GENETIC VARIABILITY AND ASSOCIATION OF YIELD AND YIELD RELATED TRAITS IN COMMON BEAN (Phaseolus vulgaris L.) ACCESSIONS IN EASTERN ETHIOPIA

Abstract

production. Therefore, the present study was conducted at Melkasa Agricultural Research Center, Meiso substation in 2018 main cropping season using 20 common bean accessions to estimate genetic variability and associations among yield and yield related traits. The experiment was laid out as randomized complete block design with three replications. Data were collected for 13 quantitative traits including plant height, number of primary branches, number of pods per plant, pod length, seeds per pod, seeds per plant, days to flowering, days to maturity, grain filling period, seed yield per ha-1, 100 seed weight, seed length and seed thickness. The statistical analysis of variance revealed highly significant differences among the accessions for all the traits studied, which could be used to improve yield and other agronomic traits of the crop through selection or hybridization. The variation observed among accessions for seed yield ranged from 1850 kg ha-1 for DAN16 to 2936 kgha-1 for SMC147 with the overall mean value of 2390. Genotypic and phenotypic coefficient of variation ranged from (2.61% and 2.95%) for days to maturity to (21.76% and 22%) for 100 seed weight. Moderate to high GCV and PCV were observed for plant height, pods per plant, seed yield ha-1 and 100 seed weight indicating selection could be effective based on these traits. Estimated heritability in broad sense(H2) and genetic advance as percent of mean (GAM) ranged from 54.28% for primary branches to 97.87% for 100 seed weight and 4.74% for days to maturity to 44.26% for 100 seed weight respectively. High H2 coupled with high GAM recorded for plant height, pods per plant, seeds per plant,100 seed weight and seed yield suggesting the higher chance of improving these traits through selection of genotypes for high mean performance. Both at genotypic and phenotypic level, seed yield ha-1 exhibited positive significant correlation with number of pods per plant, plant height and seeds per plant. Higher positive direct effect on seed yield also exerted by these traits both at genotypic and phenotypic path, which indicates, they could be major contributors of seed yield. Days to maturity exhibited significant negative correlation with seed yield both at genotypic and phenotypic level, also exerted negative direct effect on seed yield both at genotypic and phenotypic path suggesting selection for earliness would result in high seed yield. Cluster analysis grouped 20 accessions into five distinct clusters. The mean values and inter cluster distances showed highly significant difference among all clusters with the range of distance (D2 =27.3) between cluster I and III to (D2 =572.5) between cluster III and V. This confirms that, accessions among clusters were divergent from each other. Principal component analysis (PCA) revealed that, the first three components accounted for 83.06% of the total variation whereas (PC1) alone accounted for maximum variability of 47.60%. In conclusion, the result of this study demonstrated the presence of sufficient genetic variability among the common bean accessions studied, which could be used to improve the yield and other agronomic traits of the crop through selection or hybridization