Application of the EAYM model for determining the predictability of isolates of the pathogen Phomopsis helianthi on sunflower genotypes under different environmental conditions

Resistance breeding has a significant role in the creation of high-yielding sunflower hybrids. One of the most harmful diseases in the crop, caused by the pathogen Phompsis helianthi, has been poorly studied in terms of its response to various sunflower genotypes under different environmental conditions. In order to investigate the predictability of the pathogen's response to different combinations of host genotype and year conditions, a collection of 32 isolates was tested on the sunflower variety Favorit and the hybrid Deveda during the 2022 and 2023 growing periods. The EAYM (Environment Adjusted Yield Model) was applied to assess the aggressiveness and predictability of the response of the isolates. This model was applied for the first time in assessing phytopathogenic response. Based on the obtained results, it was found that the highest model aggressiveness was observed in isolates Ph21-612, Ph21-614, Ph21-6211, Ph21-411 and Ph21-413, and the lowest values ​​were observed in isolates Ph21-611, Ph21-724 and Ph21-414. The most predictable reaction was reported in isolates Ph21-724, Ph21-6213, Ph21-414, Ph21-722, Ph21-611 and Ph21-613, and the least predictable in Ph21-612, Ph21-614, Ph21-723, Ph21-411 and Ph21-413. Isolates Ph21-451, Ph21-6214, Ph21-722, Ph21-231, Ph21-211 and Ph21-212 combine a highly aggressive and predictable reaction, which allows for more precise work in assessing the resistance of breeding materials. The results obtained also show that the EAYM has a reliable performance, which makes it effective enough for its implementation in the practical breeding of sunflower resistance for economically important diseases.