Analysis of multi-environment trial (MET) Data using linear mixed model for bread wheat genotypes across low altitude areas of Ethiopia

Bread wheat is the most important food crop in Ethiopia playing a significant role in ensuring national food security and grown extensively across diverse agro-ecological zones. Consequently, Multi-environment trials (METs) are essential for developing bread wheat genotypes adapted to these varied conditions. The objective of the study was to identify high-performing and stable wheat genotypes suited to low altitude regions of Ethiopia through the analysis of MET data using linear mixed models. This study was conducted using datasets comprising 22 multi-environment trials (METs) involving 1035 bread wheat genotypes evaluated across low-altitude areas of Ethiopia during 2021–2024 cropping seasons. The row–column Alpha-lattice and Partially replicated (p-rep) designs were used. Genotypic performance, environment classification and genotype-by-environment (G×E) interactions were assessed using heat maps, dendrograms, Best Linear Unbiased Predictions (BLUPs) and Factor Analytic (FA) models. The results revealed that genetic variance for grain yield ranged from 0.02 to 1.12, while error variance ranged from 0.13 to 0.75 suggested that a wide range of environmental noise and genetic potential across the trials. Based on average Best Linear Unbiased Predictions (BLUPs) and dendrograms for grain yield, the 22 environments were classified into nine Genotype×Environment (G×E) clusters (C1–C9). In addition, heat maps and genetic correlation matrices revealed strong positive, negative and weak correlations among environments, allowing the distinction of specific trial clusters. Factor analytic (FA) models explained more than 50% of the total genetic variance, with Factor_1 (FA1) accounting for up to 99.84% in trial 22BWOEKU and Factor_2 (FA2) accounting for 99.48% in trial 24BWPNEZW. Genotypes EBW192940, EBW212724, EBW180175, EBW212777 and EBW212106 exhibited superior and consistent performance across environments and were identified as top candidates for further utilization in varietal release activities. Accordingly, genotype EBW192940 was officially released in 2025 as a new variety, named ‘Dhera’, for low-altitude wheat-growing areas of Ethiopia. The use of linear mixed models and MET analysis significantly improved the precision of genotype selection. The identification and release of ‘Dhera’ variety highlighted the effectiveness of this breeding program in identifying stable and high-yielding bread wheat varieties suited for low-altitude regions in Ethiopia.