Abstract Simultaneously identify superior performing in terms of seed yield and seed oil content and broad adaptation across a wide range of different environments is an important target for sunflower breeder. So, 10 sunflower genotypes were evaluated across the eight various environments created by sowing at four locations i. e. Kafr El Hamam/ Sharkia, Shandaweel /Sohag, Tag El Ezz/ Dakahlia and Al Arish/ North Sinai Agricultural Research Stations, Agricultural Research Center (ARC), Egypt during the two successive summer seasons 2018 and 2019 using randomized complete block designs with four replications in each environment. Results showed that mean squares due to environments, genotypes and their interaction were highly significant for seed yield and seed oil content. Most stability approaches revealed that high performing stable genotypes were L240 for seed yield and Sakha 53, L110 and L235 for seed oil content under divergent environments. Hence, these four stable sunflower genotypes could be behaved as good breeding materials stock for sunflower improvement.

Abstract 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.

Abstract Two inbreds of mutant origin, differing in the number of bracts, were crossed to obtain the F1 hybrid. One mutant line had 24.5 ± 1.01 bracts, while the other, 78.6 ± 1.69 bracts. The F1 hybrid had an average value between parents, which practically did not differ from the mean value in the F2 population. The variability of the trait under study in the F2 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 F2 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 F2 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.

Abstract 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.

Abstract In breeding programs, it is imperative to recognize the genetic variations and levels of association between traits that directly or indirectly affect the yield. Achene yield and related traits in forty-nine sunflower genotypes were studied for genetic variability, correlations and path coefficient analysis. The phenotypic coefficient of variation (PCV) were higher than the genotypic coefficient of variation (GCV) for the all the studied traits in sunflower. The most active association of achene yield was found with achene/head, 100-achene weight and plant height. However, oil contents had a negative association with achene filling percentage, 100-achene weight, number of leaves and stem diameter. The maximum direct influence on achene yield were exerted by head diameter followed by achene filling percentage, 100 achene weight, achene/head and number of leaves. In contrast, plant height, days to maturity and stem diameter had the negative direct impact on yield. The genetic correlations were higher than phenotypic correlations which suggest that environmental influences were very low. Our results showed that achene/head, 100 achene weight, plant height and head diameter are important plant traits which should be considered while planning any breeding program for higher achene yield in sunflower.

Abstract Collection of sunflower lines of the Institute of Oilseed Crops was studied based on its branching. Ten lines with the basal branching trait were identified. It was established that the inheritance of the basal branching is due to the recessive alleles of the genes. For lines InLD1240, Z1064, LD835, KG13, VIR130, KG13, LD4, basal branching trait is due to the recessive homozygote of one gene b2. In lines LD72/3, LD156, KG16, I2K2218, basal branching trait is due to the recessive homozygote of two genes b3 and b4. It was established that the genes determining basal branching are distributed in the offspring independently of the genes controlling the top branching.

Abstract Abiotic stresses including drought are major crop production constraints. However, specific functional phenotypic markers induce resistance against these stresses. Therefore, a study was initiated to study the variability, inheritance and selection of epicuticular waxes (EW) and leaf hairiness (LH) along with low cell membrane injuries (CMI) within F2 populations derived by crossing H. annuus×H. argophyllus lines. These traits have been shown to be associated with drought tolerance of Helianthus argophyllus and thus study aims to introgress these traits in Helinathus annuus. The studied parent populations showed contrasting values of the traits. The drought susceptible line CMS-14 and CMS-20 showed lower epicuticular waxes (0.79, 0.69 mg g−1), leaf hairiness (0.75, 1.53) and higher cell membrane injury (40.90, 55.76 %) respectively while drought resistant line Argo 1802 and 1806 showed higher epicuticular waxes (2.28, 3.18), leaf hairiness (3.71, 3.80) and lower cell membrane injury (14.22, 21.54 %) respectively. The F1 hybrids had mean values of the three studied parameters i. e. epicuticular waxes (1.50 mg g−1), cell membrance injury (32.54 %) and leaf hairiness (2.74) in the range of parent lines, but some of F2 individuals extend beyond this range (Parents and F1s). The two-step selections maintained high variability especially of LH for set of F2 individuals (H. annuus CMS-20×H. argophyllus 1806). Simultaneous selection of F2 individuals with high values of LH or EW with low CMI was possible. The selected plants were further studied for narrow leaf, high fertility and silver canopy color. Selected material was promoted as the candidate of inbred line. Plant (F4) having introgressed traits (silver canopy) showed lower yield (19 %) than green leafed plants (53 %) and commercial hybrids under drought stress (63 % and 53 %). The study could help to increase the abiotic stress tolerance, minimize the yield losses under drought stress and increase functional diversity within sunflower.

Abstract Two mutant inbred lines of sunflower, F

Abstract After mutagenic treatment of sunflower seeds two traits of altered leaf shape were found – obtuse shape of leaf tip and strongly sinuate (fringed) leaf margin. To study the inheritance pattern of these traits, the mutant lines were crossed with the source lines and between themselves. It was shown that the traits of obtuse leaf and fringed leaf are recessive and inherited as monogenic traits when mating with the source line. In crossings of mutants, all F