Abstract

Fifty faba bean is a multipurpose crop used as human food, animal feed, soil fertility restoration and income source for farmers and the country at large. However, the productivity of this crop is low as constrained by biotic and abiotic factors in which soil acidity takes the lions share in the highlands of Ethiopia. In order to estimate genetic variability on grain yield and related traits under soil acidity stress, 50 faba bean genotypes were evaluated in randomized complete block design with three replications at three locations, Holetta, Watebecha Minjaro and Jeldu with and without lime application in 2017. The combined analysis of variance (ANOVA) over locations for each lime level showed the presence of significant differences among genotypes for all agronomic traits except for the number of seeds per pod. The overall mean grain yields of tested faba bean genotypes were 62.93 (without) and 93.12 g/5plants (with lime)  leading a yield reductions of 32.34% were encountered due to soil acidity stress through a varied number of genotypes over locations.  Computed genotypic coefficient of variations (GCV) ranged from 1.08-23.05 and 0.94-23.88% and phenotypic (PCV) from 1.20-23.26 and 1.11-24.07%, while heritability (H2) ranged from 24.63-98.22 and 35.06-98.45% and genetic advance as percent of the mean (GAM) from 2.0-47.13 and 1.64-48.89% without and with the lime application, respectively. The highest values for all components were recorded for 100 seeds weight (HSW), whereas the lowest values except for H2 were computed for days to maturity. Under both lime levels medium to high estimates of GCV, PCV, H2 and GAM were computed for HSW and the number of pod per plant and selection based on phenotypic expression of genotypes is possible to improve these traits. Selection based on mean would be successful in improving traits that have high H2. Furthermore, selection based on phenotypic performance of genotypes would be effective to improve traits that have high GAM coupled with high H2 estimates. Performances of variability components for different traits with and without lime application were performed differently and higher values were recorded with lime as optimum environments allow for better genetic expression.  Hence soil acidity affects the production and variability components of faba bean.

Key words: Heritability, soil acidity, variability components, with lime, without lime.