One of the most threatening holoparasitic plant species is Orobanche cumana Wallr. (sunflower broomrape) mainly distributed in the Mediterranean region and Western Asia where it exclusively parasitizes sunflowers. Sunflower broomrape (BR) is a very destructive parasitic weed causing significant yield losses under high infestations that can easily spread and is vulnerable to mutations. Broomrape is highly variable controlled by vertical single dominant resistance genes leading to the rapid and frequent breakdown of resistance. This subsequently leads to the continuing need for new unique genes from multiple sources for controlling new emerging virulent races. The USDA-ARS National Plant Germplasm System crop wild relatives (CWR) collection contains 2519 accessions of 53 species with 14 annual species (1641 accessions) and 39 perennial species (878 accessions). This CWR collection provides a vast genetic resource for new BR resistance genes especially in Europe and the Middle East. Sunflower CWR evaluations for new resistance genes for BR races have demonstrated that they are a substantial reservoir for existing and new emerging virulent races. Resistance to sunflower broomrape including immunity has been reported in seven annual and 32 perennial species. These sources discovered in the sunflower CWR confer resistance to new virulent broomrape races F G and H and others that have not been assigned a race designation. Since several of the resistant CWR sources are annual and have the same chromosome number as cultivated sunflower broomrape resistance genes can be incorporated into hybrid sunflower through interspecific hybridization. The diverse sources of resistance from the CWR provide breeders with the prospect for durable broomrape control through exploiting genetic resistance for existing and newly emerging races.

The bacterial and micromycete complexes in the rhizosphere of sunflower plants non-infected and infected with broomrape ( Orobanche cumana Wallr.) have been compared. The investigations were carried out in the conditions of a stationary infectious field which was annually enriched with infected plant residues and broomrape seeds collected in different regions of Ukraine. Soil is leached low-humic chernozem with acidic pH. The soil samples selected at the end of vegetation from the rhizosphere of healthy and infected with broomrape plants of sunflower breeding samples. The total number of bacteria found in the rhizosphere of sunflower plants infected by the parasite did not differ significantly from the control and was 11.7 and 12.1 million CFU / g of soil respectively. The numbers of ammonifiers as well as bacterial microflora using for its life mineral nitrogen and pedotrophs and oligotrophs in the compared soil samples did not differ significantly and generally corresponded to this type of soil. Although in general both tested samples of soil were characterized by a low content of bacteria of the genus Azotobacter the number of representatives of this genus in the rhizosphere of parasite-infected plants was somewhat less than in control (35 % and 21 % respectively). However unlike most bacteria the number of micromycetes detected on Czapek-Dox and starch-ammonia agar media in the rhizosphere of plants infected by broomrape almost twice exceeded the number of these microorganisms in the rhizosphere of healthy plants. Analysis of the generic and species composition of microscopic fungi showed that in the rhizosphere of sunflower plants infected by the parasite a very specific mycocenosis was formed that differ from a mycocenosis of healthy plants. This mycocenosis was characterized by a much smaller number of genera and species of micromycetes. At the same time for the structure of the fungal cenosis of diseased plants there was a characteristic increase in the proportion of toxin-forming fungi of the Aspergillus and Penicillium genera with active conidiogenesis. The obtained data testify not only to the differences in the microbial complexes in the rhizosphere of sunflower plants non-infected and infected by broomrape but also indicate the direction of action of this parasite.

The objective of this work is the development of sunflower lines that are not affected by race G of broomrape as well as the determination of genetic control of resistance. The testing of the resistance of VNIIMK’s collection accessions of a cultivated sunflower of various origins was carried out on an artificial background made from the seeds of race G of broomrape. 6 lines resistant to race G were developed by the method of inbreeding on the basis of the obtained unaffected forms. The genetic control of resistance of one of them was studied. The resistance was inherited monogeneuosly with incomplete dominance. There was established the presence of a reciprocal effect and the dependence of the resistance characteristic on the genotype of a susceptible parent under crossbreeding with certain lines. The other 5 sunflower lines are in the process of a hybridological analysis in order to determine the genetic control of their resistance. The combination of different genes of resistance to the same race of broomrape in one sunflower genotype could contribute to the long-term resistance of the crop to the parasite. The results of the presented study are of high importance for breeders since the gene that we studied provides a new source of resistance to race G thereby ensuring the protection of sunflower from the spread of new Orobanche pathotypes.

The objective of this work was to find practical procedures to overcome methodological drawbacks encountered during studies on sunflower downy mildew. Techniques for recovering living isolates of Plasmopara halstedii from the field and for the preservation of infected leaf samples for further molecular analysis were developed. A Polymerase Chain Reaction (PCR)-based test for the detection of P. halstedii in sunflower leaves and a method to remove azoxystrobin from fungicide-treated seeds are proposed. In situ -inoculations of pre-germinated seeds allowed the recovery of living isolates from the field. Three sample-preservation methods were evaluated (silica heating and lyophilization) resulting in high yield and quality of the DNA extract. It was detected the presence of the pathogen in symptomless leaves through PCR using molecular markers based on expressed sequence tags. A treatment using sodium hypochlorite is recommended for the removal of azoxystrobin from fungicide treated seeds.

A set of fifty two hybrids developed through line×tester breeding design were sown in randomized block design with three replications to evaluate their performance for seed yield under two environments (normal irrigation and water stress). Drought resistant indices and multivariate statistical analysis from the pooled data obtained from water stress and normal irrigated environments over the two years. Hybrid PRUN-29A × RCR-8297 (1.55) and 40A × P100R (1.55) had the largest stress tolerance index (STI) rate and hybrid ARG-2A × P69R the smallest rate (a high STI rate for the genotype represents its high drought resistance and its high yielding potential). Hybrid ARG-6A × P69R (2.41) had the largest extent (susceptible) of Stress susceptibility index (SSI) while hybrid E002-91 × RCR-8297 (0.13) had the least (resistant) extent a large extent of this index indicates the genotype susceptibility to drought. In terms of yield stability index (YSI) hybrid 40A × RCR-8297 (0.51) and ARG-6A × P69R (0.51) and hybrid ARG-2A × P69R (1.18) had the smallest and the largest rate respectively (genotypes with high YSI are expected to yield highly in stress conditions. Hybrid 40A × RCR-8297 (30.36) and PRUN-29A × P69R (−10.07) displayed the least and the most amount of tolerance index (TOL) index a high amount of TOL is a sign of genotype susceptibility to stress. Hybrid PRUN-29A × P69R (1.53) displayed the least extent of yield index (YI) while hybrid ARG-6A × P69R (0.51) and 40A × RCR-8297 (0.51) displayed the highest extent.

Aim of our research was to study the genetic diversity and establish the inheritance of top branching trait in the collection of 34 sunflower lines of the Institute of Oilseed Crops of the NAAS. Experiments were carried out in 2005–2016 according to classical cultivation methods using manual castration crossings forced self-pollinating isolation and visual assessment of the first and second generation of obtained descendants. The statistical reliability of the obtained ratio was confirmed by calculating the Pearson’s chi-squared test. Presence of two loci determining the inheritance of the branching trait in sunflower was established. In one locus recessive alleles are responsible for manifestation of the branching trait. In the second locus dominant alleles are responsible for the manifestation of the branching trait. In 23 lines of sunflower it was established that a recessive homozygote for one gene causes phenotypical top and full branching. In 8 lines of the collection full branching trait is due to the dominant allele of the gene. In the lines InK235 APS49 the presence of two genes was established the dominant alleles of which determine full branching trait. In the APS56 line full branching is controlled by the dominant alleles of three genes.

Inbred line Mh174B with the yellow coloration of the sunflower plant top was produced by hybridization of annual wild species with cultivated sunflower. The aim research was to evaluate genetic control of yellow coloration of the sunflower plant top in combination with other morphological traits (branchiness pollen fertility restoration and ray flower coloration). A total of four F 2 hybrid combinations of were created: Сх1010А × Mh174B Сх1012А × Mh174B Сх2111А × Mh174B Мх845А × Mh174B. Yellow coloration of the sunflower plant top was shown to follow a monogenic mode of inheritance and presumably be controlled by the gene y . This trait is inherited independently from such traits as branchiness pollen fertility restoration and ray flower coloration. The mainstreams of use of yellow coloration of the sunflower plant top in sunflower breeding and seed production are discussed.

Two inbreds of mutant origin differing in the number of bracts were crossed to obtain the F 1 hybrid. One mutant line had 24.5 ± 1.01 bracts while the other 78.6 ± 1.69 bracts. The F 1 hybrid had an average value between parents which practically did not differ from the mean value in the F 2 population. The variability of the trait under study in the F 2 population was continuous varying from 20 to 84 bracts. This indicated the probable participation of several genes with an additive effect in the control of the number of bracts. Assuming that the differences between the parental lines are due to two pairs of genes the F 2 plant population grown in 2016 was divided into 5 classes. In that population the observed classes ratio turned out to be close to the theoretically expected ratio of 1 : 4 : 6 : 4 : 1. Over the next two years F 2 populations were tested in a similar way. In all the cases the calculated chi-square value did not exceed the critical value for 4 degrees of freedom and 5 % significance level. This gave reason to talk about the two-loci control of a such quantitative trait as the number of bracts. The participation of two non-allelic genes in the control of this trait is also proved by matching the actual number of plants in the parental classes to the theoretically expected number of plants. Thus the number of bracts depends on the number of dominant alleles of two different genes in the genotype.

Sunflower ( Helianthus annuus L.) cultivated accessions contains useful genes encoding different phenotypic characteristic through which the origin of sunflower oil could be hypothesized. Those genes could be later used for future breeding programs for providing better quality sunflower oil. The objective of the current study is to discriminate genetic diversity of cultivated sunflower seeds collection through the statistical methods such as PCA (principal component analysis) and Pearson correlation analysis for two characters; seed oil content and fatty acid composition. Materials and methods: In the present study the genetic diversity of 107 cultivated accessions of Helianthus annuus L. was studied for fatty acid composition and oil content. Pearson correlation and Principal Component Analysis (PCA) were used to determine the correlation between the studied parameters. A dendrogram using Ward’s method and the squared Euclidean distance coefficient was produced. The results showed that the average seed oil content in the accessions was 29.51 % with a profile of 7.23 % palmitic acid (PAL) 5.04 % stearic acid (STE) 36.85 % oleic acid (OLE) and 50.85 % linoleic acid (LIN). The highest oil content was found in accession Hopi Dye (43.66 %). High levels of OLE were observed in the Csehszlovakiai “B” (60.14 %) and Vk-47 (55.73 %) accessions. On the other hand Fuksinka 10 and Georgia accessions had the lowest mean PAL values (4.98 %) and STE (1.81 %) respectively. Palmitoleic acid (PALM) was identified in 29 accessions and linolenic acid (LIL) in 32 accessions the highest in Gonondu (0.86 %) and Oleisty Borovskil (0.76 %) respectively. A significant negative relationship between OLE STE and saturated fatty acids (SFA) with oil content was observed. The Pearson correlation of unsaturated fatty acids to saturated fatty acids ratio (UFA/SFA ratio) with oil content was positive and significant. In the PCA analysis four major principal components (PCs) were identified accounting for 87.19 % of the total variations. In PC1 PAL and STE (with positive coefficients) and UFA/SFA ratio (with negative coefficients) had the highest loadings which determined 41.33 % of the total variations. In PC 2 OLE (with negative coefficient) and LIN (with positive coefficient) had the highest values. According to the dendrogram of the accessions they were grouped into seven distinct clusters and the accessions in clusters 4 and 7 contained high UFA and low SFA values. The findings of this study showed that there is a significant genetic diversity among the accessions which can be used to maximize heterosis in sunflower breeding programs.

To evaluate the effect of different micronutrients (Mn Fe Zn) and farmyard manure (FYM) on the vegetative phenological and achene yield components of sunflower a field experiment was conducted in Maragheh North West of Iran during the growing season 2018–2019. The treatments were arranged in a split-plot design- with three replicates. The main plots assigned to two levels of FYM (0 and 20 t ha −1 ) and sub plots assigned to the recommended dose of three micronutrients (Mn Fe Zn). The results revealed significant improvements in the growth and yield of sunflower due to the main and interaction effects of farmyard manure and inorganic fertilizer application. The highest number of leaves and the highest leaf area was observed in a plant grown by FYM + Zn. However there was no significant difference between micronutrients under inorganic condition (without FYM application). The highest leaf relative water content (RWC) plant height internode distance and chlorophyll was recorded for plants grown by Fe or Zn under FYM applied condition. Application of FYM and micronutrients reduced the number of days to flowering. However the application of FYM significantly delayed plant maturity. Achene number per head 100-achene weight achene length achene width achene oil percent achene yield and harvest index significantly increased with the application of FYM and the best performance was in a plant grown by FYM + Zn and FYM + Fe. The percentage of hollow and empty achene was significantly reduced by the application of FYM. Combined applications of FYM and micronutrients has become an increasingly common practice.