Genotype × environment interaction and yield stability of food barley (Hordeum vulgare L.) varieties using AMMI and GGE biplot models

Abstract

Barley is a crucial crop worldwide, but it faces significant production challenges due to limited adaptable varieties, poor management practices, and environmental factors. Food barley varieties often struggle in unfamiliar environments, leading to crop loss. To address this issue, a study was conducted to evaluating the adaptability, performance, and yield stability of released high-performing food barley varieties over two years across 17 diverse environments during the 2023–2024 cropping years. A multi-environment trial (MET) involving 20 released food barley genotypes was conducted during the 2023–2024 main cropping years across 17 environments using a randomized complete block design with three replications. Grain yield data were analyzed using combined analysis of variance (ANOVA), Additive Main Effects and Multiplicative Interaction (AMMI), AMMI Stability Value (ASV), Yield Stability Index (YSI), and Genotype plus Genotype × Environment (GGE) biplot analyses to assess genotype performance, stability, adaptability, and test environment suitability. Combined ANOVA and AMMI revealed highly significant (P < 0.0001) effects for all sources of variation. In the ANOVA, environment, year, genotype, environment × year, genotype × environment interaction (GEI), genotype × year, and genotype × environment × year accounted for 33.06%, 10.62%, 8.00%, 13.44%, 10.72%, 2.84%, and 6.40% of the total variation, respectively. Pooled AMMI showed 61.47%, 7.09%, and 16.58% of the total variation attributable to environment, genotype, and GEI, respectively. Environmental mean grain yield ranged from 1.44 t ha⁻¹ at Ambo to 3.17 t ha⁻¹ at Debre Markos. Genotype G2 produced the highest mean grain yield (3.28 t ha⁻¹), while G11 had the lowest (1.91 t ha⁻¹). GEI biplot grouped the seventeen test environments into three mega-environments. AMMI identified genotypes G8, G9, G14, and G15 as exhibiting favourable yield and stability performance across the evaluated environments. The GGE biplot further revealed three distinct mega-environments and identified Holeta (E11) as both highly discriminative and representative, making it a suitable core testing environment. Based on the Yield Stability Index (YSI), genotypes G8 and G14 exhibited the most favourable combination of grain yield and stability, followed by G9 and G15, whereas G2 combined the highest grain yield with comparatively lower stability. Overall, G8, G9, G14, and G15 demonstrated favourable yield performance and stability and are promising candidates for further validation and recommendation in Ethiopian barley-growing environments. Genotypes G8, G9, G14, and G15 exhibited favourable combinations of grain yield and stability across the evaluated environments and are promising candidates for further validation and wider cultivation in Ethiopia, particularly across the cool sub-humid and humid Ethiopian highland barley-growing agro-ecologies represented by the test environments. These genotypes are also promising parental materials for developing broadly adapted, high-yielding, and stable food barley cultivars. Although G2 produced the highest mean grain yield, it is comparatively less stable than the most stable genotypes and is therefore particularly suited to favourable production environments where maximizing yield is the primary objective. However, its superior yield potential makes G2 a potential parent for improving grain-yield potential, particularly when combined with stable and broadly adapted genotypes. Thus, G2 may be exploited for specific adaptation to high-potential favourable environments, whereas G8, G9, G14, and G15 may be prioritized for broad adaptation across similar Ethiopian highland agro-ecologies. The identification of Holeta as an ideal testing environment will also help improve the efficiency of future national barley breeding and evaluation programs.