Genotypic and phenotypic variability, heritability, and expected genetic advance for yield and yield components in faba bean (Vicia faba L.) varieties grown in West Shewa Zone, Oromia National Regional State, Ethiopia

Abstract

Genotypic and phenotypic variability, heritability, and expected genetic advance were studied in fifteen released faba bean (Vicia faba L.) varieties grown at Ambo and Holeta during the main cropping season under phosphorus-fertilized and non-fertilized conditions. The experiment was arranged in a randomized complete block design with three replications. Data were recorded for days to 50% flowering, days to 90% maturity, grain filling period, plant height, number of pods per plant, number of seeds per pod, thousand seed weight, biological yield, grain yield, and harvest index. Combined analysis of variance revealed highly significant (P≤0.01) differences among genotypes, locations, phosphorus levels, and most interaction effects, indicating substantial genetic variability and environmental influence. High genotypic and phenotypic coefficients of variation were observed for thousand seed weight and number of pods per plant, whereas days to flowering and maturity showed low variability. Broad-sense heritability estimates ranged from low to high across traits. Thousand seed weight exhibited consistently high heritability under both phosphorus conditions, coupled with high genetic advance as percent of mean, suggesting predominance of additive gene action. Moderate heritability with moderate genetic advance was recorded for plant height and number of pods per plant. Grain yield showed moderate variability but relatively low heritability under stress conditions. The results indicate that thousand seed weight and number of pods per plant are reliable selection criteria for improving grain yield in faba bean under varying phosphorus environments.