Breeding assessment of experimental downy mildew-resistant sunflower hybrids

To determine the resistance of new sunflower starting materials to downy powdery mildew using differentiator lines. To determine the stability of plant performance and height in F1 derived from lines - donors of resistance to downy mildew in three crossing types in comparison with reference accessions bred by us. Methods. Using our own methods, to assess the presence of genetic determinants Pl, which control resistance of lines and hybrids to the pathogens of downy mildew races 710, 730, and 330, which are distributed in the eastern Forest-steppe of Ukraine, in an artificial climate. Field trials in 2022-2023 were done with assessments of major economically valuable features by conventional methods. Results. The results of the breeding assessments of the new sunflower starting materials for resistance to downy mildew in the laboratory and field trials were obtained. The effect of donors of resistance to the pathogen, Plasmopara helianthi, such as X06134ВPl, X06135ВPl, and X777БPl, on the endurance of new F1s with a significant increase in the plant performance compared to the check accessions (simple hybrid “Kadet” and three-line hybrid “Zlatson”) was proven. Negative selection was demonstrated for plant height: new plants were not taller than reference ones. It has a positive effect on plant height in an agrocenosis, which does not decrease its yield when grown in the conditions of current agriculture production. Conclusions. Promising reference accessions of resistance to downy mildew were identified: line X06135ВPl (minidisc), X06134ВPl (multidisc), and X777BPl (pollen sterility fixer), which are immune to the causative agent of downy mildew local races. The resistance of the best new hybrids to downy mildew in comparison with the specified references was characterized. Experimental hybrids of three groups: restored simple hybrids, sterile simple hybrids, and hybrid combinations obtained by artificial hybridization, were created. They are noticeable for high plant performance and optimal height and significantly better than the existing reference hybrids, “Kadet” and “Zlatson”.