Path Analysis of Yield Components in Faba bean (Vicia faba L.) Across Supplementary Irrigation Regimes

Background: Climate change threatens Mediterranean legume systems, with faba bean (Vicia faba L.) particularly vulnerable to water stress during key growth stages. While supplemental irrigation (SI) offers potential benefits, yield-trait relationships under different water regimes remain unclear. Path analysis, unlike simple correlations, separates direct and indirect effects, aiding in identifying traits that most influence yield. Methods: A two-year (2020-2022) split-plot field trial at INRA-Douyet, Morocco, tested six faba bean genotypes under three irrigation regimes: rainfed (IR1), SI of 53 mm (IR2) and SI of 106 mm (IR3) at flowering. Traits measured included stems (NTS), pods (NP), seeds (NS), 100-seed weight (WSS) and plant yield (PY). Data were analyzed via combined ANOVA, Pearson correlations and path analysis. Result: ANOVA showed significant effects of environment, genotype and their interaction. Yield was most sensitive to the environment, while WSS had the highest heritability. Path analysis revealed that WSS and NP had negative direct effects yet positive total correlations due to strong indirect influences, mainly through NP and NS. NS and NTS were generally unfavorable. The findings provide valuable insights for developing water-specific breeding strategies and optimizing agronomic practices in semi-arid Mediterranean environments.