GENOTYPE x LOCATION x MANAGEMENT AND GENETIC VARIABILITY OF FABA BEAN (Vicia faba L.) GENOTYPES BASED ON AGRO-MORPHOLOGY TRAITS

Abstract

Faba bean is an important source of protein for human and plays an important role in improving soil fertility. However, the productivity of the crop is low due to soil acidity in the highlands of Ethiopia. This research was conducted to estimate genetic variability, trait association and genotype x environment x management interaction on yield of faba bean genotypes at soil of pH 4.66, 4.96 and 4.49 at Holetta, Watebecha Minjaro and Jeldu respectively with and without lime application in 2017. The experiment comprised 50 faba bean genotypes arranged in randomized complete block design with three replications. The analysis of variance (ANOVA) for each management at each location and combined ANOVA over locations showed the presence of significant differences among genotypes for agronomic traits except number of seeds per pod. The ANOVA from AMMI model showed that environment, genotype and genotype x environment interaction contributed 58.05, 16.08 and 14.28%, to total sum square, respectively. The highest mean grain yield of 115.1 and 113.24 g/5plants obtained from Moti and CS20DK with lime over locations, respectively. Eighteen genotypes had mean yield advantage of 0.16 to 17.49% over the recently released variety Numan. However, soil acidity caused an overall mean yield reduction of 32.34% though varied number of genotypes produced higher mean grain yield under lime and without lime application over locations. Considering all stress indices, Wolki, Dosha, Obse, Hachalu and Numan were identified as relatively tolerant genotypes to soil acidity. Computed genotypic coefficient of variations ranged from 1.08-23.05 and 0.94-23.88% and penotypic from 1.20-23.26% and 1.11-24.07%, while heritability and genetic advance as percent of the mean ranged from 24.63 -98.22% and 35.06 - 98.45% and 2.0 - 47.13% and 1.64 - 48.89% without and with lime application, respectively. The highest values for all components computed recorded for hundred seeds weight (HSW) while all lowest values except for H2 computed for days to maturity. Plant height and HSW had positive and highly significant correlations with grain yield, besides HSW exerted positive direct effect on grain yield at genotypic level suggesting that HSW could be used for indirect selection of genotypes for high grain yield. The genetic distances estimated by Euclidean distances (ED) ranged from 1.23-11.52 and 1.04-11.06 with and without lime. The 50 genotypes were grouped into 10 distinct clusters by Unweighted Pair group Method with Arithmetic Means clustering method based on ED estimated from mean of genotypes for 12 traits over locations for both lime levels. The first three principal components (PC) accounted 77.35 and 77.57% of the total variations observed among genotypes without and with lime, respectively, though single or few traits were not identified as having much contribution than others traits to each PC. Genotypes Tumsa, Cool-0034, EKLS/CSR02019- 2-4 and EH07015-7 were identified as relatively stable for yield from stability parameters of AMMI and GGE biplot models. It is therefore, concluded that soil acidity affected the production of faba bean and the presence of genetic variability among faba bean genotypes for yield, yield related traits and soil acidity stress tolerance indices suggested the higher chance of developing varieties for acid soils of central highlands of Ethiopia.