Genotype × environment interaction, yield stability, and adaptability of sugar beet genotypes revealed by AMMI and GGE Biplot Analyses

This study evaluated twelve sugar beet genotypes across five contrasting environments to identify high-yielding and relatively stable genotypes for root yield (RY) and sugar yield (SY). AMMI analysis revealed significant (p ≤ 0.001) effects of environment, genotype, and genotype × environment interaction (GEI) for both traits. GEI accounted for the largest proportion of variation in RY (32.7%), whereas environment contributed the largest proportion of variation in SY (29.4%). The first two interaction principal component axes explained 77.8% and 76.7% of the GEI variation for RY and SY, respectively. Root and sugar yields ranged from 56.7–79.9 and 9.3–13.5 t ha⁻¹, respectively. The stability indices consistently ranked G2 (Arta) among the genotypes with the highest yield and favorable stability, followed by G10 (Shokofa) and G12 (Tara). AMMI and GGE biplot analyses showed substantial agreement, identifying G2, G3, and G9 as genotypes with favorable yield performance and relatively broad adaptation across the tested environments, while G3 and G9 also showed evidence of specific adaptation. One mega-environment was identified for RY and two for SY. E4 (Mahidasht) showed high representativeness, whereas E3 (Zarghan) provided strong discrimination among genotypes. Overall, G2 (Arta) showed a favorable combination of high productivity and stability across the environments evaluated in this study. Further multi-year and multi-environment testing is needed to confirm the consistency of these responses and their applicability to broader production environments.