloro genic acid was the most abundant phenol. The chlorogenic acid content strongly correlated with total phenols (r=0.93). Other marked phenolics were caffeic acid, ferulic acid, rosmarinic acid, myricetin and rutin. The total toco pherols were significantly higher (P<0.05) in kernels than in seeds of all sun flower hybrids. Concentrations in sunflower seeds ranged from 200.67 to 220.05 µg/g and from 256.62 to 267.49 µg/g in sunflower kernels where α-toco pherol was the dominant isomer in all samples. The α-tocopherol content was 98% of averaged of the total tocopherols in all analysed samples. All these nutrients with antioxidant properties influenced the capacity of DPPH• scav enging. Accordingly, sunflower kernels had a higher DPPH• scavenging activity, and a higher nutritive value than sunflower seeds.

Sunflower is an important oilseed crop, known to grow a strong dominat ing single flower head. In recent times, axillary buds initiation and formation of multi flower heads is a common feature in many sunflower hybrids. To find out the reason for multi headedness an experiment was carried out in the hybrid KBSH-41. It was found that this trait is regulated by the interaction of environmental signals and plant growth regulators such as auxin and cytoki nin. Any kind of stress induces the bud growth which affects the translocation of hormones in the transpiration system, especially auxin. When the transloca tion of basipetally moving auxin reduces, concentration of acropetally moving cytokinin increases leading to the development of axillary buds. When, under normal conditions,auxin to cytokinin ratio is not altered the plants develop sin gle flower heads. The results of this study suggest that auxin has an inhibitory effect on the growth of axillary buds, while cytokinin promotes their growth. The mechanism of axillary bud growth depends on the ratio of these two hor mones.

Immature embryos from 15 sunflower genotypes (five restorers, five cyto plasmic male steriles, and five maintainers) were studied with the aim to shorten the seed to seed cycle, because seed maturation in sunflower takes 50 60% of the life cycle duration (120-150 days). This technique allows the pro duction of fertile plants from immature embryos by reducing the breeding cycle. Ten days after pollination immature embryos were dissected from seeds grown in field plants (SGFP) and were transferred to MS medium allowing shoot and root development for 5-10 days. Young plantlets were transferred to soil, developed to maturity, and were then self pollinated and set seed. The first cycle of immature embryo-raised plants (ERP) was obtained. When these plants were at the flowering stage, 10-day-old embryos were dissected and the 2nd cycle of ERP was obtained. The plants at the flowering stage for obtaining the 3rd cycle are in the growth chamber at the moment. The majority of cultured embryos developed into vigorous plantlets with 3-6 leaves. Out of the 1710 immature embryos, the average response of the explants was 93.1% (1591) showing morphogenesis with a minimum of 42.5 [N Record 109/Sanay 1-2(N)] and a maximum of 100% [(PR6404 (cms), Narmo Sanay 6-1 (cms), RIM 1-5 (cms), BGC0565 (N), N Record 109/Iscra (N), RHA 04, RHA 06, RHA 10, RHA 14, RHA 15]. Seventy percent of the developed plantlets had vigorous roots. They were transplanted into containers with a 1:1:2 peat: perlite: soil mixture (v/v) at 24 ± 2°C in 16 h/8 h (light/dark) in a growth chamber. Only 67.3% of them were grown to maturity, either self-polli nated or pollinated with maintainers and set seeds. The overall result was an average of 40-50 regenerated and matured plants per 100 immature zygotic embryos.

Decline in crop yield has been a major problem in Northern Guinea savanna zones of Nigeria due to inherent low fertility status of the soils. Field experiments were conducted for two years (2003 and 2004) on an Alfisol of the Northern Guinea savanna of Nigeria to determine the effect of N fertilizer on growth and yield parameters of sunflower. Six rates of nitrogen (0, 30, 60, 90, 120 and 150 kg N ha-1) were applied. Plant height and number of leaves were highly significant 10 weeks after planting (WAP). Highest plant heights of 120 and 138 cm were obtained in 2003 and 2004, respectively, at 120 kg N ha-1. Application of N significantly increased seed and oil yields while excess N (150 kg N ha-1) reduced the contents of the two parameters. Optimum N require ment of sunflower obtained from this study is between 90 and 100 kg N ha-1

Soil salinity is a worldwide problem. The aim of this study was to evalu ate biomass production and partition in the organs of sunflower under a gradi ent of salinity in the soil. The Victoria sunflower was sown on 15 June 2007 at a density of 100,000 plants ha-1 in Montecillo Mex. (19° N, 48° W and 2,400 m). The area has an arid climate (less dry), an annual rainfall of 558.5 mm, and an average temperature of 14.6°C. Based on soil analysis, three areas were used as the treatments, each having 4 replicates. These were: high salinity (EC 11 dS m-1, HS), medium salinity (EC 7 dS m-1, MS), and low salinity (EC 5 dS m-1, HS). Crop emergence occurred eight days after sowing (DAS), anthesis (R5) 80 DAS, and physiological maturity (R9) 130 DAS. Dry matter accumula tion (%) in plant organs, total biomass, yield and survival all decreased with increasing salinity, whereas DM distribution did not. The highest biomass, yield and survival were found in the LS treatment (1055, 102 g m-2, and 100%), while the lowest values of these parameters were recorded in the area with HS (312, 29 g m-2, and 60%), respectively. The greatest dry matter accu mulation was observed in the stem, followed by the receptacle, seeds and leaves. The harvest index and the filled capitulum index were not affected by salinity. In conclusion, biomass accumulation, yield and survival of sunflower decreased with increasing soil salinity. The phenology and biomass distribu tion in the plant organs were not affected by salinity.

Sunflower (Helianthus annuus L.) is a new edible oil crop in Sudan. Many production constraints are responsible for fluctuation in its production and productivity. The main constraint is a lack of adapted, improved, high yield sunflower varieties. Farmers depend on imported seeds, which are usu ally unavailable and expensive. To reduce the cost of the seed and ensure seed supply at the optimum time, ten single-cross sunflower hybrids (SFH32, SFH36, SFH37, SFH310, SFH313, SFH314, SFH341, SFH345, SFH302 and SFH325) and the hybrid Hysun-33 (the check) were evaluated for yield poten tial and yield components. The experiment was laid-out in a randomized com plete block design with three replications carried over five irrigated locations during the winter season of 2008/2009. There was considerable variation for yield and its components among the hybrids and locations. Significant differ ences were observed for hybrids (G), locations (E) and G × E interaction. All the genotypes gave high seed and oil yields under irrigated conditions. Three hybrids, SFH310, SFH313 and SFH341, performed better than Hysun-33 and the other genotypes across five environments. Stability analysis identified SFH310, SFH313 and SFH341 as the most stable hybrids for seed and oil yields, since their regression coefficients were close to the value of one (bi=1) and had the lowest deviation from regression (S-2di). In contrast, hybrids such as SFH32 and SFH37, with regression coefficients greater than one, were regarded as sensitive to environmental changes for seed and oil yields. The three promising hybrids were released last June for commercial production.

This study was conducted in 2009 at the experiment field of the South East Anatolian Agricultural Research Institute in Diyarbakir in order to deter mine potential sunflower cultivars for irrigated conditions in the region. The cultivars Sanay, P-4223, Alhasa, Pactol, Armada, Sirena, C-70165, Tunca, Isera, Tarsan-1018, and Tr-3080 were tested in the experiment. Important characteristics such as plant height, head diameter, 1000-seed weight, seed yield, oil content and oil yield were investigated. According to the results, sta tistical differences were found between the cultivars for 1000-seed weight, seed yield, oil content and oil yield at the 5% probability level. The highest seed yield per hectare (4,110.7 kg) was obtained from Pioneer-4223, while the highest oil yield per hectare (139.3 kg) was produced by C-70165. The lowest oil yield per hectare was found in Tr-3080 (610.6 kg), while the lowest seed yield per hec tare was found in Tr-3080 (1,790.6 kg). The highest oil content (40.1%) was obtained from Armada and the lowest from Pioneer-4223 with 34.4%. The highest 1000-seed weight (83.7 g) was obtained from Isera and the lowest from Armada with 56.1 g. The highest plant height (249.9 cm) was obtained from C 70165 and the lowest from Tr-3080 (181.4 cm). The largest head diameter was found in Tunca (17.4 cm) and the smallest in Armada (13.9 cm). Results from this study indicate that Pioneer-4223, Pactol, Isera. C-70165, Tarsan, and Armada can be potential cultivar in terms of yield and the other important characters investigated under the irrigated conditions in Diyarbakir.