Detection of High-Yielding and Orobanche crenata-Tolerant Faba Bean (vicia faba L.) Mutant Lines by  Grain Yield, Infestation Severity and Tolerance indices

In Egypt, both the cultivation area and productivity of faba bean have declined significantly, mainly due to infestation by the parasitic broomrape ( Orobanche crenata Forssk ). Developing high-yielding, O.crenata -tolerant varieties represents a logical solution to this problem. This study aimed to evaluate the effectiveness of mutation breeding for enhancing both productivity and resistance to Orobanche across four generations (M1-M4) during the 2021-2024 growing seasons. Grain yield components, infestation severity, genetic parameters, and drought indices were used. Genotypes (mutant lines and their parents) were arranged in randomized complete blocks design with three replications. Significant differences (p ≤ 0.05) were observed among genotypes across generations and a wide genetic variability. Several mutant lines exhibiting superior productivity and reduced infestation severity compared with their parents. High heritability associated with high genetic advance was recorded for all studied traits, except plant height, indicating the predominance of additive gene action and high efficiency of early–generation selection. Principal components analysis (PCA) showed that the first two components (PC1 and PC2) jointly explained 83.8% of the total variance, with three mutant lines (3, 8, and 10) exhibited a wide genetic divergence compared to their parents. Grain yield showed a significant and positive correlation with all studied traits except plant height. Selection parameter indices detected superior mutant lines under infestation conditions. Overall, these findings illustrated that mutagenesis was an effective tool for improving yield and enhancing tolerance to Orobanche . The selected mutant lines represent valuable genetic resources for faba bean breeding programs aiming for O.crenta -affected environments.