GENETIC VARIABILITY AND ASSOCIATION OF YIELD, NUTRITIONAL QUALITY AND YIELD RELATED TRAITS IN LARGE SEEDED COMMON BEAN (Phaseolus vulgarisL.)VARIETIES AT HARAMAYA, EASTERN ETHIOPIA

Abstract

Twenty large seeded bean genotypes were tested in randomized complete block design at Haramaya University field research station with the objectives of estimating the magnitude of genetic variability, heritability and genetic advance, and associations among characters. Analysis of variance revealed statistically significant differences among the twenty genotypes for most of characters studied, indicating the existence of variability and the potential for selection and improvement of the characters. High phenotypic coefficient of variation (PVC) was recorded only for seed yield while it was medium for number of primary branches per plant, plant height, number of seeds per pod, number of pods per plant, 100 seed weight, calcium, magnesium, ash and crude protein content. Similarly, medium genotypic coefficient of variation (GVC) was observed for plant height, 100 seed weight, number of pods per plant and grain yield. High heritability coupled with high expected genetic advance as percent of the mean were estimated for plant height and 1000-seed weight; moderate heritability value coupled with relatively high genetic advance were observed for seed yield and number of pods per plant. This indicates that these characters could be improved through selection. Grain yield had high and positive phenotypic associations with plant height, number of pod per plants and 100 seed weight. At phenotypic level, plant height (rph= 0.441), number of pods per plant (rph= 0.379), and hundred seed weight (rph= 0.373) had high and positive genotypic associations with grain yield. Similarly, grain yield per plant showed positive genotypic correlation with plant height (rg = 0.511), 100-seed weight (rg = 0.400), number of pods per plant (rg = 0.431), ash content (rg =0.243), and crude protein content (rg = 0.225, while it had positive and significant (p<0.05) correlation with plant height (rg = 0.511).On the other hand, grain yield per plant showed negative genotypic association with number of seeds per pod (rg45r5e= -0.298), stand at emergence (rg = -0.407), stand at harvest (rg = -0.334), and number of seeds per pod (rg = -0.141) at genotypic level. It also had low and negative genotypic associations with magnesium content, grain filling period and pod length. Cluster analysis revealed that the 20large seeded genotypes were grouped into six clusters. Distances between these clusters are significantly different for all the cluster combinations. This indicates that there is an opportunity to bring about improvement through hybridization of genotypes from different clusters and subsequent selection from the segregating generations. Principal component analysis indicated that six Principal components explained about about 83.8 % of the total variation.The study generally implied the presence of significant genetic variability among the tested genotypeS