Alfalfa (Medicago sativa L.) is used to support livestock. A stability study was carried out over three years. The stability indices for yield and main quality characteristics such as plant height, number of nodes, the yield of green mass and dry matter, crude protein and fiber (%), and ash (%), were examined. Statistical analysis revealed significant differences that indicated the presence of high genotype–year interactions. Heritability was higher in the case of qualitative traits than quantitative traits. The most intriguing correlation was between green mass yield and crude protein content because positive correlations may lead to indirect and simultaneous selection. According to the statistical biplot models AMMI and GGE, the best genotypes for almost all traits to use, regardless of the environment and cultivation type, were the G8 (Population 2) followed by cultivar G3 (Yliki). Despite the high index values shown by the parameter number of nodes, the latter and yield showed low heritability.
