Selection of High-Yielding Soybean (Glycine max L.) Lines Based on Seed Yield and Yield Components

Soybean (Glycine max L.) yield is a complex trait determined by genotype, yield components, and environment. This study hypothesized that genotype × environment interactions influence yield stability and that yield components show differential sensitivity to interannual climatic variation in Mediterranean environments. The objectives were to (i) evaluate 31 soybean genotypes across two seasons, (ii) identify stable, high-yielding genotypes, and (iii) determine the contribution of yield components to yield variation. Field experiments were conducted in Antalya, Türkiye, during 2020 and 2021. Plant height, first pod height, pods per plant, 1000-seed weight, and seed yield were recorded. Significant differences were found among genotypes, years, and their interactions for all traits (p < 0.001). Plant height and pod number were higher in 2020 (mean: 102.5 cm and 96.2 pods plant−1), indicating favorable conditions for vegetative growth. In contrast, 1000-seed weight was markedly higher in 2021 (mean: 181.7 g vs. 81.3 g in 2020), suggesting enhanced seed filling under reduced sink demand. Seed yield ranged from 231 to 710 kg da−1, with ACSOY119 producing the highest mean yield (592 kg da−1), followed by ACSOY50 (562 kg da−1) and ACSOY83 (548 kg da−1). Pod number was the most environmentally sensitive component (r = 0.74 with yield), while increased seed weight partially compensated for yield losses. Yield was strongly correlated with pod number (r = 0.74, p < 0.01) and moderately with first pod height (r = 0.59, p < 0.01) and 1000-seed weight (r = 0.34, p < 0.05). Based on mean yield, ACSOY119 and ACSOY50 were identified as the highest-yielding and most stable genotypes. These findings emphasize multi-year evaluations and integrated component analysis for identifying high-yielding soybean genotypes with adaptability under Mediterranean conditions. Genotypes with consistent performance, such as ACSOY119 and ACSOY50, are recommended for breeding programs.