Creation of sunflower selection material with a high level of resistance to brown dry rot

Abstract

Goal. To create a sunflower selection material that is resistant to the harmful object and study its reaction to inoculation with the causative agent of brown dry rot (Rhyzopus nigricans (Ehrenb.)). Methods. General scientific (simulation of the experiment and analysis of the results), field (study of phytopathological and biological features of the development of sunflower samples), laboratory (determination of productivity and its components — fat content, mass of 1000 seeds, etc.), selection and hybridization (creation of new selection material). Results. Field studies were conducted in 2023–2025 at the infectious plot of the scientific crop rotation of the Institute of Oilseeds (IOS) of NAAS (Zaporizhzhia district, Zaporizhzhia oblast). The soil of the crop rotation was typical medium-power chornozem. Due to the epiphytotic of brown dry rot in the regions of sunflower cultivation in the Zaporizhzhia, Odesa, and Kherson regions in 2012, an infectious artificial background was formed, taking into account the infectious principle (Rhyzopus nigricans (Ehrenb.)) to study the level of resistance of parental forms and new promising hybrids against brown dry rot in the conditions of the Southern Steppe of Ukraine. The next incucht was carried out with the subsequent selection of sunflower samples according to the total combination capacity (TCC) and specific combination capacity (SCC), which had valuable economic indicators (oil content — 48–52%, yield — 0.3–1.1 t/ha, etc.). They studied 60 samples from breeding nurseries of different levels of incucht. As a result of phytopathological testing, 11 samples were selected with a relatively high level of resistance (7–9 points) against brown dry rot, which met the selection requirements. Conclusions. In field crop rotation, IOS NAAS created and maintained an artificial synthetic infectious background for selection of breeding material with a high level of resistance against complex diseases, including brown dry rot. The level of infectious load of the causative agents of the main diseases, which, with a high probability, ensured the contact of the pathogen with the plant-host, was determined. A scale for assessing the resistance of sunflower samples against brown dry rot was developed.