Evaluation of Bread Wheat ( <i>Triticum aestivum</i> L.) Advanced Lines and Commercial Varieties to the Response of Septoria tritici blotch in Northwestern Ethiopia

Septoria tritici blotch (STB), caused by Zymoseptoria tritici is among the most damaging foliar diseases of wheat, with yield losses reaching up to 82% under favorable conditions. To identify resistant sources, one hundred sixty bread wheat genotypes were screened at Dabat and Adet in northwestern Ethiopia during the 2023 and 2024 cropping seasons using an alpha lattice design with two replications. Disease severity was assessed at three growth stages and agronomic traits were recorded across environments. Combined analyses revealed that 17.5% of the tested genotypes exhibited resistant responses to STB, producing superior grain yield (≥ 4.5 t ha⁻¹) and thousand-kernel weight (≥ 45.41 g). Additionally, 52.5% of genotypes were moderately resistant, whereas 30% showed moderately susceptible reactions. Highly significant differences (P < 0.0001) were observed among genotypes for all studied traits, which were negatively correlated with disease parameters. The highest grain yield (5160.88 kg ha⁻¹) was obtained from genotype G81. This genotype also exhibited significantly lower disease severity at maturity (24.35%) and a significantly reduced AUDPC (968.6) compared with most of the tested genotypes. These findings highlight promising genetic resources for STB resistance, and further molecular studies such as QTL mapping and GWAS are recommended to identify resistance loci and accelerate their utilization in wheat breeding programs.