Abstract
The bean fly (Ophiomyia spp.) is the most destructive insect pest of common bean (Phaseolus vulgaris L.) causing significant yield losses. The objectives of this study were to determine the combining ability effects and deduce gene action controlling the inheritance of bean fly resistance and agronomic traits among common bean genotypes, and to select superior genotypes for breeding. Eight selected complementary parents were crossed using a half-diallel mating design to derive new families. Parents and 28 F2 families were evaluated in two locations using were evaluated in two locations using a 6 × 6 lattice square design with two replications. Bean fly resistance parameters such as bean fly damage severity (BDS), pupae count (PC) and plant mortality rate (PMR) and agronomic traits such as days to 50% flowering (DTF), days to maturity (DTM), number of pods per plant (NPP), number of seed per pod and grain yield (GYD) were collected. Results revealed significant genotype × location interaction effects on resistance parameters and agronomic traits allowing selection of unique families adapted to different production environments. There were negative correlations between grain yield (GYD) and bean fly damage severity (p < 0.01, r = − 0.60), pupa count (p < 0.01, r = − 0.34) and plant mortality rate (p < 0.01, r = − 0.53), implying that direct selection for bean fly resistant genotypes would improve GYD. Genotypes A429 and A55 exhibited negative general combining ability (GCA) effects for bean fly damage parameters and positive GCA effects for GYD. Good combiners for number of pods per plant (NPP) and GYD were the genotypes A55, MW365 and Sinoni, while MW466 exhibited desirable GCA effects for days to 50% flowering (DTF) and days to 90% maturity (DTM). These parental lines with desirable GCA effects for bean fly resistance and agronomic traits were selected for future breeding. Families such as Sinoni/A55, Kabanima/A55 and MW365/Kabanima showed desirable BDS, PC and PMR (SCA) effects for bean fly resistance and grain yield. Families such as Kabanima/A55, Sinoni/A55 and NUA45/MW365 exhibited desirable and significant SCA effects for traits such as NPP, number of seeds per pod (NSP) and GYD. Families with desirable SCA effects will be utilised in selecting desirable recombinant inbred lines and breeding populations for improving bean fly resistance and agronomic performance. The Baker’s ratios indicated that additive gene effects were more important for bean fly resistance and GYD. Recurrent selection would be the best strategy for improving bean fly resistance and grain yield using this germplasm.
Published Version
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