The morphological variation of 64 Secale cereale L. accessions was evaluated based on several traits using a lattice design with two replications over two years (2016 and 2017). The first two principal components of the entry × tester interaction biplot accounted for 76% (46% and 30% for PC1 and PC2, respectively) of the variability across both years. Six vertex genotypes for the first year and eight vertex genotypes for the second year were identified. Important traits, such as grain yield and seed number per spike, were favorable in the sector of genotype 23, and this vertex was the same in both years. For cultivar release, genotype 23, followed by 21, 29, and 32, can be considered after being tested under multi-environmental trials for adaptability. Evaluation of grain yield indicated that genotypes 20, 21, 23, 28, 29, and 32 were the best genotypes across the two years. According to the discriminative potential of traits, seed width, awn length, spike weight, and thousand-seed weight were more discriminative. The ideal entry biplot indicated that the same genotypes identified for obtaining high grain yield had the ability to evaluate traits in S. cereale, and they can be assumed as ideotypes. Given the importance of seed number per spike, seed weight per spike, and seed width on grain yield in the current study, these traits should be considered in S. cereale. The identified variations demonstrated a high degree of diversity within S. cereale, for genetic improvement programs
