Resistance of potato genotypes to phytopathogenic micromycetes (Alternaria, Fusarium) under abiotic stress of Central Polissia

Purpose. To study the response of potato breeding material to infection by phytopathogenic micromycetes Alternaria and Fusarium genera under abiotic stress conditions of Central Polissia of Ukraine and to identify valuable resistant genotypes for breeding work. Methods. Field, phytodiagnostic, analytical and statistical. Results. During 2023–2024, for the first time, a comprehensive assessment of a wide spectrum of crop genotypes (varieties, intervarietal and interspecific hybrids) was conducted based on their resistance level to phytopathogenic micromycetes under abiotic stress conditions. Patterns of genotype differentiation by resistance were established, allowing the selection of promising resistance sources for further breeding. The obtained results expand the experimental base of newly created samples and provide an opportunity to improve approaches to evaluating crop adaptability under changing climate conditions. The development of high-yielding potato varieties and the production of quality tubers largely depend on the resistance of genotypes to a complex of diseases that emerge both during the vegetation period and during crop storage. The intensive development of phytopathogens limits the realization of the crop’s genetic productivity potential and poses significant phytosanitary threats in agroecosystems. In this regard, breeding for resistance to major pathogens remains one of the priority directions for improving potato varieties, aiming to enhance their ecological plasticity and adaptive potential, which is especially relevant in the context of modern climate change. The research results indicate that under abiotic stress conditions, the resistance of potato breeding material to early blight decreases, which is especially pronounced in varieties and intervarietal hybrids. Interspecific hybrids demonstrated a higher level of adaptability to the disease. Similar trends were observed in the study of potato material resistance to Fusarium dry rot: an increase in the proportion of weakly resistant and non-resistant forms among intervarietal hybrids and varieties was recorded. At the same time, interspecific hybrids showed a higher proportion of moderately resistant forms and a decrease in the number of weakly resistant genotypes under abiotic stress conditions, indicating their higher adaptive capacity. Conclusions. As a result of two years of research, the following potato genotypes that demonstrated stable resistance to early blight were identified: varieties ‘Bazaliia’, ‘Opillia’, ‘Partner’, ‘Zhytnytsia’, ‘Serpanok’; intervarietal hybrids P.15.5/27, P.15.56-10, P.17.29/21, P.17.30-3, P.18.51/3, P.18.78/1; interspecific genotypes H08.194/119, H13.37с5, H.10.20/1, H.0.6/7, H10.6/23. Varieties ‘Partner’, ‘Radomysl’, intervarietal hybrid P.17.20-3 and interspecific genotype G10.6/23 showed resistance to Fusarium dry rot. These genotypes are recommended for further use in potato breeding for resistance to the mentioned phytopathogenic micromycetes when creating new varieties.