Estimates of Gene Effects of Yield and Mosaic Resistance in Yard Long bean [Vigna unguiculata subsp. sesquipedalis (L.) Verdcourt]

The incidence of viral diseases in yard long bean is becoming a severe threat in tropical regions, limiting the yield considerably. Host plant resistance is the most efficient and ecologically friendly method of managing viral infections. Resistance sources of major viruses viz; CABMV and BICMV causing mosaic disease have been identified in many cowpea breeding programmes. However, little is known about the gene action imparting virus resistance. Understanding the genetics of host resistance and genetic variability, can aid in developing breeding programs that will use genetic resistance to manage viral diseases reliably and efficiently. The current study used generation mean analysis to examine the gene action and inheritance of yield and mosaic resistance.

The six populations (P₁, P₂, F₁, F₂, BC₁ and BC₂) of three exceptional crosses, Githika × Manjari, KAU Deepika × Manjari and KAU Mithra × Manjari, which displayed heterosis and mosaic resistance in previous field trials were assessed in a replicated field experiment in Summer 2023. All the generations were screened for mosaic resistance in the field and the inheritance and gene action of mosaic resistance and yield parameters were investigated using the generation mean analysis.

Epistasis interactions were discovered in the majority of the characters in the different crosses. The scaling tests for mosaic resistance were not statistically significant, suggesting that the additive-dominance model was sufficient for Cross I and II. However, dominance×dominance epistasis was evident in Cross III. For plant yield, Crosses II and III showed the prevalence of dominant gene action, but cross I revealed dominance×dominance (l) action. The results suggested the utilization of hybridization and selection, heterosis breeding and recurrent selection for improving different traits in yard long bean.