Inheritance of Resistance to Fusarium Root Rot in Three Common Bean Genotypes

Abstract

complete diallel set of F1 and F2 crosses was generated from three resistant and two susceptible parents to study nature of inheritance and gene action governing resistance to Fusarium solani f.sp phaseoli. General combining ability and specific combining ability effects for root rot score in the screenhouse were significant. High Baker’s ratio (2σ2gca/(2σ2gca + σ2sca)) = 85% and 90% in F1 and F2, respectively, indicated that additive genetic effects were predominant. Narrow-sense coefficient of genetic determination based on an entry means was 0.76 and 0.86 in F1 and F2 respectively. Segregation for F2 progenies indicated that resistance in each cross was conditioned by one to three partially dominant loci, modified by epistasis. We concluded that using the resistant parent as a donor, with backcrossing to the adapted recurrent parent and agronomic testing would be the best breeding procedure for improving resistance in the popular large-seeded bean varieties in Uganda.

Keywords

• Dry beans
• Fusarium root rot
• Gene action
• Diallel crosses
• epistasis